Determining blood pressure in infants: use of the flush technique

The flush technique that recently has come into use is probably the most satisfactory method available for measuring blood pressures in infants and is of great aid in diagnosis of diseases associated with hypertension or hypotension. The method is practical and highly accurate. Readings obtained by this technique are not influenced by the width of the cuff, are usually higher at the wrist than at the ankle, and approximate the mean rather than the systolic blood pressure.     

Mesocosm experiments on the interaction of sediment influence, fish predation and aquatic plants with the structure of phytoplankton and zooplankton communities

1. Little Mere, U.K., received large quantities of sewage effluent until 1991, when the effluent was diverted. Experiments, carried out in mesocosms in 1992 and 1993, were designed to predict the effects of: (i) reduced external nutrient loading; (ii) reduced internal loading from the sediment; and (iii) recolonization by fish of the better aerated water. Treatments included isolation of the water from the underlying sediment or exposure to the sediment (which lacked plants in 1992, but was covered by Potamogeton berchtoldii in 1993) crossed with different population densities of Rutilus rutilus in 1992 and of Perca fluviatilis in 1993.
2. Exposure to sediment (as opposed to isolation from it) resulted in no net change in the biovolumes of most major algal groups, but this masked major complementary effects on individual species. The experiments showed a decreasing influence of the sediment, between 1992 and 1993, in determining water chemistry, and an increasing pH between years but no increase in cyanophyte dominance. This had been anticipated because a lake upstream provides abundant inocula, and conditions in Little Mere after diversion of effluent were expected to favour cyanophytes.
3. Roach and perch additions to the mesocosms resulted in reductions in Daphnia populations but increases in numbers of small Cladocera and copepods. Plant-associated Cladocera were unaffected by fish. The presence of submerged plants to some extent reduced fish predation effects on Daphnia hyalina .
4. The experimental results in general accurately predicted subsequent events in the open lake.     

Changes in a deep lake following sewage diversion – a challenge to the orthodoxy of external phosphorus control as a restoration strategy?

1. The restoration of deep lakes has traditionally focused on reducing the external phosphorus loading. 2. Following the diversion of sewage effluent, that led to marked reductions in nutrient concentrations in its main inflow, Rostherne Mere has shown no reduction in phosphorus or chlorophyll a concentrations. A shallow lake upstream (Little Mere), however, has shown a marked response to effluent diversion. 3. Nutrient budgets for Rostherne Mere reveal that sewage effluent was by far the most significant external source of total phosphorus and that diffuse drainage from the catchment was the most significant external source of dissolved inorganic nitrogen. Phosphorus loads from groundwater and a bird roost were insignificant. Internal sources of phosphorus were, however, considerable and were largely responsible for the observed delay in recovery. 4. Phosphorus limitation of phytoplankton biomass may never be attainable because of substantial internal and diffuse sources of phosphorus, combined with a long retention time. Nitrogen is likely to be more important in limiting phytoplankton biomass. Control of diffuse nitrogen sources may therefore be more effective in the restoration of the deeper lakes of this region.     

Statural growth in known-age African elephants (Loxodonta africana)

The shoulder heights of 224 females and 170 males, and hindfoot length of 236 female and 217 male known-age African elephants ( Loxodonta africana ) were measured, and growth curves constructed for each measure of size. A linear relationship between foot length and shoulder height was confirmed in simultaneous measures of 97 males and 110 females. Growth curves demonstrated the typical sexual dimorphism in both foot length and shoulder height, with males growing more rapidly than females from birth onwards. The size dimorphism in foot length and shoulder height becomes marked by the age of 10 years, with males on average being 60–70 cm taller than females at 65 years. This size dimorphism is produced through faster growth which continues for longer than does that of females. The variance in growth rates is slightly greater for females than for males. It is proposed that female growth after puberty is affected by a trade-off between growth and reproduction, while males who deviate markedly from typical patterns of growth may be subject either to mortality or energetic constraints limiting their potential variance.     

A covalently bound photoisomerizable agonist. Comparison with reversibly bound agonists at electrophorus electroplaques

After disulphide bonds are reduced with dithiothreitol, trans-3- (α-bromomethyl)-3’-[α- (trimethylammonium)methyl]azobenzene (trans-QBr) alkylates a sulfhydryl group on receptors. The membrane conductance induced by this “tethered agonist” shares many properties with that induced by reversible agonists. Equilibrium conductance increases as the membrane potential is made more negative; the voltage sensitivity resembles that seen with 50 [mu]M carbachol. Voltage- jump relaxations follow an exponential time-course; the rate constants are about twice as large as those seen with 50 μM carbachol and have the same voltage and temperature sensitivity. With reversible agonists, the rate of channel opening increases with the frequency of agonist-receptor collisions: with tethered trans-Qbr, this rate depends only on intramolecular events. In comparison to the conductance induced by reversible agonists, the QBr-induced conductance is at least 10-fold less sensitive to competitive blockade by tubocurarine and roughly as sensitive to “open-channel blockade” bu QX-222. Light-flash experiments with tethered QBr resemble those with the reversible photoisomerizable agonist, 3,3’,bis-[α-(trimethylammonium)methyl]azobenzene (Bis-Q): the conductance is increased by cis {arrow} trans photoisomerizations and decreased by trans {arrow} cis photoisomerizations. As with Bis-Q, ligh-flash relaxations have the same rate constant as voltage-jump relaxations. Receptors with tethered trans isomer. By comparing the agonist-induced conductance with the cis/tans ratio, we conclude that each channel’s activation is determined by the configuration of a single tethered QBr molecule. The QBr-induced conductance shows slow decreases (time constant, several hundred milliseconds), which can be partially reversed by flashes. The similarities suggest that the same rate-limiting step governs the opening and closing of channels for both reversible and tethered agonists. Therefore, this step is probably not the initial encounter between agonist and receptor molecules.     

Control of potato cyst-nematodes, Heterodera rostochiensis and H. pallida, in sandy, peaty and silt loam soils by oximecarbamate and organophosphate nematicides

Small amounts (5.6 or n-2 kg a.i./ha) of aldicarb or oxamyl, incorporated in the soil before potatoes were planted in spring, controlled potato cyst-nematodes (Heterodera rostochiensis and H. pallida) on susceptible cultivars equally well in sandy, peaty and silt loam soils. In soils treated with either nematicide, nematode numbers increased little or decreased; in untreated soils nematode numbers increased greatly. In contrast organophosphate nematicides, similarly applied, fenamiphos (proposed BSI common name for O-ethyl-O-(3-methyl-4-methylthiophenyI)-isopropylamido-phosphate), ethoprophos (proposed BSI common name for (O-ethyl S, 5-dipropyl phos-phorodithioate), CGA 12223 (O, O-diethyl O-[i-isopropyl-5-chloro-i,2,4-triazoIyl-(3)] phosphorothioate) and Dowco 275 (O, O-diethyl O-(6-fluoro-2 pyridyl) phosphorothioate), were ineffective at one or more of the experimental sites. Potato yields were greatly increased by oximecarbamate or organophosphate nematicides only in soils heavily infested with the nematodes.