Herpes simplex encephalitis: treatment with surgical decompression and cytosine arabinoside

Herpes simplex encephalitis in a 21-year-old man presented as a flu-like illness, followed by inappropriate behaviour, drowsiness and focal neurologic signs. Investigations indicated a lesion in the right temporal lobe. The diagnosis was confirmed by isolation of the virus from a cerebral biopsy. Pronounced clinical improvement was noted when cytosine arabinoside therapy was started in the postoperative period. This report supports the observation by some authors that cytosine arabinoside may be of value in the treatment of herpes simplex encephalitis.     

Age-dependent alterations of DNA synthesis. Terminal deoxynucleotidyl transferase and DNA polymerase activities in bone marrow subpopulations from mice

The decrease of functional capacity of cellular immunity during ageing seems to be due to cellular changes of stem cells, particularly in the growth properties and the cell density in T-cell subsets. We approached this problem at the molecular biological level by quantifying the key enzymes necessary for DNA synthesis in bone marrow cells from mice: deoxynucleotidyl transferase (TdT) and DNA polymerase alpha. The bone marrow cells were fractionated on a discontinuous bovine serum albumin density gradient and the extractable enzyme activities (expressed per 10(8) nucleated cells in the respective fraction) were determined. TdT activity was found to decrease markedly during ageing. Mature animals contain only 34% and senescent animals only 13% of the activity observed in immature mice. From the density distribution analysis it was found that a shift of TdT-containing cells to the lower density occurs. The specific DNA polymerase alpha activity also decreases in bone marrow cells with age. While the overall activity amounts in immature cells to 78 enzyme units/10(8) cells, it decreases in mature cells to 57 units/10(8) cells, and in cells from senescent animals to 36 units/10(8) cells. Density distribution analysis of the cells shows that the highest activity is observed in the low-density fraction. From these experimental data we conclude that in the fractions containing precursor T-cells, a reduced number of proliferating cells is present.     

Studies of androgen production and binding in 13 male pseudohermaphrodites and 13 males with micropenis

We studied androgen production by morphologic and biochemical criteria plus androgen binding by skin fibroblasts in 13 male pseudohermaphrodites and 13 males with micropenis, none of whom had evidence of androgen insensitivity. Seventeen of the 26 patients had evidence of deficient androgen production, suggesting this as the cause of their incomplete virilization in utero. Fibroblasts from all 26 patients demonstrated normal androgen binding and affinity of the steroid for the receptor. Although these results exclude a deficiency of androgen binding in these individuals, other end organ defects are possible. Guidelines for diagnosis and management of such patients are presented.     

Long-term effect of N and P fertilization on a pearlmillet—wheat cropping system

Results of an eight-year study on long-term effect of N and P application in a pearlmillet—wheat sequence is reported. There was little or no residual effect of N on any of the crops. Pearlmillet needed 70 to 80 kg N and wheat required more than 120 kg N ha^–1 every year for optimum grain yield. There was no soluble P build up in soil by continuous P application. Fertilizing wheat every year with 19 kg P and pearlmillet with 13 kg P ha^–1 is considered optimum.Continuous cropping leading to a production of 216 tonnes of biomass ha^–1 in 17 crops and use of high analysis N (urea) and P (triple superphosphate) fertilizers had not impaired the K and Zn supplying capacity of these alluvial soils containing illite clay minerals. The experiment is being continued to monitor the productivity of the soil as affected by continuous cropping.     

The Escherichia coli FOF1 gammaM23K uncoupling mutant has a higher K0.5 for Pi. Transition state analysis of this mutant and others reveals that synthesis and hydrolysis utilize the same kinetic pathway

The Escherichia coli FOF1 ATP synthase uncoupling mutation, gammaM23K, was found to increase the energy of interaction between gamma and beta subunits, prevent the proper utilization of binding energy to drive catalysis, and block the enzyme in a Pi release mode. In this paper, the effects of this mutation on substrate binding in cooperative ATP synthesis are assessed. Activation of ATP synthesis by ADP and Pi was determined for the gammaM23K FOF1. The K0.5 for ADP was not affected, but K0.5 for Pi was approximately 7-fold higher even though the apparent Vmax was close to the wild-type level. Wild-type enzyme had a turnover number of 82 s-1 at pH 7.5 and 30 degrees C. During oxidative phosphorylation, the apparent dissociation constant (KI) for ATP was not affected and was 5-6 mM for both wild-type and gammaM23K enzymes. Thus, the apparent binding affinity for ATP in the presence of DeltamuH+ was lowered by 7 orders of magnitude from the affinity measured at the high-affinity catalytic site. Arrhenius analysis of ATP synthesis for the gammaM23K FOF1 revealed that, like those of ATP hydrolysis, the transition state DeltaH was much more positive and TDeltaS was much less negative, adding up to little change in DeltaG. These results suggested that ATP synthesis is inefficient because of an extra bond between gamma and beta subunits which must be broken to achieve the transition state. Analysis of the transition state structures using isokinetic plots demonstrate that ATP hydrolysis and synthesis utilize the same kinetic pathway. Incorporating this information into a model for rotational catalysis suggests that at saturating substrate concentrations, the rate-limiting step for hydrolysis and synthesis is the rotational power stroke where each of the beta subunits changes conformation and affinity for nucleotide.     

Levels of genetic polymorphism: marker loci versus quantitative traits

Species are the units used to measure ecological diversity and alleles are the units of genetic diversity. Genetic variation within and among species has been documented most extensively using allozyme electrophoresis. This reveals wide differences in genetic variability within, and genetic distances among, species, demonstrating that species are not equivalent units of diversity. The extent to which the pattern observed for allozymes can be used to infer patterns of genetic variation in quantitative traits depends on the forces generating and maintaining variability. Allozyme variation is probably not strictly neutral but, nevertheless, heterozygosity is expected to be influenced by population size and genetic distance will be affected by time since divergence. The same is true for quantitative traits influenced by many genes and under weak stabilizing selection. However, the limited data available suggest that allozyme variability is a poor predictor of genetic variation in quantitative traits within populations. It is a better predictor of general phenotypic divergence and of postzygotic isolation between populations or species, but is only weakly correlated with prezygotic isolation. Studies of grasshopper and planthopper mating signal variation and assortative mating illustrate how these characters evolve independently of general genetic and morphological variation. The role of such traits in prezygotic isolation, and hence speciation, means that they will contribute significantly to the diversity of levels of genetic variation within and among species.     

Effect of Prandtl number on the average exit temperature of coolant in a heat‐generating vertical parallel plate channel: A conjugate analysis

A coupled conduction–convection heat transfer analysis is carried out for a two‐dimensional rectangular, vertical parallel plate channel producing volumetric energy (uniform and nonuniform), subjected to laminar forced‐convection incompressible fluid flow under steady‐state conditions. The equations governing the thermal and flow field are solved by using finite difference method, and the resulting algebraic equations are solved by using the tridiagonal matrix algorithm method. Four coolants with their Prandtl numbers (Pr), namely, liquid sodium (Pr = 0.005), sodium‐potassium (Pr = 0.00753), lead (Pr = 0.02252), and helium (Pr = 0.666) are used for the present conjugate analysis. Effects of different thermal and fluid flow parameters such as Reynolds number (Re_H) ranging from 500 to 1500, conduction–convection parameter (N_cc), and total heat generation (Q_t) on average exit temperature (θ_ae) of coolants are studied. From the obtained results, it is found that the θ_ae of coolant strongly depends on Pr, Re_H, N_cc, and Q_t when the aspect ratio (A_r) is kept constant. It is also found that with a nonuniform rate of heat generation, the coolant θ_ae is high compared to uniform heat generation rate, whereas with increasing N_cc, the θ_ae decreases, and with increasing Q_t, the θ_ae increases irrespective of coolants.