Predicting external sulphur requirement of alfalfa from sulphate sorption isotherm of Tanzanian soils

For Tanzanian soils dominant in hydrous oxides of iron and amorphous ferri-alumino silicate, a 48-hour (hr) mixing period with the sulphate (SO₄) solution was adequate for a near-equilibrium condition. Although differing in their SO₄ sorption capacity, all the soils sorbed SO₄ at or beyond 1µg ml^–1 sulphur (S) concentration in the supernatant. Hydroxyl (OH) ions were displaced during SO₄ sorption as indicated by a significant positive correlation between the amount of sorbed SO₄ and the difference in pH values determined in 0.1N K₂ SO₄ and 0.1N KCl, i.e. the dpH values.In a greenhouse experiment, alfalfa was grown on eight soils at six adjusted S concentrations. Sulphur deficiency symptoms appeared in the control pots of those soils which were low in native sorbed SO₄, SO₄ sorption capacity and initial soil solution S concentration. Sulphur fertilization increased dry matter (DM) yield as well as response to applied S. The external S concentration, i.e. adjusted S concentration required for 95% of the maximum DM yield, ranged from 0.8 to 8.2µg S ml^–1 with values less than 2.0 on most of the soils. The external S concentration decreased hyperbolically as the SO₄ sorption capacity of the soils increased. The total amount of fertilizer S required to obtain the external S concentration in solution, and at the same time satisfy the SO₄ sorption capacity of the soil at the external S concentration (determined from the sorption isotherm) was defined as the external S requirement for the specified yield level of alfalfa. The external S requirement for 95% of the maximum yield of alfalfa varied from soil to soil due to differences in their capacity and intensity for S nutrition.Part of a thesis by the senior author for the MSc (Agric) degree of the University of Dar es Salaam     

Effect of a high-beef diet on the fecal bacterial flora of humans

Ten human volunteers completed a 4-month diet series consisting of 1 month each of a control diet, a meatless diet, a high-beef diet, and the same control diet. Fat and fiber contents were essentially the same in all four diets, but protein content was doubled during the high-beef diet. During the 4th week on each diet, three stool specimens collected from each volunteer were analyzed for chemical composition and content of facultative, aerobic, and anaerobic bacteria. The bacteriological data are presented in this paper. High beef protein consumption had little effect on the composition of the intestinal flora. There were no significant differences in total counts of facultative and aerobic or anaerobic organisms in the feces when volunteers were on meatless or high-beef diets. At the species level, when counts during the two control diets were comparable, in only three instances did the change from the meatless to a high-beef diet significantly influence the bacterial numbers. The ratio of mean counts of anaerobic to facultative and aerobic organisms was approximately 15:1 during the meatless diet and 34:1 during the high-meat diet. The data indicate that animal protein consumption has little effect on the fecal bacterial profile in humans.     

A cannabinoid with cardiovascular activity but no overt behavioral effects

Abnormal-delta8-tetrahydrocannabinol (ABN-delta8-THC) failed to elicit central nervous system and cardiovascular effects in laboratory animals. Abnormal-cannabidiol (ABN-CBD) was also devoid of overt behavioral effects but produced marked hypotension with only slight bradycardia in anesthesized dogs.     

Temperature-sensitive mutants of influenza A virus. XIV. Production and evaluation of influenza A/Georgia/74-ts-1[E] recombinant viruses in human adults

The two temperature-sensitive (ts) lesions present in influenza A/Hong Kong/68-ts-1[E] (H3N2 68) virus were transferred via genetic reassortment to influenza A/Georgia/74 (H3N2 74) wild-type virus. A recombinant clone possessing both ts lesions and the shutoff temperature of 38 C of the Hong Kong/68 ts donor and the two surface antigens of the Georgia/74 wild-type virus was administered to 32 seronegative adult volunteers. Thirty-one volunteers were infected, of whom only five experienced mild afebrile upper respiratory tract illness. The wild-type recipient virus was a cloned population that induced illness in five of six infected volunteers. Therfore, the attenuation exhibited by the Georgia/74-ts-1[E] virus could reasonably be assumed to be due to the acquisition of the two ts-1[E] lesions by the Georgia/74 wild-type virus. The serum and nasal wash antibody responses of the ts-1[E] vaccinees were equivalent to those of the volunteers who received wild-type virus. The two ts lesions present in the Hong Kong/68-ts-1[E] virus have now been transferred three times to a wild-type virus bearing a new hemagglutinin, and in each instance the new ts recombination exhibited a similar, satisfactory level of attenuation and antigenicity for adults. It seems likely that the transfer of the ts-1[E] lesions to any new influenza virus will regularly result in attenuation of a recombinat virus possessing the new surface antigens.     

Present prognosis in neonatal meningitis

A retrospective study of neonatal meningitis for a period of 6 years (1970 to 1975) is described. It was found that though the survival rate had increased since the introduction of the aminoglycosides, it was at the expense of major neurological sequelae in the survivors. It is suggested that breast feeding of all infants in the first few days of life will reduce the incidence of neonatatl meningitis. It is recommended that pooled human breast milk should not be heat-sterilized as this destroys anti-Escherichia coli immunoglobulin A.     

Prevalence of wheeze and asthma and relation to atopy in urban and rural Ethiopia

BACKGROUND: Asthma and allergy in developing countries may be associated with adoption of an urbanised "western" lifestyle. We compared the rates of asthma symptoms and atopy in urban populations in Jimma, southwest Ethiopia, at an early stage of economic development with those among the population of remote, rural, subsistence areas, and assessed the potential role of environmental aetiological factors leading to the differences. METHODS: Information on wheeze of 12 months' duration, diagnosed asthma, and cough for 3 months of the year was gathered by questionnaire in random household samples of 9844 people from urban Jimma and of 3032 from rural areas. Atopy was defined by allergen skin-test response to Dermatophagoides pteronyssinus and mixed threshings measured in a one-in-four subsample of those aged 5 years and older from both groups. FINDINGS: All respiratory symptoms were rare in children and were significantly less common overall in the rural than in urban group (wheeze odds ratio 0.31 [95% CI 0.22-0.43], p < 0.0001). Asthma was reported by 351 (3.6%) of the urban group, with a median reported duration of 8.5 years (IQR 4-17 years) that was unrelated to age. Atopy was a strong risk factor for asthma in urban Jimma. In the rural areas, skin sensitivity to mixed threshings was only slightly less common than in urban Jimma (0.67 [0.40-1.12], p = 0.13), whereas sensitivity to D pteronyssinus was significantly more common (3.24 [2.40-4.38], p < 0.0001), and since none of the 119 atopic individuals in the rural area reported wheeze or asthma, atopy was possibly associated with a reduction in the risk of disease among this group. Wheeze or D pteronyssinus sensitivity were positively associated with housing style, bedding materials, and use of malathion insecticide, but no single factor accounted for the urban-rural differences. INTERPRETATION: Wheeze and asthma are especially rare in rural subsistence areas, and atopy may be associated with a reduced prevalence of these symptoms in this environment. In urban Jimma, self-reported asthma seemed to emerge as a clinical problem about 10 years before our study began, which is consistent with an effect of new environmental exposures. The factor or factors leading to the increase in asthma and allergy have not been identified, although exposures related to general changes in the domestic environment are likely to be involved.     

Molecular parameters of type IV alpha-internexin and type IV-type III alpha-internexin-vimentin copolymer intermediate filaments

During neuronal development, a dynamic replacement mechanism occurs in which the type VI nestin and type III vimentin intermediate filament proteins are replaced by a series of type IV proteins beginning with alpha-internexin. We have explored molecular details of how the type III to type IV replacement process may occur. First, we have demonstrated by cross-linking experiments that bacterially expressed forms of alpha-internexin and vimentin form heterodimer molecules in vitro that assemble into copolymer intermediate filaments. We show using a urea disassembly assay that alpha-internexin molecules are likely to be more stable than those of vimentin. Second, by analyses of the induced cross-links, we have determined the axial lengths of alpha-internexin homodimer and alpha-internexin-vimentin heterodimer molecules and their modes of alignments in filaments. We report that these dimensions are the same as those reported earlier for vimentin homopolymer molecules and, by implication, are also the same for the other neuronal type IV proteins. These data suggest that during neuronal development, alpha-internexin molecules are readily assimilated onto the pre-existing vimentin cytoskeletal intermediate filament network because the axial lengths and axial alignments of their molecules are the same. Furthermore, the dynamic replacement process may be driven by a positive equilibrium due to the increased stability of the alpha-internexin network.     

Expression of apolipoprotein(a) kringle IV type 9 in Escherichia coli: demonstration of a specific interaction between kringle IV type 9 and apolipoproteinB-100

A number of studies have provided evidence that lipoprotein(a) [Lp(a)] assembly is a two-step process in which initial non-covalent interactions between apolipoprotein(a) [apo(a)] and apolipoproteinB-100 (apoB-100) precede specific disulfide bond formation. We have designed a construct encoding apo(a) kringle IV type 9 (KIV9) in which the unpaired cysteine at position 67 in this kringle is replaced with a tyrosine. The single kringle was expressed in bacteria and purified to homogeneity from cell homogenates. The purified derivative (designated KIV9deltaCys) was assessed for its ability to bind to purified human LDL. This interaction was detected either by ELISA using immobilized LDL or by column chromatography in which LDL binding to KIV9deltaCys immobilized on Ni2+-Sepharose was determined. In both cases, the interaction of KIV9deltaCys and LDL was observed. Further, we demonstrated that the binding interaction was sensitive to the addition of amino acids including lysine, the lysine analogue epsilon- aminocaproic acid, arginine, phenylalanine and proline, with arginine and lysine having the greatest inhibitory effect. Binding of KIV9deltaCys to an immobilized apoB peptide spanning residues 3732-3745 of apoB was also demonstrated by ELISA. As was the case for LDL, this binding interaction was sensitive to the addition of arginine and lysine. Computer modeling of KIV9 demonstrated an excellent fit with residues 3732-3738 (PSCKLDF) of the apoB peptide. The modeling predicts the presence of overlapping lysine and phenylalanine-binding pockets in KIV9 which explains the inhibitory effects of lysine, arginine and phenylalanine which were observed in the binding assays. In summary, this study represents the first demonstration that KIV9 can interact directly with LDL through non-covalent interactions which may contribute to the first step of Lp(a) formation.      

Enhanced photocatalytic properties of N–P co-doped TiO<Subscript>2</Subscript> nanosheets with {001} facets

Nitrogen (N) and phosphorus (P) co-doped anatase TiO₂ nanosheets were realized by low-temperature self-doping N–TiO₂ followed by high-temperature P doping with foreign precursor. It is found that P doping process can maintain good TiO₂ nanosheets morphology with exposed {001} facets. Chemical state of dopants indicates that N and P atoms replace O on O sites in TiO₂ lattice. Compared with pure TiO₂ and N-doped TiO₂, N–P co-doped TiO₂ nanosheets exhibits stronger optical absorption and higher degradation rate of dye molecules in visible light regime. The enhanced photocatalytic properties are attributed to two factors. On one hand, N–P co-doping can effectively reduce band gap of TiO₂ from 3.20 to 2.48 eV, leading to an enhancement of the absorption in visible light regime. On the other hand, the presence of exposed {001} facets of TiO₂ nanosheets can induce the effective separation of photogenerated electrons and holes in reaction.