Isethionate and taurine transport sites at brain cell membranes: Influx studies with brain slices

The influx of [¹⁴C]isethionate (ISA) into rat brain slices was studied with and without taurine. This influx was relatively rapid, but took place largely by a non-saturable, passive mechanism, which transferred much less ISA into the brain cells than taurine. Taurine inhibited the influx of ISA competitively (K _m=50 and 100 mol/l) at low ISA concentrations, and ISA that of taurine non-competitively (V=200 and 400–700 mol×min^–1×kg^–1 wet weight) at high taurine concentrations. It thus appears that ISA and taurine may have a small number of common transport sites at brain cell membranes, but these are apparently of little significance for the total transport of ISA.     

Comparison of Four Enrichment Media in the Recovery of Campyloracter Jejuni

The effectiveness of 4 enrichment media for the recovery of low levels of inoculated cells of Campylobacter jejuni was evaluated. The media contained antibiotics or antibiotics and bile acids as selective compounds. Three of the media recovered most of the inoculated low numbers of 6 C. jejuni strains. In the 3 media the growth rate of 3 strains, indicated by the increase in the log number of cells during 24 h or 48 h incubation at 42 ° C, was about the same as in the control medium without selective compounds. The same 3 media also recovered a low number of Campylobacter cells from artificially contaminated raw milk or ground meat samples. The enrichment medium B containing 40 I.U. Colistin, 5 μg novobiocin, 2 mg Na-cholic acid and 50 mg cycloheximide per ml was inhibitory for most Campylobacter strains studied.     

Quantum yield and energy dependence for photooxidation of chlorophyllide in greening wheat

Dark grown leaves of wheat were irradiated with red light of different intensities, at a temperature close to 0°C. The rate of photoreduction of the protochlorophyllide 650-form into chlorophyllide 684-form was measured. On continued irradiation the chlorophyllide 684-form was photodecomposed. By comparing the rates of the two processes the quantum yield for photooxidation of the chlorophyllide 684-form was calculated. The quantum yield was 2°10^-5 at an intensity of 2200 W m^-2, and increased with decreasing light intensity to 3.2°10^-5 at an intensity of 170 W m^-2.     

Tissue specific variation of C-glycosylflavone patterns in oat leaves as influenced by the environment

A comparison is made between the flavone patterns accumulating in epidermal tissues and in the mesophyll of oat primary leaves grown in a phytotron and under field conditions. In developing leaves cultivated under standard conditions, varying patterns of two vitexin-derived O-rhamnosides and of one isovitexin O-arabinoside are produced in the basal region as the result of basal meristem activity. These patterns are tissue specific and differ quantitatively in the epidermis and the mesophyll. During the course of subsequent growth and differentiation, this pattern is constant as the compounds are moved upwards due to basipetal leaf growth. In comparison, the flavone patterns generated in the basal section of leaves grown in the field do not vary significantly. There is the additional accumulation of isoorientin O-arabinoside. Again flavone patterns are tissue specific, but in contrast to standard growth they are modified characteristically in those leaf tissues which are already morphologically differentiated. It is possible that the isovitexin moiety of the O-arabinoside is oxidized to the corresponding isoorientin derivative in the mesophyll. Moreover, field-grown leaves show a two-fold increase in flavone content in each leaf epidermis and a six-fold increase in the mesophyll when compared to the corresponding tissues of phytotron-grown leaves.     

The differential distribution of vasoactive intestinal polypeptide in the normal human female genital tract

Summary VIP-like immunoreactive material is present in the female reproductive tract, with a distinct pattern of distribution. The highest concentrations of extractable material and immunoreactive nerve fibres were found in the cervix and vagina. In the cervix these fibres were seen below the surface epithelium and around cervical glands as well as in association with blood vessels and smooth muscle bundles. In the vagina the nerve fibres were most abundant in the superficial regions of the lamina propria. Scattered fibres were also present in the rest of the uterus and in the fallopian tubes. Chromatographic evidence indicates that this VIP-like material is of a similar molecular size to that extracted from other organs. Possible roles for VIP in the regulation of myometrial activity and of cervical and vaginal dilation and secretion are proposed.     

Ribonucleotide reductase: A structural study of the dimeric iron site

The iron-containing B2 subunit of ribonucleotide reductase from Escherichia coli has been investigated by Raman spectroscopy. Both the tyrosyl radical-containing native protein and the radical-free protein exhibit a resonance-enhanced Raman band at 500 cm^?1. This band is assigned to an Fe-O vibrational mode arising from an oxygen-containing ligand. The failure to observe any tyrosinate ring modes makes it unlikely that ribonucleotide reductase is an iron-tyrosinate protein and rules out tyrosinate oxygen as a ligand. It is proposed that the 500 cm^?1 band in ribonucleotide reductase is analogous to the 510 cm^?1 Fe-O vibrational mode of methemerythrin and arises from an oxo- or carboxylate-bridge between the antiferromagnetically-coupled Fe(III) ions.     

Structural studies of the capsular antigen of haemophilus infuenzae type c

The structure of the capsular antigen from Haemophilus influenza type c has been investigated, n.m.r. spectroscopy being the principal method used. It is concluded that the antigen is composed of repeating-units having the following structure:

O-Acetyl groups are present in ～90% of the repeating-units.     

Genetic control of effector cell characteristics: con A-induced suppressor cells carry H-2 I region encoded determinants.

Activation of splenic lymphocytes with Con A leads to the formation of suppressor cells capable of interfering with the activity of several polyclonal B-cell-activating substances. Thus, these suppressor cells, or their products, most probably act directly on B cells. Suppressor cells could be recovered from the effluent cell population of nylon wool columns, and they were absent from the spleens of athymic nude mice. Furthermore, they were absent from the thymus of normal as well as cortison-treated mice. Cortisone treatment did not abolish the formation of Con A-induced suppressor cells in the spleen. Treatment of activated suppressor cells with antisera specific for distinct products of the H-2 I region revealed that they carried I-J cell surface antigens. We conclude that the suppressor cells in our test system, which unlike other Con A-induced suppressor cell populations have a direct effect on B cells, had antigenic characteristics similar to those previously described for I-J carrying suppressor cells.