Circulatory effects of VIP in anesthetized man

VIP was given intravenously over 1 min at the doses 0.1 and 0.2 micrograms X kg X min-1 to twenty-one anesthetized patients undergoing abdominal surgery. Intra-arterial blood pressure was monitored and various blood flows were measured simultaneously by electromagnetic technique. Following VIP, intra-arterial blood pressure was decreased. The blood flows were increased in the gastroduodenal-, and the left gastric arteries. The flow in the hepatic artery proper was increased only following the 0.2 micrograms dose. The flow in the superior mesenteric artery varied considerably inter-individually. In branches supplying only the small intestine, it seemed to be unaffected. The flow in the splenic artery was decreased in normal-sized spleens, but unaffected in enlarged spleens. The flow in the external iliac artery initially decreased and thereafter increased. Changes in vascular resistances showed that VIP acted as a vasodilator in the splanchnic region except in the superior mesenteric vasculature, where it was ineffective. In normal spleens it was a vasoconstrictor. In the external iliac artery, an initial insignificant vasoconstriction was followed by vasodilation. It seemed that VIP acts directly on the vessels and has a specific pattern of vasoactivity of probable physiological significance.     

Proline cis-trans isomers in calbindin D9k observed by X-ray crystallography.

In a structure of recombinant bovine calbindin D9k, determined crystallographically to 1.6 A resolution, a proline in mixed, approximately equally populated, cis and trans conformation is observed. Isomers of this kind have not been reported in structure determinations of calbindin D9k to 2.3 A resolution or in any other crystallographically determined protein structure. The cis-trans isomerization occurs at the peptide bond between Gly42 and Pro43, which is in agreement with results from two-dimensional 1H nuclear magnetic resonance spectroscopy experiments on solutions of calbindin D9k. Alternative backbone stretches have been modeled and refined by stereochemical restrained least-squares refinement for the segment Lys41 to Pro43. The final R-value was 0.188. The structural perturbations accompanying the cis-trans isomerization are found to be very localized. The largest positional differences are observed at residue Gly42, in which the alternative positions of the oxygen atom are 3.6 A apart.     

Wajira gen. et sp. nov. (Leguminosae) from Kenya

Wajira albescens Thulin (Leguminosae–Papilionoideae–Phaseoleae–Phaseolinae) is described as a new monotypic genus confined to the arid bushlands of E Kenya.     

New and noteworthy species of Indigofera (Leguminosae) from NE Africa

Six new species of Indigofera are described: I. eremophila Thulin from E Ethiopia, I. mooneyi Thulin from the highlands of SW Ethiopia, I. boranica Thulin from SE Ethiopia and NE Kenya, I. gyrata Thulin and I. ammophila Thulin from NE Kenya, and I. cana Thulin from north–central Ethiopia. I. cavallii Chiov., previously known only from the type from S Somalia, is reported also from NE Kenya.     

Identification of Diplostomum spp. in the retina of perch Perca fluviatilis and the lens of roach Rutilus rutilus from the Baltic Sea — an experimental study

Metacercariae of the genus Diplostomum dwelling in the retina of perch Perca fluviatilis and the lens of roach Rutilus rutilus were identified on the basis of adults obtained by feeding various piscivorous birds of the families Laridae, Anatidae and Phasianidae with metacercariae on an experimental basis. Both morphological studies of the metacercariae and adults obtained from the intestine of the infected birds, as well as the suitability in these hosts, indicated that we were dealing with two different species of Diplostomum. The perch form was recognised as D. baeri Dubois, 1937. Although metacercariae of this species matured both in herring gull Larus argentatus and common tern Sterna hirundo, the principal final host seemed to be goosanders Mergus merganser. In contrast, the lens form in roach was identified as D. spathaceum (Rudolphi, 1819) and it seemed to be restricted to birds of the family Laridae. These experimental results agree with parasitological findings from birds infected in the wild.     

A new species of Hibiscus (Malvaceae) from Somalia

Hibiscus ceratophorus , sp. nov. in H . sect. Furcaria , from coastal and subcoastal dunes in southern Somalia, is described and illustrated.     

Ionization behavior of acidic residues in calbindin D(9k).

The ionization state of seven glutamate residues, one aspartate, and the C-terminal alpha-COOH group in bovine apo calbindin D(9k) has been studied by measurement and modeling of the pH titration curves and apparent pK(a) values. The observed pK(a) ranged from 3.0 to 6.5. Most of the observed acidic groups were half-ionized at lower pH values than those in unstructured proteins. As a rule, the ionization equilibria extended over a wider pH range than in the case of unperturbed single titrations, indicating a complex influence of protein charges on the charge state of each individual residue. Glu17, which is a backbone Ca(2+)-ligand in the N-terminal binding loop of calbindin D(9k), was half-protonated at pH 3.6 but manifested biphasic titration with apparent pK(a) values of 3.2 and 6.5. Complementary Monte Carlo simulations of the titration process and pK(a) values of the acidic groups in calbindin D(9k) reproduce the experimentally observed titration features, except for the pronounced double titration of Glu17. Discrepancies between the results from direct measurement and from modeling may be partly caused by changes in the protein structure when the net charge changes from -8 to +11 over the isoelectric point at pH 5. Proteins 1999;37:106-115.     

Redox sensitive cysteine residues in calbindin D28k are structurally and functionally important

Human calbindin D(28k) is a Ca(2+) binding protein that has been implicated in the protection of cells against apoptosis. In this study, the structural and functional significance of the five cysteine residues present in this protein have been investigated through a series of cysteine-to-serine mutations. The mutants were studied under relevant physiological redox potentials in which conformational changes were monitored using ANS binding. Urea-induced denaturations, as monitored by intrinsic tryptophan fluorescence, were also carried out to compare their relative stability. It was shown that the two N-terminal cysteine residues undergo a redox-driven structural change consistent with disulfide bond formation. The other cysteine residues are not by themselves sufficient at inducing structural change, but they accentuate the disulfide-dependent conformational change in a redox-dependent manner. Mass spectrometry data show that the three C-terminal cysteine residues can be modified by glutathione. Furthermore, under oxidizing conditions, the data display additional species consistent with the conversion of cysteine thiols to sulfenic acids and disulfides to disulfide-S-monoxides. The biological function of calbindin D(28k) appears to be tied to the redox state of the cysteine residues. The two N-terminal cysteine residues are required for activation of myo-inositol monophosphatase, and enzyme activation is enhanced under conditions in which these residues are oxidized. Last, oxidized calbindin D(28k) binds Ca(2+) with lower affinity than does the reduced protein.     

A new species of Asparagus (Asparagaceae) from Somalia

Asparagus brachiatus , a new unarmed species from limestone rocks in north-eastern Somalia, is described, illustrated, and compared with A. leptocladodius and A. africanus.