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Biomedical subjects

B Lindberg

Publications and source records attributed to B Lindberg.

At least 19 recordsLinked to original sources
PubMed1992

Distribution of substituents in O-(2-hydroxypropyl) derivatives of cyclomalto-oligosaccharides (cyclodextrins: influence of increasing substitution of the base used in the preparation, and of macrocyclic size.

Samples of O-(2-hydroxypropyl)derivatives of cyclomaltoheptaose (beta-cyclodextrin) with increasing substitution were prepared by withdrawing aliquots at different times from a reaction mixture containing cyclomaltoheptaose and an excess of (S)-propylene oxide in 0.39 M aqueous sodium hydroxide. The distributions of substituents between the different molecules and between the different alpha-D-glucopyranosyl residues in these samples were determined by mass spectrometry and methylation analysis, respectively. The solubilities of the samples and their association constants with phenolphthalein were also determined. The relative reactivities at O-2 and O-3 versus O-6, calculated using Spurlin's equations, decreased with increasing degree of substitution, probably because of steric hindrance. No significant differences were observed when different strong bases were used as promoters of the hydroxypropylation of cyclomaltoheptaose. The hydroxypropylation of cyclomaltohexaose (alpha-cyclodextrin) and cyclomalto-octaose (gamma-cyclodextrin) was briefly investigated.

Carbohydrate Conformation↗
PubMed1991

Synthesis of some 2-O-(2-hydroxyalkyl) and 2-O-(2,3-dihydroxyalkyl) derivatives of cyclomaltoheptaose.

On alkylation of cyclomaltoheptaose with oxiranes, promoted by alkali of low concentration, substitution at secondary positions, particularly at O-2, is favoured. The reaction has been used to prepare the 2-O-[(R)- and (S)-2-hydroxypropyl], 2-O-(2-hydroxy-2-methylpropyl), 2-O-[(R)- and (S)-2,3-dihydroxypropyl], and 2-O-[(R)- and (S)-2,3-dihydroxy-2-methylpropyl] derivatives. Each of these derivatives is less soluble in water than cyclomaltoheptaose, and their complexes with toluene, in contrast to that of cyclomaltoheptaose, are well soluble in water.

Carbohydrate Conformation↗
PubMed1991

Structural studies of the Vibrio cholerae O:3 O-antigen polysaccharide.

The structure of the Vibrio cholerae O:3 O-antigen polysaccharide has been investigated, mainly by n.m.r. spectroscopy, mass spectrometry, sugar and methylation analysis, and specific degradations, and is proposed to involve the following tetrasaccharide repeating-unit. [formula: see text]. In this structure, D-D-Hep is D-glycero-D-manno-heptose, Asc is 3,6-dideoxy-L-arabino-hexose (ascarylose), and Sug is 2,4-diamino-2,4,6-trideoxy-D-glucose (bacillosamine) in which N-2 is acetylated and N-4 is acylated with a 3,5-dihydroxyhexanoic acid. That the 2,4-diamino-2,4,6-trideoxy-D-glucose residue is linked through O-3 and not through one of the hydroxyl groups in the 3,5-dihydroxyhexanoyl group is indicated but not definitely proved. The configuration of the latter group has not been determined. The f.a.b.-mass spectrum of the methylated O-antigen indicates that the structure given above also represents the biological repeating-unit.

Carbohydrate Conformation↗
PubMed1991

Structural studies of a rhamnogalacturonan from the stipules of Musanga cercropoides.

The major water-soluble polysaccharide isolated from the stipules of Musanga cercropoides has been investigated, using n.m.r. spectroscopy, methylation analysis, and solvolysis in liquid hydrogen fluoride as the main methods. It is concluded that the polysaccharide is of the rhamnogalacturonan type and is, at least mainly, composed of tetrasaccharide repeating-units having the following structure [formula: see text] The polysaccharide further contains approximately two O-acetyl groups per repeating unit, which have not been located.

Carbohydrate Conformation↗
PubMed1991

Cross-linked, degradable starch microspheres as carriers of paramagnetic contrast agents for magnetic resonance imaging: synthesis, degradation, and relaxation properties.

Biodegradable particles were produced by the cross-linking of starch with epichlorohydrin. Diethylenetriaminepenta-acetic acid (DTPA) was covalently linked to the particles by using DTPA bisanhydride. The small, gadolinium-labelled particles were 40-260% more efficient in vitro proton relaxation agents than the corresponding unbound chelate gadolinium-DTPA. The relaxation properties were dependent on the metal chelate, the particle size, the metal content, and the degree of substitution (d.s.). For the small gadolinium-DTPA particles, an increased d.s. decreased the rate of degradation by alpha-amylase.

Biodegradation, Environmental↗
PubMed1991

Structural studies of the extracellular polysaccharide elaborated by Azotobacter vinelandii strain 1484.

The structure of the extracellular polysaccharide from Azotobacter vinelandii strain 1484 has been investigated, specific degradations and n.m.r. spectroscopy being the main methods used. It is concluded that the polysaccharide is composed of tetrasaccharide repeating-units having the following structure, [sequence: see text] in which Sug is 3-deoxy-D-threo-hexulosonic acid. The polysaccharide also contains a non-stoichiometric amount of O-acetyl groups, distributed over at least two positions.

Azotobacter↗
PubMed1991

Stability and change of personality in old age and its relation to survival.

Stability of personality characteristics with increasing age was analyzed in a Swedish longitudinal study using a modified version of the Rod-and-Frame Test. This test was analyzed in a serial manner in order to emphasize cognitive style. Two important findings emerged. First, during the 6 years between the ages of 67 and 73, 80% of the study participants showed stability in the field independence-dependence dimension. Second, stability of the field independence-dependence trait between ages 67 and 73 predicted survival to age 83, whereas destabilization (i.e., changes of Rod-and-Frame Test classification) was significantly associated with earlier death. In most cases, destabilization meant that field-independent subjects became field dependent. The results are discussed in relation to dispositional and situational factors. Causative factors for destabilization are hypothesized.

Aged↗
PubMed1991

Maternal blood volume in placenta of the rhesus monkey measured in vivo by positron emission tomography.

The relative volume of the intervillous space of the placenta of the rhesus monkey was measured in vivo using positron emission tomography (PET), a noninvasive tracer technique. 11CO-Hb and 68GaCl3 were both used in three experiments and 68Ga-EDTA in two. The tracers were administered intravenously as bolus doses to 6 pregnant monkeys during 7 different pregnancies. Measurements with 11CO-Hb gave a volume of 48.0% of the total placental volume. Transplacental transfer of 11CO to the fetal circulation is probably a minor problem due to the small fetal blood volume and the prolonged time before the same concentration is reached in the maternal and fetal blood. Measurements with 68GaCl3, which binds to transferrin, gave an intervillous space volume of 55.6% of the placental volume. The concentration of radioactivity in the placenta did not attain a steady state, indicating a clearance of the tracer from the blood only to a small extent. Measurements with 68Ga-EDTA displayed a volume of 60.4% of the placental volume. Transplacental transfer and the additional distribution of radioactivity to fetal and maternal extracellular spaces, including the placenta, when 68Ga-EDTA was used will make this tracer unsuitable in measurements of the blood volume of the placenta with PET.

Animals↗
PubMed1991

Measurement of fibronectin concentration in benign and malignant ascites.

Fifty-eight consecutive patients who were admitted to two departments of general surgery with ascites of unknown origin were investigated by measurement of ascitic fluid fibronectin concentration in a prospective study. A fibronectin concentration of 100 ml/l or more was chosen as indicative of malignant disease. In 40 patients with malignant disease, the median fibronectin concentration was 160 mg/l (interquartile range 120-270, range 20-560). In 18 patients with ascites from benign disease the corresponding figures were 40 mg/l (30-70, 20-90) (p less than 0.01). The diagnostic specificity (predictive value of a positive test) was 1.00 (34/34) (95% confidence interval 0.90 to 1.00), while the diagnostic sensitivity (predictive value of a negative test) was 0.75 (18/24) (95% CI 0.53 to 0.90). In this series an ascitic fluid fibronectin concentration of 100 mg/l or more indicated malignant disease, but a lower value did not exclude it. The test should be investigated in combination with another test with high diagnostic sensitivity to optimise its diagnostic value.

Adult↗
PubMed1990

Structural studies of the capsular polysaccharide from Aerococcus viridans var. homari.

The capsular polysaccharide from Aerococcus viridans var. homari has been investigated, using n.m.r. spectroscopy, methylation analysis, and specific degradations as the main methods. The polysaccharide is composed of tetrasaccharide repeating-units having the following structure. (Formula; see text) In this structure, D-QuiN stands for 2-amino-2,6-dideoxy-D-glucose (quinovosamine). Two of the three acidic sugars found, namely, L-altruronic acid and 4-O-[(S)-1-carboxyethyl]-D-glucose, have not been found in any other natural source. As evident from the n.m.r. spectra, the L-altruronic acid is not present in the 1C4 conformation, but flips to a conformation close to this on carboxyl reduction.

Carbohydrate Sequence↗
PubMed1990

Distribution of substituents in 2-hydroxypropyl ethers of cyclomaltoheptaose.

The distribution of substituents in 2-hydroxypropyl ethers of cyclomaltoheptaose, prepared by alkylation of the carbohydrate with propylene oxide in aqueous sodium hydroxide, was investigated. The samples were fully methylated and hydrolyzed, and the resulting mixture of alkylated sugars analyzed as their alditol acetates by g.l.c.-m.s. High and low alkali concentration favored the formation of 2-hydroxypropyl ethers at O-6 and O-2, respectively; substitution at O-2 increased the reactivity of O-3. The overall extent of substitution had only secondary effects on the relative reactivities of O-6 and O-2, and the 2-hydroxypropyl groups remained unevenly distributed among the glucose residues, even when the overall substitution increased. Only small proportions of the isomeric 2-(1-hydroxypropyl) ethers were formed, and the percentage of oligopropylene glycol ethers was also low.

1-Propanol↗
PubMed1990

Disposition of morphine-3-glucuronide in the pregnant rhesus monkey.

Morphine-3-glucuronide (M3G) is the major metabolite of morphine and is present in the circulation of persons treated with morphine or abusing heroin. This project was designed to study the kinetics of M3G in the foeto-maternal compartment, since this metabolite may be of relevance for the abstinence syndrome observed in neonates of pregnant abusers. The kinetics of M3G were studied in two non-pregnant and four pregnant Rhesus monkeys. M3G was given as a bolus injection in four of the animals and as a long-term infusion for 12 hr in two animals. M3G passed slowly across the placenta to the foetus and amniotic fluid. After 10 hr of M3G infusion, the foetal plasma M3G concentration was measured in two cases and found to be 37% and 72%, respectively, of the maternal concentration.

Amniotic Fluid↗
PubMed1990

Acupuncture before delivery: effect on pain perception and the need for analgesics.

Pain experience and the amount of analgesics needed during labor were studied in 32 primiparous women who had received repeated treatment with acupuncture (AP) during the month prior to term and in 16 nontreated primiparous women. The women's psychological profiles were evaluated by a psychiatric interview at week 38 of pregnancy. Treatment with AP did not reduce the need for analgesics in labor. During labor, all women experienced successively rising pain irrespective of whether or not they had been treated with AP prior to labor or delivered under local anesthesia. Experience of pain was not reduced in subjective assessments in women treated with AP. There was a strong correlation between assessments of pain made during labor and 6 months after delivery. In the group that did not receive AP, cerebrospinal fluid dynorphin A was significantly lower in parturients who chose epidural anesthesia.

Acupuncture Analgesia↗