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Biomedical subjects

M Nyman

Publications and source records attributed to M Nyman.

At least 19 recordsLinked to original sources
PubMed2006

Nuclear isomers in superheavy elements as stepping stones towards the island of stability.

A long-standing prediction of nuclear models is the emergence of a region of long-lived, or even stable, superheavy elements beyond the actinides. These nuclei owe their enhanced stability to closed shells in the structure of both protons and neutrons. However, theoretical approaches to date do not yield consistent predictions of the precise limits of the 'island of stability'; experimental studies are therefore crucial. The bulk of experimental effort so far has been focused on the direct creation of superheavy elements in heavy ion fusion reactions, leading to the production of elements up to proton number Z = 118 (refs 4, 5). Recently, it has become possible to make detailed spectroscopic studies of nuclei beyond fermium (Z = 100), with the aim of understanding the underlying single-particle structure of superheavy elements. Here we report such a study of the nobelium isotope 254No, with 102 protons and 152 neutrons--the heaviest nucleus studied in this manner to date. We find three excited structures, two of which are isomeric (metastable). One of these structures is firmly assigned to a two-proton excitation. These states are highly significant as their location is sensitive to single-particle levels above the gap in shell energies predicted at Z = 114, and thus provide a microscopic benchmark for nuclear models of the superheavy elements.

Journal Article↗
PubMed2006

Collectivity and configuration mixing in 186,188Pb and 194Po.

Lifetimes of prolate intruder states in 186Pb and oblate intruder states in 194Po have been determined by employing, for the first time, the recoil-decay tagging technique in recoil distance Doppler-shift lifetime measurements. In addition, lifetime measurements of prolate states in 188Pb up to the 8+ state were carried out using the recoil-gating method. The B(E2) values have been deduced from which deformation parameters |beta2|=0.29(5) and |beta2|=0.17(3) for the prolate and the oblate bands, respectively, have been extracted. The results also shed new light on the mixing between different shapes.

Journal Article↗
PubMed2002

Fermentation and bulking capacity of indigestible carbohydrates: the case of inulin and oligofructose.

The bulking index (i.e. the increase in faecal fresh weight in gram per gram indigestible carbohydrate ingested) with oligofructose and inulin is similar to that produced with other easily fermented fibres such as pectins and gums. Most studies in man have been performed at a level of 15 g/d and more investigations on lower intakes are needed to appoint the least intake for an effect. Concerning short-chain fatty acids (SCFA) most studies have been using oligofructose and points at an increased butyric acid formation in the caecum of rats. In one study on rats with inulin high caecal proportions of propionic acid were obtained. As inulin has a higher molecular weight than oligofructose it might be speculated if this could be a reason to the different SCFA-profile formed. No effects on faecal concentrations of SCFA in humans have been revealed with inulin and oligofructose, which neither is expected as most of the SCFA formed during the fermentation already has been absorbed or utilized by the colonic mucosa.

Animals↗
PubMed2001

Accumulation of perfluorooctane sulfonate in marine mammals.

Perfluorooctane sulfonate (PFOS) is a perfluorinated molecule that has recently been identified in the sera of nonindustrially exposed humans. In this study, 247 tissue samples from 15 species of marine mammals collected from Florida, California, and Alaskan coastal waters; and northern Baltic Sea; the Arctic (Spitsbergen); and Sable Island in Canada were analyzed for PFOS. PFOS was detected in liver and blood of marine mammals from most locations including those from Arctic waters. The greatest concentrations of PFOS found in liver and blood were 1520 ng/g wet wt in a bottlenose dolphin from Sarasota Bay, FL, and 475 ng/mL in a ringed seal from the northern Baltic Sea (Bothnian Sea), respectively. No age-dependent increase in PFOS concentrations in marine mammals was observed in the samples analyzed. The occurrence of PFOS in marine mammals from the Arctic waters suggests widespread global distribution of PFOS including remote locations.

Alkanesulfonic Acids↗
PubMed2001

Measurement of CP-violating asymmetries in B0 decays to CP eigenstates.

We present measurements of time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates. The measurement uses a data sample of 23x10(6) Upsilon(4S)-->BbarB decays collected by the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we find events in which one neutral B meson is fully reconstructed in a CP eigenstate containing charmonium and the flavor of the other neutral B meson is determined from its decay products. The amplitude of the CP-violating asymmetry, which in the standard model is proportional to sin2beta, is derived from the decay time distributions in such events. The result is sin2beta = 0.34+/-0.20 (stat)+/-0.05 (syst).

Journal Article↗
PubMed2001

Bioaccumulation of polychlorinated biphenyls (PCBs) and dichlorodiphenylethane (DDE) methyl sulfones in tissues of seal and dolphin morbillivirus epizootic victims.

Polychlorinated biphenyl (PCB) and dichlorodiphenylethane (DDE) methyl sulfone (MSF) metabolites possess high affinities for binding two homologous 16,000 Da homodimeric receptor proteins in the lung (Clara cell secretory protein, CCSP) and the uterus (uteroglobin, UG), leading to selective bioaccumulation of MSFs in these tissues. As marine mammals are highly exposed to organochlorines, concentrations of PCBs, PCB MSFs, DDT, and DDE MSF were analyzed in blubber, lung, and uterus samples from harbor seal (Phoca vitulina) and striped dolphin (Stenella coeruleoalba) morbillivirus epizootic victims to investigate uterine and lung MSF accumulation. Mean uterus concentrations of PCB MSFs and DDE MSF in harbor seals were 0.61 and 0.04 microg/g lipid weight and in striped dolphins 0.05 and 0.01 microg/g lipid weight. Mean lung concentrations of PCB MSFs and DDE MSF in harbor seals were 0.96 and 0.02 microg/g lipid weight and in striped dolphins 0.16 and 0.01 microg/g lipid weight. To ascertain whether uterine and lung bioaccumulation of MSFs is possible due to the presence of CCSP and UG in seals, CCSP and UG proteins in uterine flushings and in uterine and lung and epithelial tissue from Baltic gray and ringed seals were characterized using gel electrophoresis and Western blotting techniques. UG- and CCSP-like proteins with molecular weights of 16,000 Da were resolved in all samples. This is the first demonstration of this protein in any marine mammalian species. The toxicological implications of MSF binding with UG and CCSP in marine mammals are discussed.

Adipose Tissue↗
PubMed2001

Distribution of cytochrome P4501A (CYP1A) in the tissues of Baltic ringed and grey seals.

Information about the expression of CYP1A in wildlife species is essential for understanding the impact of organochlorine exposure on the health status of an exposed population. Therefore, we aimed at characterising a putative CYP1A enzyme expression in both hepatic and extrahepatic tissues of ringed and grey seals from the Baltic Sea and from less polluted waters. The cellular localisation of CYP1A was identified using a monoclonal antibody against scup P4501A1 (MAb 1-12-3). Immunohistochemical staining showed the highest level of CYP1A expression in liver hepatocytes, and the second highest level in the endothelial cells of capillaries and larger blood vessels in the liver and other organs. The most frequent and strongest staining was found in Baltic ringed seals. Although CYP1A-positive staining was observed in only a few tissues in the other seal populations, it was more intense in Baltic grey seals than in Canadian grey seals. The CYP1A enzyme activity, expressed as ethoxyresorufin O-deethylation (EROD), followed a similar tissue distribution and geographical pattern as the immunohistochemistry with clearly elevated EROD activities in most tissues of both Baltic seal populations. Immunochemical characterisation by immunoblotting confirmed the presence and elevation pattern of a putative CYP1A protein in ringed and grey seals, supporting our findings using other methods. The evenly distributed elevation of CYP1A expression among most of the tissues examined indicates that Baltic seals are exposed to CYP1A inducing agents affecting the whole body. This may result in an increased or decreased toxic potential of foreign substances, which may ultimately determine the biological effects of the contaminants.

Animals↗
PubMed2001

Mercury, cadmium, lead and selenium in ringed seals (Phoca hispida) from the Baltic Sea and from Svalbard.

The concentrations of mercury (Hg), cadmium (Cd), lead (Pb) and selenium (Se) were determined in liver, kidney and muscle samples from 20 Baltic ringed seals (Phoca hispida botnica) (3-32 years), and from 17 ringed seals (Phoca hispida) (0-20 years) from Svalbard, in the Arctic. The concentrations of Hg and Se were considerably higher in the Baltic ringed seals, but the Cd concentrations lower than in the Svalbard ringed seals. There was no big geographical difference with respect to Pb concentrations. Se and Hg concentrations showed a significant positive correlation in both regions. By comparison with earlier studies on Baltic seals, the metal concentrations have remained at the same level since the 1980s. Of the metals we studied, only the level of Hg in Baltic ringed seals can be considered high (mean 53 mg/kg, range 6.5-124 mg/kg wet wt. for liver), but probably not high enough to cause metal intoxication. No pathological changes associated with metal intoxication were observed in the seals.

Animals↗
PubMed2001

Characterization of xenobiotic-metabolizing cytochrome P450 (CYP) forms in ringed and grey seals from the Baltic Sea and reference sites.

Earlier studies have shown that members of the cytochrome P4501 (CYP1) enzyme family are constitutively expressed, and are elevated in the livers of ringed seals (Phoca hispida) and grey seals (Halichoerus grypus) living in the heavily polluted Baltic Sea. In this study, we compared the expression profiles of several additional CYP enzymes in the liver and extrahepatic tissues of Baltic ringed and grey seals with the corresponding CYP expression in seals from relatively unpolluted waters. We used marker enzyme activity levels, diagnostic inhibitors and immunoblot analysis to assess members of the CYP2A, CYP2B, CYP2C, CYP2D, CYP2E and CYP3A sub-families. Coumarin 7-hydroxylation (COH), a marker of CYP2A activity, was high in the liver and the lungs of all the studied seal populations. The presence of a putative CYP2A form in these seals was further supported by the strong inhibition of COH activity by a chemical inhibitor and by an anti-CYP2A5 antibody. However, antibodies to human and rodent CYP2B, CYP2C and CYP2E forms did not recognize any proteins in these seal species. Dextromethorphan O-demethylation (marker for CYP2D activity) and chlorzoxazone 6-hydroxylation (marker for CYP2E activity) were measurable in the livers of all the seals we studied. Both activities were elevated in the Baltic seal populations, showed a strong positive correlation with CYP1A activity and were at least partly inhibited by a typical CYP1A inhibitor, alpha-naphthoflavone. Further studies are needed to determine the presence and characteristics of CYP2D and CYP2E enzymes in ringed and grey seals. Testosterone 6beta-hydroxylation, a CYP3A marker, showed a relatively high level of activity in the livers of both seal species and was potently inhibited by ketoconazole, a CYP3A-selective inhibitor. The putative CYP3A activity showed an opposing geographical trend to that of CYP2D and CYP2E, since it was elevated in the control area. CYP3A protein levels, revealed by immunoblotting, showed a positive correlation with testosterone 6beta-hydroxylation. We conclude tentatively that CYP2A- and CYP3A-like enzymes are expressed in ringed and grey seals, but that CYP2B- and CYP2C-like ones are not. Further information on the individual contaminant profile is needed before any conclusions can be drawn on a possible connection between the varying CYP expressions and the contaminant load.

Animals↗
PubMed2000

Expression and inducibility of members in the cytochrome P4501 (CYP1) family in ringed and grey seals from polluted and less polluted waters.

The expression and inducibility of cytochrome P4501A (CYP1A) were investigated in hepatic microsomes of ringed seals (Phoca hispida) and grey seals (Halichoerus grypus) from polluted (Baltic Sea) and less polluted (Svalbard and Sable Island) areas. Liver CYP1A protein levels and activities were assessed by immunoblot analysis and determining catalytic activities towards ethoxyresorufin (EROD) and pentoxyresorufin (PROD). The amount of CYP1A apoprotein and its catalytic activity were increased up to 5-fold in Baltic ringed and grey seal populations in comparison with ringed seals from Svalbard and grey seals from Sable Island. EROD and PROD activities correlated in all seal groups, indicating catalysis by the same CYP form(s). Enzyme kinetic studies suggested that PROD activity is catalysed by CYP1A enzymes in both ringed and grey seals. In immunoblot analysis, a protein was revealed in liver with an antibody against human CYP1B1, indicating that a CYP1B1 like protein could be present in ringed and grey seals. In conclusion, these data strengthen the concept that CYP1A is markedly induced in seals living in polluted waters and that both EROD and PROD activities are mediated by CYP1A forms in the seal liver. In addition, this study provides the first evidence for the presence of a CYP1B like protein in seal liver.

Journal Article↗
PubMed2000

[Parvovirus B19 infection--an incidious chameleon].

Parvovirus B19 is a common source of infection with a seroprevalence of 60-70 per cent in the adult population. The most common manifestation is erythema infectiosum ("fifth disease"), with exanthem, fever and upper airway symptoms in children. The infection can give rise to a multifaceted clinical picture and is probably underdiagnosed, particularly in risk groups (individuals with haemolytic anaemia or immunosuppression, and fetuses). Serological diagnosis can now be complemented with the demonstration of viral DNA using the PCR (polymerase chain reaction) test in various body fluids, or tissue biopsy. Recent years have witnessed manifest increase in clinical knowledge of parvovirus B19-associated complications, and their diagnosis and treatment.

Adolescent↗
PubMed2000

Parvovirus B19 infection: association with third-trimester intrauterine fetal death.

OBJECTIVE: To identify the presence of parvovirus B19 infection as a possible cause of fetal loss in the third trimester. DESIGN: Prospective study of women experiencing third-trimester intrauterine fetal death (IUFD). SETTING: All cases of IUFD at Danderyd Hospital from 1992 to 1998. POPULATION: Ninety-three women with IUFD in 33,759 deliveries (0.3%). METHODS: Detection of B19 DNA by polymerase chain reaction (PCR) in placental and fetal tissue. Placental pathology and B19-specific immunohistochemistry. Maternal serology in consecutive samples. RESULTS: Among 93 cases of IUFD, seven (7.5%) had detectable B19 DNA in freshly-frozen placental tissue. The detection of B19 DNA in these tissues was confirmed by detection of B19 DNA in six separately stored paraffin-embedded placental tissues. No other explanations for the fetal deaths were found. None of the women had experienced any clinical signs of infection prior to fetal demise. None of the seven fetuses were hydropic. Histopathologic examination of the placentas revealed only minor abnormalities. Serology on maternal samples at birth revealed delayed or absent B19 IgG responses in five of seven cases. Two women were B19 IgG seropositive at the time of delivery but had unusual infection patterns; persistent viraemia for at least five months before birth in one case and likely persistence or re-infection by B19 in the other. CONCLUSION: In our study, 7.5% of IUFDs in the third trimester may have been caused by parvovirus B19 infection, without signs of fetal hydrops. This finding indicates that B19 PCR should be included in the routine investigation of IUFD.

Adult↗
PubMed1999

[Parvovirus B19 infection--an insidious chameleon].

Parvovirus B19 is a common source of infection with a seroprevalence of 60-70 per cent in the adult population. The most common manifestation is erythema infectiosum ('fifth disease'), with exanthem, fever and upper airway symptoms in children. The infection can give rise to a multifacetted clinical picture and is probably underdiagnosed, particularly in risk groups (individuals with haemolytic anaemia or immunosuppression, and fetuses). Serological diagnosis can now be complemented with the demonstration of viral DNA using the PCR (polymerase chain reaction) test in various body fluids, or tissue biopsy. Recent years have witnessed manifest increase in clinical knowledge of parvovirus B19-associated complications, and their diagnosis and treatment.

Adolescent↗
PubMed1999

Antimicrobial susceptibilities and biotypes of Arcanobacterium haemolyticum blood isolates.

Isolates obtained from the blood of ten patients with Arcanobacterium haemolyticum septicaemia were biotyped as smooth or rough using morphological and biochemical criteria, and their susceptibilities to 18 antibacterial agents were determined. Nine of the clinical cases included here have not been reported previously and are discussed in brief. One of the strains was highly resistant to macrolides and clindamycin. With one exception, the strains belonged to the smooth biotype. The data presented here indicates that the treatment of systemic Arcanobacterium haemolyticum infections should be based on the antibacterial susceptibility profiles of individual strains and on the site of the infection.

Adolescent↗
PubMed1999

Intestinal degradation of dietary fibre in green beans--effects of microwave treatments.

Intestinal degradation of dietary fibre in blanched and microwaved green beans was studied by using a rat experimental model. Content and composition of dietary fibre as well as molecular weight distribution of water-soluble polysaccharides (WSP) were analysed. There was a solubilization and a shift towards lower Mw of mainly uronic acid-containing polysaccharides with repeated microwave treatment in the raw material. Thus, the apparent Mw of water-soluble polysaccharides decreased from approximately 1,550,000 to approximately 300,000. After the beans had been digested the Mw of the WSP was significantly reduced, to approximately 100,000, and the differences in Mw seen between various processed raw materials had been evened out. After fermentation the Mw of the WSP decreased further approximately 10 times. Fibre fermentability was high (approximately 90%) and similar for the various processed beans.

Animals↗
PubMed1998

Survival of Lactobacillus plantarum DSM 9843 (299v), and effect on the short-chain fatty acid content of faeces after ingestion of a rose-hip drink with fermented oats.

In a controlled and randomised double-blind study, 26 healthy adult volunteers consumed, for 21 d, 400 ml of a rose-hip drink containing oats (0.7 g/100ml) fermented with Lactobacillus plantarum DSM 9843 (RHL; containing 5 x 10(7) cfu ml(-1)), and 22 volunteers in a second group the same amount of a pure rose-hip drink (RH). Significant increases in the total faecal concentration of carboxylic acids (P < 0.05 after 1 week and P < 0.01 after 3 weeks of intake), acetic acid (P < 0.01 after 3 weeks of intake) and propionic acid (P < 0.01 after 3 weeks of intake and P < 0.05 eight days after intake ceased) were recorded in the RHL group, indicating increased fermentation in the colon. In both groups a significant increase was obtained in the concentration of faecal lactic acid (P < 0.001 after 1 and 3 weeks of intake). No changes were seen in the concentration of faecal butyrate. The numbers of faecal bifidobacteria and lactobacilli increased significantly in both groups after 3 weeks of intake. Sulphite-reducing clostridia rapidly decreased in the group receiving the product with Lb. plantarum DSM 9843 after 1 week of intake, and then also in the pure rose-hip group after 3 weeks of intake. No changes were seen in the numbers of total anaerobes, gram-negative anaerobes or total aerobes during administration. Lb. plantarum DSM 9843 was recovered in faeces from all volunteers in the RHL group. Median amounts were 7.0 (5.0-8.8) log10 cfu g(-1) after one week of intake, and 6.7 (5.0-8.9) log10 cfu g(-1) after 3 weeks, respectively. The strain was still recovered from faeces of five volunteers 8 d after administration ceased (> 4.8 log10 cfu g(-1)). During the period of intake the volunteers in the RHL group experienced a significant increase in stool volume, a significant decrease in flatulence and slightly softer stools. Volunteers in the RH group experienced a slight but significant decrease in stool volume.

Adult↗