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M Nylander

Publications and source records attributed to M Nylander.

At least 19 recordsLinked to original sources
PubMed2001

The low-temperature- and salt-induced RCI2A gene of Arabidopsis complements the sodium sensitivity caused by a deletion of the homologous yeast gene SNA1.

Two closely related, tandemly arranged, low-temperature- and salt-induced Arabidopsis genes, corresponding to the previously isolated cDNAs RCI2A and RCI2B, were isolated and characterized. The RCI2A transcript accumulated primarily in response to low temperature or high salinity, and to a lesser extent in response to ABA treatment or water deficit stress. The RCI2B transcript was present at much lower levels than RCI2A, and could only be detected by reverse transcription-PCR amplification. The predicted 6 kDa RCI2 proteins are highly hydrophobic and contain two putative membrane-spanning regions. The polypeptides exhibit extensive similarity to deduced low-temperature- and/or salt-induced proteins from barley, wheat grass and strawberry, and to predicted proteins from bacteria, fungi, nematodes and yeast. Interestingly, we found that a deletion of the RCI2 homologous gene, SNA1 (YRD276c), in yeast causes a salt-sensitive phenotype. This effect is specific for sodium, since no growth defect was observed for the sna1 mutant on 1.7 M sorbitol, 1 M KCl or 0.6 M LiCl. Finally, we found that the Arabidopsis RCI2A cDNA can complement the sna1 mutant when expressed in yeast, indicating that the plant and yeast proteins have similar functions during high salt stress.

Amino Acid Sequence↗
PubMed2001

Stress-induced accumulation and tissue-specific localization of dehydrins in Arabidopsis thaliana.

Stress-induced accumulation of five (COR47, LTI29, ERD14, LTI30 and RAB18) and tissue localization of four (LTI29, ERD14, LTI30 and RAB18) dehydrins in Arabidopsis were characterized immunologically with protein-specific antibodies. The five dehydrins exhibited clear differences in their accumulation patterns in response to low temperature, ABA and salinity. ERD14 accumulated in unstressed plants, although the protein level was up-regulated by ABA, salinity and low temperature. LTI29 mainly accumulated in response to low temperature, but was also found in ABA- and salt-treated plants. LTI30 and COR47 accumulated primarily in response to low temperature, whereas RAB18 was only found in ABA-treated plants and was the only dehydrin in this study that accumulated in dry seeds. Immunohistochemical localization of LTI29, ERD14 and RAB18 demonstrated tissue and cell type specificity in unstressed plants. ERD14 was present in the vascular tissue and bordering parenchymal cells, LTI29 and ERD14 accumulated in the root tip, and RAB18 was localized to stomatal guard cells. LTI30 was not detected in unstressed plants. The localization of LTI29, ERD14 and RAB18 in stress-treated plants was not restricted to certain tissues or cell types. Instead these proteins accumulated in most cells, although cells within and surrounding the vascular tissue showed more intense staining. LTI30 accumulated primarily in vascular tissue and anthers of cold-treated plants. This study supports a physiological function for dehydrins in certain plant cells during optimal growth conditions and in most cell types during ABA or cold treatment. The differences in stress specificity and spatial distribution of dehydrins in Arabidopsis suggest a functional specialization for the members of this protein family.

Arabidopsis↗
PubMed1998

Dental radiography after age 25 years, amalgam fillings and tumours of the central nervous system.

The aim of the study was to investigate the importance of diagnostic dental radiography and amalgam fillings as risk factors for tumours of the central nervous system (CNS). This population-based case-control study included subjects aged 25-74 years, living in the catchment area of the Neurosurgery Department of Uppsala University Hospital in Sweden. A total of 192 cases of glioma, 99 cases of meningioma and 42 cases of acoustic neurinoma were identified between 1987 and 1990. A control group of 343 subjects was matched on age, gender and parish. Information about dental exposure was obtained by a self-administered questionnaire and from dental records. For those who had a dental radiography at least once a year after age 25 years, a relative risk of 2.1 (95% confidence interval (CI) 1.0-4.3) was seen for meningioma, while for other subgroups of CNS tumours the relative risk was close to unity. No association was observed between the number of amalgam fillings and CNS tumours. In conclusion, there was no clear evidence that dental radiography or amalgam fillings is related to the development of tumours of the CNS.

Adult↗
PubMed1997

Activities of vitamin Q10 in animal models and a serious deficiency in patients with cancer.

New data on blood levels of vitamin Q10 in 116 cancer patients reveal an incidence of 23.1% of patients (N=17) with breast cancer whose blood levels were below 0.5 microg/ml. The incidence of breast cancer cases with levels below 0.6 microg/ml was 38.5%. The incidence is higher (p<0.05) than that for a group of ordinary people. Patients (N=15) with myeloma showed a mean blood level of 0.67 +/- 0.17 microg/ml. The incidence of a vitamin Q10 blood level below 0.7 microg/ml for these 15 cases of myeloma was 53.3%, which is higher (p<0.05) than the 24.5% found for a group of ordinary people.

Animals↗
PubMed1995

An estimation of the uptake of mercury from amalgam fillings based on urinary excretion of mercury in Swedish subjects.

Mercury is released from amalgam fillings in several forms, i.e. as elemental vapour, ions and in fine particles. Despite many investigations there is still considerable uncertainty concerning the uptake of such mercury. Most available estimates have calculated the pulmonary uptake of mercury vapour based on measurements of concentrations intra-orally or in expired breath. Presented estimates vary by an order of magnitude from approximately 1 to 20 micrograms/day. The possibility of estimating this uptake based on levels of mercury in a biological index medium has received comparatively little attention. The purpose of the present work is to estimate the uptake of mercury from amalgam fillings based on urinary concentrations of mercury. It is estimated that the average uptake of mercury from amalgam fillings in Swedish subjects is within the interval 4-19 micrograms/day. This interval was arrived at after a detailed evaluation of the uncertainties in the data used and in the different assumptions. Notwithstanding the considerable range of this estimate it indicates a higher uptake than several other estimates, some of which have had a large impact on the scientific debate concerning this issue.

Dental Amalgam↗
PubMed1995

Selenium concentrations in brain after exposure to methylmercury: relations between the inorganic mercury fraction and selenium.

Three groups of female monkeys (Macaca fascicularis) were exposed to methylmercury (MeHg, p.o. 50 micrograms Hg/kg body wt per day) for 6, 12, or 18 months. One group was exposed to MeHg for 12 months and kept unexposed for 6 months before sacrifice. Another group of three monkeys was exposed to HgCl2 i.v. for 3 months. Total and inorganic mercury concentrations in occipital pole and thalamus were determined by cold vapor atomic absorption spectroscopy. Selenium concentrations were analyzed by hydride generation atomic absorption spectroscopy. The results indicated an association between concentrations of inorganic mercury and selenium in both occipital pole and thalamus in the MeHg-exposed animals. A linear regression model using concentrations of inorganic mercury (nmol/g wet wt) as independent variable, and selenium concentrations (nmol/g wet wt) as the dependent variable showed significant correlations between the variables in both occipital pole and thalamus (r = 0.85 and r = 0.91, P < 0.0001). The intercept of the regression line was slightly lower (about 2 nmol Se/g wet wt) than the selenium concentrations found in control monkeys (about 3 nmol Se/g wet wt). There was a tendency to a "hockey stick"-shaped relationship between concentrations of selenium and inorganic mercury in the thalamus of monkeys with ongoing exposure to MeHg. An important role for selenium in the retention of mercury in brain is indicated.

Animals↗
PubMed1994

Characterization and differential expression of dhn/lea/rab-like genes during cold acclimation and drought stress in Arabidopsis thaliana.

We have characterized cDNAs for two new dhn/lea/rab (dehydrin, late embryogenesis-abundant, responsive to ABA)-related genes from Arabidopsis thaliana. The two genes were strongly induced in plants exposed to low temperature (4 degrees C) and were accordingly designated lti45 and lti30 (low temperature-induced). The lti45 gene product contains the conserved serine stretch and three lysine-rich repeats characteristic of DHN/LEA/RAB proteins and is very similar to another low temperature-responsive protein of A. thaliana, COR47 [17]. Both proteins have the same repeat structure and an overall amino acid identity of 64%. This structural similarity of the proteins and the tandem array of the genes suggest that this gene pair arose through a duplication. The other polypeptide, LTI30, consists of several lysine-rich repeats, a structure found in CAP85, a low temperature- and water stress-responsive protein in spinach [41] and similar proteins found in wheat [20]. The expression pattern of the five dhn/lea/rab-related genes (cor47, dhnX, lti30, lti45 and rab18) identified so far in A. thaliana, was characterized in plants exposed to low temperature, drought and abscisic acid (ABA). Expression of both lti30 and lti45 was mainly responsive to low temperature similar to cor47. The lti45 and lti30 genes show only a weak response to ABA in contrast to cor47, which is moderately induced by this hormone. The three genes were also induced in severely water-stressed plants although the expression of lti30 and lti45 was rather low. In contrast to these mainly low temperature-induced genes, the expression of rab18 was strongly induced both in water-stressed and ABA-treated plants but was only slightly responsive to cold. The dhnX gene showed a very different expression pattern. It was not induced with any of the treatments tested but exhibited a significant constitutive expression. The low-temperature induction of the genes in the first group, lti30 and lti45, is ABA-independent, deduced from experiments with the ABA-deficient (aba-1) and ABA-insensitive (abil) mutants of A. thaliana, whereas the induction of rab18 is ABA-mediated. The expression of dhnX was not significantly affected in the ABA mutants.

Abscisic Acid↗
PubMed1994

Mercury and selenium distribution in human kidney cortex.

Concentration of mercury and selenium were analyzed in tissue fractions of human kidney cortex samples from seven autopsy cases. Total mercury content ranged between 0.3-9.0 nmol Hg/g wet wt. Between 27-61% of the total mercury was found in the 105,000g supernatant of the tissue homogenate from six cases. In kidney cortex from the seventh case, a decreased dentist with the highest concentration of mercury, only 3% of the total mercury was found in the 105,000g supernatant and about 88% in a SDS-insoluble fraction. In this fraction the molar ratio between mercury and selenium was close to 1:1. This study supports results from previous animal studies and indicates that mercury in human kidney cortex could be deposited in forms with different solubility. It could be of importance to speciate different forms of mercury in tissues according to solubility and association to selenium when interpretations of mercury concentrations are made.

Adolescent↗
PubMed1993

The relationship between mercury concentration in human organs and different predictor variables.

Samples from different tissues were collected from autopsies of individuals of the general population of the Stockholm area, Sweden. The samples were analysed for total mercury content using radiochemical neutron activation analysis. Average concentrations of mercury in occipital cortex, abdominal muscle, pituitary gland and kidney cortex were, 10.6 (2.4-28.7), 3.3 (0.9-5.4), 25.0 (6.3-77) and 229 (21.1-810) micrograms/kg wet weight, respectively. Possible predictor variables for mercury concentrations were tested in multiple linear regression models. An effect of a number of tooth surfaces with amalgam was seen in occipital lobe cortex, abdominal muscle and pituitary gland, but not in kidney cortex. In occipital lobe cortex and abdominal muscle, concentrations of mercury increased with age. Explanations discussed include: that a significant fraction of the mercury retained from amalgam fillings has a very long biological half-life; a decreasing capacity of mercury excretion with age; or higher fish consumption in the older individuals. In kidney cortex mercury concentrations decreased with age. The reason for this remains unclear, but it might indicate a decreasing capacity of mercury excretion with age. Chronic alcohol abuse was associated with decreased concentrations of mercury in occipital cortex.

Adolescent↗
PubMed1991

Neuropeptides in temporomandibular joints with rheumatoid arthritis: a clinical study.

There is evidence that neuropeptides play a role in the development of arthritis. Synovial fluid from arthritic temporomandibular joints in patients with rheumatoid arthritis was therefore investigated for presence of the neuropeptides calcitonin gene-related peptide, substance P, neurokinin A and neuropeptide Y. All four peptides were found in the synovial fluid above plasma level, but calcitonin gene-related peptide showed the highest concentration and substance P the lowest.

Adult↗
PubMed1991

Mercury and selenium concentrations and their interrelations in organs from dental staff and the general population.

Mercury (Hg) and selenium (Se) concentrations were determined by radiochemical neutron activation analysis in samples from the pituitary glands, occipital cortices, renal cortices, abdominal muscles, and thyroid glands of cadavers. Samples were retrieved from dental staff occupationally exposed to Hg and from the general population. Increased concentrations of both Hg and Se in samples from dental staff showed that Se accumulated together with Hg. Regression analysis of data from the pituitary glands and occipital cortices of dental staff indicated the accumulation of Se at a rough stoichiometric ratio of 1:1 with Hg. The same stoichiometric ratio between the elements was seen in the renal cortices from the general population. The regression analysis showed that a substantial fraction of Se was not associated with Hg; it is assumed that this corresponds to biologically available Se. Concentrations of biologically available Se decreased with advancing age in the pituitary gland, but not in other organs, and varied appreciably between organs.

Abdominal Muscles↗
PubMed1990

Does mercury from amalgam restorations constitute a health hazard?

Amalgam is the most extensively used implant material in dentistry. There have been no clinical trials of this substance and there are no epidemiological studies that allow any conclusions on the safety of amalgam fillings. Amalgam restorations continuously emit mercury vapour, which is absorbed in considerable quantities via the lungs. A comparison with dose-effect relationships, obtained in occupational studies, for certain effects on the kidneys and central nervous system (CNS), suggests that individuals with unusually high emission of mercury from amalgam fillings are at risk. It is unclear whether or not clinically significant effects could be expected. The limited sensitivity of available occupational studies, together with insufficient knowledge of possible host factors affecting resistance to mercury, implies that other more severe effects in susceptible individuals cannot be excluded. Information on long-term effects on organs other than brain or kidney is sparse. Animal studies suggest the possibility of immune system reactions to mercury, i.e. development of autoimmunity, that are not primarily dose-dependent, but rather depend on genetic susceptibility. From a toxicological point of view, amalgam is an unsuitable material for dental restorations.

Dental Amalgam↗
PubMed1989

Dental amalgam and mercury.

Mercury concentration in intraoral air and urine of seven females with dental amalgam was measured before and after intake of one hard-boiled egg. A considerable decrease in mercury concentration in intraoral air was found. Twenty women with about equal dental amalgam status, with or without subjective symptoms related to dental amalgam, were also studied. Mercury concentrations in intraoral air and urine were measured. For all the 27 women the basal intraoral air concentration of mercury ranged over 0.6-10.4 micrograms/m3 (median value 4.3 micrograms/m3). This corresponds to a release of 0.02-0.38 ng/s (median value 0.16 ng/s). In urine, the mercury concentration varied from less than 0.8-6.9 micrograms/g creatinine (median value 1.9 microgram/g creatinine). Data from both parameters were significantly correlated to the total number of teeth areas with dental amalgam. Protein values in urine indicated no renal damage. Maximum concentrations of mercury vapour in intraoral air for the 27 women who had chewed chewing gum for 5 min varied between 2-60 micrograms Hg/m3 (median value 19 micrograms Hg/m3). This corresponds to 0.07-2.20 ng Hg/s and a median value of 0.70 ng Hg/s.

Adult↗
PubMed1989

Mercury accumulation in tissues from dental staff and controls in relation to exposure.

Samples, mainly from occipital cortex and pituitary gland, but also from rental cortex, olfactory bulbs, thyroid gland and liver were collected from autopsies of 8 dental staff cases and 27 controls. These samples were analysed for total mercury content using radiochemical neutron activation analyses. The results revealed high mercury concentrations (median 815, range 135-4,040 micrograms Hg/kg wet weight) in pituitaries from the dental staff cases compared to controls (N = 23, median 23 range 6-1, 170 micrograms Hg/kg). In occipital cortex, the cases had a median of 17, range of 4-300 micrograms Hg/kg and the controls (N = 20) had a median of 10, range 2-29 micrograms Hg/kg. A few samples from olfactory bulbs show low mercury concentrations for both cases and controls. Renal cortex was analysed from three cases and contained clearly higher concentrations (945, 1,545, 2,110 micrograms Hg/kg) compared to controls (N = 12, median 180, range 21-810 micrograms Hg/kg). There is no control material for the other analysed samples, but one thyroid sample had an extremely high concentration of 28,000 micrograms Hg/kg.

Adolescent↗
PubMed1987

Correlation of dental amalgam with mercury in brain tissue.

Data from this project demonstrate a positive correlation between the number of occlusal surfaces of dental amalgam and mercury levels in the brain (p less than .0025 in white matter). This is indirect evidence suggesting that mercury from dental amalgam fillings may contribute to the body burden of mercury in the brain. The toxic levels of mercury in human tissues have not been sufficiently investigated and the amount of mercury in human brain tissue from dental amalgam may or may not be clinically significant. Nevertheless, dental amalgam exposure should be considered in monitoring sources of mercury accumulation in human brain tissue.

Adolescent↗
PubMed1987

Mercury concentrations in the human brain and kidneys in relation to exposure from dental amalgam fillings.

Samples from the central nervous system (occipital lobe cortex, cerebellar cortex and ganglia semilunare) and kidney cortex were collected from autopsies and analysed for total mercury content using neutron activation analyses. Results from 34 individuals showed a statistically significant regression between the number of tooth surfaces containing amalgam and concentration of mercury in the occipital lobe cortex (mean 10.9, range 2.4-28.7 ng Hg/g wet weight). The regression equation y = 7.2 + 0.24x has a 95% confidence interval for the regression coefficient of 0.11-0.37. In 9 cases with suspected alcohol abuse mercury levels in the occipital lobe were, in most cases, somewhat lower than expected based on the regression line. The observations may be explained by an inhibition of oxidation of mercury vapour. The regression between amalgams and mercury levels remained after exclusion of these cases. The kidney cortex from 7 amalgam carriers (mean 433, range 48-810 ng Hg/g wet weight) showed on average a significantly higher mercury level than those of 5 amalgam-free individuals (mean 49, range 21-105 ng Hg/g wet weight). In 6 cases analysis of both inorganic and total mercury was carried out. A high proportion (mean 77% SD 17%) of inorganic mercury was found. It is concluded that the cause of the association between amalgam load and accumulation of mercury in tissues is the release of mercury vapour from amalgam fillings.

Adolescent↗