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Biomedical subjects

M L Andersen

Publications and source records attributed to M L Andersen.

34 records · Page 2Linked to original sources
PubMed2000

[Prevalence of idiopathic scoliosis in the municipality of Hillerod].

Among Scandinavian paediatric spinal surgeons there has been a debate whether the prevalence of idiopathic adolescent scoliosis (AIS) has declined. We examined all children in the town of Hillerød, Denmark attending third and fifth grade (age 10 and 12) with forward-bending-test using a scoliometer. All children with more than seven degrees of trunk inclination were referred to a PA radiogram of the spine. We found a 0.4 percent prevalence of AIS with Cobbangles greater than 19 degrees. This is similar to earlier findings, suggesting that the declining referral rate is due to late detection of idiopathic adolescent scoliosis.

Adolescent↗
PubMed2000

Potential antioxidants in beer assessed by ESR spin trapping.

A number of potential antioxidants have been evaluated for their effect on formation of radicals in beer using the electron spin resonance (ESR) lag phase method. Sulfite was found to be the only compound that was able to delay the formation of radicals, whereas phenolic compounds such as phenolic acids, catechin, epicatechin, and proanthocyanidin dimers had no effect on the formation of radicals. Ascorbate, cystein, and cysteamin were on the other hand found to be prooxidants. It is suggested that antioxidants must be able to either scavenge peroxides or trap metal ions in order to be effective in beer. The effectiveness of sulfite is suggested to be a consequence of its two-electron nonradical producing reaction with peroxides.

Antioxidants↗
PubMed2000

Reduction of ferrylmyoglobin by the spin trap N-tert-butyl-alpha-phenylnitrone (PBN) in aqueous solution and during freezing.

The hypervalent muscle pigment ferrylmyoglobin, formed by activation of metmyoglobin by hydrogen peroxide, was found to be reduced in a second-order reaction by N-tert-butyl-alpha-phenylnitrone (PBN, often used as a spin trap). In acidic aqueous solution at ambient temperature, the reduction is relatively slow (deltaH++ = 65+/-2kJ x mol(-1) and deltaS++ = -54+/-7 J x mol(-1). K(-1) for pH = 5.6), but phase transitions during freezing of the buffered solutions accelerates the reaction between ferrylmyoglobin and PBN. In these heterogenous systems at low temperature (but not when ice-formation was inhibited by glycerol), a PBN-derived radical intermediate was detected by ESR-spectroscopy, identified as a nitroxyl radical by a parallel nitrogen hyperfine coupling constant of 31.8 G, and from microwave power saturation behavior concluded not to be located in the heme-cleft of the protein. The acceleration of the reaction is most likely caused by a lowering of the pH during the freezing of the buffered solutions whereby ferrylmyoglobin becomes more oxidizing.

Cyclic N-Oxides↗
PubMed2000

Altered sleep and behavioral patterns of arthritic rats.

The present study sought to evaluate concomitant alterations of behavioral and sleep patterns of arthritic rats. Rats were implanted with electrodes for polysomnographic recordings and submitted to the model of arthritis by a subcutaneous (s.c.) administration of Freund adjuvant in the posterior right paw and saline in the posterior left paw. The SHAM group was injected with saline in both paws, whereas the control group (CTL) was not submitted to any manipulation. Behavioral tests were carried out twice before induction of arthritis, on the second day of arthritis, and once a week afterwards until the eighth week. Body weight, colonic temperature, and measurements of the injured paw were carried out on the same days. Arthritic rats presented a reduction of total sleep time, increased latency to synchronized sleep, augmented number of episodes of synchronized sleep, reduction of sleep efficiency, more stage shifts, and increased total alert time. Moreover, these animals presented a lower pain threshold than control and SHAM animals. This reduction was observed on the second day of arthritis and remained so reduced until the end of the study. The data appear to indicate a relationship between altered sleep pattern and increased pain sensitivity in arthritic rats.

Analysis of Variance↗
PubMed1999

Acid-catalysed autoreduction of ferrylmyoblobin in aqueous solution studied by freeze quenching and ESR spectroscopy.

Decay of the hypervalent muscle pigment ferrylmyoglobin, formed by activation of metmyoglobin by hydrogen peroxide, was found, when studied by a combination of ESR and UV/VIS spectroscopy in aqueous solution at physiological pH, to proceed by parallel second- and first-order kinetics. At pH below 6.5 a sharp ESR signal (g = 2.003) with an increasing intensity for decreasing pH were observed in solutions frozen in liquid nitrogen, and a broad signal (g = 2.005) was seen throughout the studied pH range also in frozen solutions. The g = 2.005 signal is suggested to arise from an intermediate formed in an intramolecular rate-determining electron-transfer in ferrylmyoglobin, whereas the g 2.003 signal is caused by a radical formed in a proton-assisted electron-transfer initiating the specific acid-catalysed autoreduction.

Electron Spin Resonance Spectroscopy↗
PubMed1995

Structure of metal site in azurin, Met121 mutants of azurin, and stellacyanin investigated by 111mCd perturbed angular correlation (PAC).

The geometries of the metal sites in cadmium-substituted azurins have been investigated by 111mCd perturbed angular correlation (PAC). The study includes wild type azurin as well as Met121 mutants of azurin, where methionine has been substituted by Ala, Asn, Asp, Gln, Glu, and Leu. The nuclear quadrupole interaction of wild type azurin analyzed in the angular overlap model is well described as coordination of His46, His117, and Cys112 and cannot be described by coordination of Met121 and/or Gly45. For most of the mutants, there exist two coordination geometries of the cadmium ion. With the exception of the Glu and Asp mutants, one of the conformations is similar to the wild type conformation. The other coordination geometries are either best described by a coordinating water molecule close to the original methionine position or by coordination by the substituting amino acid. These experiments show that even though the methionine does not coordinate it plays an important role for the geometry of the metal site. The nuclear quadrupole interaction of stellacyanin was also measured. The value resembles the most prominent nuclear quadrupole interaction of the Met121-->Gln mutant of Alcaligenes denitrificans azurin, indicating that the structures of the two metal sites are similar.

Azurin↗
PubMed1978

A comparison of 99Tc and 123I scintigraphy in nodular thyroid disorders.

Out of 450 patients referred for thyroid scintigraphy 83 consecutive patients with nodular goitre were selected for dual scintigraphy with 99mTc and 123I. Seventy-four patients had one or more palpable nodules and the other nine patients had palpably diffuse goitres with one or more nodules on the routine 99mTc scintigram. For the comparison of scintigrams an eight level colour display was used, and regional differences between the 99mTc and 123I scintigrams were defined as a minimum of 25% (2 colour levels) variation of the relative activity in well defined areas. Thirteen patients, i.e. 16% of those with nodular goitre, had discordant scintigrams. All 13 patients had non-malignant thyroid disorders, (simple goitre, radio-iodine treated hyperthyroidism, autonomous adenoma, subacute thyroiditis, Riedel's and lymphocytic thyroiditis). The diagnosis was verified histologically in eight of these patients. Eight of the 13 patients had a high 99mTc activity relative to 123I, five patients showed the opposite discrepancy. Another 5 patients with a follicular or mixed follicular thyroid carcinoma had identical scintigrams. These findings indicate that 123I does not offer such diagnostic advantages over the cheap and readily available 99mTc, that its use for routine scintigraphy of the thyroid gland seems to be justified at present.

Adenoma↗