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Biomedical subjects

J Schott

Publications and source records attributed to J Schott.

At least 19 recordsLinked to original sources
PubMed2002

Surface chemistry and dissolution kinetics of divalent metal carbonates.

A surface complexation model (SCM) for divalent metal carbonates (Ca, Mg, Sr, Ba, Mn, Fe, Co, Ni, Zn, Cd, and Pb) is developed based on new electrophoretic measurements and correlation between aqueous and surface reactions stability constants. This SCM postulates the formation of the following surface species: >CO3H0, >CO3-, >CO3Me+, >MeOH0, >MeO-, >MeOH2+, >MeHCO30, and MeCO3- within the framework of a constant capacitance of the electric double layer. It can be used to describe the surface-controlled dissolution kinetics of divalent metal carbonates and allows determination of the order of dissolution reactions with respect to rate-controlling protonated carbonate surface groups in acid solutions (>CO3H0) and hydrated metal groups (>MeOH2+) in neutral to alkaline solutions. The reaction order with respect to protonated carbonate groups increases from 2 for MnCO3 and ZnCO3 to 4 for NiCO3, whereas for hydrated surface metals, it augments from 2 for ZnCO3 to approximately 4 for MnCO3 and NiCO3. The dissolution rates at 5 < or = pH < or = 8 increase in the order Ni < Mg < Co < Fe < Mn < Zn < Cd < Sr < or = Ca approximately = Ba approximately = Pb and correlate nicely with water exchange rates from the aqueous solution into the hydration sphere of the corresponding dissolved cations. Such a correlation allows the generation for all carbonates of a model describing their dissolution/precipitation kinetics, including the effect of various ligands, provided that rate constants and their activation volumes for water exchange around Me(II)-ligand dissolved complexes are available.

Carbonates↗
PubMed2001

The Fe(2+)-His(F8) Raman band shape of deoxymyoglobin reveals taxonomic conformational substates of the proximal linkage.

The band shape of the Raman line attributed to the Fe(2+)-N(epsilon)(His(F8)) stretching mode in deoxymyoglobin contains significant information on the nature of the Fe-His proximal linkage. Raman lines appearing close to it, however, obscure the true line profile. To isolate this from its accompanying lines we use its isotopic shift of approximately 1 cm(-1) when (56)Fe in natural-abundance deoxymyoglobin is substituted by (54)Fe. This enables us to isolate the true line shape. We have measured this line shape in sperm whale myoglobin dissolved in a 66% vol/vol glycerol/water solution for nine temperatures from 10 K to 300 K. The nu(Fe-His) band shows a complex temperature-dependent profile, with a shoulder on its high-frequency wing, which becomes more prominent with increasing temperature. Detailed analysis reveals that the band is composed of five distinct lines attributable to taxonomic conformational substates of the nu(Fe-His) linkage. These are in thermodynamic equilibrium above the glass transition temperature T(f) but freeze in into the thermodynamic distribution at T(f) for lower temperatures. Alternative models that try to explain the nu(Fe-His) band shape by either an anharmonic coupling of the nu(Fe-His) to a low-frequency heme doming mode or by conformational substates related to a Gaussian distribution of iron out-of-plane displacements are at variance with the distinct features observed experimentally.

Animals↗
PubMed2000

Protein dynamics in an intermediate state of myoglobin: optical absorption, resonance Raman spectroscopy, and x-ray structure analysis.

A metastable state of myoglobin is produced by reduction of metmyoglobin at low temperatures. This is done either by irradiation with x-rays at 80 K or by electron transfer from photoexcited tris(2, 2'-bipyridine)-ruthenium(II) at 20 K. At temperatures above 150 K, the conformational transition toward the equilibrium deoxymyoglobin is observed. X-ray crystallography, Raman spectroscopy, and temperature-dependent optical absorption spectroscopy show that the metastable state has a six-ligated iron low-spin center. The x-ray structure at 115K proves the similarity of the metastable state with metmyoglobin. The Raman spectra yield the high-frequency vibronic modes and give additional information about the distortion of the heme. Analysis of the temperature dependence of the line shape of the Soret band reveals that a relaxation within the metastable state starts at approximately 120 K. Parameters representative of static properties of the intermediate state are close to those of CO-ligated myoglobin, while parameters representative of dynamics are close to deoxymyoglobin. Thus within the metastable state the relaxation to the equilibrium is initiated by changes in the dynamic properties of the active site.

Animals↗
PubMed1999

[Lifestyle, living conditions and health status--a cross-sectional study of the Saxon population in the period 1993 to 1994].

The aim of this cross-sectional study was to record the living conditions, lifestyle variables and health status in a part of the population of Saxony and to examine statistical relationships between the three categories. The interview by post took place from March 1993 to August 1994. The sample consisted of 602 participants, i.e. a return of 52.3%. The survey proved conditionally representative for the population of Saxony. Statistical methods used were Chi2 test, H test, Spearman correlation and multiple regression procedures. Males and females showed clear differences in their lifestyles and in the state of health. It was found that the lifestyle was associated with age. The following variables were significantly associated with the subjective health status: sex, daily routine, number of negative life events, utilisation of preventive measures, contentment, age, and domicile. Significant connections were found between the objective health status (number of chronic diseases) and the variables: utilisation of preventive measures, number of negative life events, employment, daily routine, smoking, alcohol consumption, contentment, and age. In the statistical relationship the primary health status had the most distinct influence on the lifestyle and this covered the influence of lifestyle on health status.

Adolescent↗
PubMed1998

[Changes in the median life expectancy in free Saxony with reference to age-specific parameters].

When analysing an intensified mortality table of the population in Saxony (which is situated in central Germany) it became evident that by 1994 in contrast to 1988 there has been an overall positive development in respect of median life expectancy, but it also transpired that this development presented a highly differentiated pattern with regard to age-specific parameters among both the female and male populations. As far as the female population was concerned, social progress resulted in a systematic improvement of survival possibilities in childhood and at an advanced age. In the male population there were two age brackets (around the 18th year of life and between 32 and 50 years of age) where the survival probabilities had still not re-attained the 1988 level. In the pensioners' age bracket (starting around the 63rd year of age) the overall mortality rate did not attain a lower level compared to 1988. We are at present preparing an analysis of this life expectancy pattern with special reference to the causes of death.

Adolescent↗
PubMed1998

[Trends in average life expectancy in the Saxony Free State--results of a cause of death-specific table analysis].

We conducted a specific table analysis on mortality causes that was mainly oriented on the lines of the chapters of ICD-9 to explore the average life expectancy for the population in Saxony particularly since 1988. The drop in average life expectancy of males observed since 1990 can be fully explained only for those around 18 years of age by "accidents" as the cause of death. Between 30 and 55 years of age there were additional losses of average life expectancy via the mortality causes "diseases of the digestive tract", "neoplasms" and "psychiatric diseases". The significance of neoplasms and of psychiatric diseases is receeding in respect of the average life expectancy. In 1991 there was an increase in the incidence of suicide in the age bracket around 51 years in males. Seen on an overall scale across all age brackets the development of the suicide rate has increased average life expectancy. Significant average life expectancy increase developed in the range of death causes due to embryonic or congenital damage as well as cardiovascular diseases, diseases of the respiratory system and infectious diseases. As far as the female population is concerned, only accidents and diseases of the digestive tract had a negative effect on average life expectancy in 1990 and 1991 whereas the negative effect exercised by the mortality cause "neoplasms" is systematically flattening out. There are excessive gains in life expectancy in respect of cardiovascular diseases, clearly in the range of embryonal and congenital diseases and remarkably in respect of suicide. How many of these specific differentiations of causes of death are due to changes in coding, has not yet been assessed. Leaving aside the unnatural causes of death these figures point to a marked influence of improved medical care on average life expectancy.

Adolescent↗
PubMed1998

[Development of an immuno-neutral lipid emulsion for optimal postoperative management of intensive care patients].

Lipid emulsions prolong the rejection of allogeneic rat heart grafts in relation to their n-3 to n-6 fatty acid ratio. Because of the predominance of n-6 fatty acids soybean oil, which is clinically applied, shows an immunosuppressive effect. An n-3 to n-6 fatty acid ratio of 1 to 2 proved to be immunoneutral. Intravenous fat emulsions with an impaired n-3 to n-6 fatty acid ratio reduce cytokine release, infiltration and proliferation of immunocompetent cells. Lipids rich in n-3 fatty acids additionally reduce the release of the potent vasoconstrictor thromboxane A3 and increase the synthesis of leukotriene B5, which unlike leukotriene B4 does not activate polymorphonuclear neutrophils. Based on our results, the production of a clinically applicable lipid emulsion with a n-3 to n-6 fatty acid ratio of 1 to 2 can be recommended for the optimal parenteral nutrition of ICU patients with a markedly reduced immune system.

Animals↗
PubMed1997

[Calculation of mortality tables and trends longevity figures for the Saxony population 1980 to 1994].

Basing on the population figures and deaths between 1980 to 1994, we calculated mortality tables for the Grman province (or "Free State", as 1st is called) of Saxony. The method for calculating the period mortality tables according to Becker, Zeuner based on the year of dying, was modified for small parent populations (correction of baby mortality according to Rahts, smoothing algorithm). The influence exercised by baby mortality and migration on life expectancy is shown. Estimated errors of the model are calculated for the first time (maximum absolute deviation for eo scatter, 95% confidence interval for eo). Presentation of different lifespan data proves that the positive trend of the life prolongation process is continuing. For example, the life expectancy of male newborn increased during the observation period by 1.94 years (from 69.38 to 71.31 years), that of female newborn by 3.50 years (from 75.2 to 78.62). Women increased their lead in life expectancy against men by 1.56 years (from 5.75 to 7.31 years). The reduction in baby morality and in the standardised mortality rate are other favourable factors. These figures dropped during the observation period from M: 12.0 on 7.0 and from F: 8.9 on 4.8, respectively from M: 14.4 on 1.0 and F: 13.3 on 12.7 per 1000 of the population.

Adolescent↗
PubMed1995

The role of metabolites in strength training. II. Short versus long isometric contractions.

The role of intramuscular metabolite changes in the adaptations following isometric strength training was examined by comparing the effect of short, intermittent contractions (IC) and longer, continuous (CC) contractions. In a parallel study, the changes in phosphate metabolites and pH were examined during the two protocols using whole-body nuclear magnetic resonance spectroscopy (NMRS). Seven subjects trained three time per week for 14 weeks. The right leg was trained using four sets of ten contractions, each lasting 3 s with a 2-s rest period between each contraction and 2 min between each set. The left leg was trained using four 30-s contractions with a 1-min rest period between each. Both protocols involved isometric contractions at 70% of a maximum voluntary isometric contraction (MVC). The MVC, length:tension and force:velocity relationships and cross-sectional area (CSA) of each leg were measured before and after training. The increase in isometric strength was significantly greater (P = 0.041) for the CC leg (median 54.7%; P = 0.022) than for IC (31.5%; P = 0.022). There were no significant differences between the two protocols for changes in the length:tension or force:velocity relationships. There were significant increases in muscle CSA for the CC leg only. NMRS demonstrated that the changes in phosphate metabolites and pH were greater for the CC protocol. These findings suggest that factors related to the greater metabolite changes during CC training results in greater increases in isometric strength and muscle CSA.

Adult↗
PubMed1995

Nutrition and allorejection impact of lipids.

Polyene n-3 and n-6 fatty acids are claimed to have immunomodulating properties. The impact of nutritional variations on transplant rejection was therefore studied in the heterotopic rat heart allotransplant model with particular focus on lipids. Twenty per cent fat emulsions with differing n-3/n-6 fatty acid ratios were continuously infused (9 g fat per kg bodyweight per day; n = 10 in each group) after transplantation until rejection: safflower oil (n-3/n-6 = 1/370), fish oil (7.6/1), soybean oil (1/6.5) and a 1:1 mixture of safflower and fish oil (1/2.1; oil control group). Graft survival time, subpopulations of infiltrating and circulating immunocompetent cells and interleukin-6 release by circulating mononuclear cells were analysed. In the safflower oil, fish oil and soybean oil groups graft survival was prolonged to 13.3, 12.3 and 10.4 days vs. 6.7 days in the oil control group and 7.8 days in the saline control group (p < 0.01). In the two groups with the highest prolongation of graft survival the number of infiltrating cells was reduced by up to 50% and the peripheral blood mononuclear cell interleukin-6 release by up to 45%. Beyond that, circulating T-cells were reduced in the fish oil group. The n-3/n-6 fatty acid ratio determines the immunomodulating effect of lipids. Both n-6 and n-3 fatty acids, if applied as the main fatty acid source, exert immunosuppressive effects by diminished infiltration, mobilization and cytokine release by immunocompetent cells. A n-3/n-6 fatty acid ratio of 1/2 proved to be immunologically neutral. The recipient's disposition to reject an allotransplant is influenced by the fatty acid composition of exogenously supplied lipids.

Animal Nutritional Physiological Phenomena↗
PubMed1995

Contractile properties of the quadriceps muscle in growth hormone-deficient hypopituitary adults.

1. Growth hormone-deficient hypopituitary adults often complain of weakness and fatigue. The cause of the fatigue is unknown but could be an increased proportion of fast, fatiguable, type 2 fibres in the muscle. The aim of this study was to examine the contractile properties of the quadriceps muscle in a group of these patients compared with healthy controls. Changes in these properties were also examined in a small subset of the patients following growth hormone replacement. 2. Isometric strength, half-relaxation time from a twitch (t1/2) and the force-frequency relationship were measured using electrically evoked contractions in 14 growth hormone-deficient patients and 14 age- and sex-matched controls. Six patients were restudied following 6-24 month's replacement therapy with growth hormone (daily dose 0.04 +/- 0.01 i.u./kg). 3. The growth hormone-deficient patients had a significantly lower t1/2 than the controls (46.1 +/- 6.1 ms versus 56.1 +/- 10.5 ms respectively; P = 0.0072; mean +/- SD). The 10/100% ratio was also significantly lower in growth-hormone-deficient patients (38.6 +/- 9.9% versus 52.3 +/- 8.0%; P = 0.0005), as was muscle strength (349 +/- 99 N versus 493 +/- 215 N; P = 0.036). Following growth hormone replacement, muscle strength increased significantly (P < 0.05). The 10/100% ratio also increased towards control values, but this change was not significant. 4. These results demonstrate that the relaxation times of the quadriceps are significantly shorter and that the force-frequency relationship shifted to the right in growth hormone-deficient patients, which is consistent with a greater proportion of type 2 fibres within the muscles.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗