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M Siry

Publications and source records attributed to M Siry.

3 recordsLinked to original sources

Comparing the influence of site quality, stand age, fire and climate on aboveground tree production in Siberian Scots pine forests.

Temporal patterns of stem and needle production and total aboveground net primary production (ANPP) were studied at the tree and stand level along four chronosequences of Siberian Scots pine (Pinus sylvestris L.) forests differing in site quality (poor lichen type or the more fertile Vaccinium type) and in frequency of surface fires (unburned, moderately burned (fire return interval of approximately 40 years), or heavily burned (fire return interval of approximately 25 years)). The maximum range of variability in aboveground production was quantified for: (1) possible long-term changes in site quality; (2) stand age; (3) non-stand-replacing, recurring surface fires; and (4) interannual climate variability. For (1) and (2), total ANPP was low in the lichen-type chronosequence, reached a maximum of 170 g C m(-2) year(-1) after 100 years and decreased to 100 g C m(-2) year(-1) in older stands. Maximum ANPP in the Vaccinium-type chronosequence was 340 g C m(-2) year(-1) and occurred earlier in the 53-year-old stand than in the other stands. Along the lichen-type chronosequences, peak ANPP was paralleled by maximum carbon allocation to stem growth. (3) In mature trees, damage by recurrent surface fires decreased stem growth by 17 +/- 19% over a 10-year period relative to pre-fire values. At longer timescales, ANPP was hardly affected by fire-related differences in mortality. (4) Needle- plus stem-NPP, reconstructed for a 3-year period, varied within a range of 15 g C m(-2) year(-1) in the lichen-type stands and 35 g C m(-2) year(-1) in the Vaccinium-type stands. For the same period, the coefficient of variance was higher for needle-NPP (20 +/- 10%) than for stem-NPP (12 +/- 7%). Needle- and stem-NPP did not covary in time. Most 30-year time series of stem-NPP at the tree level exhibited strong autocorrelation. In older trees, stem-NPP was positively correlated with growing season precipitation. Thus, the factors driving variability in ANPP ranked according to their maximum influence as: stand age (controlled by the frequency of stand-replacing fires) > site quality > growth depression because of surface fire damage approximately equal age-related reduction in ANPP > interannual variability approximately equal long-term effects of fire (stand density reduction). In lichen-type forests, we found that ANPP at the landscape level declined sharply when the interval between stand-replacing fires was less than 120 years, illustrating that fire strongly influences ANPP of boreal Scots pine forests.

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[First diagnosis of celiac disease in a 67-year old female patient].

HISTORY AND CLINICAL FINDINGS: A 67 year old female patient presented herself to our emergency room with paraesthesia in both hands, chronic diarrhea and continuous weight loss. From the past medical history, only an autoimmune hypothyroidism was known. On initial, examination leading features were carpopedal spasms and a pulse deficit. Her general condition, especially the nutritional status was low. INVESTIGATIONS: Serum levels of potassium (2.2 mmol/l) and calcium (1.45 mmol/l) were low, as well as the levels of total protein (5.1 g/dl) and albumin (2.94 g/dl). Clotting time was prolonged (Quick 51%). The ECG showed a ventricular bigeminus and a prolonged QT-period (120% rel). Endoscopy and biopsy showed a total villous atrophy suggesting celiac disease as probable cause. This was emphasized by the high antibody levels against gliadin (1:80) and endomyosin (1:40). Furthermore, the Human Leukocyte Antigen molecules HLA-B8 and HLA-DR3 showed increased expression. TREATMENT AND COURSE: After normalizing the electrolyte imbalance intravenously the neurological symptoms disappeared as well as the arrhythmia. The QT-period went back to normal. Under initial drip feeding and a strict gluten-free diet the general condition improved quickly and the diarrhea stopped. A follow-up investigation 3 months later showed the woman in a good condition having gained 10 kg weight and an improvement in histological findings, so that diagnosis of celiac disease could be proved. CONCLUSIONS: The possibility of ventricular arrhythmia and a prolonged QT-period in the ECG should be taken into account for patients diagnosed with celiac disease, especially in case of electrolyte imbalance. In these cases addition to a strict gluten free diet a rapid correction of the electrolyte imbalance is necessary because of the risk of sudden cardiac death. Furthermore associated disorders like autoimmune diseases expressing the same HLA-antigens (HLA-B8 and HLA-DR3) must be considered. Combined incidence of celiac disease and autoimmune hypothyroidism is well documented. For patients with celiac disease we therefore recommend a routine testing of thyroid hormone levels.

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