Forecasting PM10 in metropolitan areas: Efficacy of neural networks.

Deterministic photochemical air quality models are commonly used for regulatory management and planning of urban airsheds. These models are complex, computer intensive, and hence are prohibitively expensive for routine air quality predictions. Stochastic methods are becoming increasingly popular as an alternative, which relegate decision making to artificial intelligence based on Neural Networks that are made of artificial neurons or 'nodes' capable of 'learning through training' via historic data. A Neural Network was used to predict particulate matter concentration at a regulatory monitoring site in Phoenix, Arizona; its development, efficacy as a predictive tool and performance vis-à-vis a commonly used regulatory photochemical model are described in this paper. It is concluded that Neural Networks are much easier, quicker and economical to implement without compromising the accuracy of predictions. Neural Networks can be used to develop rapid air quality warning systems based on a network of automated monitoring stations.

Evidence for non-enzymatic glycosylation in Escherichia coli.

Non-enzymatic glycosylation (glycation) is a chain of chemical reactions affecting free amino groups in proteins of long-living eukaryotes. It proceeds in several steps leading to the consecutive formation of Schiff bases, Amadori products and advanced glycation end-products (AGEs). To our knowledge, this process has not been observed in prokaryotes so far. However, the present study provides clear-cut evidence that glycation takes place in bacteria despite their short life span. We have detected AGEs in recombinant human interferon gamma (rhIFN-gamma) produced in Escherichia coli as well as in total protein of the same bacterium using three different approaches: (i) Western blotting using two monoclonal antibodies raised against AGEs; (ii) fluorescent spectroscopy; and (iii) investigation of the effect of known AGE inhibitors (such as acetyl salicylic acid and thiamine) on the glycation reaction. Our study shows that non-enzymatic glycosylation is initiated during the normal growth of E. coli and results in AGE formation even after isolation of proteins. This process seems to be tightly associated with some post-translational modifications observed in the cysteineless rhIFN-gamma, such as covalent dimerization and truncation.

Assessment of serum osteocalcine level in pre-dialysis patients with chronic renal failure.

UNLABELLED: The application of serum osteocalcine as a marker of osseous synthesis in patients with renal osteodystrophy is still disputable because of its predominantly renal excretion. The aim of the present study was to investigate the level of serum osteocalcine in pre-dialysis patients with chronic renal failure (CRF). MATERIAL AND METHODS: 47 patients aged 22-60 years (26 males and 22 females) with chronic renal failure were studied. 23 of them were stage I CRF patients (creatinine up to 353.6 mumol/l) and 24 were stage II and III CRF patients (creatinine up to 800 mumol/l). 35 healthy subjects (15 males and 20 females) were used as controls. Serum osteocalcine was measured by a radioimmunologic assay (ELSA-OSTEO-CIS, France). Serum creatinine, calcium, phosphorus and alkaline phosphatase were detected on a biochemical analyzer "Optima" (Kone Instruments, Finland) using the standard techniques recommended by IFCC. RESULTS: Serum osteocalcine was significantly elevated in patients with stage I CRF (45.61 +/- 7.75 ng/ml), compared to the control group (14.61 +/- 1.02, p < 0.001; u = 3.96). A significant increase was also found in patients with stage II and III CRF (120.48 +/- 15.96 ng/ml, p < 0.001; u = 4.22). No significant difference in osteocalcine level was found between male and female patients (83.77 +/- 15.09 vs. 94.52 +/- 16.88). 32 (68%) patients of the entire sample had osteocalcine above the reference values. These included 11 out of 23 patients with stage I CRF (47%) and 21 out of 24 patients with stage II and III CRF (87%). A moderately positive correlation was established between osteocalcine level and the duration of CRF (0.57), as well as between serum creatinine (0.39) and phosphorus (0.34). A moderately negative correlation was discovered between creatinine clearance (-0.42) and total serum calcium (-0.37). CONCLUSIONS: Serum osteocalcine could be used as a marker for bone synthesis in pre-dialysis patients with CRF. Our results indicate that more than 50% of the patients show evidence for renal osteodystrophy.

Influence of age, sex and body weight on renal osteodystrophy in predialysis patients with chronic renal failure.

UNLABELLED: The aim of the present investigation was to examine the influence of age, sex and body weight on osseous changes in pre-dialysis patients with chronic renal failure (CRF). 87 patients (44 males and 43 females) aged 18-60 years with CRF were studied. The levels of serum creatinine, total and ionized calcium, phosphorus, alkaline phosphatase, intact parathormone and serum osteocalcine were followed up. Body weight is presented as BMI. 47 of the patients were subjected to double X-ray absorptiometry of lumbar vertebra (Lunar) and 40 patients were examined by computed tomography osteometry. RESULTS: No reliable differences in the levels of biochemical parameters in male and female patients with the same degree of CRF were established. A tendency towards an increase in the level of intact parathormone and serum osteocalcine in women with both initial and advanced CRF was recorded. The BMI in patients with advanced CRF was lower as compared to those with initial CRF. Different stages of osseous changes were observed in 29 males (74.35%) and in 25 females (60.97%). A tendency for a higher frequency and severity of osseous changes in men aged up to 40 years was observed. After this age males and females were equally affected. A high positive correlation (r = 0.50) between BMI and the percentage of the normal Bone Mineral Density/Bone Mineral Content in females with CRF stage II and III was noticed. CONCLUSIONS: No significant difference in the frequency and severity of osseous changes in male and female uremic patients was observed. Bone changes were more frequent and pronounced in males up to 40 years of age, while this tendency reversed after the menopause. The higher body weight was beneficial for the osseous changes only in females with advanced CRF, while in all other patients no correlation with densitometric parameters was noticed.

Dynamic follow-up of the intact parathormone levels in hemodialysis patients treated with Rocaltrol and calcium.

UNLABELLED: The object of the present study was to follow prospectively the serum levels of intact parathormone (PTH) of hemodialysis patients and the subsequent changes following the oral administration of 1.25(OH)D3 and calcium. METHODS: We studied 30 chronic renal failure hemodialysis patients--16 men and 14 women, aged 20-70 years. Twenty-one of them were on hemodialysis with duration of up to 5 years (Group 1) and nine--up to 10 years (Group 2). All patients received oral supplementation therapy with 1.0 elemental calcium and Rocaltrol (Roche) 0.25 microgram/day. We measured the serum calcium, ionized calcium, serum phosphorus, alkaline phosphatase and the intact serum PTH levels in intervals of 12 months. RESULTS: Patients with duration of dialysis of up to 5 years had a significantly lower baseline PTH level of 392.5 +/- 94.7 pg/ml versus 896.4 +/- 160.7 pg/ml for those from the second group (P < 0.01). The intact PTH levels showed a tendency towards decrease--at the end of the study they were as follows: 372.02 +/- 76.9 for group 1 versus a significant increase for those from group 2--serum PTH levels of 1793.65 +/- 290.3 (P < 0.02). The differences in alkaline phosphatase and serum phosphorus levels at the end of the study period failed to reach statistical significance. Serum calcium levels were increased in both groups following the initiation of treatment but the difference was statistically significant only for group 2. A significant positive correlation was observed between the duration of hemodialysis treatment and the intact serum PTH levels. CONCLUSIONS: 1. Long-term low-dose conventional calcitriol therapy in combination with calcium supplementation could slow the progression of secondary hyperparathyroidism in some hemodialysis patients. 2. Low-dose therapy with active vitamin D-metabolites is effective only in hemodialysis patients with baseline serum PTH levels below 500 pg/ml and without pronounced hyperphosphatemia.

Analytic performance of digoxin laboratory monitoring.

Since therapeutic drug monitoring is rapidly becoming a widely-used tool in clinical medicine we prospectively assessed 547 control samples over a period of 18 months using fluorescence polarization immunoassay, calibrators and control samples to determine the analytical performance of Abbott TDx in measuring serum digoxin levels. Recovery of the controls (within-run and between-run coefficient of variation) evaluated at the low, target therapeutic and intoxication ranges was 14%, 8% and 7% and precision was -3.57, -7.02, -3.38, respectively. Our clinical utility analysis showed that the prescribed dose provided serum digoxin levels within, above and below the targeted therapeutic range for 50.2%, 38.4% and 11.4% of the patients, respectively. The discrepancy between the calibrators and the controls, the tendency towards lower prescription dosage and patient noncompliance with the prescribed dose all account for these findings. The direct costs for digoxin serum concentration monitoring amount to 10 US $. A closer collaboration between the laboratory and the prescribing physician will undoubtedly form the basis of a more effective cost-efficacy strategy of digoxin serum monitoring as an indispensable tool and cornerstone of clinical decision-making.

[Epidemiology and early diagnosis of thyroid cancer (based on data from the Oncology Dispensary of the city of Stara Zagora, the People's Republic of Bulgaria)]. / Ob épidemiologii i rannei diagnostike raka shchitovidnoi zhelezy (po materialam onkologicheskogo dispansera g. Stara Zagora, NRB).

An epidemiologic study on thyroid gland cancer in the catchment area of Stara Zagora District Oncological Dispensary with a population of 645,000 was conducted in 1964-1983. The morbidity rate was 1.62/100,000 population, thyroid cancer amounting to 0.83% of all malignancies. Female morbidity was 2.7 times that of males. The highest level of morbidity for both sexes was in the age interval of 31-50 years. Morbidity in urban and rural areas was on the ratio of 1.5:1.