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Biomedical subjects

B L Li

Publications and source records attributed to B L Li.

61 records · Page 4Linked to original sources
PubMedDate not supplied

Influence of rapid correction of metabolic acidosis on serum osteocalcin level in chronic renal failure.

Metabolic acidosis induces a combination of inhibited osteoblastic and stimulated osteoclastic activity. To determine the role of alkali therapy in osteoblast function in chronic renal failure, serum bone isoenzyme of alkaline phosphatase (BAP) and osteocalcin were assessed before and after bicarbonate infusion. Eighteen patients with mild to moderate metabolic acidosis, none of whom had received dialysis therapy, were enrolled in this study. Metabolic acidosis was corrected by continuous bicarbonate infusion while plasma ionized calcium was monitored at 5 min intervals and held at the preinfusion level by calcium solution infusion during the entire procedure. The end-point of the study was reached when the plasma bicarbonate was approximately 24 mmol/l or pH was approximately 7.4 and plasma ionized calcium was clamped at the preinfusion level with only a 0.01 mmol/l fluctuation. The plasma pH (7.31 +/- 0.04 vs. 7.40 +/- 0.03, P < 0.001), bicarbonate (18.46 +/- 2.49 vs. 23.66 +/- 2.72 mmol/l, P < 0.001), serum total calcium, and osteocalcin (15.61 +/- 6.45 vs. 18.79 +/- 6.71 mg/l, P < 0.05) levels were significantly increased, whereas serum concentrations of alkaline phosphatase and albumin levels were significantly decreased after bicarbonate infusion. The serum BAP (1.85 +/- 1.29 vs. 1.79 +/- 1.18 mukat/l, P = 0.252), and inorganic phosphorus levels showed no significant differences before and after bicarbonate infusion. These results demonstrate that rapid correction of metabolic acidosis improves osteoblast function and may underline the importance of maintaining normal acid-base homeostasis in chronic renal failure.

Acid-Base Equilibrium↗
PubMedDate not supplied

Vascular dementia, with special reference to its vascular and immunological events.

Vascular dementia (VaD) is an poorly defined entity; it relates to different vascular mechanisms and different changes in the brain and has different clinical manifestations with different etiologies. From the pathogenetic and therapeutic point of view, we tried to find some practical events that could help identify VaD. We combined critical review with our own clinical and laboratory experience and found that some vascular, nonvascular, and immunological components are involved in the pathogenesis and treatment of VaD. We concluded that although the definition, etiology, clinical manifestation, laboratory data, and treatment are still controversial, it is useful to find some common, key points in the pathogenesis and treatment of VaD.

Dementia, Vascular↗
PubMedDate not supplied

[Interdependence of plankton spatial distribution and plancton biomass temporal oscillations: mathematical simulation].

The dynamics of aquatic biological communities in a patchy environment is of great interest in respect to interrelations between phenomena at various spatial and time scales. To study the complex plankton dynamics in relation to variations of such a biologically essential parameter as the fish predation rate, we use a simple reaction-diffusion model of trophic interactions between phytoplankton, zooplankton, and fish. We suggest that plankton is distributed between two habitats one of which is fish-free due to hydrological inhomogeneity, while the other is fish-populated. We show that temporal variations in the fish predation rate do not violate the strong correspondence between the character of spatial distribution of plankton and changes of plankton biomass in time: regular temporal oscillations of plankton biomass correspond to large-scale plankton patches, while chaotic oscillations correspond to small-scale plankton patterns. As in the case of the constant fish predation rate, the chaotic plankton dynamics is characterized by coexistence of the chaotic attractor and limit cycle.

Algorithms↗
PubMedDate not supplied

[Effect of the rate of phytoplankton growth on the spaced-time dynamics of plankton communities in an homogeneous environment].

We use a conceptual mathematical reaction-diffusion model to investigate the mechanisms of spatial structure formation and complex temporal dynamics of plankton in a heterogeneous environment. We take into account basic trophic interactions, namely, "prey-predator" interactions between phytoplankton, zooplankton, and fish in upper layers of natural waters. We consider plankton as a passive contaminant in turbulent waters. We show that plankton structure formation can result from the difference in phytoplankton growth rate in neighboring habitats. Phytoplankton and zooplankton biomass is shown to undergo both regular and chaotic oscillations. The fish predation rate substantially affects the spatial and temporal dynamics of plankton in a heterogeneous environment.

Animals↗
PubMedDate not supplied

[A conceptual model of the dynamics of the Syamozero lake community].

We have developed a conceptual mathematical model of the dynamics of a spatially heterogeneous population system, the prototype of which is the Syamozero lake fish community. Based on the analysis of solutions of the model, we show that interrelations between prey and predator populations in two neighboring habitats (pelagic and offshore zones) can lead to both undamped oscillations and stationary values of the population size. The population density was found to be close to the values oblained in the course of long-term observations of the biota of the Syamozero lake. Besides, we showed that the transition to the stationary states can be accompanied by long-term (dozens and hundreds of years) damped oscillations of the prey and predator population size. In natural waters, long-term transition periods can prevent the attainment of stationary regimes of fish community functioning.

Animals↗
PubMedDate not supplied

Construction of a modified murine interferon alpha with increased stability.

The mutant [Ser86] murine interferon alpha A was constructed by oligodeoxyribonucleotide-directed site-specific mutagenesis and expressed under the control of lambda phage PL promoter in Escherichia coli. The effect of the substitution of serine for the cysteine residue at position 86 in the murine interferon alpha A was studied. It was observed that the mutant Ser86 murine interferon alpha A which does not contain the free cysteine residue in the peptide was inactivated more slowly than its parent with a free cysteine residue at position 86. Heat-inactivated murine interferon alpha A cannot be reactivated, but the heat-inactivated Ser86 derivative can be reactivated significantly to about 27.5 per cent of the original activity in the presence of sodium dodecylsulfate. These results suggest that the free cysteine in the peptide is a factor contributing to the instability of the protein.

Bacteriophage lambda↗