Growth Kinetics Assay Research Articles

Influence of Age and Body Mass Index on the Yield and Proliferation Capacity of Adipose-Derived Stem Cells

Adipose tissue is commonly used for volume restoration. It is also a source of adipose-derived stem cells (ASCs), easy to obtain in large quantities by liposuction or resection techniques. The aim of this study was to determine the influence of body mass index (BMI) and age on the number (yield) and proliferation capacity of ASCs. A prospective study was conducted in 42 women. They were divided into two groups: age≤40 or >40 and BMI≤25 or >25. Fat tissue was harvested via manual lipoaspiration always from the abdominal region. After centrifugation in the OR, the harvested fat (100cc) was sent to the laboratory for isolation and cultivation of ASCs. The yield of viable ASCs was evaluated by the trypan blue exclusion test. Viable ASCs were cultured and their proliferation capacity was evaluated by the growth kinetics assay. Results were statistically analyzed. The average cell yield was 0.380×10(6)/ml. Cell yield and proliferation capacity did not show statistically significant correlation to the age and BMI of patients, with regression lines showing null correlation. There was no significant difference between the cell yield and proliferation capacity between the different groups. The results from this study suggest that there is no statistically significant correlation between ASC yield and proliferation capacity and age and BMI.

Isolation and identification of phenol degrading bacteria from Lake Parishan and their growth kinetic assay.

Phenol and its components are extremely toxic and can easily be isolated from different industrial sewage such as oil refinery, petrochemical industry and mines, especially collier and chemical factories. Hence the presence of these compounds in the environment could cause environmental pollution, especially in water resources. In the past, physicochemical method was used for the elimination of phenol and its compounds, but today, bioremediation is preferable. The aim of this study is to isolate and identify phenol degrading bacteria from Lake Parishan and to assay their kinetic growth. Sixty samples of water and sedimentation of different area of Lake Parishan were collected. In order to isolate phenol degrading bacteria, samples were cultured on salt base phenol broth media. For screening of degrading bacteria, bromothymole blue indicator was added to media, which formed green color in it. Finally, the ability of bacteria to degrade different concentration of phenol was measured using culturing bacteria in different concentration of phenol from 0.2 to 0.9 g/l. Cultivated bacteria on the salt base phenol broth containing indicator changed the color of the media from green to yellow by using the phenol and decreasing the pH. These bacteria were, chiefly, gram negative and they belong to Pseudomonaceae and Acinetobacteraceae Family. Psuodomonas spp. are the most important phenol degrading bacteria in Lake Parishan which showed vast diversity in different parts of this lake. Species of Acinetobacter and other species such as Kelibsiella, Citrobacter and Shigella were found as well. Most of the isolated bacteria showed a good ability of degradation of phenol, where Pseudomonas and Acinetobacter showed 0.8 - 0.9 g/l, and Kelibsiella, Citrobacter and Shigella showed 0.6 - 0.7 g/l and the rest showed 0.2 - 0.3 g/l of phenol degradation. Findings show that the Lake Parishan has a lot of high ability phenol degrading bacteria. The most important species belong to Psuodomonas and Acinetobacter . Key words : Phenol, degrading, Pseudomonas, Acinetobacter , Lake Parishan.

Occurrence of nisin Z production in Lactococcus lactis BFE 1500 isolated from wara, a traditional Nigerian cheese product

Screening for bacteriocin production of 500 strains of lactic acid bacteria (LAB) from various African fermented foods resulted in the detection of a bacteriocin producing Lactococcus lactis (BFE 1500) isolated from a dairy product called wara. The bacteriocin inhibited not only the closely related LAB, but also strains of Listeria monocytogenes, Listeria innocua, Clostridium butyricum, Clostridium perfringens, Bacillus cereus and Staphylococcus aureus. It was heat stable even at autoclaving temperature (121°C for 15 min) and was active over a wide pH range (2–10), but highest activity was observed in the lower pH range. The bacteriocin was inactivated by α-chymotrypsin and proteinase K, but not by other proteases. Growth kinetic assay indicated stronger growth inhibition by the bacteriocin produced by Lc. lactis BFE 1500 on L. monocytogenes WS 2250 and B. cereus DSM 2301 than with the nisin A producing strain DSM 20729. Polymerase chain reaction indicated the presence of the nisin operon in strain BFE 1500 and sequencing of its structural gene showed that Lc. lactis BFE 1500 produced the natural nisin variant, nisin Z, as indicated by the substitution of asparagine residue instead of histidine at position 27. The genetic determinants for bacteriocin production in strain BFE 1500 are located on a conjugative transposon. The ability of the bacteriocin produced by Lc. lactis BFE 1500 to inhibit a wide range of food-borne pathogens is of special interest for food safety, especially in the African environment with perennial problems of poor food hygiene.

Interactions of interferon and vinblastine on experimental tumor modei melanoma B-16 in vitro

In this study, we tried to define in vitro interactions of two antitumor agents that have different sites and different mechanisms of action. Vinblastine (VLB) in combination with human recombinant interferon-alpha A/D (rHuIFN-alpha A/D) and in combination with murine recombinant interferon-gamma (rMuIFN-gamma) was studied. The effect of the combination was determined with cell growth kinetics assay on B-16 melanoma and the interaction defined by means of Spector's formula. Both the combination of rHuIFN-alpha A/D with VLB and the combination of rMuIFN-gamma with VLB synergistically inhibited cell growth in vitro. There was a positive biochemical modulation between the two drugs, but it is still unknown whether it occurred at the level of uptake into the cell, metabolism within the cell or egress from the cell.

Seasonal Phytoplankton Demographic Processes and Experiments on Interspecific Competition

Population dynamics of Lake Tahoe phytoplankton species were studied during 1985. Four dominant diatoms were examined: Cyclotella glomerata, Cyclotella ocellata, Synedra amphicephala, and Synedra radians. The role of interspecific resource—based competition during spring and summer was tested in three ways: (1) species distribution patterns along the vertical gradient (upper 100 m of the water column), (2) measurements of in situ growth and loss (sinking, grazing, natural death, diffusion) processes, and (3) transplants of assemblages between depths. All three tests indicated that resource—based competition was important. Species clearly segregated with thermal stratification and nutrient depletion in the epilimnion. C. glomerata peaked within the epilimnion (0—20 m), S. radians became dominant in the deep chlorophyll maximum region (60—90 m), and the other species peaked at intermediate depths. Resource—limited growth was a dominant process during this time, and sinking and natural death were significant losses. Experimental transplants of assemblages between two depths (15 and 75 m) demonstrated competitive interactions in the phosphate—limited region near the surface, but there was no evidence of competition in the deeper light—limited region. This suggested asymmetrical competition along the vertical gradient. Primary productivity nutrient—enrichment bioassays and growth kinetic assays (phosphate, nitrate, light) also indicated that phosphate and light limitation were important bases of species interactions.

Dexamethasone enhances human cytomegalovirus replication in human epithelial cell cultures

An epithelial human hepatoma cell line (PLC/PRF/5) and a primary epithelial human baby kidney (HBK) cell culture showed restricted growth of human cytomegalovirus (HCMV). Treatment of these two epithelial cell cultures with dexamethasone greatly enhanced their ability to support HCMV replication. Growth kinetic experiments and infectious center assay revealed that in both the hormone-treated cultures infectious progeny virus appeared earlier by 1 or 2 days and 5- or 10-fold more cells are able to produce infectious virus. There was an approximate 50- or 100-fold increase in virus yield compared to that in the untreated control cultures. Enhanced HCMV replication in the hormone-treated cultures was not due to differences in the cell growth or the virus adsorption and was supported by evidence of increased synthesis of HCMV-specific immediate early antigens and DNA.

Antagonism of ampicillin and chloramphenicol for meningeal isolates of group B streptococci.

The increasing prevalence of ampicillin-resistant Haemophilus influenzae type b has led to the recommendation that ampicillin and chloramphenicol be given as the initial therapy for suspected bacterial meningitis in infants and children. However, during the first 2 months of life, H. influenzae type b is a rare cause of meningitis, whereas group B streptococcus is the most frequently isolated agent. Since ampicillin and chloramphenicol have been shown to be antagonistic for other streptococci, an in vitro study of their effect on group B streptococci was performed. The effect of ampicillin and chloramphenicol, alone and in combination, on 18 meningeal isolates was determined for 2 different inocula of group B streptococci, using microtiter broth dilution and growth kinetic assays. Isoboles, fractional lethal concentration indices, or both indicated antagonism for all strains. Growth kinetic assays for two representative strains demonstrated inhibition of the early bactericidal activity of ampicillin by chloramphenicol. These findings of in vitro antagonism suggest that this combination may be contraindicated for the treatment of infants with group B streptococcal meningitis.