Synthesis of iron nanoparticles, its characterization and anti-microbial activity assessment

We report the efficacy of the Iron nanoparticles (IONPs) and assessed two different approaches for the synthesis of IONPs i.e. Polyol and co-precipitation method and further, evaluate their antimicrobial properties. Ferrous sulphate heptahydrate salts were reduced with ethylene glycol to obtain IONP and Fe+2 and Fe+3 co-precipitation reaction was performed with KOH at optimum heating. Further, synthesized (IONPs) were characterized by hydrodynamic radii measurement done by DLS clearly indicating the size of IONPs is 79.75nm in polyol based and 135.1 nm in co-precipitation method. The biological efficacy in terms of antimicrobial activity was assessed by the Kirby Bauer method, applied for both Gram-positive and Gram-negative bacteria such as Staphylococcus aureus and Escherichia coli, respectively. The ZOI values i.e. Zone of inhibition diameter was found to be clearly visible in both S. aureus and E. coli, indicating bactericidal activity. Further growth kinetics studies and bacterial genotoxicity was also assessed. Hence, IONPs synthesized are proposed to have great potential as an antibacterial agent and can be used in drug delivery.

Morphology and activity of human nucleus pulposus cells under different hydrostatic pressures / 中国组织工程研究

BACKGROUND: Compressive stress can change the morphology and activity of cells, but whether the morphology and activity of nucleus pulposus cells change under hydrostatic pressure still needs further study. OBJECTIVE: To study the morphology and activity of human nucleus pulposus cells in vitro. METHODS: The human nucleus pulposus cells were separated, cultured and passed on for three generations, and pressurized for 2, 4 and 6 hours under the hydrostatic pressure of 0.3, 1, and 3 MPa. Then, the morphological changes and growth of the cells before and after pressurization were observed by inverted phase contrast microscope. Transmission electron microscope was used to observe the ultrastructural changes and differences of the cells. Cell counting kit-8 was used to detect the proliferation activity, morphology and activity of the cells under different hydrostatic pressures. RESULTS AND CONCLUSION: (1) Cell culture and passage: The growth curves of the first, second and third generations of human nucleus pulposus cells were S-shaped, and the cells proliferated fastest in a straight line from 3 to 7 days. The protuberances of the 5th and 6th generation cells were long shuttle shaped, grew slowly and degenerated. (2) Cell morphology: the human nucleus pulposus cells were shrunk under hydrostatic pressures of 0.3, 1, 3 MPa. At 0.3 and 1 MPa, the cells became slightly smaller and the morphology was basically complete; at 3 MPa, the cells were most obviously shrunk and the morphology was incomplete. The results showed that when the human nucleus pulposus cells were pressurized for 2, 4 and 6 hours under 0.3, 1 and 3 MPa hydrostatic pressures, the change of cell morphology was the most obvious under 3 MPa hydrostatic pressure, but there was no obvious change under the same hydrostatic pressure for different time. (3) Cell viability: Under 0.3 MPa hydrostatic pressure, the proliferation rate of human nucleus pulposus cells first increased and then decreased with the increase of time, and the cell proliferation rate reached the peak at 4 hours. Under 1 and 3MPa hydrostatic pressures, the proliferation rate of the cells gradually decreased with the increase of time, and the cell proliferation rate under 1 MPa hydrostatic pressure was significantly higher than that under 3 MPa hydrostatic pressure at the same action time (P < 0.05). These findings indicate that proper hydrostatic pressure stimulation helps to promote the proliferation of human nucleus pulposus cells, and long-term improperly high hydrostatic pressure stimulation can reduce the proliferation rate of human nucleus pulposus cells, leading to the occurrence of intervertebral disc degeneration.

Dye degradation potential and its degradative enzymes synthesis of Bacillus cereus SKB12 isolated from a textile industrial effluent

The degradation of textile dyes using microbes has been recently identified as most promising, cost effective,and eco-friendly technique than any physiochemical techniques. On this backdrop, a potential Reactive Black5 dye degrading bacterium was isolated from effluent sediment samples of a textile industry, Salem district,Tamil Nadu, India which was identified as a Bacillus cereus SKB12 based on morphological and biochemicalmethods. This bacterium exhibited promising dye degradation of Reactive Black 5 which was initiatedfrom first hours of lag phase and showed its maximum dye degradation of 88.7% at the end decline growthphase (144 hours). Furthermore, this strain revealed the synthesis of laccase, veratryl alcohol oxidase, ligninperoxidase, polyphenol oxidase, and azoreductase enzymes with the presence of Reactive Black 5 dye. Theseoverall observations proved that this strain, B. cereus SKB12 has the possibility to use as a potential textile dyeeffluent bioremediation agent

Differential susceptibility & replication potential of Vero E6, BHK-21, RD, A-549, C6/36 cells & Aedes aegypti mosquitoes to three strains of chikungunya virus

Background & objectives: Chikungunya virus (CHIKV), a mosquito-borne arthritogenic virus causes infections ranging from febrile illness to debilitating polyarthralgia in humans. Re-emergence of the virus has affected millions of people in Africa and Asia since 2004. During the outbreak, a new lineage of the virus has evolved as an adaptation for enhanced replication and transmission by Aedes albopictus mosquito. A study was designed to compare the susceptibility of four vertebrate cell lines, namely Vero E6 (African green monkey kidney), BHK-21 (Baby hamster kidney), RD (human rhabdomyosarcoma), A-549 (human alveolar basal epithelial cell) and C6/36 (Ae. albopictus) to Asian genotype and two lineages of East, Central and South African (E1:A226 and E1:A226V) of CHIKV. Methods: One-step growth kinetics of different CHIKV strains was carried out in the above five cell lines to determine the growth kinetics and virus yield. Virus titre was determined by 50 per cent tissue culture infectious dose assay and titres were calculated by the Reed and Muench formula. Growth and virus yield of the three strains in Ae. aegypti mosquitoes was studied by intrathoracic inoculation and virus titration in Vero E6 cell line. Results: Virus titration showed Vero E6, C6/36 and BHK-21 cell lines are high virus yielding with all the three lineages while RD and A-549 yielded low virus titres. C6/36 cell line was the most sensitive and yielded the maximum titre. Ae. aegypti mosquitoes, when inoculated with high titre virus, yielded an almost equal growth with the three strains while rapid growth of E1:A226V and Asian strain was observed with 1 log virus. Interpretation & conclusions: C6/36 cell line was found to be the most sensitive and high yielding for CHIKV irrespective of lineages while Vero E6 and BHK-21 cell lines yielded high titres and may find application for vaccine/diagnostic development. Infection of Ae. aegypti mosquitoes with the three CHIKV strains gave almost identical pattern of growth.

Production of low value and eco-friendly bio-preservatives from Lactobacillus plantarumgrown on dairy whey

Aim: The current study aimed to evaluate the potential of milk whey medium to produce low value bio-preservatives. Methodology: Lactobacillus plantarum NZ7100 was obtained from NIZO Food Research, Netherlands. To analyze optimal biomass, desired product and precursor production under whey/whey permeate supplemented with various yeast extract concentration (0, 5, 10, 15 and 20 g l-1) and other economical media, batch fermentation was conducted and metabolites were analyzed using HPLC. Results: The study showed that whey permeate containing 15 g l-1 yeast extract supported maximum biomass formation of 1.7 g l-1 with significant production of total lactic acid and D-lactic acid of about 9.78 g l-1 and 4.41 g l-1. The kinetic parameters evaluated with commercial growth medium such as MRS-glucose and MRS-lactose demonstrated relatively lesser growth and lactate yield in whey permeate medium than in MRS medium. Interpretation: The study demonstrated the prospective of utilizing whey permeate medium to co-produce effective, eco- friendly, low cost natural preservatives using L. plantarum for usage in food and feed industry.

Carbon Dioxide Biofixation and Production of Spirulina sp. LEB 18 Biomass with Different Concentrations of NaNO3 and NaCl

ABSTRACT Microalgae are efficient at using solar energy to turn CO2 and nutrients into biomass containing lipids, proteins, carbohydrates and other compounds that may be used to produce bioproducts for human and animal consumption and pharmaceutical use. The aim of this study was to assess the effect of the NaNO3 and NaCl concentration on the growth kinetics, the biomass composition and the ability to biofix CO2 using the microalga Spirulina sp. LEB 18. The assays were carried out according to a 22 central composite design (CCD) with different concentrations of NaNO3 (1.25, 1.88 and 2.50 g L-1) and NaCl (1.00, 15.0 and 30.0 g L-1). The assays were carried out in 2 L vertical tubular photobioreactors at 30°C, 12 h light/dark and an injection of 12.0% v/v of CO2 at 0.3 vvm. The best growing results (Xmax = 1.60 g L-1, Pmax = 0.109 g L-1 d-1, μmax = 0.208 d-1) and CO2 biofixation rate (197.4 mg L-1 d-1) were observed in the assay with 1.25 g L-1 NaNO3 and 1.00 g L-1 NaCl. Increasing the NaCl concentration produced biomass with a higher carbohydrate content, while increasing the NaNO3 concentration reduced the protein concentration. According to the results, in addition to using Spirulina as a source of protein, it can also be used as a source of carbohydrates and to biologically remove CO2 from the atmosphere.

Large-scale Isolation, Expansion and Characterization of Human Amniotic Epithelial Cells

BACKGROUND AND OBJECTIVES: The human Amniotic epithelial cells (AME) derived from amniotic membrane of placenta have been considered as the potential fetal stem cell source with minimal or no ethical concerns and are important therapeutic tool for anti-fibrotic and regenerative therapies. METHODS AND RESULTS: Here, we evaluated the isolation, media screening, scale-up and characterization of AME cells. The isolation, expansion of AMEs were performed by sequential passaging and growth kinetics studies. The AMEs were characterized using immunocytochemistry, immunophenotyping, In-vitro differentiation, and anti-fibrotic assays. The growth kinetics study revealed that the AME cultured in Ultraculture (UC) and DMEM knockout (DMEM-KO) have prominently higher growth rate compared to others. Overall, the AMEs cultured from 5 different media retained basic morphological characteristics and the functional characteristics. CONCLUSIONS: Our result suggests that the AMEs can be successfully cultured in UC based complete media without losing its epithelial cell characteristics even after passaging for passage 2 (P2). However, a careful and methodical pre-clinical and clinical translation studies need to be conducted to show its safety and efficacy.

Construction of Human Cytomegalovirus Han?ΔUS12?BAC Strain and Studies on Its Replication in Human Embryonic Lung Fibroblasts / 中国医科大学学报

Objective To construct human cytomegalovirus(HCMV)Han?ΔUS12?BAC strain and to study the role of US12 in HCMV replica?tion in human embryonic lung fibroblasts(HELF). Methods Kanamycin?resistant gene was amplified with primers containing homology arms se?quence flanking US12 and then electroporated into E.coli DY380?Han?wt?BAC competent cells. Successfully recombinant Han?ΔUS12?BAC clones were identified by PCR,sequenced for confirmation Han?ΔUS12?BAC plasmids were electroporated into HELF to produce infectious viri?ons. Han?ΔUS12?BAC and Han?wt?BAC were inoculated onto HELF at the multiplicity of infection of 0.1 pfu/cell. The viral titer in the supernatant was measured by TCID50 assay and growth kinetics of the viruses in HELF was studied. Results Han?ΔUS12?BAC clone was successfully con?structed. Han?ΔUS12?BAC was reconstructed in HELF to generate infectious virions. Growth kinetics assay indicated that Han?ΔUS12?BAC and Han?wt?BAC showed no differences in their growth and dissemination in HELF. Conclusion US12 in HCMV clinical strain Han is dispensable for HCMV growth and dissemination in HELF.

Comparative growth of spotted fever group Rickettsia spp. strains in Vero cells

In Brazil, the spotted fever group (SFG) Rickettsia rickettsii and Rickettsia parkeri related species are the etiological agents of spotted fever rickettsiosis. However, the SFG, Rickettsia rhipicephali, that infects humans, has never been reported. The study of growth dynamics can be useful for understanding the infective and invasive capacity of these pathogens. Here, the growth rates of the Brazilian isolates R. rickettsii str. Taiaçu, R. parkeri str. At#24, and R. rhipicephali HJ#5, were evaluated in Vero cells by quantitative polymerase chain reaction. R. rhipicephali showed different kinetic growth compared to R. rickettsii and R. parkeri.

Molecular characterization of a Xylanase-producing fungus isolated from fouled soil

Xylanase (EC 3. 2. 1. 8), hydrolyzes xylo-oligosaccharides into D-xylose and required for complete hydrolysis of native cellulose and biomass conversion. It has broad range of applications in the pulp and paper, pharmaceutical and Agri-food industries. Fifty fungal species were isolated from the fouled soil around an oil refinery and screened for the production of xylanase enzyme by enrichment culture techniques. The isolated fungal strain was identified as Hypocrea lixii SS1 based on the results of biochemical tests and 18s rRNA sequencing. The phylogenetic tree was constructed using the MEGA 5 software. Further, Hypocrea lixii SS1 was tested for the ability to utilize the sunflower oil sludge (waste from the oil industry) as the sole carbon source for xylanase production. The growth characteristics of Hypocrea lixii SS1 were also studied and maximum growth was found on the 7th day of incubation. The fungus showed a remarkable xylanase production of 38.9 U/mL. Xylanase was purified using a combination of 0-50% NH4SO2 precipitation, DEAE-sepharose and Sephacryl S-200 chromatography. Single peak obtained in RP-HPLC confirms the purity of xylanase. Further the enzyme produced was affirmed as xylanase with its molecular weight (29 kDa) using SDS-PAGE.

Screening of wild type Streptomyces isolates able to overproduce clavulanic acid

The selection of new microorganisms able to produce antimicrobial compounds is hoped for to reduce their production costs and the side effects caused by synthetic drugs. Clavulanic acid is a β-lactam antibiotic produced by submerged culture, which is widely used in medicine as a powerful inhibitor of β-lactamases, enzymes produced by bacteria resistant to antibiotics such penicillin and cephalosporin. The purpose of this work was to select the best clavulanic acid producer among strains of Streptomyces belonging to the Microorganism Collection of the Department of Antibiotics of the Federal University of Pernambuco (DAUFPE). Initially, the strains were studied for their capacity to inhibit the action of β-lactamases produced by Klebsiella aerogenes ATCC 15380. From these results, five strains were selected to investigate the batch kinetics of growth and clavulanic acid production in submerged culture carried out in flasks. The results were compared with the ones obtained by Streptomyces clavuligerus ATCC 27064 selected as a control strain. The best clavulanic acid producer was Streptomyces DAUFPE 3060, molecularly identified as Streptomyces variabilis, which increased the clavulanic acid production by 28% compared to the control strain. This work contributes to the enlargement of knowledge on new Streptomyces wild strains able to produce clavulanic acid by submerged culture.

Establishment of cell suspension cultures of two Costa Rican Jatropha species (Euphorbiaceae) / Establecimiento de suspensiones celulares de dos especies Jatropha (Euphorbiaceae) de Costa Rica

J. curcas has been studied in different countries and some interesting agronomic, pharmacological and industrial properties have been reported. More recently, it has been considered an important alternative source for biofuel production. The objective of this study was to establish a long-term method for the maintenance of calli and cell suspension cultures of the local species J. curcas and J. gossypifolia, in order to allow future studies for novel compounds with pharmaceutical or industrial applications. For this, friable calli were successfully induced from hypocotyl segments of J. curcas and J. gossypifolia that were cultured in semisolid MS media supplemented with 1.5mg/L, and 0.5mg/L of 2,4-D, respectively. Cell suspension cultures of J. curcas were established using 1g of 35 and 60-day calli, in 50mL of liquid MS media supplied with 1.5mg/L of 2,4-D; sucrose and maltose were additionally evaluated as carbon sources. After 35 days, cell suspension cultures initiated with 35-day calli, showed greater cell growth with a maximum biomass of 194.9g/L fresh weight, 6.59g/L dry weight and 17.3% packed volume. The exponential phase ended at day 35 for cultures initiated with 35-day calli, and at day 21 for cultures initiated with 60-day calli. Higher biomass production was obtained with sucrose. Cell cultures were established with 35-day calli in MS media with the same 2,4-D concentration used for calli induction and 30g/L sucrose. This medium was considered optimum for the maintenance and growth of cell suspensions for both species, with sub-cultures every 20 days. The biotechnological potential for the production of bioactive compounds in these species for pharmacological, agricultural and industrial applications is being evaluated.

J. curcas es un importante recurso alternativo de biocombustible. Por otro lado, propiedades de interés agronómico, farmacológico e industrial han sido reportadas para esta especie. El objetivo de este estudio fue el establecimiento y mantenimiento a largo plazo de callos y cultivos celulares en suspensión de J. curcas y J. gossypifolia, con el objetivo de permitir futuros estudios para nuevos compuestos con aplicaciones farmaceúticas e industriales. Los callos friables fueron exitosamente inducidos a partir de segmentos de hipocótilos J. curcas and J. gossypifolia cultivados en medio MS semisólido suplementado con 1.5mg/L y 0.5mg/L of 2,4-D, respectivamente. Los cultivos celulares en suspensión de J. curcas fueron establecidos utilizando 1g de callos de 35 y 60 días de edad en 50mL de medio MS líquido adicionado con 1.5mg/L de 2,4-D. Después de 35 días, los cultivos en suspensión celular iniciados con callos de 35 días, mostraron mayor crecimiento celular con una biomasa máxima de 194.9g/L de peso fresco y 6.59g/L de peso seco y 17.3% de volumen empacado. La fase exponencial finalizó al día 35 en los cultivos iniciados con callos de 35 días, y al día 21 en los cultivos iniciados con callos de 60 días. Dos fuentes de carbono fueron evaluadas: sacarosa y maltosa. La producción de mayor biomasa fue obtenida con sacarosa. Los cultivos celulares se establecieron con callos de 35 días cultivados en medio MS con la misma concentración de 2,4-D utilizada para la inducción de callos y 30g/L de sacarosa. Este medio fue considerado el óptimo para el mantenimiento y crecimiento de suspensiones celulares en ambas especies con subcultivos cada 20 días. El potencial biotecnológico para la producción de compuestos bioactivos en estas especies, para aplicaciones farmacológicas, agrícolas e industriales está siendo evaluado.

Growth and biopigment accumulation of cyanobacterium Spirulina platensis at different light intensities and temperature

In order to find out optimum culture condition for algal growth, the effect of light irradiance and temperature on growth rate, biomass composition and pigment production of Spirulina platensis were studied in axenic batch cultures. Growth kinetics of cultures showed a wide range of temperature tolerance from 20 ºC to 40 ºC. Maximum growth rate, cell production with maximum accumulation of chlorophyll and phycobilliproteins were found at temperature 35 ºC and 2,000 lux light intensity. But with further increase in temperature and light intensity, reduction in growth rate was observed. Carotenoid content was found maximum at 3,500 lux. Improvement in the carotenoid content with increase in light intensity is an adaptive mechanism of cyanobacterium S.platensis for photoprotection, could be a good basis for the exploitation of microalgae as a source of biopigments.

Ex Vivo Observation of Human Nucleus Pulposus Chondrocytes Isolated From Degenerated Intervertebral Discs

STUDY DESIGN: We performed an ex vivo study to observe cell morphology and viability of human nucleus pulposus (NP) chondrocytes isolated from degenerated intervertebral discs (IVD). PURPOSE: To better understand the biological behavior of NP chondrocytes in monolayer cultures. OVERVIEW OF LITERATURE: Biological repair of IVDs by cell-based therapy has been shown to be feasible in clinical trials. As one of the most promising transplanting seeds, how the isolated NP chondrocytes behavior ex vivo has not been fully understood. METHODS: Human NP chondrocytes were harvested from 20 degenerated IVDs and cultured in monolayers. Histological and immunochemistry staining was used to detect cell morphology change. Cell viability was studied by analyzing cell cycle distribution and apoptotic rate in the primary and subculuted cells. RESULTS: The round or polygonal primary NP chondrocytes had an average adherence time of 7 days and took nearly 31 days to reach 95% confluence. The spindle-shaped P1 NP chondrocytes increased growth kinetics and took about 12 hours to adhere and 6.6 days to get 95% confluent. Immunochemistry staining of collagen II was positive in the cell cytoplasm. Nearly 90% of the confluent NP chondrocytes stayed in G1 phase while 16% underwent apoptosis. No significant difference of the collagen II expression, cell cycle distribution or the apoptosis indices were detected between the primary and subcultured NP chondrocytes. CONCLUSIONS: Human NP chondrocytes undergo significant morphological change in monolayer cultures. Cell cycle distribution pattern and apoptosis index of the cutured NP chondrocytes potentially influence their clinical transplantation or laboratory use.

Chandipura virus growth kinetics in vertebrate cell lines, insect cell lines & embryonated eggs.

Background & objectives: Since not much information on Chandipura virus is available, an attempt was made to study the growth kinetics of the virus in certain vertebrate, invertebrate cell lines and embryonated chicken eggs. Methods: Comparative study of Chandipura virus (CHPV) growth kinetics in three vertebrate cell lines [Vero E6, Rhabdo myosarcoma (RD), Porcine stable kidney (PS) cell lines], two insect cell lines [Aedes aegypti (AA) and Phlebotomus papatasi (PP-9) cell lines] and embryonated pathogen free chicken eggs was conducted, by tissue culture infective dose 50 per cent (TCID50) and indirect immunofluorescence assay (IFA). Results: All the cell lines and embryonated egg supported the growth of CHPV and yielded high virus titre. The vertebrate cell lines showed distinct cytopathic effect (CPE) within 4-6 h post infection (PI), while no CPE was observed in insect cell lines. PP-9 cell line was the most sensitive system to CHPV as viral antigen could be detected at 1 h PI by IFA. Interpretation & conclusions: Our results demonstrated that all the systems were susceptible to CHPV and achieved high yield of virus. However, the PP-9 cell line had an edge over the others due to its high sensitivity to the virus which might be useful for detection and isolation of the virus during epidemics.

Growth kinetics of mycobacterium tuberculosis measured by quantitative resazurin reduction assay: a tool for fitness studies

We standardized a method to evaluate the growth kinetics of Mycobacterium tuberculosis by measuring quantitatively the reduction of resazurin by spectrophotometry. Growth curves and the rate of growth of twenty-one M. tuberculosis clinical isolates were determined. The method showed technical simplicity and is inexpensive to assess the fitness of each isolate.

Catechol biodegradation kinetics using Candida parapsilopsis

This study evaluated the biodegradation of catechol by a yeast strain of Candida parapsilopsis in standard medium in Erlenmeyer flasks. Results shown that the highest concentration of catechol caused the longer lag period, demonstrating that acclimatized cultures could completely degrade an initial catechol concentration of 910 mg/L within 48 h. Haldane's model validated the experimental data adequately for growth kinetics over the studied catechol concentration ranges of 36 to 910 mg/L. The constants obtained for this model were µmax = 0.246 h-1, Ks = 16.95 mg/L and Ki = 604.85 mg/L.

Neste trabalho foi estudada a biodegradação de catecol em frascos de Erlenmeyers em água residuária sintética pela levedura Candida parapsilopsis. As respostas dos ensaios cinéticos mostraram que altas concentrações de catecol ocasionaram uma fase lag longa para a levedura. Portanto, a aclimatização da cultura de levedura empregada para biodegradação de catecol é de fundamental importância, sendo possível reduzir toda a concentração inicial de catecol da água residuária sintética de 910 mg/L em 48 horas. Os dados experimentais da cinética de biodegradação do catecol foram ajustados pelo modelo de Haldane adequadamente, sobre a faixa de concentração de catecol investigada de 36 a 910 mg/L. Os parâmetros cinéticos obtidos do modelo de Haldane foram: µmax = 0,246 h-1, Ks = 16,95 mg/L e Ki = 604,85 mg/L.

Sequential use of ammonium and leucine as nitrogen sources during growth of Geotrichum candidum on a glucose based medium / Uso secuencial del amonio y leucina como fuentes de nitrógeno durante el crecimiento de Geotrichum candidum en un medio basado en glucosa

Geotrichum candidum growth on ammonium and leucine as nitrogen sources and glucose as a carbon source was examined. A clear preference of G. candidum for ammonium over leucine as a nitrogen source was shown. Indeed, ammonium was completely exhausted at the end of exponential growth after less than 35 hrs of culture; in contrast only 5 percent of leucine was concomitantly assimilated. Growth continued at slower rates on glucose and leucine as carbon and nitrogen sources respectively, and at the end of culture (185 hrs), leucine was completely exhausted.

Effects of extremely low frequency magnetic field on growth kinetics, metabolism and cell cycle of human liver cancer cells / 现代生物医学进展

Objective: To study the effects of extremely low frequency (ELF) magnetic field with fixed parameters on human liver cancer cells (SK-HEP-1) at different aspects. Methods: SK-HEP-1 cells were exposed to 50Hz, 20mT magnetic field during the whole culture process, and then proliferation activity, growth kinetics, metabolic profile and cell cycle were analyzed. Results: 50Hz, 20mT magnetic field inhibits the growth and metabolism of SK-HEP-1 cells, and hampers their mitotic division. Conclusion: 50Hz, 20mT magnetic field could be a potential therapy in the treatment of human malignant tumors.

Stereological Analysis of gamma-Glutamyl Transpeptidase Positive Foci in Diethylnitrosamine-Induced Hepatocarcinogenesis of Sprague-Dawley Rats / 대한간학회지

BACKGROUND/AIMS: Hepatocarcinogenesis of microscopically altered foci could be shown to be progressed into a trabecular pattern of hepatocellular carcinoma. And it is reported that down-regulation of TGF beta II receptor and up-regulation of TGF alpha and c-myc reveal the progression of diethylnitrosamine-induced foci into liver cell cancer. Up-regulation of TGF beta II receptor, however, causes apoptosis of foci. To determine characteristic morphology and growth kinetics of putatively precancerous y glutamyl transpeptidase (GGT) positive foci and hyperplastic nodules, a stereological quantification was attempted in the Peraino's neonatal rat model initiated by diethylnitrosamine and promoted by phenobarbital. MATERIALS/METHODS: Fifteen Sprague-Dawley rats were I.p. injected with 0.15 pmole/g of body weight of diethylnitrosamine mixed in corn oil at one day after birth. From weaning at 4 weeks of life, the rats were continuously fed 0.035% phenobarbital in drinking water and sacrified 5 rats at each time point of 8 weeks, 16 weeks, and 32 weeks. Teklad standard diet was fed after weaning. The livers obtained were fixed in freshly prepared, cold ethanol-acetic acid (99:1 vo1%). For the GGT histochemical staining, Rutenberg's method was modified, and counterstained with H & E or toluidine blue. For the stereological analysis GGT positive foci and nodules were traced in 200 consecutive tissue sections and quantified the 3 dimensional volumes by computer assisted planimetry. Either spheroidal or non-spheroidal morphology was determined by parabola 2nd degree equation ' y=ax+bx+c (sphere a=-P,). RESULTS: Thirty nine (55.71%) out of 70 representative lesions were nonspheroidal. Especially at 8 weeks, the 28 out of 40 GGT positive foci were irregular, nonspheroidal shape. Later times, however, GGT positive foci and reprogrammed nodular lesions were become spheroidal. Lilliefors probabilities test for spheroidal frequency was statistically significant (p<0.05). CONCLUSION: Stereologically non-spheroidal characteristics of the early GGT positive foci limit growth kinetic estimation by 3 dimensional volume quantitation but permit in later times in spheroidal, GGT positive foci and reprogrammed nodules showing fade-out of GGT activity. In other words, GGT positive foci may be clonally selected for growing into hyperplastic nodules and hepatocellular carcinoma or regressed by apoptosis.