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PubMed1999

Antisense oligodeoxynucleotides downregulated c-sis mRNA expression to inhibit proliferation of vascular smooth muscle cells.

AIM: To assess the inhibitory effect of c-sis antisense oligodeoxynucleotides (ODN) on vascular smooth muscle cells (VSMC) proliferation and c-sis proto-oncogene mRNA expression. METHODS: The VSMC were cultured with Dulbecco's modified Engle's medium (DMEM) containing synthesized c-sis antisense or sense oligomers, [3H]thymidine (TdR) incorporation into DNA was determined by liquid scintillation counter and the numbers of cells were counted by cell counting plate, the mRNA level was observed by using of reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: C-sis antisense ODN 2, 4, 6, 8, and 10 mumol.L-1 inhibited VSMC proliferation (10.3% +/- 0.7%, 22.6% +/- 0.9%, 31.0% +/- 1.1%, 35.4% +/- 0.9%, and 43.3% +/- 1.2%) and [3H]TdR incorporation (6.8% +/- 0.3%, 9.7% +/- 0.7%, 29.0% +/- 0.6%, 32.0% +/- 0.7%, and 50.6% +/- 1.3%) in a concentration-dependent manner. When VSMC were treated with antisense ODN 10 mumol.L-1 for 4 d, the highest inhibitory rate of VSMC growth and that of [3H]TdR incorporation were 60.3% +/- 1.0% and 56.3% +/- 0.9%, respectively. RT-PCR showed that c-sis proto-oncogene antisense ODN downregulated c-sis mRNA expression obviously, while c-sis sense ODN did not inhibit VSMC proliferation and expression of c-sis proto-oncogene mRNA. CONCLUSION: The c-sis antisense ODN inhibited VSMC proliferation and downregulated c-sis mRNA level.

Animals↗
PubMed1999

Phospholipase C activation by Na+/Ca2+ exchange is essential for monensin-induced Ca2+ influx and arachidonic acid release in FRTL-5 thyroid cells.

BACKGROUND: Monensin, a Na+ ionophore, can increase cytosolic Ca2+ ([Ca2+]i) by reversing the Na+/Ca2+ exchange mechanism. This study provided additional insights into the mechanism of this Na+ ionophore-induced increase in [Ca2+]i, and emphasized the critical role of phospholipase C (PLC) in amplifying Na+/Ca2+ exchange-induced Ca2+ influx and subsequent arachidonic acid (AA) release in FRTL-5 thyroid cells. The possible involvement of protein kinase C (PKC), mitogen-activated protein kinase (MAPK), and GTP-binding (G) protein in mediating monensin-induced AA release was also explored. METHODS: FRTL-5 thyroid cells were maintained in Coon's modified Ham's F-12 medium supplemented with a 6-hormone (6H) mixture. Cytosolic Ca2+ was measured by using indo-1 AM and a dual-wave-length spectrofluorometer. Release of 3H-labeled inositol trisphosphates and arachidonic acid were determined by a scintillation counter. RESULTS: In Hank's balanced salt solution with Ca2+ (HBSS+), monensin (100 mumol/L) induced a 2.3-fold sustained Ca2+ increase associated with IP3 generation and a 6-fold increase in AA release. Deletion of extracellular Ca2+, or replacement of Na+ by choline chloride in the medium, reduced the [Ca2+]i increase by 77% and completely prevented the monensin-induced rise in AA release. Similar inhibitory effects were observed in cells pretreated with a Na+ channel blocker, or Na+/Ca2+ exchange inhibitors. In HBSS without Ca2+ (HBSS-), monensin induced a 1-fold transient [Ca2+]i increase but did not increase the AA. This Ca2+ increase was not suppressed by U-73122, a PLC inhibitor. In HBSS+, U-73122 did not affect the monensin-induced initial transient peak increase of [Ca2+]i, but reduced the sustained second phase of [Ca2+]i from 400 nmol/L to 250 nmol/L, and completely blocked AA release. A phospholipase A2 (PLA2) inhibitor blocked the monensin-induced AA release without affecting the [Ca2+]i increase. Inhibition of PKC prevented 87% to 94% of the monesin-stimulated AA release. The monensin-induced AA release was also inhibited 94% by pertussis and 51% by a MAP kinase cascade inhibitor. CONCLUSIONS: The results suggest that monensin initiates an increase in [Ca2+]i via a Na+/Ca2+ exchange mechanism that triggers more pronounced and sustained [Ca2+]i increase via activation of PLC and Ca2+ influx. The PLC activation, followed by sustained Ca2+ influx and PKC activation, is a prerequisite for PLA2-mediated processes in monensin-challenged FRTL-5 thyroid cells.

Animals↗
PubMed1998

[A pharmacokinetic study of 125I-VIP in rat].

To investigate the pharmacokinetics of 125I-VIP in normal rats, a single dose of 125I-VIP was given intravenoualy to rats and from 0.5 to 240 min after the administration, serial blood samples were taken and measuredp by gamma scintillation counter and finally expressed as mu Ci/ml blood. The data were analyzed by computer for the estimation of pharmacokinetic parameters and the judgment of compartment model with a program of 3P87. The results demonstrated that the pharmacokinetics of 125I-VIP in rat fitted with the three-compartment model(Wi = 1) based on either the comparison of the calculated theoretic value with measured concentration, the values of AIC and r2 or F test for the model judgment, and that the average distributive half-life of 125I-VIPk in blood was 1.36 min, the elimination half-life(T1/2 beta was 67.3 min, the K12(3.589 min-1) was markedly higher than that of K12(0.045 min-1), and the K21:K12(0.0127) was obviously lower than that of K31:K13(0.215). The present study indicates that 125I-VIP has a rapid uptake and slow elimination in the tissues with high density and affinity VIP receptors (the second compartment).

Animals↗
PubMed1999

Local drug delivery via transvascular injection.

BACKGROUND: In this experimental series we tested drug distribution and systemic leakage using local drug delivery with a new transvascular injection system. METHODS: Porcine femoral and carotid arteries (n = 56) underwent local drug application with a new 5 French (Fr) over-the-wire needle-injection catheter system (NIC) using three needles. A radioactive indicator [C14-Carvedilol, 2.0 milliliter (ml); 0.03 milligram (mg)] was injected in two carotid and two femoral vessels in parallel. Serial blood withdrawal was performed thereafter. After randomization to different explantation times, the vessels, perivascular tissue, liver and spleen were removed [0.5, 1, 1.5, 3 and 4 hours after injection, respectively]. Radioactivity was determined in a scintillation counter or with autoradiography. The indicator amount was calculated in relation to total drug amount (100%). RESULTS: Use of the NIC caused vessel texture alteration in non-diseased porcine vessels, seen as vessel wall penetration and perivascular edema. After single injection the maximum of the indicator was found in perivascular tissue 0.5 hours at the application site (carotid perivascular tissue: 7.48%; femoral perivascular tissue: 2.56%). Thereafter, radioactivity in the artery increased and perivascular content declined. The maximum in femoral arteries (1 hour; 1.96%) occurred earlier and was significantly lower compared to carotid arteries (2 hours; 7.75%). Four hours post-injection, 1.4% of total drug amount was detectable in the carotid arteries and 0.6% was detected in the femoral arteries. Systemic content was measured after C14-Carvedilol application with a maximum in serum of 28% (10 minutes), liver 30% (0.5 hour) and spleen 0.6% (0.5 hour). After 3 hours, still 5% of the indicator was still measureable in the serum and liver and less than 0.1% was measurable in the spleen. LDD with the NIC system is dependent on the vascular anatomy. The data indicate redistribution from perivascular to vascular space thus allowing a prolonged vascular and perivascular drug delivery. The amount deliverable is lower than expected due to substantial systemic drug contamination with this catheter.

Animals↗
PubMed2000

[Effects of biorhythm regulator melatonin on DNA synthesis in short-term cultures of human malignant tumors].

The cytotoxic action of melatonin on DNA synthesis was studied in short-term human tumor tissue cultures. Twenty tumors (ovarian, renal, colorectal, gastric, skin, testicular, thyroid, adrenal gland, endometrial, cervical uterus ones, and melanoma) were isolated from patients at surgery. The effect of melatonin (concentrations of 5 x 10(-5) M to 5 x 10(-13) M on the level of 3H-thymidine incorporation into tumor tissue DNA (4-hour exposure) was evaluated. After exposure, 3H-thymidine was added to the medium for an hour. The quantity of DNA was determined in the hydrolysate by spectrometry; the level of 3H-thymidine incorporation into DNA was radiometrically evaluated by a scintillation counter. The quantity corresponding to 3H-thymidine incorporation per unit of DNA was determined. The control group and the melatonin-treated groups were compared by ANOVA. Melatonin inhibited DNA synthesis in 11 (55%) of the 20 tumors and was ineffective in 9 (45%) of the 20 ones. Melatonin-sensitive tumors were as follows: endometrial CA (33% vs 75% inhibition, p < 0.01), gastric CA (71% inhibition, p < 0.05), adrenal gland CA (38% inhibition, p < 0.01). Ovarian, cervical, skin CA and melanoma were unresponsive to melatonin. Renal cell CA, colonic and rectal CA were sensitive in some cases. In sensitive tumors, melatonin was effective even at concentrations of 5 x 10(-13) M to 5 x 10(-7) M. Thus, melatonin has an oncostatic effect on some human tumors in vitro occasionally at physiological concentrations.

Adult↗
PubMed2000

Retinoic acid receptor status in mouse spleen during a primary immune response against beta-galactosidase.

OBJECTIVE: Evaluation of the dynamics of all-trans retinoic acid receptor binding properties in mouse spleen nuclear extracts during a primary immune response against beta-galactosidase. METHODS: Female BALB/c mice, aged between 5 and 6 weeks were immunized intradermally into the shaved back (4 spots each) with 100 microg beta-galactosidase in 100 microl sterile phosphate buffered saline (pH 7.2) and blood was taken by tail bleeding on days 0 (preimmune serum), 4 and 6. Production of antibody in serum and the detection of cytokines (IL-4, IFN-gamma) from proliferation supernatants were determined by ELISA. Antigen-specific proliferation assay of isolated spleen cells was based on [3H]-thymidine incorporation measured in a liquid scintillation counter. Both, the maximal binding capacity (Bmax) and the affinity (Ka) of all-trans retinoic acid nuclear receptors (RAR) were evaluated according to Brtko (1994). RESULTS AND CONCLUSIONS: Injection of beta-galactosidase induced the first detectable antibody responses on day 4 (IgM) and on day 6 (IgG). These points of time, reflecting the early and the mature immune response served to measure the antigen-specific proliferation and production of IL-4 and IFN-gamma in the supernatants of the proliferation cultures as well as all-trans retinoic acid receptor (RAR) binding characteristics in spleen nuclear proteins. The RAR Bmax was significantly (P<0.05) decreased only at the time of the first specific IgG antibody production. CONCLUSIONS: The data obtained indicate the involvement of RAR in the late phase of an in vivo immune response.

Animals↗
PubMed2000

Effect of lactoperoxidase system on glucosyltransferase D of Streptococcus mutans.

OBJECTIVE: To investigate the effects of the peroxidase system (LP, H2O2, SCN) and its components on the activity of glucosyltransferase D (GtfD) originating from Streptococcus mutans (S. mutans). METHODS: GtfD was incubated in buffered-KCl assay mixture that contained 20 microM dextran and 100 mM sucrose including 14C-glucose. The activity of GtfD was measured with a scintillation counter. The effects of lactoperoxidase system and its components on GtfD activity were examined by incubating different components separately and together with GtfD. RESULTS: The lactoperoxidase system-generated hypothiocyanite (OSCN) had no effect on the activity of streptococcal GtfD, while the lactoperoxidase enzyme inhibited GtfD. The ratio between the 2 enzymes, LP and GtfD, was important for the inhibition. However, if LP was combined with its substrates, SCN and/or a high concentration of H2O2, it enhanced the activity of GtfD. CONCLUSION: Peroxidase-generated antimicrobial agent HOSCN/OSCN is not inhibitory against GtfD, whereas low concentrations of the LP-enzyme inhibit GtfD.

Anti-Bacterial Agents↗
PubMed2001

Dermal absorption and distribution of (14)C carbaryl in Wistar rats.

The level of (14)C carbaryl was determined in blood (leukocytes, erythrocytes, all blood cells, plasma) and organs (brain, heart, lungs, liver, spleen, skin at the site of exposure) of male Wistar rats after dermal administration. The application liquid was (14)C carbaryl solution in 96% ethyl alcohol. This preparation, possessing an activity of 670 kBq/ml, containing 1.67 mg of carbaryl, was applied to the skin of the tail according to Massmann's method in own modification. The amount of the preparation per 1 cm(2) of the tail skin was 0.19 mg of carbaryl (74.4 kBq). The tails of experimental rats were exposed to (14)C carbaryl by soaking for 4 h daily: once, twice or three times. Beta radiation from (14)C was measured in homogenized organs (brain, heart, lungs, liver, skin) and in blood by computer controlled Wallac scintillation counter Model 1409, using Multi Calc software. The dermal absorption of carbaryl at the site of exposure and in the surrounding area of about 2 cm was observed already during 4 hour exposure. Carbaryl reached plasma within 4 h of a single dermal exposure and penetrated into leukocytes, erythrocytes, heart, liver, lung, kidney and brain. The largest amount of (14)C carbaryl, about 2% of absorbed dose, was detected in liver

Administration, Cutaneous↗
PubMedDate not supplied

14C-urea breath test for assessment of gastric Helicobacter pylori colonization and eradication.

BACKGROUND AND OBJECTIVE: Urea breath test (UBT) is a reliable noninvasive technique for detecting gastric Helicobacter pylori colonization. 14C isotope-based test requires simple equipment and is inexpensive. We studied the utility of 14C-UBT in diagnosis of gastric H. pylori infection. METHODS: Presence of H. pylori was studied using antral histology and culture in patients with rapid urease test (RUT)-positive peptic ulcer. 14C-UBT was performed using a 185-kBq dose. Radioactivity in 15-min breath samples was measured using a beta-scintillation counter and result expressed as % dose recovered/mmol CO2. H. pylori was considered positive when any two tests were positive. All tests were repeated one month after completion of H. pylori eradication therapy. RESULTS: Among 41 patients (duodenal ulcer 36, gastric ulcer 5), H. pylori was detected by histology in 23 (56%) and by culture in 27 (66%). Overall, H. pylori was detected in 28 (68%) patients. Follow-up assessment was possible in 28 patients: 26 cleared the infection (all three tests negative). Mean 14C recovery values at 15 minutes associated with H. pylori-positive status were significantly higher (12.3 [SD 6.8] x 10(-3); n=30; p<0.001) than those associated with H. pylori-negative status (2.1 [0.9] x 10(-3); n=26). Using receiver-operating-characteristic analysis of 15-minute 14C recovery values, a cut-off of 6.5x10(-3) gave the best separation of H. pylori-positive and -negative cases. 14C-UBT had 93% sensitivity, 96% specificity and 95% accuracy. CONCLUSION: 14C-UBT appears to be a reliable noninvasive test for diagnosis of H. pylori infection.

Adolescent↗
PubMed1975

Analyses of small bowel propulsion, ileo-caecal passage and serum gastrin after truncal vagotomy. A methodological study in the rat with continuous intraduodenal infusion.

A test substance containing 51CrO--4 was administered to the duodenum of vagotomized or sham-operated, conscious rats for 5 hours at a rate of 3.3 mul/min. The distribution of 51Cr in the stomach, small bowel, caecum and colon was measured with a scintillation counter. Data reduction was made with automatic methods. The activity distribution in the small bowel was found to be irregular. A transit time of about 3 hours was observed between the duodenum and the caecum. The proximal 40% of the small bowel was passed in about 30 min at a constant rate. No differences between vaotomized animals and controls could be demonstrated. The passage from ileum to caecum in vagotomized animals indicated a process, with constant portions, each discharge containing about 11% of the total administered activity, implying two discharges per hour.

Animals↗
PubMed2001

Preliminary study for sentinel lymph node identification with Tc-99m tin colloid in patients with esophageal or gastric cancer.

The purpose of this study is to determine whether a lymph node identified with high radioisotope (RI) activity is a sentinel node. We studied 26 patients with either esophageal or gastric cancer whose preoperative imaging studies showed no lymph node metastasis. Before surgery, Tc-99m tin colloid was injected via endoscopy into the submucosa. In lymph nodes dissected at surgery, RI activity was measured by a scintillation counter, and metastatic status was examined by hematoxylin-eosin staining. The number of dissected nodes was 45 +/- 15 (mean +/- SD) per patient, and the number of nodes with high RI activity was 4 +/- 1. Nodal metastasis occurred in 11 of 26 patients. In 9 of these 11 patients, metastatic foci were found in one or more nodes with high RI activity. In one of the 2 remaining patients, endoscopic clipping was applied just above the injection sites, and in the other patient, the tumor invasion was beyond the muscle layer. For further analysis, the case with clipping was excluded, and only those in which the tumor invasion was confined within the muscle layer were evaluated. Six of 18 patients in this analysis showed nodal metastasis. Each of the 6 patients had at least one node that showed high RI activity and that was positive for metastasis. We conclude that when tumor invasion remains within the muscle layer, lymph nodes with high RI activity can be regarded as sentinel nodes.

Aged↗
PubMed2001

Toxicokinetics of waterborne bisphenol A in landlocked salmon (Salmo salar m. sebago) eggs at various temperatures.

Eye-pigmented eggs of landlocked salmon were exposed to waterborne [14C]-labeled bisphenol A at four temperatures (2, 6, 8, and 12 degrees C). Both in accumulation and depuration experiments, the eggs were exposed to a bisphenol A concentration of 1 microg/L for 196 h. In the depuration experiment, the exposed eggs were placed into clean water for 96 h. At each sampling time, the eggs were dissected into three parts (eggshell, embryo, and yolk sac), and all of these parts were weighed and analyzed separately in a liquid scintillation counter. The results show that waterborne bisphenol A accumulates in developing salmon eggs. Accumulation of bisphenol A showed a clear trend both in whole eggs and in dissected parts: the higher the temperature, the higher the uptake rate constant and the concentration of bisphenol A. Steady state was reached only in the embryos at the lowest temperature; in other cases, accumulation was linear. Depuration was significant only in the embryos at 2 and 6 degrees C. As the accumulation and the depuration results show, the elimination of bisphenol A was evidently more significant at lower temperatures.

Animals↗
PubMed2001

Uptake of cyclosporine A loaded colloidal drug carriers by mouse peritoneal macrophages in vitro.

AIM: To investigate the uptake of cyclosporine A loaded colloidal drug carriers by mouse peritoneal macrophage (MPM) in vitro. METHODS: The [3H]cyclosporine A loaded colloidal particles: polylactic acid nanospheres, polylactic acid nanocapsules, and microemulsions were prepared. The [3H]cyclosporine A loaded colloidal particles were incubated with MPM for 30 min at 37 degrees C, then the cells were separated from the colloidal particles and the radioactivity was measured by a liquid scintillation counter. RESULTS: In comparison to the cyclosporine A solution, the binding to polylactic acid nanospheres produced a 20-fold increase in the uptake of cyclosporine A by MPM in 30 min incubation, whereas some obvious decrease in the uptake of cyclosporine A by MPM was observed in the binding of cyclosporine A with polylactic acid nanocapsules or microemulsions. The surfactant coating and plasma protein adsorption were found to have marked effects on the uptake of cyclosporine A loaded nanospheres by MPM. CONCLUSION: Our present study indicated that colloidal drug carriers might affect the targeting of cyclosporine A to mononuclear phagocyte system.

Animals↗
PubMed2002

Effects of two barrier creams on the diffusion of benzo[a]pyrene across human skin.

Barrier hand creams, often containing antiseptic agents, may provide a form of protection not only for health care professionals, but also for workers in the chemical and pharmaceutical industries. To evaluate the efficacy of two such barrier creams available on the South African market, the in vitro diffusion of a model compound, benzo[a]pyrene, through human skin at 20 degrees and 37 degrees C was studied. Treated (10 min) and untreated human skin disks (4 mm in diameter) were mounted in flow cells of a continuous flow-through diffusion apparatus. Buffer/tritiated benzo[a]pyrene was collected from the acceptor chambers at 2-hour intervals for a total of 24 hours and counted in a liquid scintillation counter. At 20 degrees C no significant differences could be detected between the flux rates of benzo[a]pyrene across barrier cream treated and untreated skin. However, at 37 degrees C Skinguard significantly increased flux rates of this carcinogen. Skin barrier creams therefore need to be carefully scrutinised with respect to their protective effects because the latter may vary for molecules with different chemical properties.

Analysis of Variance↗
PubMed1975

[Proceedings: Studies on the digoxin resorption in patients with decompensated right cardiac insufficiency].

Digoxin absorption was investigated in 7 patients suffering from severe right cardiac failure. After successful treatment and disappearance of the symptoms of right cardiac failure, the study was repeated in the same patients. Tritium-labelled digoxin in a dose of 0.1 mg as a solution, and non-labelled digoxin as a 0.25 mg tablet, were given to the patients in the fasting state. Blood samples were taken at specified time intervals up to 120 h and the urine was collected during the same period. The concentrations of digoxin in plasma and urine were measured in a liquid scintillation counter. The unlabelled digoxin was estimated by radioimmunoassay. The concentrations obtained in the plasma and urine were used to compute pharmacokinetic parameters. There was no significant difference in the plasma concentration curves in severe right cardiac failure and after successful treatment, nor did the calculated pharmacokinetic parameters differ significantly. Inhibition of digoxin absorption in severe right cardiac failure therefore seems unlikely.

Digoxin↗
PubMed1975

[Radioisotope cisternographic study on cerebrospinal fluid circulation after subarachnoid hemorrhage].

Although recent advance in neurological surgery has diminished mortality rate of aneurysmal surgery, there still exist several complex problems for the management of aneurysms. Persistent neurological deficits or clinical deterioration after subarachnoid hemorrhage can result from subsequent communicating hydrocephalus which can be treated by shunting operation. We have studied alterations in the cerebrospinal fluid (CSF) circulation after SAH in 43 patients. Sources of hemorrhages were aneurysm in 30 cases, arteriovenous malformation in 6 and unknown in 7. Radioisotope cisternography was performed using 0.5 to 1.0 mCi of 169Yb-DTPA which was given intrathecally by lumbar injection. Results of cisternogram were classified into 4 groups and 7 subgroups; group 0: non filling (4%), group I: persistent ventricular filling (45%), A) absence of convexity flow (11%), B) partial convexity flow (34%), group II: transient ventricular filling (23%), A) delayed convexity flow (11%), B) normal convexity flow (12%), group III: no ventricular filling (28%), A) delayed convexity flow (17%), B) normal convexity flow (11%). The radioactivity in serial blood samples was measured by a well-type scintillation counter. Three types of curves for transfer of 169Yb-DTPA from CSF to blood were classified; delayed type, medium type, and normal type. In delayed type, the count ratio of blood activity at 24 hr to that at 3 hr is over 30%. In normal type, it is below 10%. There was a close correlation between cisternogram and transfer curve. In most cases with persistent ventricular filing, the transfer curve showed a delayed type. The relationship of cisternogram to classification of patient's condition by Hunt was studied. The grade of patient's condition was found to be closely related to the degree of abnormality in CSF circulation. The existence of rebleeding in the patients history was also found to influence the degree of abnormality in CSF circulation. However, single bleeding may also cause abnormality, such as persistent ventricular filling on cisternogram. In regard to the site of aneurysms, those of anterior communicating artery appeared to cause communicating hydrocephalus more frequently. Laterality of convexity flow was analyzed in 17 cases. All cases with internal carotid aneurysms showed decreased activity on the side of bleeding. Shunt operation was performed on 10 cases according to the results of cisternography, transfer curve, pneumoencephalography, and angiography. Seven cases showed improvement and 2 died of other complications soon after the shunt, and the effect of the procedure cannot be evaluated. Patients with clinical signs of NPH and abnormal cisternogram (group I) with evidence of ventricular dilatation are indicated for shunting operation.

Adult↗
PubMed2002

Kinetic studies of glutaraldehyde binding in liver.

To study the kinetics of glutaraldehyde fixation, fresh rabbit liver cubes were immersed in 3% buffered 3H-glutaraldehyde for various periods of time. Following weighing and a brief rinse in water, the tissues were solubilized, and the radioactivity was measured in a scintillation counter. Binding of the isotope was half-maximal after approximately 4 h and a plateau was reached after approximately 20 h. We also investigated the reversibility of glutaraldehyde fixation. Fixed liver cubes were weighed and immersed in water for various periods of time, and after solubilization, the radioactivity was determined. After rinsing for 48 h, approximately 95% of the radioactivity was lost from the tissue specimens, indicating that fixation with glutaraldehyde is largely reversible. Light and electron microscopy of specimens rinsed for 1 and 48 h showed essentially similar morphology. Rinsing for 48 h restored some of the immunoreactivity that was absent after rinsing for only 1 h.

Animals↗
PubMed2002

[Primary study on establishment of namalwa 12/MTX resistant cell strain and its mechanism].

BACKGROUND & OBJECTIVE: Methotrexate has been used to treat malignant tumor for 50 years. Different mechanisms of methotrexate resistance has been known in various kinds of leukemias. Because of individualized chemotherapy according to different drug metabolism in different leukemia patients, the treatment became more reasonable and scientific and the treatment effect has been gradually improved. However, there was few report about its drug resistance mechanism in lymphoma. This study was designed to establish Burkitt's lymphoma methotrexate resistant cell strain--Namlwa 12/MTX and study its resistant mechanism. METHODS: Namlwa 12/MTX resistant cell strain was established by repeated impulsed exposure to methotrexate. The difference of the methotrexate effect on Namlwa 12/MTX and Namlwa cell strains were evaluated with MTT method. The level of dihydrofolate reductase (DHFR) mRNA expression was assayed with RT-PCR. The function of the reduced folate carrier (RFC) were tested with 3H-MTX labeling and counted with beta-liquid scintillation counter. The capacity to form the polyglutamate methotrexate (MTXPG) in these cell strains was assayed with 3H-MTX labeling and high pressure liquid chromatography (HPLC) separation. RESULTS: More than 20 times methotrexate resistance was found in Namalwa 12/MTX cell strain in comparison with the Namalwa cell strain. This resistance was not associated with the dysfunction of the RFC, but was closely associated with the amount of MTXPG formed. The amount of total MTXPG (MTXPG1-6) formed in these 2 cell strains was (1583 +/- 26) pmol/10(9) tumor cells and (4453 +/- 236) pmol/10(9) tumor cells, respectively (P < 0.05), while the amount of long chain MTXPG (MTXPG4-6) formed only accounted for 5.5% and 25.4% of the MTXPG1-6, respectively (P < 0.05). The level of DHFR mRNA expression was gradually increased with the formation of the drug resistance in Namalwa 12/MTX. CONCLUSION: Synthesizing difficulty of MTXPG and over-expression of DHFR mRNA level result in methotrexate resistance in Namalwa 12/MTX cell strain.

Antimetabolites, Antineoplastic↗