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At least 55 records · Page 3Linked to original sources
PubMed2005

A comparison of complications associated with colostomy reversal versus ileostomy reversal.

BACKGROUND: The incidence of complications after reversal of Hartmann's procedure is unknown. This study compares the morbidity of Hartmann's reversal versus loop ileostomy reversal. METHODS: Two groups of 20 patients were studied retrospectively over a 5-year period. One group underwent Hartmann's takedown, and the other underwent loop ileostomy takedown. Postoperative complications were compared between the 2 groups. RESULTS: Similar demographics were noted between each group. The most common initial indications for Hartmann's procedure were diverticulosis (11 patients, 55%) and colon cancer (4 patients, 20%). For patients who had undergone colectomy with primary anastomosis and ileostomy, colon cancer was the most common indication (12 patients, 60%) followed by diverticulosis (3 patients, 15%). Complications were more common after Hartmann reversal than loop ileostomy reversal (16 complications/11 patients versus 6 complications/4 patients, P = .047). CONCLUSION: Segmental colonic excision with anastomosis and loop ileostomy may be an attractive alternative to minimize morbidity with stoma reversal.

Adult↗
PubMed2006

An examination of the Runs Test, Reverse Arrangements Test, and modified Reverse Arrangements Test for assessing surface EMG signal stationarity.

The purpose of this study was to examine the accuracy of the Runs Test, Reverse Arrangements Test, and modified Reverse Arrangements Test for assessing stationarity of surface electromyographic (EMG) signals. Five stationary signals were generated by custom programs written with LabVIEW programming software. These signals consisted of sine waves, sums of sine waves, and sums of sine waves and random noise. The sixth signal was a stationary computer generated surface EMG signal downloaded from the surface EMG for the non-invasive assessment of muscles (SENIAM) project database. There were no changes in the amplitude or frequency contents of the stationary signals over time. Several nonstationary signals were also created, including a nonstationary chirp signal generated with LabVIEW programming software, a nonstationary computer generated surface EMG signal downloaded from the SENIAM project database, and a real surface EMG signal recorded from the biceps brachii during a concentric isokinetic muscle action of the forearm flexors at a velocity of 30 degrees s(-1). Both the stationary and nonstationary signals were tested for stationarity using the Runs Test, Reverse Arrangements Test, and modified Reverse Arrangements Test. The results indicated that each of the three stationarity tests demonstrated at least one form of inaccuracy (i.e. false positive and/or false negative results) in examining the stationarity of the test signals. These findings may reflect the fact that these tests were designed to determine whether or not a signal is random, rather than examine signal stationarity exclusively. Thus, the Runs Test, Reverse Arrangements Test, and modified Reverse Arrangements Test may not be appropriate for assessing stationarity in surface EMG signals.

Databases, Factual↗
PubMed2002

Technique and timing in the women's reverse two and one half somersault tuck (305C) and the men's reverse two and one half somersault pike (305B) 3m springboard dives.

The purpose of this study was to compare the reverse two and one half somersault dive in a tuck position (305C) performed by females (n = 24), and the reverse two and one half somersault dive in a pike position (305B) performed by males (n = 21), to determine changes required by females to successfully perform 305B. Key performance variables in reverse dives were also compared to those of forward dives. Video data of the dives performed at the 1999 FINA World Diving Cup were captured and digitised to obtain times and postures of the divers at specific events including hurdle landing, takeoff, and entry. Estimates of hurdle flight height and mass-normalised work done on the springboard were obtained from hurdle and flight times. The males did more work on the springboard to achieve greater height and rotation than females. Females performing 305C had less hip and knee flexion at hurdle landing than males performing 305B and took longer to achieve maximum hip flexion after takeoff from the springboard. To progress from 305C to 305B females need to adjust their techniques to put more energy into the system. Desirable changes include increased height in the hurdle and increased hip and knee flexion prior to hurdle landing. Comparison of results for reverse dives with data previously presented for forward dives indicated that divers are more limited in the number of somersaults and dive position in reverse dives than forward dives despite equivalent or better height in reverse dives than forward dives.

Adolescent↗
PubMed2003

Reversal of neuromuscular blockade and simultaneous increase in plasma rocuronium concentration after the intravenous infusion of the novel reversal agent Org 25969.

BACKGROUND: The purpose of this study was to determine the changes in the plasma concentration of rocuronium and the reversal of its neuromuscular blockade after the intravenous infusion of Org 25969, the novel neuromuscular block-reversal agent, in anesthetized guinea pigs. METHODS: Rocuronium was infused for 1 h at a rate of 12-19 nmol.kg-1.min-1 to produce a steady-state 90% neuromuscular block. After 30 min, a concomitant infusion of either the reversal agent Org 25969 at a rate of 50 nmol.kg-1.min-1 or an infusion of an equivalent volume of saline was started. The time course of plasma concentrations of rocuronium was determined by use of liquid chromatography-mass spectrometry/mass spectrometry. RESULTS: In both treatment groups, a steady-state plasma concentration of rocuronium was obtained after 30 min. In the saline-treated group, the plasma concentration of rocuronium and depth of block remained constant. In the Org 25969 group, neuromuscular block was reversed while the rocuronium infusion was ongoing. Simultaneously, an increase in the total plasma concentration of rocuronium (free and complexed) was observed, even though the infusion rate of rocuronium was not changed. Compared with the saline-treated group, a small increase in the postmortem bladder concentration of rocuronium was detected. CONCLUSIONS: The authors propose that the capture of rocuronium by Org 25969 causes the rapid reversal of neuromuscular block. The reversal can be explained by the rapid transfer of free rocuronium from the effect compartment (neuromuscular junction) to the central compartment, in which it is bound to Org 25969. This explains the increase in total plasma concentration of rocuronium (free and bound to Org 25969).

Androstanols↗
PubMed1988

The reversible dementias: do they reverse?

Thirty-two studies (2889 subjects) that investigated the prevalence of the causes of dementia were critically reviewed. Particular attention was paid to potential and actual reversibility. Although dementia manifests itself primarily in old age (particularly age 75 and older), the mean age of patients for the studies that reported age data (56%) was 72.3 years. Twenty-five studies originated from secondary or tertiary centers, and four were community-based. Dementias consisted of Alzheimer disease, 56.8%; multi-infarct, 13.3%; depression, 4.5%; alcoholic, 4.2%; and drugs, 1.5%. No single other cause contributed more than 1.6% of the cases. Potentially reversible causes made up 13.2% of all cases. However, the more important question of whether patients with potentially reversible causes were followed and reversal actually seen was not always examined. In 11 studies (34%) that provided follow-up, 11% of dementias resolved, either partially (8%) or fully (3%). The commonest reversible causes were drugs, 28.2%; depression, 26.2%; and metabolic, 15.5%. Due to the presence of various biases (selection, lack of "blinded" investigators, and others) in the surveyed works, it is probable that the true incidence of reversible dementias in the community is even lower than that reported. Research implications as well as a conservative approach to the workup of a new case of dementia are offered.

Age Factors↗
PubMed2005

[Basic research on the mechanism of venous reverse flow in reverse-flow island flap].

OBJECTIVE: To investigate the basic mechanism of venous flow in reverse-flow island flap. METHODS: Recent relevant literature on the mechanism of venous reverse flow in reverse-flow island flap were extensively reviewed. RESULTS: The mechanism of venous reverse flow was a multifactorial phenomenon. "Communicating and collateral by pass route" and "incompetent valve route" were two theories. CONCLUSION: The two routes of venous reverse flow in reverse-flow island flap coexist and complement each other.

Blood Pressure↗
PubMed1993

Reversal of gallium arsenide-induced suppression of the antibody-forming cell response by vehicle supernatants. II. Nature and identification of reversing factors.

Previous studies have demonstrated that several immunological events which are T cell mediated are significantly suppressed by a single exposure to gallium arsenide (GaAs). In addition, in the in vitro-generated antibody-forming cell (AFC) response supernatants from vehicle (VH) cultures were able to time-dependently reverse suppression induced by either in vivo (200 mg/kg) or in vitro (50 microM) exposure to GaAs. The present studies were designed to determine the nature and identification of the reversing factors present in VH supernatants. VH supernatants (25-100%) were able to dose-dependently reverse suppression of the AFC response (from 45% suppression to 48% enhancement of the VH response) induced by GaAs exposure (200 mg/kg). Concentration of 24-hr VH supernatants and treatment with proteinases revealed that the reversing factors were protein in nature with a molecular weight between 5,000 and 50,000 Da. This molecular weight range encompasses many of the lymphokines known to be necessary for the generation of an immune response. In antibody cultures exposed either in vivo or in vitro to VH or GaAs, HT-2 bioassay and antigen capture enzyme-linked immunosorbent assays demonstrated that GaAs exposure alters production of interleukin (IL)-2, IL-4, IL-5 and IL-6. Interestingly, the alterations in lymphokine production differed between the exposure regimes. Direct addition of IL-2 to antibody cultures resulted in a dose-dependent (6.25-50 ng/ml) reversal of GaAs-induced suppression (in vivo exposure) and was also dependent on the concentration of GaAs (50-200 mg/kg). IL-4 suppressed the VH AFC response and failed to reverse GaAs suppression.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1998

Prevalence of potentially reversible dementias and actual reversibility in a memory clinic cohort.

BACKGROUND: Although clinics for the evaluation of cognitive dysfunction have typically emphasized the detection and treatment of the reversible causes of dementia, it remains unclear whether the treatment of such causes results in reversal of the dementia. Therefore, the appropriate work-up for dementia is in dispute. METHODS: A chart review was performed with records from an urban tertiary care referral-based memory clinic. The records for 196 patients with dementia or suspected dementia, seen between October 1991 and December 1993, were examined to determine the prevalence of potentially reversible dementias and whether the cognitive dysfunction improved or resolved after treatment. Data abstracted from the medical charts included demographic information, medication use, presence of depression, and results of neuropsychological tests, blood work and neuroimaging. The clinical diagnosis, the response to treatment, if applicable, and the outcome (mean follow-up period 16 months) were analysed. The recommendations of the 1989 Canadian Consensus Conference on the Assessment of Dementia (CCCAD) on the use of CT were retrospectively applied in each case. RESULTS: Of the 196 patients, 45 (23.0%) had a potentially reversible condition identified by history, physical examination, blood testing or CT; in only 7 (3.6% of the total) did treatment result in improvement or resolution of the dementia. These 7 patients had higher results for the Mini-Mental State examination (mean result 26) and exhibited only mild cognitive deficits. Potentially reversible lesions were found in the CT scans of 6 (3.1%) patients: 4 had normal-pressure hydrocephalus and 2 had a brain tumour. If the CCCAD recommendations had been followed, CT would have been performed in 76 (38.8%) of the patients, and 1 of the 6 patients with a lesion would have been missed. INTERPRETATION: Both potential and actual reversibility of dementia was low in these memory clinic patients. The patients whose condition improved with intervention had early and milder cognitive deficits, which suggests that thorough evaluation of early memory loss is warranted.

Aged↗
PubMed1997

Functional differences between the human LINE retrotransposon and retroviral reverse transcriptases for in vivo mRNA reverse transcription.

We have analysed the reverse transcriptase (RT) activity of the human LINE retrotransposon and that of two retroviruses, using an in vivo assay within mammalian (murine and human) cells. The assay relies on transfection of the cells with expression vectors for the RT of the corresponding elements and PCR analysis of the DNA extracted 2-4 days post-transfection using primers bracketing the intronic domains of co-transfected reporter genes or of cellular genes. This assay revealed high levels of reverse-transcribed cDNA molecules, with the intron spliced out, with expression vectors for the LINE. Generation of cDNA molecules requires LINE ORF2, whereas ORF1 is dispensable. Deletion derivatives within the 3.8 kb LINE ORF2 allowed further delineation of the RT domain: > 0.7 kb at the 5'-end of the LINE ORF2 is dispensable for reverse transcription, consistent with this domain being an endonuclease-like domain, as well as 1 kb at the 3'-end, a putative RNase H domain. Conversely, the RT of the two retroviruses tested, Moloney murine leukemia virus and human immunodeficiency virus, failed to produce similar reverse transcripts. These experiments demonstrate a specific and high efficiency reverse transcription activity for the LINE RT, which applies to RNA with no sequence specificity, including those from cellular genes, and which might therefore be responsible for the endogenous activity that we previously detected within mammalian cells through the formation of pseudogene-like structures.

3T3 Cells↗
PubMed1995

A screen in Escherichia coli for nucleoside analogs that target human immunodeficiency virus (HIV) reverse transcriptase: coexpression of HIV reverse transcriptase and herpes simplex virus thymidine kinase.

Human immunodeficiency virus (HIV) reverse transcriptase substitutes for temperature-sensitive DNA polymerase I (Pol Its) in Escherichia coli, providing a screen for anti-HIV reverse transcriptase nucleoside analogs in bacteria. Since phosphorylation of nucleosides in E. coli is limited to thymidine and its derivatives, we coexpressed herpes simplex virus thymidine kinase, an enzyme that phosphorylates a wide variety of nucleoside analogs, together with HIV reverse transcriptase. Coexpression of herpes simplex virus thymidine kinase and HIV reverse transcriptase rendered Pol Its cells sensitive to dideoxycytidine. Studies with different nucleoside analogs indicate that this bacterial screening system is able to select and identify nucleoside analogs that specifically target HIV reverse transcriptase.

Antiviral Agents↗
PubMed1999

Reversion of a human immunodeficiency virus type 1 matrix mutation affecting Gag membrane binding, endogenous reverse transcriptase activity, and virus infectivity.

We previously characterized mutations in the human immunodeficiency virus type 1 matrix (MA) protein that displayed reduced infectivity in single-round assays, defects in the stable synthesis of viral DNA in infected cells, and impaired endogenous reverse transcriptase activity. The mutants, which contained substitutions in a highly conserved Leu at MA amino acid 20, also increased binding of Gag to membrane. To elucidate further the role of MA in the virus replication cycle, we have characterized a viral revertant of an amino acid 20 mutant (20LK). The revertant virus, which replicates with essentially wild-type kinetics in H9 cells, contains second-site compensatory changes at MA amino acids 73 (E-->K) and 82 (A-->T), while retaining the original 20LK mutation. Single-cycle infectivity assays, performed with luciferase-expressing viruses, show that the 20LK/73EK/82AT triple mutant displays markedly improved infectivity relative to the original 20LK mutant. The stable synthesis of viral DNA in infected cells is also significantly increased compared with that of 20LK DNA. Furthermore, activity of revertant virions in endogenous reverse transcriptase assays is restored to near-wild-type-levels. Interestingly, although 20LK/73EK/82AT reverses the defects in replication kinetics, postentry events, and endogenous reverse transcriptase activity induced by the 20LK mutation, the reversion does not affect the 20LK-imposed increase in Gag membrane binding. Mutants containing single and double amino acid substitutions were constructed, and their growth kinetics were examined. Only virus containing all three changes (20LK/73EK/82AT) grew with significantly accelerated kinetics; 73EK, 73EK/82AT, and 20LK/82AT mutants displayed pronounced defects in virus particle production. Viral core-like complexes were isolated by sucrose density gradient centrifugation of detergent-treated virions. Intriguingly, the protein composition of wild-type and mutant detergent-resistant complexes differed markedly. In wild-type and 20LK complexes, MA was removed following detergent solubilization of the viral membrane. In contrast, in revertant preparations, the majority of MA cosedimented with the detergent-resistant complex. These results suggest that the 20LK/73EK/82AT mutations induced a significant alteration in MA-MA or MA-core interactions.

Amino Acid Sequence↗
PubMed1983

Reversed memory coding and symbol reversal in children.

The present study examined an hypothesized mirror-reversed memory-coding phenomenon whereby aligned and mirror-reversed memory records in opposite cerebral hemispheres are confused. Two groups of 7-yr.-old boys were chosen on the basis of tendency to confuse mirror and aligned written symbols. The experimental task required discrimination as same or different of letter pairs which were either same or different and either aligned or mirror-reversed. The pairs were simultaneously presented to right, left, or both cerebral hemispheres. The reversing group had slower reaction times than the normal group in all conditions. Evidence was insufficient to conclude that mirror-same bilateral presentation facilitated responses of either group over aligned-same or peripheral conditions. This result would have been necessary to indicate the presence of a mirror-reversed code across the hemispheres. Research utilizing delayed as well as simultaneous presentation of stimuli to children of various ages would clarify this ambiguity. Bilateral processing across conditions proved easier for both groups, indicating adequate hemispheric integration on a visual-perceptual task even in children who tended to confuse mirror images.

Attention Deficit Disorder with Hyperactivity↗
PubMed1985

Reversible and non-reversible enlargement of cerebrospinal fluid spaces in anorexia nervosa.

Brain CT studies of 35 patients with anorexia nervosa confirmed the observations of other authors: cerebral dystrophic changes correlate with weight loss and the reversibility of these changes also correlates with the normalization of body weight. Other corroborated facts are: the most numerous and most pronounced enlargements are of the cortical sulci and the interhemispheric fissure, moderate widening affects the ventricles and the rarest and most insignificant changes are those of the cerebellum. The reversibility of the changes showed a parallel to the extent of the changes themselves and to the duration of improvement of the body weight. The reversibility of the enlargement of the cortical sulci and of the distances between the frontal horns of the lateral ventricles was more often significant than that of the abnormal measurements of the cella media. This difference is based on minimal early acquired brain damage which occurs in 60% of our patients. This high incidence of early acquired minimal brain disease in patients with anorexia nervosa is here discussed as a nonspecific predisposing factor. Although there is no exact explanation of the etiology of the reversible enlargement of cerebrospinal fluid (CSF) spaces in anorexia nervosa, the changes resemble those in alcoholics. The mechanisms of brain changes in alcoholism, as shown experimentally, seem to us to throw light on the probable mechanism of reversible dystrophic brain changes in anorexia nervosa.

Adolescent↗
PubMed1986

Autoradiographic studies with 3H dihydrotestosterone in the brain of sex reversed mice, heterozygous for androgen insensitive testicular feminization (Tfm). A comparison with normal female mice and sex reversed male mice.

Specific binding sites for 3H dihydrotestosterone are demonstrated by autoradiography in brain nuclei of sex reversed mice heterozygous for testicular feminization (Tfm) which are phenotypically intersexes with testes and accessory sex glands that consist of a mosaic of androgen insensitive Tfm cells which lack specific dihydrotestosterone binding and androgen sensitive normal cells. The nuclear group evaluated include: nucleus (n.) septi lateralis, n. interstitialis striae terminalis, n. medialis amygdalae, the hypothalamic n. arcuatus, n. ventromedialis lateralis, n. pre-mammillaris ventralis, n. preopticus medialis, and nuclei of the cranial nerves VII, X, and XII. In the sex reversed males and the female, used as controls, the frequency of neurons with specific DHT binding show a distinct male-female difference in the caudal part of the arcuate nucleus. In the sex reversed Tfm heterozygotes, in all brain nuclei studied, the frequency of labeled neurons is reduced. The extent of reduction of androgen binding in the different brain nuclei varies among as well as within individual sex reversed Tfm heterozygotes, suggesting variations of the ratio of normal to Tfm neurons in sex reversed Tfm heterozygotes. The differentially reduced androgen binding of different brain systems corresponds to a differentially reduced androgen dependent behaviour reported in the literature.

Amygdala↗
PubMed1986

Serological relationship between reverse transcriptases from human T-cell lymphotropic viruses defined by monoclonal antibodies. Evidence for two forms of reverse transcriptases in the AIDS-associated virus, HTLV-III/LAV.

The immunological relationship between reverse transcriptases purified from human T-cell lymphotropic viruses (HTLV-I, HTLV-II, HTLV-III) was defined using monoclonal antibodies specific for HTLV-III reverse transcriptase, secreted by a mouse/mouse hybridoma clone (4F8) developed in our laboratory. The viral proteins from HTLV-I and HTLV-II do not bear any cross-reactive epitope to antibodies secreted by this clone. These antibodies specifically cross-react with HTLV-III reverse transcriptase. The antibodies failed to neutralize the catalytic activity of reverse transcriptase; however, after immunoprecipitation with a magnetic conjugate of goat anti-mouse IgG, the residual activity was completely inhibited. This shows that the antibodies are not directed towards the catalytic active center of the enzyme. Using an immunoblotting technique (Western blotting), we have found two cross-reactive proteins with HTLV-III lysate with molecular masses of 53 and 66 kDa. This suggests that HTLV-III possesses two reverse transcriptase activities with a common determinant recognized by the same epitope.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Reverse genetics of the mouse central nervous system: targeted genetic analysis of neuropeptide function and reverse genetic screens for genes involved in human neurodegenerative disease.

The development of gene targeting technology in mouse embryonic stem cells allows reverse genetics to be used to investigate the function of any cloned gene in the developing and adult brain. Promoter-trap, replacement and insertion vector strategies can be used to generate defined mutations in the chromosomal copy of a cloned gene in embryonic stem cells. These cells can be used to make chimaeric mice, some of which transmit the in vitro mutation via the germline to transgenic offspring. The phenotype of complete loss-of-function mutations (gene knock-outs) can be studied at molecular, cell biological, neurophysiological and behavioural levels, and allows inferences about gene function to be made. Precise small mutations can also be made using integrative vector or two-step replacement vector strategies, allowing specific questions to be asked about regulation and protein structure-function relationships. Reverse genetics can therefore be used as an alternative or additional approach to pharmacology for the study of molecular functions in the central nervous system. Reverse genetic studies of the involvement of particular molecules in neurological disease syndromes may be superior to pharmacological studies to the extent that the syndrome is determined by genetic predisposition. The general ways in which reverse genetics of the mouse can be used to ask questions about molecules in the central nervous system are illustrated by examples from ongoing work of this laboratory. Neuropeptides are an important class of transmitters in the brain, but only in very few cases have specific CNS functions been assigned to a particular neuropeptide. Targeted mutation of neuropeptide precursor and receptor genes offers a rapid way to learn about neuropeptide function. Complete loss-of-function mutations will provide information on any developmental roles of a neuropeptide and on overall behavioural and physiological effects of loss-of-function. More specific targeted mutations allow dissection of the individual roles of multiple neuropeptides that derive from a common precursor protein, and allow in vivo studies of the functional importance of particular amino acids. Experimental progress towards targeted mutation of the neurotensin receptor is described as an example. Recent technological improvements makes targeted mutation of a number of genes possible. This allows reverse genetic screening to be undertaken for genes involved in particular neurobiological phenomena: genes are identified on the basis of molecular criteria (e.g. expression pattern), and gene-targeting used to check their relevance to a phenotype. Neurodegenerative disease is an important aspect of the human phenotype.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed2002

Isolation and characterization of a Japanese flounder clonal line, reversed, which exhibits reversal of metamorphic left-right asymmetry.

We have isolated a clonal line reversed (rev) of homozygous Japanese flounder through gynogenesis. The homozygous offspring gynogenetically produced from rev exhibited reversal of organization of the metamorphic L/R asymmetry such as the direction of eye-migration at a high frequency (20-30%). The molecular analysis using a left-specific marker pitx2 revealed that the embryonic L/R axis was ambiguously established: in more than half of rev embryos, pitx2 was expressed bilaterally in the lateral plate mesoderm (LPM). Previous studies in other animals demonstrated that ectopic pitx2 expression in the LPM could cause laterality defects of the visceral organs. Likewise, our results using rev imply that bilateral pitx2 expression could lead to randomization of the visceral organs. Coincidence of ectopic pitx2 expression and reversal of the direction of eye-migration in the population of rev offspring suggests that the rev locus is critical in specification of both the metamorphic and the visceral L/R asymmetries. However, reversal of the sidedness of the orientation of the visceral organs was not always accompanied by reversal of the direction of metamorphic eye-migration, suggesting that different mechanisms should be involved downstream of the rev locus in directing these two phases of asymmetric morphogenesis in the Japanese flounder.

Amino Acid Sequence↗
PubMed2001

Study of tea polyphenol as a reversal agent for carcinoma cell lines' multidrug resistance (study of TP as a MDR reversal agent).

The aim of this study was to examine MDR1 expression product P-glycoprotein (Pgp) and study the effect and mechanism of tea polyphenol (TP) in reversion of multidrug resistance (MDR) in carcinoma cell lines. Immunocytochemical method was used for qualitative detection of Pgp. A comparative study of cytotoxicity and multidrug resistance reversion effect was made by MTT assay for tea polyphenol and quinidine in MCF-7 and MCF-7/Adr cell lines. The multidrug resistance reversion effect and mechanism were studied by measuring the uptake of 99mTc-tetrofosmin in the carcinoma cell lines. (1) The Pgp overexpression in MCF-7/Adr cells was found to be strong positive, while the Pgp expression of MCF-7 was negative. (2) Although both tea polyphenol and quinidine could not remarkably change the toxicity of adriamycin to MCF-7, they could improve the sensitivity of MCF-7/Adr to adriamycin. The reversion index of tea polyphenol and quinidine was 3 and 10 respectively. (3) The cellular uptake of 99mTc-tetrofosmin was remarkably lower in MCF-7/Adr than in MCF-7. The uptake of 99mTc-tetrofosmin in MCF-7/Adr exhibited a 4, 13, 16 fold increase in the presence of 200, 400 and 500 microg/ml of tea polyphenol respectively. The uptake of 99mTc-tetrofosmin in MCF-7/Adr exhibited only a 4-fold increase in the presence of 200 microM of quinidine. Immunocytochemistry can detect P-glycoprotein expression level qualitatively. Tea polyphenol is not only an anti-tumor agent, but also a multidrug resistant modulator similar to quinidine. The multidrug resistance reversion mechanism of tea polyphenol seems to be its inhibition of the activity of P-glycoprotein. Tea polyphenol has the advantage of very low toxicity in tumor treatment.

ATP Binding Cassette Transporter, Subfamily B, Mem↗