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PubMed1986

Blockade and recovery of the acetylcholine receptor produced by a thienyl analog of phencyclidine: influence of voltage, temperature, frequency of stimulation and conditioning pulse duration.

The effects of the thienyl analog of phencyclidine, 1-[1-(2-thienyl)cyclohexyl]piperidine (TCP), were examined on the end-plate region of the frog neuromuscular junction using a two microelectrode voltage clamp technique. Among the phencyclidine analogs studied, TCP was the most potent in blocking the end-plate current (EPC), producing the largest voltage- and time-dependent blockade. The current-voltage relationship in the presence of TCP (5-25 microM) displayed a large hysteresis loop and a negative slope conductance at hyperpolarized membrane potentials. The rate of decay of the EPC increased linearly with drug concentration, but the voltage-sensitivity of this parameter remained essentially unchanged. The reduction of the peak amplitude, in contrast to the alterations in the kinetics of EPC decay, were influenced by temperature and length of the conditioning pulse. The hysteresis loop in the EPC amplitudes was eliminated at low temperatures (10 degrees C) and when short conditioning voltage pulses (less than 100 msec) were used. At negative membrane potentials, trains of EPCs evoked at a rate of 0.33 Hz decreased progressively in amplitude, the relationship between peak and amplitude and time being approximately exponential. The rate of blockade was voltage-dependent, increasing by about 1.7-fold with a 70-mV membrane hyperpolarization. However, at positive membrane potentials, the peak amplitude of the EPC recovered linearly with time such that by the 150th pulse it was about 4 times the first EPC, a value similar to that obtained under control conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Detection of tricresyl phosphates and determination of tri-o-cresyl phosphate in edible oils.

Tricresyl phosphate (TCP) in contaminated edible oils was extracted using acetonitrile and detected by thin layer chromatography as well as gas chromatography (GC). The chromatoplate was developed with isooctane-ethyl acetate (90 + 10) and visualized by spraying with 2,6-dichloroquinone chloroimide. TCP gives a characteristic blue-violet spot when heated at 100 degrees C for 15 min. The method is direct and sensitive and can be used to detect as low as 2.5 micrograms TCP or TOCP (tri-o-cresyl phosphate). GC was carried out using 10% OV-101 as the stationary phase and flame ionization detection for confirmation and quantitation of TOCP in oils.

Acetonitriles↗
PubMedDate not supplied

Comparative metabolism of 1,2,4-trichlorobenzene in the rat and rhesus monkey.

1,2,4-Trichloro[14C]benzene (TCB) was administered po (10 mg/kg) and iv (10 mg/kg) to rats and rhesus monkeys. Urine was collected at 24 hr and the major urinary metabolites were quantified and identified. By 24 hr, the monkey had excreted 22% of the iv dose and roughly 40% of the po dose in the urine. Less than 1% of the radioactivity was found in the monkey's feces. An isomeric pair of 3,4,6-trichloro-3,5-cyclohexadiene-1,2-diol glucuronides accounted for between 48 and 61% of the urinary metabolites. Glucuronides of 2,4,5- and 2,3,5-trichlorophenol (TCP) accounted for 14 to 37%, and unconjugated TCP's accounted for 1-37% of the monkey's urinary metabolites. For the rat, 84% of the po dose and 78% of the iv dose were collected in the urine by 24 hr; 11% and 7%, respectively, were the amounts collected in the feces. Two isomers, 2,4,5- and 2,3,5-, of N-acetyl-S-(trichlorophenyl)-L-cysteine accounted for 60-62% of the rat's urinary metabolites. Free 2,4,5- and 2,3,5-isomers of trichlorothiophenol amounted to 33% of the urinary metabolites in the po dosed rats and 28% in the iv dosed rats; free 2,4,5- and 2,3,5-TCP's amounted to 1% and 10%, respectively. These results show that there is a sharp division in the types of conjugates formed in the metabolism of 1,2,4-TCB by the rat and rhesus monkey.

Acetylcysteine↗
PubMed1984

On the food favoritism of twins.

In the present study, there is a continuation of the authors' earlier investigations concerning food preference/refusal patterns in a group of Hungarian adult MZ and DZ twin pairs. A "Food Like/Dislike Chart" (FLDC), adapted to local nutritional habits, was applied. In order to characterize the degree of intra-pair concordance referring to the food favoritism, the concept of the "Taste Concordance Point" (TCP) was introduced. On the basis of the comparison of the TCP values obtained for the MZ and DZ pairs the conclusion can be drawn that gustatory habits are presumably influenced also by genetic factors. The results allow the possibility of applying TCP to testing zygosity.

Adolescent↗
PubMed1984

[Radiosensitization by oxygen in Ehrlich tumor receiving artificial blood substitute (FOB 20%)].

To enhance tissue PO2 of radioresistant hypoxic cells of tumor, artificial blood substitute (FOB) was applied, because it is excellent solvent for oxygen and allows the blood circulation system to recover and consequently increase the oxygen supply from blood to the tissue. When trasplanted Ehrlich tumor of mice on thigh grew about 1,000 mm3 in volume, those were divided into three groups, group 1: 60Co gamma-ray irradiation alone, group 2: irradiation under breathing oxygen, and group 3: irradiation under breathing oxygen after exchange transfusion with FOB. The radiosensitization of FOB was studied by comparing with the OER values of three groups for 50% TGD time, 50% SD time, and 50% and 75% TCP. The OER values of 50% TGD time, 5, 10 and 50% SD time 10 of oxygen group were 1.46, 1.29, and 1.22, respectively, and oxygen effect was observed in this group. Those values of FOB group were 2.02, 1.56, and 1.56, respectively and oxygen effect of FOB group was greater than those of oxygen effect of FOB group was greater than those of oxygen group. Animals receiving FOB were apparently radiosensitized by oxygen against animals breathing oxygen at small doses irradiation effect (50% TGD time, and 50% SD time). The OER values of 50% and 75% TCP at 30 days and 90 days after irradiation of oxygen group were about 1.5 (1.46-1.61) and these of FOB group about 1.3 (1.15-1.38). Radiosensitization by oxygen of animals receiving FOB was not clearly recognized against animals breathing oxygen in TCP effect at high dose irradiation. These results indicate that radioresistant hypoxic cells of tumor receiving artificial blood substitute (FOB) increase the sensitivity of 60Co gamma-ray irradiation, especially at small dose irradiation.

Animals↗
PubMed1980

Extraction of pentachlorophenol and tetrachlorophenol residues from field-contaminated carrots and potatoes: comparison of several methods.

A number of solvent extraction systems were investigated for their efficiency in removing residues of pentachlorophenol (PCP) and tetrachlorophenol (TCP) from field-contaminated carrots and potatoes. Greatest numerical yields of PCP and TCP, for both carrots (9 and 5 ng/g, respectively) and potatoes (147 and 11 ng/g, respectively), were obtained by Soxhlet extraction with acidified acetone for 44 hr. Within the limits of experimental error, equivalent results could be obtained by using a 20 hr Soxhlet extraction with acidified acetone for carrots, and a 5 min blending with acidified acetone for potatoes. Extracts were reacted with diazoethane to form the ethyl ethers of PCP and TCP, followed by cleanup on a Florisil column. A gas-liquid chromatograph equipped with a 63Ni linearized electron capture detector was used for identification and quantitation.

Chlorophenols↗
PubMed1978

[Test of 0,0-dimethyl(1-hydroxy-2,2,2-trichlorethyl)phosphonate (Trichlorfon) for carcinogenic activity in Syrian golden hamsters (Mesocricetus auratus Waterhouse) by intraperitoneal administration (author's transl)].

0,0-Dimethyl(1-hydroxy-2,2,2-trichlorethyl)phosphonate (Trichlorfon; TCP) was tested for carcinogenic activity in male and female Syrian hamsters (Mesocricetus auratus Waterhouse) by intraperitoneal administration. The period of administration was 90 weeks, when maximum total doses of 204 mg (male) and 206 mg (female) TCP per animal had been injected. The study was terminated at 100 weeks. There was no statistically significant difference, when compared the total tumour incidence, or the incidence of malignant and benign tumours separated, of the groups of treated and control animals. These findings were independent from whether the groups of TCP-injected animals and controls were combined or divided by sex.

Animals↗
PubMed1993

Trypanosoma cruzi acidic ribosomal P protein gene family. Novel P proteins encoding unusual cross-reactive epitopes.

We have cloned and characterized cDNA molecules that encode members of the acidic ribosomal protein family (TcP proteins) from the protozoan parasite Trypanosoma cruzi. These proteins have been shown to be antigenic in individuals with T. cruzi infection. Unlike other known eukaryotic cells, T. cruzi possesses at least four types of P protein genes TcP0, TcP1, TcP2a, and TcP2b, each of which is present in multiple copies in the genome. These genes are present on at least three different chromosomes. Although the abundance of TcP0, TcP2a, and TcP2b transcripts do not appear to vary among the parasite life-cycle stages, TcP1 is predominantly expressed in the epimastigote (insect) stage. TcP0 has a C-terminal heptapeptide sequence that is similar to those of archaebacterial acidic (P-like) proteins, but the TcP1/P2 proteins terminate with a shared sequence characteristic of the P proteins of higher eukaryotes. The serine residues or other potential phosphorylation sites typically found within the highly charged C-terminal acidic domain are absent in T. cruzi P proteins. Using synthetic peptides, we demonstrated that approximately 80% of T. cruzi-infected individuals produce two distinct but cross-reactive anti-P antibody specificities directed against the C-termini of TcP0 and TcP1/P2. We also expressed the full length (non-fusion) recombinant human P0 and demonstrated that the T. cruzi anti-P antibodies cross-react with the C-terminal residues of human P-proteins. Conversely, human anti-P protein antibodies in sera from patients with SLE cross-react with the C-terminal epitope of T. cruzi TcP1/P2 proteins. The cross-reactivity of anti-TcP antibodies with human P proteins suggests that, through antigenic conservation, TcP proteins may contribute to the development of autoreactive antibodies in Chagas' disease patients.

Amino Acid Sequence↗
PubMed1994

Purification and pharmacological and immunochemical characterization of synaptic membrane proteins with ligand-binding properties of N-methyl-D-aspartate receptors.

A method was developed for the solubilization of approximately 50% of proteins in synaptic membranes that have ligand-binding characteristics of N-methyl-D-aspartate (NMDA) receptors. Affinity chromatographic separation of the solubilized proteins through L-glutamate-derivatized matrices and subsequent elution by NMDA-containing buffers led to the purification of four predominant proteins with estimated sizes of 67-70, 53-62, 41-43, and 28-36 kDa. The co-purification of NMDA-sensitive L-glutamate binding, dizocilpine-sensitive thienylcyclohexyl piperidine (TCP)-binding, and strychnine-insensitive glycine-binding proteins was achieved by this affinity chromatographic procedure. Glutamate, glycine, and the polyamine spermidine increased both the "on" rate and the equilibrium level of [3H]TCP binding to the isolated proteins. The group of proteins eluted by NMDA from the glutamate-derivatized matrices could be further purified through size exclusion chromatography of the NMDA-sensitive glutamate-binding from the dizocilpine-sensitive TCP-binding proteins. Polyclonal and monoclonal antibodies to the cloned NMDA receptor protein NMDAR1 did not react with any proteins in the solubilized membrane proteins or the purified fractions. However, immunoreaction of antibodies raised against a glutamate-binding protein and a phosphonoaminocarboxylic acid-binding protein indicated that these are two of the major proteins in the purified fractions. These studies indicate that these two proteins might be components of a complex that has some of the characteristics of NMDA receptors and that neuronal membranes may contain varieties of NMDA-like receptors composed of protein subunits that differ from the NMDAR1 and NMDAR2 receptor proteins.

Amino Acid Sequence↗
PubMed1994

The influence of repopulation kinetics on isoeffect doses for permanent implants.

PURPOSE: Determination of isoeffect doses for permanent implants with different half-life times. METHOD: To calculate the isoeffective doses a model is used which describes the number of clonogenic tumor cells as a function of time. The effective irradiation time for permanent implants depends on the half-life T1/2 of the used isotope. During the irradiation tumor cells may repopulate, an effect which is well known in fractionated radiotherapy. The longer the radiation treatment lasts the more dose will be needed to kill these repopulating tumor cells. A differential equation has been constructed where cell kill is determined by an alpha-beta term and cell proliferation by a constant tumor cell doubling time Tpot. The solution of the differential equation gives the number of clonogenic tumor cells as a function of time. RESULTS: For our model an analytic solution has been found. The number of repopulating tumor cells shows a minimum if the dose rate is sufficiently high. Otherwise cell kill by radiation is overcompensated by growing tumor cells. The minimum value Nmin of tumor cells depends on the initial cell number N0, the total dose Dtot, the half-life T1/2 of the implant, the half-life Tr for repair of the sublethal damage, the alpha and beta values of the tumor cells, and the effective clonogen doubling time Tpot of the tumor. Assuming that the tumor is cured if no clonogenic cell survives, the tumor control probability (TCP) is determined by the Poisson statistics TCP = exp(-Nmin). Isoeffective doses are doses with constant TCP. Isoeffective doses Dtot have been calculated for different Tpot as a function of the half-life T1/2 of the isotope. CONCLUSIONS: The model allows the calculation of isoeffective doses for permanent implants. Care must be taken to use the results in clinical practice unless all of the radiobiological parameters are known for a specific tumor.

Brachytherapy↗
PubMed1993

A quantitative analysis of modulations occurring in cellular c-myc protein content, %S phase and growth balance under growth-inhibitory conditions.

The c-myc protein was one of the first proto-oncogene products to be linked to the increased proliferative activity of neoplastic cells. However, few studies have attempted to quantify changes occurring in cellular c-myc protein content in response to growth-inhibitory conditions, or to relate such changes to total cellular protein (TCP) levels, %S phase cells and/or cellular growth balance. Knowledge of such relationships is important for determining the biological relevance of the c-myc protein as a marker for proliferating cells. In this study, a dual-laser flow cytometric technique employing three fluorescent dyes was used to quantify cellular changes in c-myc protein, TCP, DNA and growth balance in exponentially-growing and serum deprived U118MG, A-172 and HL-60 cells. Results obtained by flow cytometry were verified using other techniques. Changes in c-myc protein content were found to occur independently of changes in TCP, %S phase or cellular growth balance, and varied between cell lines. These results indicate that cellular c-myc protein determinations convey information that is unique from other indicators of cellular growth and proliferation. Such information may be linked, however, to the nutritional status and origin of the cells being assayed.

Brain Neoplasms↗
PubMed1993

Fluid restriction prior to cycle exercise: effects on plasma volume and plasma proteins.

The purpose of this study was to test the hypothesis that changes in exercise intensity dominate the PV response to cycle exercise in the heat independent of the initial plasma volume (PV) and total circulating protein (TCP) content. The two experimental treatments (counterbalanced design) were performed by nine trained male cyclists (age = 23 +/- 1 yr, VO2peak = 63 +/- 4 ml.kg-1.min-1) in both a euhydrated (EU) and hypohydrated (HP, 24-h fluid restriction) state. Blood volume was measured (carbon monoxide dilution) 30 min prior to each test and subsequent changes in PV were calculated from serial venous blood samples using hematocrit and hemoglobin concentration. Following 20 min of seated rest in a warm environment (Tdb = 30 degrees C, 50-60% RH), each subject cycled in a semi-reclining posture for 60 min at three successive intensities (60, 120, and 180 W for 20 min each, representing approximately 22, 37, and 53% VO2peak). Fluid restriction reduced (P < 0.05) body weight by 1.4 +/- 0.3 kg (1.8 +/- 0.4%), PV by 353 +/- 73 ml (8 +/- 2%), TCP by 20 +/- 7 g (7 +/- 2%), and elevated serum osmolality by 6 +/- 2 mOsm.kg-1 (2 +/- 1%). After 20 min of passive heat exposure (prior to exercise), TCP content remained lower (P < 0.05) in HP (17 +/- 5 g) compared with EU as PV increased (P < 0.05) in EU (222 +/- 27 ml) but not (P > 0.05) in HP (122 +/- 35 ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

An autoradiographic study of calcium phosphate ceramic bone implants in turkeys.

Sintered, porous cylinders of beta-tricalcium phosphate ceramic (TCP) and hydroxyapatite (HAP) labeled with 45Ca were implanted into turkey ulnae for up to six months. Histologic examination of ground sections revealed extensive bone remodeling in the defect regions and resorption of both TCP and HAP. Autoradiograms suggest time- and composition-dependent events. Initial release of calcium ions was observed from both ceramics into adjacent new bone. Diffusion of calcium from TCP, but not HAP, extended into original bone at later periods. At six months, however, calcium from HAP was located intracellularly and within channels of distribution in hard tissue, away from the implant site. These data suggest that physical processes dominate initial HAP resorption while biologic (cellular) mechanisms become more significant later.

Animals↗
PubMed1996

Establishment of the functional importance of thiamin carrier protein in pregnant rats by using monoclonal antibodies.

Monoclonal antibodies (mAbs) to chicken thiamin carrier protein (TCP) have been produced by hybridoma technology to identify the crucial epitopes involved in bioneutralization of the vitamin carrier. The monoclonality of these mAbs (A4C4, F3H6, H8H3, C8C1 and G7H10) was sought to be confirmed by sub-class isotyping; they all belong to IgG1, k type. The epitopes recognized by all the five mAbs are conserved in TCP from the chicken to the rat as assessed by liquid phase RIA and immunoprecipitation of 125I-labelled proteins from pregnant rat serum. Among these mAbs. passive immunization of pregnant rats with the mAb C8C1 only on three consecutive days (day 10, 11 and 12) resulted in embryonic resorption. These results demonstrate the importance of epitopic structure specified by the mAb C8C1 on TCP during pregnancy in rats.

Animals↗
PubMed1996

[Ticlopidine-induced neutropenia].

Ticlopidine (TCP) is a drug that inhibits platelet aggregation. Several studies have demonstrated its superiority over aspirin in preventing stroke and other thromboembolic diseases. However, neutropenia occurs in about 2% of TCP-treated patients, which therefore may advance to agranulocytosis, sepsis and death. They should be carefully followed with blood counts. We report 2 patients hospitalized with severe neutropenia while on TCP, despite having had regular blood counts. Their complications underline the need for patient selection and meticulous follow-up when ticlopidine is prescribed.

Aged↗
PubMed1997

[The in vitro biological behavior of TiNb30 alloy treated with hydroxyapatite and tricalcium phosphates].

An in vitro study has been carried out in different cell systems to determine the biological response of TiNb30 alloy before and after a surface treatment with hydroxyapatite (HA) and tricalcium phosphate (TCP) by the sol-gel method. TiNb30 pure Ti induce favorable cell viability with respect to pure Ni showing a high cytotoxic effect. After surface treatment with HA or HA-TCP mixtures, no difference in cell proliferation can be observed between amorphous and cristalline forms. However, HA decreases (75 +/- 15%) and HA-TCP mixtures increase (133 +/- 11%) significantly cell proliferation compared with controls.

Alloys↗
PubMed1997

The preliminary study and tentative animal study on the sintered PDLLA/TCP composites as bone fracture internal fixation.

Polyesters based on the lactic acid have been reported safety and biodegradation in the human beings for two decades. The greatest advantage of the material is its degradation only conducted by the hydrolysis, where the ester backbones are supposed to be unchained in the aqueous condition. The final degradable products are carbon dioxide and water which can be metabolized and digested in the physiological environment. The goal of this study was aimed to develop a composite sintered with poly-DL-lactide (PDLLA) and tricalcium phosphate (TCP) ceramic particles as orthopedic application. The TCP particles in a range of 30-60 wt% (with 5 wt% increment) were doped into the PDLLA matrix for the reinforcement, which were prepared by the melting and hot pressing techniques. The basic mechanical strength, biodegradable behavior, and biological response of the composites will be investigated in the study. Various techniques, such as pH meter, UV, FTIR, XRD ect., were used to examine and record the degradable process of the composites soaked in the saline for 1-16 weeks. The rabbit femur condyle fracture fixation test was used to evaluate the tissue compatibility and the effects of bone fracture fixation of the composites. The histological observation and x-ray photography were applied for investigating assistance. In the histological evaluation of rabbit femur condyle fracture fixation test, the surface of the composite with 50 wt% TCP addition was attached by the new generated bone without fibrous tissue around after 8 weeks implantation. The fracture bone was gradually healing and the composite always firmly and properly fixed on the fracture area during the implanted period, which provided a breeding environment for normal bone remodeling. The developed composite was thought to be an alternative material for orthopedic application in the future, especially in bone screw and bone plate.

Animals↗
PubMed1999

Molecular chaperones in cilia and flagella: implications for protein turnover.

The mechanisms of protein incorporation and turnover in 9+2 ciliary axonemes are not known. Previous reports of an HSP70-related protein, first in Chlamydomonas flagella and then in sea urchin embryonic cilia, suggested a potential role in protein transport or incorporation. The present study further explores this and other chaperones in axonemes from a representative range of organisms. Two-dimensional gel electrophoresis proved identity between the sea urchin ciliary 78 kDa HSP and a constitutive cytoplasmic HSP70 cognate (pI = 5.71). When isolated flagella from mature sea urchin sperm were analyzed, the same total amount and distribution of 78 kDa protein as in cilia were found. Antigens of similar size were detected in ctenophore comb plate, molluscan gill, and rabbit tracheal cilia. Absent from sea urchin sperm flagella, TCP-1alpha was detected in sea urchin embryonic and rabbit tracheal cilia; the latter also contained HSP90, detected by two distinct antibodies. Tracheal cilia were shown to undergo axonemal protein turnover while tracheal cells mainly synthesized ciliary proteins. TCP-1alpha progressively appeared in regenerating embryonic cilia only as their growth slowed, suggesting a regulatory role in incorporation or turnover. These results demonstrate that chaperones are widely distributed ciliary and flagellar components, potentially related to axonemal protein dynamics.

Animals↗