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At least 865 records · Page 48Linked to original sources
PubMed2002

[Application of rat tail collagen in patch clamp experiment with vestibular hair cells].

OBJECTIVE: To study the feasibility of application of rat-tail collagen in patch clamp research in vestibular hair cells. METHODS: The effect of self-made rat-tail collagen on promoting adhesion of vestibular hair cells in whole cell patch clamp experiment was observed. RESULTS: A seal was hard to be formed when the vestibular hair cells suspended among the external solution without rat-tail collagen. However, when the vestibular hair cells were firmly adhesive to the bottom of the recording chamber with rat-tail collagen, a seal can be formed easily, which fitted to the long-term observation and recording. The effect of rat-tail collagen on adhesive to vestibular hair cells is obvious. CONCLUSION: Rat-tail collagen could facilitate the vestibular hair cells to adhesive with the bottom of the recording chamber, which is helpful for long-term patch clamp research, and the collagen is considered as an optimal adhesive reagent to vestibular hair cells for patch clamp research.

Animals↗
PubMed2003

[Changes of potassium channel activity of hindlimb arterial smooth muscle cells in tail-suspended rats].

OBJECTIVE: To examine the change of potassium channel function in hindlimb arterial smooth muscle cells in tail-suspended rats and to elucidate the underlying electro-physiological mechanisms responsible for the depressed vascular responsiveness of hindlimb arteries induced by simulated weightlessness. METHOD: The contractile responsiveness of femoral arterial rings of 1-wk and 4-wk tail-suspended rats to potassium channel blockers, tetraethylammonium chloride (TEA) and 4-aminopyridine (4-AP), were recorded, and the currents of large conductance calcium-dependent potassium channel (BK(Ca)) and voltage activated potassium channel (Kv) of vascular smooth muscle cells (VSMCs) in saphenous arteries from 1-wk tail-suspended rats were recorded using the whole cell recording mode of patch clamp technique. RESULT: The femoral arteries from of 1-wk and 4-wk tail-suspended rats showed a decreased contractile response to 60 mM KCl, and the ratio of their contractile responses induced by TEA or 4-AP to their responses induced by 60 mM KCl increased significantly after 1-wk and 4-wk simulated weightlessness. However no difference was found between 1-wk and 4-wk tail-suspended rats. The whole cell current recording showed that BK(Ca) current densities and K(v) current densities of VSMCs in saphenous artery increased significantly after 1-wk simulated weightlessness. CONCLUSION: The contractile response of hindlimb arteries to KCl decreased after simulated weightlessness. The activities of BK(Ca) and K(v) of smooth muscle cells in hindlimb arteries from tail-suspended rats increased, and these changes might be among the electro-physiological mechanisms involved in the depressed vasoreactivity of hindlimb arteries due to simulated weightlessness.

4-Aminopyridine↗
PubMed2001

Changes in trabecular bone turnover and bone marrow cell development in tail-suspended mice.

Skeletal unloading induces trabecular bone loss in loaded bones. The tail-suspended mouse model simulates conditions associated with lack of mechanical stress such as space flight for the loaded bones. In such a model, the tail supports the body weight. The forelimbs are normally loaded and the movement of its hindlimbs is free without weight bearing. Histomorphometric analyses of the murine tibiae of the elevated hindlimbs show that trabecular bone volume rapidly diminishes within one week and stabilizes at that level in the subsequent week of tail suspension. Two-week reloading after one-week unloading completely restores trabecular bone volume, but this does not happen after two-week unloading. Unloading for one or two weeks significantly reduces bone formation rate and increases both the osteoclast surface and number compared with age-matched ground control mice. Subsequent reloading restores reduced bone formation and suppresses increased bone resorption. In bone marrow cell cultures, the numbers of alkaline phosphatase (ALP)-positive colony-forming units-fibroblastic (CFU-f) and mineralized nodules are significantly reduced, but the numbers of adherent marrow cells and total CFU-f are unaltered after tail suspension. On the other hand, subsequent reloading increases the number of adherent marrow cells. Unloading for one week significantly increases the number of tartrate-resistant acid phosphatase (TRAP)- positive multinucleated cells compared with the control level. Our data demonstrate that tail suspension in mice reduces trabecular bone formation, enhances bone resorption, and is closely associated with the formation of mineralized nodules and TRAP-positive multinucleated cells in bone marrow cultures obtained from tibiae. Two-week reloading restores bone volume reduced after one-week unloading, but does not after two-week unloading. The tail-suspended model provides a unique opportunity to evaluate the physiological and cellular mechanisms of the skeletal response to unloading and reloading.

Journal Article↗
PubMed1990

Pore formation associated with the tail-tip protein pb2 of bacteriophage T5.

Upon binding of bacteriophage T5 tails to purified FhuA receptor protein the tail-tip protein pb2 became extremely sensitive to trypsin and other proteases. However, when T5 tails were bound to FhuA integrated into liposomes, pb2 was found to retain some resistance to trypsin. Electron microscopic examination of tail-liposome complexes supported the idea that trypsin resistance of pb2 in such complexes was caused by insertion of the tail-tip into the liposomes. pb2 was isolated from tails by treatment with sodium dodecyl sulfate and was further purified by gel filtration using a fast protein liquid chromatography system. pb2 obtained with this procedure was most likely monomeric. It was extremely sensitive to trypsin. When reconstituted into black lipid bilayer membranes, it formed pores with an average single-channel conductance of 4.6 nanosiemens in 1 M KCl. Zero-current potential measurements showed only a very slight preference, if any, for cations over anions. The data are compatible with pb2 forming a large water-filled transmembrane channel. The functioning during infection of pb2 in cytoplasmic membrane depolarization and phage DNA uptake into the cell is discussed.

Electric Conductivity↗
PubMed1991

Targeting of lysosomal integral membrane protein LIMP II. The tyrosine-lacking carboxyl cytoplasmic tail of LIMP II is sufficient for direct targeting to lysosomes.

Time course experiments of the localization of rat LIMP II expressed in COS cells show that the protein is transported directly from the Golgi complex to lysosomes. Substitution of the tyrosine-lacking carboxyl cytoplasmic tail of LIMP II for the native cytoplasmic tails of the plasma membrane proteins CD36 and CD8 resulted in straight transport of both proteins to lysosomes. The synthetic tyrosine-containing heptapeptide, RGTGVYG, did not replace the natural carboxyl cytoplasmic tail of LIMP II in its ability to transport both CD36 and CD8 to lysosomes, and the two constructs were transported to and expressed at the plasma membrane. Substitution of the cytoplasmic tails of either CD36 or CD8 for the carboxyl cytoplasmic tail of LIMP II resulted in transport of the mutants to the plasma membrane where they underwent endocytosis before accumulating into lysosomes. The results indicate that a motif contained in the tyrosine-lacking carboxyl cytoplasmic tail of LIMP II is sufficient to target proteins directly from the Golgi complex to lysosomes.

Amino Acid Sequence↗
PubMed1986

Association of the S-100-related calpactin I light chain with the NH2-terminal tail of the 36-kDa heavy chain.

Calpactin I, a Ca2+- and phospholipid-binding cytoskeletal protein, which serves as a major substrate of protein-tyrosine kinases, was isolated from bovine intestine and lung as a species containing two 36-kDa heavy chains and two 10-kDa light chains. The heavy chain is comprised of two distinct domains which can be identified by limited proteolysis: a COOH-terminal 33-kDa core, which contains the Ca2+- and phospholipid-binding sites, and an NH2-terminal tail, which contains the major site of phosphorylation by pp60v-src. To determine the site of association of the light chain on the heavy chain, we analyzed the association states of the light chain, core, and tail by sucrose gradient centrifugation after limited chymotryptic digestion. The core was not detected in higher Mr complexes with the light chain, and the tail cosedimented with a light chain dimer. The tail, isolated from chymotryptic digests and radiolabeled with 125I, was found to form a specific complex with the light chain, but not the core. The authentic tail and a synthetic peptide corresponding to residues 1-29 of the calpactin I heavy chain were both able to specifically inhibit the reassociation between heavy and light chain, whereas a synthetic peptide corresponding to residues 15-33 was inactive. These results suggest that the tail may serve as a site of regulation by light chain or phosphorylation.

Animals↗
PubMed1986

Slow outward tail currents in molluscan bursting pacemaker neurons: two components differing in temperature sensitivity.

Bursting pacemaker neurons of Tritonia and Aplysia were studied in voltage-clamp experiments to determine the ionic requirements of the slow outward tail current. This current is important for terminating bursts and hyperpolarizing the neuron during the interval between bursts and therefore contributes to the timing of pacemaker activity. A method for rapid extracellular perfusion of the neuron soma with solutions of different ionic composition was used to study the ionic dependence of the tail current. Measurements of the current-voltage relationship were made at different times during the decay of the tail current to determine the reversal potential in different ionic solutions. These experiments showed that 2 or more slow outward currents contribute to the tail current. Temperature had a large effect on these currents. At cold temperatures (10-15 degrees C), the tail current was predominantly a K current. At warm temperatures (20-23 degrees C), both a K current and a K-insensitive outward current were seen. Bursting pacemaker activity occurred throughout this temperature range. Both the K current and the K-insensitive current required Ca influx for activation. These findings help to reconcile conflicting reports in the literature concerning the ionic dependence of the slow outward tail current and suggest a mechanism for temperature compensation of bursting activity in these pacemaker cells.

Action Potentials↗
PubMed1984

[Low energy tail spectra of characteristic X-rays detected by a Si(Li) X-ray detector].

Characteristic X-ray spectra are inherently accompanied by the tail spectra in the low energy side when X-rays are detected with a semiconductor X-ray detector. The tail spectra of Mg, Al, Si, P, S, Cl, K, Ca, Ti, Cr and Mn KX-rays have been observed using two different Si(Li) X-ray detectors. An annular source of 55Fe has been used to excite the Mg (1.25 keV) to Ti (4.5 keV) KX-rays, and 54Mn and 55Fe sources have been used for the detection of Cr (5.4 keV) and Mn (5.9 keV) KX-rays, respectively. Observed intensity ratios of the tail area Nt to the Gaussian X-ray peak area NP have exhibited to change remarkably at the Si-K adsorption edge energy 1.84 ke V. When X-ray spectra detected with different Si(Li) detectors are compared at some specific characteristic X-ray, different values of Nt/Np intensity ratios as well as different line shapes of tail spectra have been observed. Using a simple model, the thickness of Si layer which generates the tail spectrum has been estimated, i.e., the thicknesses are about 0.05 micron for one detector and 0.09 micron for the other detector. The generation of the tail spectrum is known to be partially due to the escape effect of photoelectrons or Auger electrons from the intrinsic region.(ABSTRACT TRUNCATED AT 250 WORDS)

Diffusion↗
PubMed1982

Maturation of the tail spike endorhamnosidase of Salmonella phage P22.

As part of a genetic analysis of the in vivo folding and subunit assembly of the P22 tail spike endorhamnosidase, we have studied the maturation of the newly synthesized 76,000-dalton polypeptide chains into thermostable tail spike oligomers. Four of 15 temperature-sensitive mutations in the structural gene for this protein result in electrophoretically distinct tail spikes. Cells mixedly infected with wild type and an electrophoretic variant produce two hybrid species, with mobilities intermediate between the parental species, indicating that the native tail spike is a trimer. Mature trimers are resistant to denaturation by sodium dodecyl sulfate (SDS): at room temperature the trimer migrates in an SDS gel as if it were not binding significant amounts of SDS, whereas the heat-denatured chain migrates as expected of an SDS-polypeptide complex. The mature trimer is also resistant to trypsin digestion. Lysates of infected cells contain SDS and trypsin-sensitive forms of the newly synthesized tail spike polypeptide chains. These are probably incompletely or incorrectly folded chains. SDS and trypsin resistance were used to measure the efficiency of in vivo folding and subunit assembly of the mature trimer from its polypeptide chains. This decreased from 90% at 27 degrees C to only 15% at 42 degrees C. These results are consistent with the existence or a labile intermediate or step in the folding or subunit assembly of the thermostable tail spike protein. We discuss the possibility that the achievement of certain structural features of mature proteins may entail difficulties in their folding pathways.

Glycoside Hydrolases↗
PubMed1980

[Tail gut regression and associated phenomena in chick embryo (author's transl)].

The regression of the tail gut and the associated phenomena in chick embryo were studied using cytological and biochemical methods. The cells of the tail gut begin degenerating at stage 20. The regression is completed at stage 24. The remnant of the primitive streak which have been incorporated into the tail bud degenerate at the same time. During this period dead cells are sporadically found in the other tissues of the tail bud, chiefly in the mesenchym. The morphological characteristics of cell degeneration and elimination, in the tail gut as in the mesenchyme, are defined. The biochemical study showed that the degenerative phenomena correspond to an enhanced activity of acid phosphatase. This study shows further that these phenomena do not change the total growth rate of the tail bud while they are developing.

Acid Phosphatase↗
PubMed1993

The role of the carboxyl-terminal tail in human O6-methylguanine DNA methyltransferase substrate specificity and temperature sensitivity.

The human O6-methylguanine DNA methyltransferase (MGMT) repairs O6-methylguanine (O6-MG) in DNA at a much lower rate than the Escherichia coli Ada protein, and only MGMT repairs the altered base, O6-benzylguanine (O6-BG). The diversity in DNA repair properties between MGMT and Ada may be a result of divergent amino acid sequences outside their common proline-cysteine-histidine-arginine-valine (PCHRV) acceptor site. One notable sequence difference is an MGMT 28-amino acid carboxyl-terminal tail which is highly conserved among all mammalian alkyltransferases. The role of this tail sequence in substrate specificity was assessed by expressing full-length MGMT and Ada proteins, and mutant MGMT proteins lacking either 10 or 28 amino acids from the carboxyl terminus, as GST fusion proteins in alkyltransferase-deficient E. coli cells, and comparing rates of repair of O6-MG containing DNA and O6-BG by these fusion proteins at 4 degrees C and 37 degrees C. The MGMT carboxyl-terminal tail was not required for repair of O6-MG in DNA at 37 degrees C although the deletion of this tail sequence reversibly inhibited the ability of MGMT to repair O6-MG in DNA at 4 degrees C. Therefore, the absence of this region affects the ability of the protein to repair O6-MG in DNA at lower temperatures. Furthermore, removal of the tail sequence from MGMT decreased the rate of O6-BG repair 5-fold. We conclude that the 28-amino acid carboxyl-terminal MGMT tail, while not required for activity, modulates the rate of MGMT repair at reduced temperatures and plays a role in substrate specificity.

Amino Acid Sequence↗
PubMed1997

Contribution of the C-terminal tail of U1A RBD1 to RNA recognition and protein stability.

The N-terminal RNA binding domain (RBD1) of the human U1A protein interacts specifically with a short RNA hairpin containing the U1 snRNA stem/loop II sequence. Previous RNA binding studies have suggested that the C-terminal tail of RBD1 contributes to RNA recognition in addition to interactions on the beta-sheet surface of the protein. To evaluate the contributions of these C-terminal residues in RBD1 to RNA binding affinity and specificity, as well as to study the thermodynamic stability of RBDs, a number of RBD1 mutants with truncated tails, with single amino acid substitutions, and with both a truncation and an amino acid substitution, have been constructed. The thermodynamic stabilities of these mutants have been measured and compared by GdnHCI unfolding experiments. The RNA binding affinity and specificity of these mutant proteins have been assessed by measuring the binding of each protein to the wild-type RNA hairpin and to selected RNA mutants with nucleotide substitutions in the RNA loop. The results demonstrate first that, although the C-terminal tail of RBD1 makes significant contributions to RNA binding affinity, it is not required for RNA binding, and second, its contributions to binding specificity are mediated only through selected nucleotides in the RNA loop, for in the absence of the tail, the protein continues to use other nucleotides to discriminate among RNAs. In these truncated proteins, the secondary structure intrinsic to the C-terminal tail is absent, yet their affinity and discrimination for RNAs are not lost. Thus, a structured tail is not required for RNA recognition.

Amino Acid Sequence↗
PubMed1997

[Morphological anomalies in "tailed" lymphocyte nuclei and their connection with dicentric chromosomes in irradiated patients].

Lymphocyte nuclei with a narrow outgrowth into the cytoplasm ("tail") were detected on peripheral blood smears of patients exposed to ionizing radiation during the clean up after the Chernobyl meltdown (liquidators). On average, lymphocytes with tailed nuclei occurred at a frequency of 0.43% and 0.15% in exposed patients (n = 101) and healthy donors (n = 50), respectively; the difference between the samples was significant, P < 0.001. The coefficient of correlation between frequencies of lymphocytes with tailed nuclei and those with dicentric chromosomes was 0.74 (n = 27, P < 0.001). The frequency of lymphocytes with dicentric chromosomes was increased in 9 out of 10 patients, in which lymphocytes with tailed nuclei occurred at a frequency larger than 0.8%. A double-color FISH was used to localize centromeric (not more than two signals) and telomeric (not more than one signal) regions in nuclear tails. Abnormal tailed lymphocyte nuclei were assumed to result from breaking the chromosome bridges formed by the dicentric chromosomes.

Cell Nucleus↗
PubMed1998

Description and development of compulsive tail chasing in terriers and response to clomipramine treatment.

OBJECTIVE: To identify factors associated with onset and continued elicitation of tail chasing in Bull Terriers and other terriers and to determine response to treatment with clomipramine hydrochloride, a serotonin-reuptake inhibitor. DESIGN: Prospective study. ANIMALS: 18 tail-chasing terriers (15 Bull Terriers, 1 Miniature Bull Terrier, 1 American Staffordshire Terrier, 1 Jack Russell Terrier). PROCEDURE: 5 dogs were evaluated for tail chasing by a veterinarian at the behavior clinic of the veterinary teaching hospital and 13 dogs were evaluated by the owner's local veterinarian, who confirmed the diagnosis and treated the dog. It was recommended that all dogs in the study be given clomipramine orally at a dosage of 1 to 2 mg/kg (0.5 to 0.9 mg/lb) of body weight, every 12 hours. RESULTS: Of the 18 dogs, 15 were treated with clomipramine within the recommended dosage range, and 3 dogs required treatment at a slightly higher dosage range to control tail chasing. After 1 to 12 weeks of treatment, 9 of 12 (75%) dogs were reported to have a 75% or greater improvement (reduction) in tail chasing. CLINICAL IMPLICATIONS: Findings of this study may aid in recognition and treatment of compulsive tail chasing. In conjunction with appropriate management changes, clomipramine administration appears to be an effective treatment for this otherwise refractory condition.

Age of Onset↗
PubMedDate not supplied

Distal pancreatectomy--does it have a role for pancreatic body and tail cancer.

BACKGROUND/AIMS: Pancreatic resection is the only hope for clinical improvement for patients with carcinoma of the body and tail of the pancreas. However, it is unclear whether palliative pancreatic resection is effective or not for patients with carcinoma of the body and tail of the pancreas. METHODOLOGY: To determine the appropriate treatment for patients with pancreatic body and tail cancer, we analyzed the records of 74 patients with ductal carcinoma of the body or tail of the pancreas who were treated at Kanazawa University Hospital between 1970 and 1995. RESULTS: Using a multivariate Cox proportional-hazard model (factors: age, sex, chemotherapy, radiotherapy, hepatic metastasis, peritoneal dissemination, operative procedure), the presence of hepatic metastasis, peritoneal dissemination, and the type of operative procedures (resection or not) were found to be significant prognostic factors. Surgical resection was the most important prognostic factor. The patients with surgical resection had a significantly higher survival rate than those without resection (p < 0.0001). The survival rate of the patients with palliative resections was also significantly higher than that of the patients without resection, except for the patients with advanced liver metastasis (H3). The survival rate of the patients with palliative resections was also higher than that of the patients without resection, even in patients with peritoneal dissemination. CONCLUSIONS: Surgical resection prolongs the average survival for patients with carcinoma of the body and tail of the pancreas, except for the patients with multiple liver metastasis. These data support the role of palliative pancreatectomy in patients with carcinoma of the body and tail pancreas.

Adult↗
PubMed1998

Rat tail replantation as a training model for microvascular procedures of digit replantation.

In this study we sought to evaluate the potential of rat tail replantation as a tool for very-small-vessel microvascular anastomoses. We used 10 adult Sprague-Dawley rats. The tail was completely amputated 2.0-cm distal to the base of the tail. Then the tail was replanted with anastomoses of two superficial dorsal veins from both sides and one artery. All 10 replanted tails were pink, viable, and normal-appearing at all daily inspections performed from the first to the fourteenth postoperative days. This model can provide a training tool for the acquisition of superior microvascular surgical technique for the repair of very small vessels that stimulate digital replantation.

Amputation, Traumatic↗
PubMed1994

Prevention of spinal neural tube defects in the curly tail mouse mutant by a specific effect of retinoic acid.

Curly tail mouse mutant embryos (ct/ct) develop spinal neural tube defects (NTD) in 54% of cases, comprising isolated tail flexion defects and spinal bifida with tail flexion defects. Both types of spinal NTD result from delayed closure of the posterior neuropore (PNP). Previous studies (Seller et al. [1979] Proc. R. Soc. Lond. Biol. 206:95-107; Seller and Perkins [1982] Prenat. Diagn. 2:297-300) described a paradoxical effect of retinoic acid (RA) on the phenotypic expression of the ct mutation: Treatment with low doses of RA on day 8 of gestation increased the incidence of total NTD, whereas low doses of RA administered on day 9 resulted in reduced incidence of total NTD. In order to investigate further the reported preventive effect of RA, we have carried out detailed analyses of the effects of maternal treatment with 5 mg/kg RA on the incidence of NTD at different developmental stages, and on the development and growth of ct/ct embryos. We found that 5 mg/kg RA reduces the incidence of spinal NTD in a stage-specific manner, without increasing the incidence of cranial NTD. The effect of RA is specific: There were no other alterations in morphogenesis, growth, development, resorption rate, or litter size. RA was more effective in the prevention of isolated tail flexion defects than of spina bifida. Prevention of isolated tail flexion defects was maximal (50% reduction) when RA was administered between 10 days 4 hours and 10 days 8 hours post coitum (p.c.) inclusive (24 to 34 somite stage).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2006

Maintenance of above-branch balance during primate arboreal quadrupedalism: coordinated use of forearm rotators and tail motion.

Animals that live and travel in trees display a variety of morphological and behavioral adaptations to help them maintain balance on narrow flexible supports. Among these adaptations are long tails that can be used as counterweights, and freely mobile limbs in order to reach discontinuous supports. Here we describe two additional ways in which these features can contribute to balance during arboreal locomotion. Electromyographic (EMG) recordings of the forearm rotators pronator quadratus and supinator during over-ground and above-branch quadrupedal locomotion in five species of Old World monkeys revealed their contribution to shifting the weight of the body to help change the direction of travel and maintain balance on a branch. In addition, we observed a coordinated mechanism consisting of a sweeping tail rotation toward the direction of imbalance, to impart an angular momentum to the body that assists in the restoration of balance. While all five primate species utilized forearm rotators to shift their bodies toward one side or the other during quadrupedal walking along a branch, the tail-whip mechanism was most frequently used by the largest and most terrestrial species. We suggest that their large size and/or terrestrial habits have made them less adept at arboreal locomotion, and therefore most likely to utilize auxiliary balancing mechanisms. The usefulness of a long tail as a balancing aid during arboreal locomotion highlights the puzzling nature of the evolutionary loss of a tail in the ape and human lineage.

Animals↗