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At least 19 recordsLinked to original sources
PubMed2002

Arsenic trioxide induces apoptosis equally in T lymphoblastoid leukemia MOLT-4 cells and P-gp-expressing daunorubicin-resistant MOLT-4 cells.

PURPOSE: To investigate the effects of arsenic trioxide (As(2)O(3)) on human T-lymphoblastoid leukemia MOLT-4 cells and P-gp-expressing daunorubicin-resistant MOLT-4 (MOLT-4/DNR) cells. METHODS: Cell growth was measured by an MTT assay. Cell viability was determined by a dye exclusion test. The level of P-gp expression was estimated using phycoerythrin-conjugated anti-P-gp monoclonal antibody 17F9. The function of P-gp was evaluated in terms of rhodamine 123 (Rh123) efflux. The percentage of cells undergoing apoptosis was determined by flow cytometry after staining with annexin V-FITC and propidium iodide. RESULTS: As(2)O(3) inhibited the growth and survival of MOLT-4 and MOLT-4/DNR cells in a time- and dose-dependent manner. The 50% inhibitory concentrations of As(2)O(3) (IC(50)) against the growth of these cell lines were 5.1 micromol/l and 5.0 micromol/l, respectively, when the cells were treated with As(2)O(3) for 96 h. As(2)O(3) induced an apoptotic morphology in both MOLT-4 and MOLT-4/DNR cell lines. These effects of As(2)O(3) were time- and dose-dependent when the two cell lines were incubated in the presence of 1-8 micromol/l of As(2)O(3) for 3-144 h. As(2)O(3) treatment for 3 to 24 h at 5.0 micromol/l did not change the percentage of P-gp-expressing cells or the efflux ability of MOLT-4/DNR cells. CONCLUSION: As(2)O(3) inhibited growth and induced apoptosis equally in MOLT-4 and MOLT-4/DNR cells, and this suppressive effect did not influence P-gp expression or function in MOLT-4/DNR cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1989

Molt induced by gonadotropin-releasing hormone agonist as a model for studying endocrine mechanisms of molting in laying hens.

Molt induced by infusion of a gonadotropin-releasing hormone agonist (GnRH-A, ([D-Leu6,Pro9]-GnRH N-ethylamide]) has been used as a model for studying the endocrine mechanisms of molting. Molt induced by GnRH-A was also compared with that induced by feed withdrawal (FW). Thirty-three laying hens were divided into three groups: 1) sham infused (controls), 2) molted by GnRH-A infusion (GnRH-A), or 3) molted by FW. All groups had reduced day length. Birds were weighed and blood was sampled twice per week. Plasma was assayed for thyroxine (T4), triiodothyronine (T3), and progesterone (P4); egg production was recorded. A separate group of GnRH-A molted (n = 8) and control (n = 4) hens were killed during the molt and liver, ovary, and oviduct were weighed. Plasma T4 concentrations were elevated (P less than .01), whereas plasma T3 did not change and plasma P4 decreased (P less than .05) in the GnRH-A group compared with the control group. Plasma T4 was higher (P less than .05) in the GnRH-A group than in the FW group, whereas plasma T3 was higher (P less than .05) in the FW group than in the GnRH-A group. Plasma P4 concentrations declined to similar low levels in the GnRH-A and FW groups. The GnRH-A caused weight loss (P less than .05) from the ovary, oviduct, and liver. The GnRH-A-molted hens lost less BW (P less than .001) and were out of lay for 12 days less than FW-molted hens. Postmolt rates of lay were not significantly different for the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2003

Modulation of foregut synaptic activity controls resorption of molting fluid during larval molts of the moth Manduca sexta.

We examined the role of the foregut in the resorption of molting fluid (MF) from the exuvial space during the last larval-larval molt of the moth Manduca sexta. In intermolt larvae, the activity of the foregut is characterized by robust peristaltic contractions. With the onset of the molt, MF is secreted into the exuvial space where it digests and weakens the old cuticle. The appearance of MF in the exuvial space is accompanied by a dramatic reduction in the amplitude of the foregut contractions. Foregut peristalsis returned about halfway through the molt, followed shortly by the appearance of MF in the gut. These observations suggested that larvae use their foreguts to remove MF from the exuvial space. Animals whose foreguts were surgically inactivated did not resorb their MF and most failed to successfully shed their old cuticles. The reduction in foregut motility at the onset of the molt was correlated with a sharp decline in the amplitude of the excitatory junctional potentials. With the onset of the molt there was also a decline in the number of presynaptic terminals on the foregut that loaded with the activity-dependent dye FM1-43. In the second half of the molt, the appearance of MF in the foregut and the return of foregut motility was correlated with an increase in FM1-43 loading. These data reveal that during a larval-larval molt, vesicle release and/or recycling of the presynaptic endings on the foregut muscles is modulated to assure the proper timing of MF resorption.

Animals↗
PubMed1988

Immunophenotypic and cytogenetic analysis of Molt-3 and Molt-4: human T-lymphoid cell lines with rearrangement of chromosome 7.

Molt-3 and Molt-4 are T-cell lines originally derived in 1971 from a patient with T-cell acute lymphoblastic leukemia. An unusual T-cell antigen receptor gamma-chain gene (T-gamma) rearrangement detected by Southern blot analysis of Molt-4 prompted an in-depth study of the immunophenotype and karyotype of both cell lines. Molt-3 and Molt-4 had immunophenotypic characteristics of thymocytes with expression of CD1 and CD5. Both cell lines had a hypertetraploid karyotype with two rearranged no. 7 chromosomes: 2der(7)t(7;7)(p15;q11). The presence of a break in chromosome band 7p15 suggested the involvement of T gamma. We cloned the rearranged BamHI fragments spanning the known T-gamma constant and joining regions. Comparison with germline clones of T gamma did not suggest any of the clones included a breakpoint region. Thus the 7p15 chromosomal abnormality in Molt-3 and Molt-4 is not associated with the currently described joining and constant regions of T gamma.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1994

Evaluation of molt induction to body weight loss of fifteen, twenty, or twenty-five percent by feed removal, daily limited, or alternate-day feeding of a molt feed.

Postmolt egg production variables were compared among hens induced into molt by feed removal, by limited daily feeding of a low-density and low-energy molt feed at 22.8 g per hen, or by limited alternate-day feeding at 45.5 g per hen, until approximate body weight loss of 15, 20, and 25% was obtained. Hens were housed two per cage (25.4 x 45.7 cm) in a house of environmental design, and photoperiod was reduced to 8 h during the 28-d molt period. When target body weight loss was obtained, packed cell volume was determined and hens were maintained on 45.5 g/d of 1.2% calcium prelay feed through the 28-d molt period. Egg production and mortality were recorded daily; egg weight, egg specific gravity, body weight, and feed intake were recorded at 4-wk intervals postmolt. Packed cell volume of hens molted by feed removal (36.4%) was higher (P < .01) than that of alternate-day (34.1%) or daily limited (33.6%) hens. Hens that lost 25% of their body weight had higher packed cell volume (36.3%) than hens that had body weight loss of 20% (34.4%) or hens that lost 15% (33.4%). Postmolt mortality and egg production were not different (P > .05) as a result of molt induction method or percentage body weight loss. At the 4th wk postmolt, body weights were 50 and 57 g heavier for hens that had lost 15% body weight than those that lost 25 or 20%, respectively, and egg production was negatively linearly related to body weight loss.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1975

Molting in stomatopod crustaceans. I. Stages of the molt cycle, setagenesis, and morphology.

The description of stages of the molt cycle in mantis shrimp (emphasizing Gonodactylus but compared in a number of Gonodactylidae, Squillidae, and Lysiosquillidae) includes data on texture, hardness, and color of the exoskeleton; behavior; and the micromorphology of the integument and developing setae. After stage A1, when the exoskeleton feels soft and soapy, and A2, when the abdomen attains parchment consistency, the exoskeleton continues to harden until stage C1, when the telson carinae can no longer be depressed with a fingernail. The propodus (C2) and the merus (C3) of the raptorial appendage are the last elements to become rigid. The meral spot achieves indistinct coloration at B1 and distinct but pale coloration at B2; body color continues to intesify until C4. Changes in behavior are particularly marked before and after the molt. After the molt defensive and avoidance behaviors characterize A1 and A2. Threatening increases from low to intense levels in A2 and B1. Striking and offensive behavior increase from weak to normal intensities from B2 to C4. One or two days before the molt, animals lower activity and dominance and feeding levels, exhibit reclusive behavior, and sometimes seal the cavity entrance. The morphology of setagenesis is particularly valuable for determining the stage of the molt after the exoskeleton hardns. The raatio of setae containing cellular contents sthroughout the lumen to those condensed into strands separates stages A2 throught C3...

Animals↗
PubMed1974

Immunological functions of human T-lymphoid cell line (MOLT). I. Release of immunosuppressive factors from the mixture of MOLT-4 cells and sheep red blood cells.

A short term incubation of the mixture of established human T-lymphoid cells (MOLT) and sheep red blood cells (SRBC) resulted in the release of factors which nonspecifically suppressed the response of mouse spleen cells against heterologous erythrocytes in vitro. Neither human B-cell line (RPMI 1788), nor the supernate of MOLT cell suspension in the absence of SRBC had such suppressive effects. The supernate of the mixture of MOLT cells with chicken red blood cells (CRBC) did not suppress either anti-CRBC or anti-SRBC responses of mouse spleen cells. Since CRBC did not form rosettes with MOLT cells, it is suspected that the origin of the production of these factors might be MOLT cells forming SRBC rosettes. Some of these factors are dialysable.

Animals↗
PubMed1977

Cockroach molting. II. The nature of regeneration-induced delay of molting hormone secretion.

1. The amount of regenerating limb tissue does not control the length of molting delay in cockroaches; rather, a programmed delay associated with each autotomy level and segment allows an appropriate delay for accomplishing the necessary regeneration. 2. Delay of molting is accomplished by inhibiting ecdysiotropin release. 3. Each regenerating limb produces a delay independent of other regenerating limbs. 4. Single and simultaneous double autotomies can be used to obtain substantially increased synchrony of the molting cycle of a wide variety of cockroach species. 5. The signal to delay molting is transmitted to the brain along the ventral nerve cord and requires the stereotyped sensory input associated with autotomy to initiate it. 6. There are two phases of ecdysone titer increase during the molting cycle of cockroaches. An early transitory or gradual increase is associated with the regeneration critical period, while a later major peak is associated with apolysis. The major ecdysone peak was shown to be delayed during leg regeneration.

Amputation, Surgical↗
PubMed1998

Molt-inhibiting hormone mRNA levels and ecdysteroid titer during a molt cycle of the blue crab, Callinectes sapidus.

Synthesis of ecdysteroid molting hormones by crustacean Y-organs is believed to be regulated by a neuropeptide, molt-inhibiting hormone (MIH), produced in eyestalk neural ganglia. In the present study, steady-state MIH mRNA and hemolymph ecdysteroid levels were determined by Northern blot and radioimmunoassay, respectively, during the molt cycle of the blue crab, Callinectes sapidus. The level of MIH mRNA dropped steadily during premolt (D1-D4), reaching a minimum in D3/D4, then increased by 10-fold in postmolt (A/B) and remained elevated during intermolt (C4). These stage-specific changes in MIH mRNA levels were accompanied by significant fluctuations in the hemolymph ecdysteroid titer. The ecdysteroid titer increased steadily to a peak of 377.0 ng/ml in D3 of premolt, then dropped to 120.0 ng/ml in D4 (just prior to molting), and was low during postmolt (A/B, 4.4 ng/ml) and intermolt (C4, 3.3 ng/ml). The results represent the first report of developmental changes in MIH gene expression and are generally consistent with the hypothesis that MIH negatively regulates ecdysteroid synthesis in crustaceans.

Animals↗
PubMed1991

Uridine fluxes in healthy proliferating T-lymphocytes, MOLT-3 T-ALL cell-line cells and differentiated MOLT-3 cells.

Incorporation of 14C-uridine into UTP and CTP and fluxes of label through these nucleotide pools to RNA and DNA were greater in MOLT-3 cells compared to T-lymphocytes. In growth-arrested, differentiated MOLT-3 cells overall incorporation of radiolabel into nucleotides and nucleic acids was lowered compared to exponentially growing cells. Turnover of UTP and CTP however, retained the profile of exponentially growing MOLT-3 cells, implicating the characteristically higher conversion of UTP to CTP is independent of the MOLT-3 cells proliferative capacities. We conclude that drugs interfering with CTP-synthetase activity are good candidates to be used as selective substances in the battle against T-ALL.

Carbon Radioisotopes↗
PubMed1968

The fine structure of the ventral intersegmental abdominal muscles of the insect Rhodnius prolixus during the molting cycle. I. Muscle structure at molting.

Rhodnius prolixus, a South American insect, molts five times in its development to an adult after emerging from the egg. Each molting cycle is triggered with a blood-meal. The ventral intersegmental abdominal muscles of Rhodnius develop during each molting cycle and are functional at molting. The fine structure of these fully developed muscles from fourth stage larval insects is studied. They have the characteristic structure of slow muscles. They have multiple motor nerve endings, and the myofibrils are poorly defined in cross-section. Longitudinal sections show long sarcomeres (8-10 micro), irregular Z-lines, and no apparent H zones. No M line is seen. Transverse sections through the A-band region show that each hexagonally arranged thick filament is surrounded by 12 thin filaments. Two thin filaments are shared by two neighboring thick filaments. The ratio of thin to thick filaments is 6:1. This structure is related to that found in vertebrate skeletal muscle and insect flight muscle.

Abdomen↗
PubMed1986

Primary feather molt and serum luteinizing hormone concentration in chukar partridge (Alectoris chukar) during a photoperiodically induced molt with or without fasting.

In two experiments, 135 adult chukar partridge of two genetic lines, one selected for high egg production and a random-bred control line, were induced to molt by reducing photoperiod from 16 hr light/day to 8 hr light/day on Day 0. In Experiment 1, feed was removed from approximately half the birds on Day 0 and returned on Day 7. Birds in Experiment 2 were not fasted. Photoperiod was increased to 16 hr light/day on Day 56. Primary feather molt scores, body weights, and, in Experiment 2, serum luteinizing hormone (LH) levels were monitored weekly through Day 85. Prior to the short day period, birds selected for high egg production and females had lower molt scores than controls or males, respectively. Fasting had no effect on molt scores, egg production, or body weights (except during the fasting period). Selected-line birds returned to lay approximately 3 days earlier and laid approximately 16 more eggs during the second production period than controls. Six days before photoperiod was reduced, immunoreactive serum LH levels were 5 to 8 ng/ml; they declined during short days to about 4 ng/ml. Within 8 days after relighting, LH levels increased to approximately 33 ng/ml in males and 18 ng/ml in females. Luteinizing hormone levels remained elevated in males throughout the subsequent 4 weeks but declined in females as egg production resumed.

Animals↗
PubMed1968

The fine structure of the ventral intersegmental abdominal muscles of the insect Rhodnius prolixus during the molting cycle. II. Muscle changes in preparation for molting.

The development of the ventral intersegmental abdominal muscles of Rhodnius prolixus is triggered by feeding. The early muscle (1 day after feeding) contains essentially nonstriated fibrils. However, in cross-sections, areas indicating early I bands, Z lines, and A bands can be recognized. Interdigitating thick and thin myofilaments do not assemble into a precise lattice until sometime between 4 and 5 days after feeding. As development continues, the number of fibrils increases, the region corresponding to the Z line increases in density, and the fibrils contain more recognizable striations. The newly formed fibrils broaden as myofilaments are added peripherally. At all stages throughout development, the ratio of thin to thick myofilaments is always 6:1. The formation of fibrils in the abdominal muscles of Rhodnius is different from that in chick embryo skeletal muscle. The major differences are that at all stages in Rhodnius there are (1) a constant ratio of thin to thick myofilaments, and (2) detectable Z-line material. Other findings in Rhodnius suggest (1) that fusion of mononucleated cells with the multinucleated muscle cell occurs, (2) that microtubules develop in the tendon cell concomitantly with development of myofibrils in the associated muscle cell, and (3) that filaments 55A in diameter aggregate into microtubules.

Abdomen↗