Temporary Delay Research Articles

Comparison of ovarian electrocautery and oral contraceptives in the treatment of hyperandrogenism in women with polycystic ovary syndrome

Endocrine treatment of hyperandrogenism in women with polycystic ovary syndrome (PCOS) aims at reduction of androgens and increasing sex hormone binding globuline (SHBG), which are also side effects of ovarian electrocautery (OE) when used for induction of ovulation.Hormonal effects of ovarian electrocautery were compared with the effects of oral contraceptives (OC) containing desogestrel (DG) or cyproteron acetate (CPA). OCs were given to 18 women with PCOS as their sole treatment (group A) and to 23 women after the restoration of regular ovulatory cycling by ovarian electrocautery (group B).Ovarian electrocautery induced ovulation and increased the concentration of estrogens and especially progesterone, while OC induced the opposite effects. In the androgens and SHBG the two treatments induced changes that were in the same direction, but OC treatment induced changes that exceeded those of OE. The concentration of SHBG increased from 27.9 to 127.7 nmol/L on OC treatment (Group A), compared with 37.2 to 44.9 after OE (Group B). The androgens decreased, for testosterone the decreases were 2.1 and 0.99 nmol/L, respectively, for androsterone 5.36 and 3 nmol/L, for dihydrotestosterone 0.12 and 0.1 nmol/L, and for DHEAS 3.28 and 1.8 umol/L. No further gain was obtained by the combination of the two treatments.Hyperandrogenism in women with PCOS can be effectively treated with OCs containing DG or CPA. In women with concurrent infertility, however, ovarian electrocautery can be recommended. The only indication for the combination of these two treatments is ambivalence with regard to the fertility after ovulation induction by OE. A temporary delay of ovulatory cycling with OC-treatment after OE has no negative impact upon the future fertility.

The role of cytotoxic chemotherapy in the management of aggressive and malignant pituitary tumors.

Pituitary tumors are mostly benign lesions, although 5-35% are locally invasive. A small number exhibit a more aggressive course, infiltrating dura, bone and sinuses, and are designated highly aggressive. However, the presence of metastases separate from the pituitary in the central nervous system or at a distance is necessary to designate pituitary tumors as carcinomas, i.e. truly malignant. When conventional therapeutic modalities fail, systemic chemotherapy remains the last option. We report seven such patients, three with highly aggressive and four with malignant pituitary tumors (n=4) four women; median age, 32 yr; range, 23-48 yr), who received one or more courses of chemotherapy with lomustine and 5-fluorouracil (median, two courses; range, one to six courses). Three patients with systemic metastatic disease had a shorter survival (median, 5 months; range, 1-14 months) than the one patient with central nervous system metastases alone (10 yr). A patient with an aggressive nonmetastatic prolactinoma who initially responded to chemotherapy died from another nondisease-associated cause. Two patients, one with an aggressive and one with a metastatic tumor, achieved symptomatic improvement with a median duration of 6 months. A hormonal reduction greater than 50% was observed in two of seven patients; only one patient who had an aggressive tumor obtained an objective tumor response. The median survival from the time of initiation of chemotherapy in patients with malignant tumors ranged from 3-65 months. Two patients with malignant tumors developed disease progression while receiving chemotherapy; no patient with extracranial metastases showed a response. Treatment was well tolerated, with minimal individual side-effects. Three patients with no response to initial treatment received different chemotherapeutic regimens with no additional response. All patients with metastatic malignant tumors eventually died. Treatment with cytotoxic chemotherapy is noncurative, and current experience is limited. Until another more specific form of treatment is available, chemotherapy may still be of some value in patients with highly aggressive and malignant pituitary tumors, at least in achieving a temporary remission or delay in progression. The combination of lomustine/5-fluorouracil proved easy to administer with minimal toxicity, although the response rate was only 14%. Until a more specific treatment is found, an optimal chemotherapeutic regimen needs to be established.

Delay analysis for train operation

The paper studies the delay pattern of a rail line by system simulation with the data of Taiwan's south rail line. The running time of a train between two successive stations and the platform dwell time of a train at a station were defined as stochastic distributions, which can be calibrated by observed data. A stochastic model was developed to simulate the operations of the trains planed in the timetable, and the dispatching of the traffic control system. The primary result of the model is the spatial and temporary delay pattern of an operating rail network.

Production of micronucleoli and onset of cotton fiber growth

Experiments focused on the early development of fiber cells of cotton (Gossypium hirsutum L. cv. MD51 ne) ovules produced two novel findings: one biological, the other methodological. The first concerns a micronucleolus in the nucleus of fibers. This developmental marker appears at or a little before 4 days postanthesis (dpa) in about 10% of the fibers and increases thereafter to nearly 80% provided the fibers are growing on fertilized ovules. Micronucleoli are neither seen in nuclei of fibers at 0–2 dpa nor in nuclei of non-fiber cells. Consequently, it is postulated that they are the product of specific developmental genes associated with fiber growth. The second, methodological finding, involves a cytological means of directly counting the number of fibers produced on young ovules at 1–4 dpa. The method provides quantitative data unavailable in the past. We used this method to show that emasculation caused a temporary 24-h delay in the initiation of fibers, that 30% of the fibers are affected, and that at 3 dpa both fertilized and unfertilized ovules have about 14 500 fibers. These data indicate that the fibers on fertilized and unfertilized ovules represent the same cell populations, a finding heretofore unknown.

Glial-cell cultures from brains of carbonic anhydrase II-deficient mutant mice: delay in oligodendrocyte maturation.

Carbonic anhydrase II (CAII) is a multifunctional enzyme found in oligodendrocytes and astrocytes in normal mouse brains. We have begun to compare the glial cells in primary cultures from neonatal genetically CAII-deficient (Car) mice to those from normal (con) mice in order to detect developmental defects, if any, in Car glial cells. In con cultures intensely CAII-positive cells costained with antibodies against the oligodendrocytic markers, O4 and myelin basic protein (MBP), respectively. Most (82%) of the CAII-positive cells were O4-positive, but only approximately 60% were MBP-positive. Some clumps of GFAP-positive cells were CAII-positive. At each respective number of days in vitro (DIV) total numbers of O4-positive cells were similar in Car and con cultures, and total numbers of galactocerebroside-positive cells also were similar in Car and con cultures. However, compared to cells in con cultures at 7 DIV, a lower percent of Car cells in the oligodendrocyte lineage expressed MBP, and morphological differentiation also was subnormal in that the Car cells showed fewer processes and membrane sheets. Car and con cultures expressed similar numbers of MBP-positive cells by 10 DIV. The results suggest a temporary delay in the maturation of Car oligodendrocytes.

Effect of cisplatin chemotherapy on extracortical tissue formation in canine diaphyseal segmental replacement.

The reconstruction of large bone and joint defects after the resection of malignant tumors remains a major challenge. Chemotherapy has significantly lowered the risk of metastasic disease, but complications associated with reconstructive techniques continue to result in late morbidity. In the present study, biomechanical torsion testing, gait analysis, and histomorphometric and scanning electron microscopic evaluations of 24 dogs were used to examine the effects of preoperative and postoperative administration of cisplatin on the biologic fixation of a porous-coated segmental replacement prosthesis. The chemotherapy consisted of four cycles of cisplatin administered at a dosage of 75 mg/m2 preoperatively or postoperatively. The healing was enhanced by use of an autogenous corticocancellous bone graft. The graft was placed evenly around the prosthesis and the adjacent femoral cortex. Mechanical analyses of torsional stiffness, yield strength, and maximum strength revealed no statistically significant differences between the groups at 12 weeks. Such lack of difference was mainly due to the penetration of highly organized fibrous tissue into the porous surface; this provided strong fixation of the implant to bone even in the absence of bone ingrowth. Although bone ingrowth into the prostheses was not affected, electron microscopic, histomorphometric, and radiologic analyses showed a clear difference in the formation of new bone around the prosthesis. Preoperative chemotherapy did not alter the formation of new bone, but specimens from animals treated postoperatively with cisplatin showed significantly less bone graft resorption and less new bone formation. Hence, the effect of cisplatin administration caused only a temporary delay, not a permanent effect, on extracortical capsule formation. The formation of extracortical bone and soft tissue might prevent debris-incised osteolysis and, therefore, prevent late complications by forming a tight capsule around the bone-prosthetic interface.

Diffusion-weighted MRI of myelination in the rat brain following treatment with gonadal hormones.

Previous studies have demonstrated the ability of high-resolution diffusion-weighted MRI to show maturation of white-matter structures in the developing rat brain. The purpose of this study was to investigate the influence of gonadal steroid hormones on the rate of this development. Starting from their second postnatal day, 16 rat-pups of either sex were repeatedly treated with subcutaneous implants containing 17-beta estradiol or delta-androstene 3,17 dione, respectively. Serial T1-, T2- and diffusion-weighted MRI was performed weekly for 8 weeks using a 4.7 T unit. Maturation of anterior optic pathways and hemisphere commissures was assessed. Diffusion-weighted images were processed to produce "anisotropy index maps", previously shown to be sensitive to white-matter maturation. Compared with untreated rat-pups, estrogen-treated animals showed accelerated, and testosterone-treated animals delayed maturation on anisotropy index maps and histological sections. In all animals, maturational changes appeared earlier on anisotropy index maps than on other MRI sequences or on myelin-sensitive stained sections. Diffusion-weighted imaging, and the construction of spatial maps sensitive to diffusion anisotropy, seem to be the most sensitive approach for the detection of maturational white-matter changes, and thus may hold potential for early diagnosis of temporary delay or permanent disturbances of white-matter development.

Inhibition of apoptosis by overexpressing Bcl-2 enhances gene amplification by a mechanism independent of aphidicolin pretreatment.

To study the effect of apoptosis on gene amplification, we have constructed HeLa S3 cell lines in which the expression of bcl-2 (BCL2) can be controlled by tetracycline in the growth medium. Induction of Bcl-2 expression caused a temporary delay of apoptosis and resulted in roughly a 3-fold increase in the frequency of resistant colonies when cells were selected with trimetrexate. This resistance was due to amplification of the dihydrofolate reductase gene. Cells grown out of the pooled resistant colonies retained the same level of resistance to trimetrexate whether Bcl-2 was induced or repressed, consistent with the theory that Bcl-2 functions by facilitating gene amplification, rather than being the resistance mechanism per se. Pretreating cells with aphidicolin is another method to increase gene amplification frequency. When Bcl-2-expressing cells were pretreated with aphidicolin, the resulting increase in gene amplification frequency was approximately the product of the increases caused by aphidicolin pretreatment or Bcl-2 expression alone, indicating that Bcl-2 increases gene amplification through a mechanism independent of that of aphidicolin pretreatment. These results are consistent with the concept that gene amplification occurs at a higher frequency during drug-induced cell cycle perturbation. Bcl-2 evidently increases the number of selected amplified colonies by prolonging cell survival during the perturbation.

Response of potato tubers to hypoxia followed by re-aeration

Potato tubers kept under hypoxia (1%) showed improved viability in comparison to anoxia, which was associated with the maintenance of intermediate adenylate energy charge values (A.E.C.=0.6) and stable adenylate pools at 50% of the initial levels. Re-admission of oxygen to the tuber resulted in an almost full recovery of adenylate energy charge and total adenylates after up to 3 days of hypoxic pretreatment. Tubers exhibited a mixed fermentation. The high lactate, ethanol and acetaldehyde levels proved to be non toxic. Ethanol was degraded to acetaldehyde during re-aeration. Posthypoxic lipid peroxidation was indicated by malondialdehyde and ethane formation. Both products occurred with a temporary delay and in lower amounts compared to post-anoxia. Ethylene release was also considerably smaller. Severe hypoxia and posthypoxia postponed tissue death compared to anoxia. Survival was correlated with an improved energy supply which stabilized membranes.

Censorship of the atomic bomb casualty reports in occupied Japan. A complete ban vs temporary delay

For the last 50 years, widely believed misunderstandings have existed concerning allegations of US suppression of the atomic bomb casualty reports in Occupied Japan.^1,2This article clarifies these misunderstandings, discussing both the US and Japan sides of history. The research is based on declassified records from several sections of the Supreme Commander for the Allied Powers (SCAP), which were verified with Japanese records. <h3>Atomic Bomb Injury</h3> On August 9,1945, at 11:02 AM, Shigeyasu Aritomi, a medical student of Nagasaki Medical College, experienced the atomic bomb. Despite fatigue and dizziness, Shigeyasu dug himself out of the crushed hospital ward and walked home.³Seven days later, Shigeyasu died of radiation sickness, then called "the symptoms of the first period of atomic bomb injury": extreme fatigue, nausea and vomiting, fever, hematuria, mucous bloody stools, hemoptysis, and gingival bleeding, caused by severe damage to the internal organs and blood cells. Some survived

Branch mortality and potential litterfall from Douglas-fir trees in stands of varying density

Forest floor characteristics influence nutrient cycling and energy flow properties of forest ecosystems, and determine quality of habitat for many forest plants and animals. Differential crown recession and crown development among stands of differing density suggest that an opportunity may exist to control the input of fine woody litter into the system by manipulating stand density. The objective was to measure the rate of branch mortality among stands of differing density and to estimate the range in total per hectare necromass inputs. Although litter traps are reliable for estimating per hectare rates of litterfall, branch mortality dating on sectioned stems uniquely allows assessment of several other litterfall components: (1) individual tree contributions to total litterfall; (2) the amount of branch material released by mortality, regardless of whether the branches are shed to the forest floor; (3) the distribution of basal diameters characterizing the litterfall from a given tree and stand. Twenty-four trees were felled and sectioned on permanent plots that were part of a silvicultural study of stand density regimes in Douglas-fir ( Pseudotsuga menziesii (Mirbel) Franco.). Whorl branches were dissected out of bole sections to determine the dates of mortality, and a branch biomass equation was applied to estimate potential rate of litterfall. Periodic annual rates were expressed in four ways: (1) number of branches per tree; (2) mass of branches per tree; (3) mass of branches per unit of crown projection area; (4) mass of branches per hectare. For the growth periods investigated, larger trees and trees growing on denser plots tended to release a greater necromass through branch mortality. Average branch basal diameter generally decreased with increasing stand density. Annual branch mortality ranged from 33 to 430 g m −2 crown projection area for individual trees, and from 236 to 1035 kg ha −1 for individual plots. These rates approached the low end of the range of previously published fine litterfall rates for Douglas-fir. Rates on these plots were relatively low owing to the temporary delay in crown recession imposed by artificial thinning. A conceptual model of branch litter dynamics is presented to depict consistencies with crown development among stands managed under different density regimes.

The effect of dietary α‐tocopherol supplementation and antioxidant spraying on colour stability and lipid oxidation of turkey meat

AbstractVitamin E was supplemented in the diet (250 mg kg−1) of turkeys or sprayed directly on turkey meat. Turkey breast muscles were cut into 1.5 cm slices, wrapped with oxygen‐permeable film and stored at 2–4°C for 1 week. Colour coordinates (L*, a*, b*), pH and reflectance values between 630 and 580 nm were determined at various times post mortem, TBARS (thiobarbituric acid‐reactive substances) values and vitamin E content were assessed immediately after slaughter and at 7 days post mortem for vitamin E‐supplemented, sprayed and control groups. Vitamin E supplementation or antioxidant spraying resulted in a lower myoglobin oxidation (P &lt; 0.05) and a higher a* value at day 2, but not thereafter. No differences in TBARS values and ultimate pH were detected. When peroxidation was induced experimentally by addition of an activated mixture, vitamin E supplemented or antioxidant‐sprayed samples exhibited lower TBARS values than the controls. Vitamin E supplementation in the diet or antioxidant spraying of meat produced a temporary delay in the rate of discoloration of turkey meat.

Postnatal development of hippocampal and neocortical cholinergic and serotonergic innervation in rat: Effects of nitrite-induced prenatal hypoxia and nimodipine treatment

Postnatal development of ingrowing cholinergic and serotonergic fiber patterns were studied in the rat hippocampus and parietal cortex employing a histochemical procedure for acetylcholinesterase as a cholinergic fiber marker, and immunocytochemistry of serotonin for serotonergic fiber staining. The rat pups were killed at postnatal days 1, 3, 5, 7, 10, and 20. The development of cholinergic and serotonergic innervation was described and the fiber density quantified under normal conditions and after long-term prenatal anemic hypoxia induced by chronic exposure to sodium nitrite. Furthermore, a third group was studied in which the nitrite hypoxia was combined with a simultaneous treatment with the Ca 2+ entry blocker nimodipine to test the neuroprotective potential of this drug. Quantitative measurement of fiber density from postnatal day 1 to day 20 yielded the following results: (i) both neurotransmitter systems revealed an age-dependent and an anatomically-organized developmental pattern; (ii) the serotonergic innervation of the dorsal hippocampus preceded that of cholinergic afferentation in postnatal days 1–3; (iii) prenatal hypoxia induced a transient delay in the innervation of parietal neocortex and dentate gyrus for both neurotransmitter systems, but left the innervation of the cornu ammonis unaffected; and (iv) the hypoxia-induced retardation of cholinergic and serotonergic fiber development was prevented by concomitant application of the Ca 2+ -antagonist nimodipine during the hypoxia. The results indicate that prenatal hypoxia evokes a temporary delay in the cholinergic and serotonergic fiber outgrowth in cortical target areas in a region-specific manner. The hypoxia-induced growth inhibition is prevented by the calcium antagonist nimodipine, which supports the importance of the intracellular Ca 2+ homeostasis of cells and growth cones in regulating axonal proliferation.

The Politics of Impoundments

Impoundments are actions that eliminate or delay the use of previously appropriated funds. Traditionally, since they were presidential decisions, they have represented the means by which presidents can redress dissatisfaction with regular appropriations outcomes. Since the Impound ment Control Act of 1974, however, the president and Congress both have a role in those decisions. This study addresses the influences on presidential and congressional impoundment behavior, both before and after the Impoundment Act. The analysis suggests that in both periods presidents have attempted to impound appropriations for programs they oppose, although Congress has opposed those proposed impoundments since the Impoundment Act. With few exceptions, about all that presidents now can accomplish with impoundments is a temporary delay in the use of budget authority. In the absence of an effective im poundment instrument, and given recent developments in the budgetary process, the Congress retains ultimate control over budgetary detail.

Assessment Considerations in the Evaluation of Second-Language Learners: A Case Study

The learning of a second language before the primary language is fully developed may result in arrested development or loss of proficiency in the first language. Therefore, the finding that a child is delayed in both languages does not necessarily mean that the child has a language disorder. This article presents a case study of a child who was classified as communication disabled but seems to have suffered from language loss or arrested development of the primary language (Spanish) before attaining full competence in English. The child experienced a temporary delay of development in both languages but eventually mastered English.

Raphe of the posterior neural tube in the chick embryo: its closure and reopening as studied in living embryos with a high definition light microscope.

Chick embryos cultured on a curved substratum show a transient enlargement of the posterior neuropore (PN), mimicking the temporary delay of PN closure as seen in the curly tail (ct) mouse mutant (van Straaten et al. [1993] Development 117:1163-1172). In the present study the PN enlargement in the chick embryo was investigated further with a high definition light microscope (HDmic), allowing high resolution viewing of living embryos in vitro. The temporary PN enlargement appeared due to considerable reopening of the raphe of the posterior neural tube, which was followed by reclosure after several hours. The raphe was subsequently studied in detail. It appeared very irregular, with small zones of apposed, open and fused neural folds. During closure, these raphe features shifted posteriorly. A distinct fusion sequence between surface epithelium and neuroepithelium was not seen. During experimental reopening of the raphe in vitro, small bridges temporarily arose, broke and disappeared quickly; they likely represented the first adhesion sites between the neural folds. More prominent adhesion sites partly detached, resulting in bridging filopodia-like connections; they probably represented the first anteroposterior locations of neural fold fusion. Our observations in the living chick embryo in vitro thus show that the caudal neural tube has an irregular raphe with few adhesion sites, which can be readily reopened. As a result of the irregularity, the PN does not close zipper-like, but button-like by forming multiple closure sites.

Pharmacokinetic and tumour-photosensitizing properties of the cationic porphyrin meso-tetra(4 N-methylpyridyl)porphine

The pharmacokinetic behaviour and the photodynamic properties of the cationic porphyrin meso-tetra (4 N-methylpyridyl)porphine (T 4MP yP2.1 mg/kg) were examined in Balb c mice bearing an MS-2 fibrosarcoma. The porphyrin shows good tumour localizing properties; 24 h after drug administration the tumour concentration of T 4MP yP was approximately 1.2 ng/mg, while the concentrations in normal tissues were substantially lower, except for liver and spleen. In the serum, T 4MP yP is preferentially transported by albumin and globulins (80.5%), while minor amounts are associated to lipoproteins (19.5%). The phototherapeutic efficiency of T 4MP yP was tested by following the growth curves of fibrosarcoma irradiated by 600–680 nm (450 J/cm 2) 24 h after the i.v. injection of T 4MP yP (2.1 mg/kg). PDT-treated tumours showed a temporary delay in their growth compared with control tumours. The excellent selectivity of T 4MP yP and its antitumour activity on photoexcitation encourage further studies for assessing the usefulness of this porphyrin in photodynamic therapy.

Changes in the Constitution of Thylakoid Membranes in Spruce Needles During an Open‐top Chamber Experiment

AbstractThe goal of the presented paper was to study the emission effects of natural air pollutants on the protein complexes of the thylakoid membrane. The tests were carried out in the frame of a long‐term experiment in which spruce trees kept in open‐top chambers with unfiltered ambient‐air were compared to spruce trees in chambers with purified‐air. The reaction centres of photosystem I (P‐700), cytochrome f, cytochrome b‐563, cytochrome b‐559, as well as the oxidation speed of the antennae chlorophylls were quantified.The concentrations of the cytochromes f and b‐563 indicate a marked annual rhythm with decreased concentrations during the summer months. The spruce trees in chambers with ambient‐air showed a smaller amount of the studied redox components in relation to 1000 molecules of chlorophyll than did the spruce trees in chambers exposed to purified‐air. In addition, increased oxidation speed of antennae chlorophylls could be observed on the isolated thylakoid membranes of the spruce trees in chambers with ambient‐air conditions. A relationship between the oxidation speed and the ozone concentration of the ambient air could be observed, i.e. with increasing ozone levels the oxidation of the antennae chlorophylls accelerated. However, the damage occurred only with a temporary delay (the so‐called memory effect).In case of the cytochromes f and b‐563 (components of the cytochrome b6f‐complex), a chamber effect related to changed light conditions became obvious when comparing spruce trees kept in chambers to trees left in their natural surrounding. The reduced photosynthetically active radiation — it is reduced in the chambers by 10 − 30% — led to a decrease of both cytochromes.In spite of the effects due to the chambers, the results indicate that ozone could be an effective damage factor and this will be of importance with regard to the situation in the low mountain range of Germany.

Recovery of starter nitrogen-15 fertilizer with supplementarily applied ammonium nitrate on irrigated potato

Nitrogen contamination in ground water of potato (Solanum tuberosum L.) producing areas has indicated a need for improved management of N and water, particularly on sandy soil. Therefore, a field experiment was conducted with the objective of following the recovery and partitioning of starter15NH4 and15NO3 into potato plant tops and tubers in conjunction with additional supplementarily applied NH4NO4. Potato plants treated with starter15NH4 or15NO3 tended to increase the percent recovery of starter15N in tubers sampled from one growth time to the next to reach nearly 40% recovery toward the end of the season. Whole plants reached peak recovery of around 50% of the starter15N near mid-season. From then on, there was a trend for loss of starter15N by senescence, defoliation or translocation to the roots. The percent recovery of starter15N was significantly higher at final tuber harvest (not whole plants) for the treatment with starter15NH4 at 112 kg ha−1 combined with 112 kg ha−1 of supplemental N as compared to the treatment with 112 kg ha−1 of starter15NH4 plus 224 kg ha−1 of supplemental N. This difference may have been a result of isotope dilution. Early in June the accumulation of starter15NO3 in whole plants was about five times as high as that from starter15NH4. Later there was no difference in percent recovery of these two forms of N. The temporary delay in starter15NH4 uptake was probably related to slow nitrification early in the season instead of preferential uptake of starter15NO3.

Calcium oscillations in freshly dispersed and cultured interstitial cells from canine colon.

Spontaneous oscillations in intracellular Ca2+ concentration ([Ca2+]i) and membrane potential were used to monitor rhythmicity in freshly dispersed and cultured interstitial cells (IC) from the canine colon. The frequency of oscillations and responses to a number of channel blockers, agonists, ionic substitutions, and temperature were similar in freshly dispersed and cultured cells. An increase in the amplitude of Ca2+ oscillations after 3-6 days in culture and an increase in the rate of decline of [Ca2+]i in cultured IC were two differences noted between freshly dispersed and cultured cells. The frequency and amplitude of oscillations were a function of extracellular Ca2+ concentrations, and oscillations were abolished when the transmembrane flux of Ca2+ was reduced by nicardipine, La3+, or removal of Ca2+ from the extracellular medium. Oscillations persisted in the presence of ryanodine and ouabain. Lowered temperatures or a reduction in the concentration of Ca2+ in the medium reduced the frequency of spontaneous oscillations. Carbachol and substance P caused a transient increase in [Ca2+]i. Substance P then abolished spontaneous events. ATP and calcitonin gene-related peptide increased the frequency of spontaneous activity. Vasoactive intestinal peptide caused a temporary delay in spontaneous oscillations when added to the medium. Results indicate that freshly dispersed and cultured IC may be useful in studies of the mechanisms of rhythmicity in the gastrointestinal system.