Pellet Removal Research Articles

Removal of a pellet from the left ventricle trabeculae: A case report

Cardiac gunshot wounds, despite being rare, have a high mortality rate, and their proper management and prompt decision-making are critical.Here we present a case of cardiac gunshot woundin a young male who was shot at close range in the left shoulder from behind. The patient admitted at hospital with stable vital signs, but after a while, shortness of breath was begun and pneumothorax was diagnosed. Due to the instability of the pellet which localized in the LV using echocardiography, surgical excision of the pellet was planned. Patient was discharged two week the pellet removal with no complications.

Pharmacokinetic comparison of three delivery systems for subcutaneous testosterone administration in female mice

Transmasculine individuals are often prescribed testosterone (T) for masculinizing hormone therapy. Mouse models mimicking transmasculine T therapy require reliable long-term T administration. The objectives of this study were three-fold, namely, to compare: 1) the release dynamics of three different subcutaneous delivery systems of T enanthate administration (subcutaneous injections, commercially available pellets, and silastic implants) over a 6-week period in postpubertal C57BL/6N mice, 2) to compare the timing for T levels in plasma to return to baseline and cyclicity to resume after cessation of T between injections and pellets, 3) to utilize silastic implants to achieve sustainable increase in T levels utilizing T enanthate and crystalline T. All three modes of T administration resulted in an increase in T levels in plasma. Pharmacokinetic analyses showed a similar overall exposure to T enanthate over 6 weeks (integrated area) for, subcutaneous injection (0.45 mg two times per week and 0.90 mg one time per week), pellet (5 mg 60-day release), and silastic implant (5 mg 21 week) groups. Crystalline T had lower solubility and a decreased integrated area compared to T enanthate, even when implanted at a higher dosage, indicating different pharmacokinetic profiles based on type of T formulation when utilizing the same silastic delivery method. Surgical removal of pellets and silastic tubing led to a quick drop in T levels and resumption of estrous cyclicity, while cessation of injections required a long washout period for T levels to drop and estrous cycles to resume. Sustained elevation in T levels was achieved for at least 21 weeks with silastic implants. As all three delivery methods are able to elevate T levels in female mice for at least 6 weeks, choice of T administration method should be based on outcomes of interest and study design.

Arthroscopic removal of multiple foreign bodies in the knee: A case report

We report the uncommon case of knee arthroscopic removal of multiple bullet pellets. A 25-year-old male professional footballer was admitted with left knee swelling, pain, and limitation of movement following a gunshot injury. Radiographs revealed multiple pellets in and around the left knee, each measuring about 5 mm in diameter. There were several pellets in the subcutaneous, intramuscular, and intra-articular parts of the left knee. The pellets were metallic, contraindicating magnetic resonance imaging to assess intra articular structures. He was booked for an urgent knee arthroscopy and the pellets were retrieved, and the other vital intra articular structures were examined. Three 5 mm diameter spherical bullet pellets were removed from the joint cavity. The synovial membrane was debrided, and the knee lavaged. Recovery was satisfactory with no complications. The patient was discharged to physiotherapy and followed up at 3 and 6 months after surgery. Foreign bodies in the knee are not uncommon; however, the presence of multiple bullet pellets is rare, especially in the index case of a sportsman. Its removal can be challenging, even arthroscopically. Such a procedure can result in severe complications, such as infections and joint deformities. The decision to use the arthroscopic approach requires careful deliberation regarding the status of the patient vis-a-vis the available skill and experience of the managing team.

Biomechanics of pollen pellet removal by the honey bee

Honey bees (Apis mellifera) carry pollen back to their hive by mixing it with nectar and forming it into a pellet. The pellet must be firmly attached to their legs during flight, but also easily removable when deposited in the hive. How does the honey bee achieve these contrary aims? In this experimental study, we film honey bees removing pollen pellets and find they peel them off at speeds 2-10 times slower than their typical grooming speeds. Using a self-built pollen scraper, we find that slow removal speeds reduce the force and work required to remove the pellet under shear stress. Creep tests on individual pollen pellets revealed that pollen pellets are viscoelastic materials characterized by a Maxwell model with long relaxation times. The relaxation time enables the pellet to remain a solid during both transport and removal. We hope that this work inspires further research into viscoelastic materials in nature.

Comparative benefits of social housing and buprenorphine on wheel running depressed by morphine withdrawal in rats.

Social support and opioid replacement therapy are commonly used to treat opioid withdrawal. The present study tested the hypothesis that social housing and buprenorphine administration can restore wheel running depressed by morphine withdrawal in rats. Experiment 1 assessed disruptive side effects of buprenorphine and found that administration of low doses (3.2, 10, & 32µg/kg, s.c.) had no impact on voluntary wheel running. Experiment 2 assessed the impact of social housing and acute buprenorphine administration (10µg/kg) on morphine withdrawal. Two 75mg morphine pellets were implanted for 3days to induce dependence. Removal of the morphine pellets caused a decrease in body weight, increase in wet dog shakes, and depression of wheel running during the normally active dark phase of the circadian cycle. Social housing restored wheel running and reduced the number of wet dog shakes but did not affect body weight. Administration of buprenorphine restored wheel running depressed by morphine withdrawal for 2days in individually housed rats and produced time-dependent changes in socially housed rats: Depression of wheel running in the 3h following administration and restoration of running subsequently compared to saline-treated controls. The impact of buprenorphine and social housing to reduce the effect of morphine withdrawal in rats is consistent with the use of opioid substitution therapy and psychotherapy/social support to treat opioid withdrawal in humans. These data provide further validation for the clinical relevance for the use of wheel running to assess spontaneous opioid withdrawal.

Reversibility of testosterone-induced acyclicity after testosterone cessation in a transgender mouse model

To establish if the cessation of testosterone (T) therapy reverses T-induced acyclicity in a transgender mouse model that allows for well-defined T cessation timing. Experimental laboratory study using a mouse model. University-based basic science research laboratory. A total of 10 C57BL/6NHsd female mice were used in this study. Postpubertal C57BL/6NHsd female mice were subcutaneously implanted with T enanthate (n = 5 mice) or placebo (n = 5 mice) pellets. Pellets were surgically removed after 6 weeks to ensure T cessation, after which the mice were followed for four estrous cycles after the resumption of cyclicity. Primary outcomes included daily vaginal cytology and weekly T levels before, during, and after T enanthate or placebo pellet implantation and removal. Secondary outcomes included ovarian follicle distribution and corpora lutea numbers, body metrics, and terminal diestrus hormone levels. T-treated mice (100%) resumed cycling within one week of T pellet removal after six weeks of T therapy. T levels were significantly elevated during T therapy and decreased to control levels after surgical pellet removal. No detectable differences were observed in the follicle count, corpora lutea formation, diestrus hormone levels, or body metrics after four estrous cycles, with the exception of persistent increased clitoral area between T-treated mice and controls. One T-treated mouse was sacrificed early due to vaginal prolapse and not included in subsequent analyses. Our results demonstrated a close temporal relationship between estrous cycle return and T levels dropping to control levels following T pellet removal. The return of regular cyclic ovulatory function is also supported by the formation of corpora lutea and the lack of detectable differences in key reproductive parameters as compared to controls four cycles after T cessation. These results may be relevant to understanding the reversibility of T-induced amenorrhea and possible anovulation in transgender men interested in pausing T to pursue pregnancy or oocyte donation. Results may be limited by the duration of T treatment, lack of functional testing, and physiological differences between mice and humans.

Novel use of XSTAT 30 for mitigation of lethal non-compressible torso hemorrhage in swine.

Management of Non-Compressible Torso Hemorrhage (NCTH) consists primarily of aortic occlusion which has significant adverse outcomes, including ischemia-reperfusion injury, in prolonged field care paradigms. One promising avenue for treatment is through use of RevMedx XSTAT 30™ (an FDA approved sponge-based dressing utilized for extremity wounds). We hypothesized that XSTAT 30™ would effectively mitigate NCTH during a prolonged pre-hospital period with correctable metabolic and physiologic derangements. Twenty-four male swine (53±2kg) were anesthetized, underwent line placement, and splenectomy. Animals then underwent laparoscopic transection of 70% of the left lobe of the liver with hemorrhage for a period of 10min. They were randomized into three groups: No intevention (CON), XSTAT 30™-Free Pellets (FP), and XSTAT 30™-Bagged Pellets (BP). Animals were observed for a pre-hospital period of 180min. At 180min, animals underwent damage control surgery (DCS), balanced blood product resuscitation and removal of pellets followed by an ICU period of 5 hours. Postoperative fluoroscopy was performed to identify remaining pellets or bags. Baseline physiologic and injury characteristics were similar. Survival rates were significantly higher in FP and BP (p<0.01) vs CON. DCS was significantly longer in FP in comparison to BP (p = 0.001). Two animals in the FP group had pellets discovered on fluoroscopy following DCS. There was no significant difference in blood product or pressor requirements between groups. End-ICU lactates trended to baseline in both FP and BP groups. While these results are promising, further study will be required to better understand the role for XSTAT in the management of NCTH.

The role of thermal improvements in indurating machines for pellet production from high-sulfur magnetite concentrate

Mostly, magnetite iron ore mine materials contain significant amounts of sulfur base components. This can cause disturbance in production process of steel. Although high-sulfur magnetite concentrate has not been inciting enough yet to be employed by steel industry, these compounds are potential alternatives for iron ore resources. In this work, oxidation and sulfur removal of magnetite iron ore pellets were studied during the thermal treatment in the pelletizing indurating machine. The oxidation phenomenon and sulfur removal, in the magnetite iron ore pellets, were assessed by determination of appropriate thermal conditions employing thermogravimetric as well as differential scanning calorimetric tests accompanied by heat treatment procedure in a laboratory furnace. The residual sulfur-based compounds were considered as an indicator for the reaction rate; the results showed the reaction progress had a lower rate in the temperature range of 500–750 °C. Furthermore, the high-rate pre-heating and firing processes of pellets caused a higher level of residual magnetite phase within the microstructure, whereas crack initiation and growth were probable within the oxide pellets. The findings did highlight the role of thermal profiling and eventually, led to redesigning the thermal profile for pelletizing indurating machines.

Social housing promotes recovery of wheel running depressed by inflammatory pain and morphine withdrawal in male rats

The increased use of opioids to treat pain has led to a dramatic increase in opioid abuse. Our previous data indicate that pain may facilitate the development of opioid abuse by increasing the magnitude and duration of opioid withdrawal. The present study tested the hypothesis that social housing would facilitate recovery of activity depressed by pain and opioid withdrawal. Male Sprague Dawley rats were housed either in pairs or alone and then moved to a cage with a running wheel for 6 h daily to assess pain- and opioid withdrawal-induced depression of wheel running. Rats were implanted with two morphine (75 mg each) or placebo pellets to induce opioid dependence and were simultaneously injected with Complete Freund’s Adjuvant or saline into the right hind paw to induce persistent inflammatory pain. Hind paw inflammation depressed wheel running whether rats were implanted with a morphine or placebo pellet. Pair-housed rats showed greater recovery of wheel running than individually housed rats. Spontaneous morphine withdrawal precipitated by removal of the morphine pellets caused a reduction in wheel running that was greater in rats with hind paw inflammation compared to pain free rats. Social housing facilitated recovery from withdrawal in rats with hind paw inflammation, but slowed recovery in pain free rats. These data suggest that social housing facilitates recovery by reducing pain both before and during opioid withdrawal. Our findings are consistent with previous studies showing that social buffering reduces pain-evoked responses.

Prognostic factors and management of civilian craniocerebral gunshot injuries; an institutional experience

Introduction: Surgeons face unique challenge in the management & prognosis related issues with intracranial gunshot injuries. These injuries are more commonly seen in military conflict zone. With easy availaibility of weapon and increase in the conflict between civilian and paramilitiary forces, clinician are facing more numbers of civilian gunshot injuries. In India the presentation and prognosis of gunshot injuries is different as many of these gunshot injuries are by country made weapons. Country made weapons have low velocity and caliber; henceforth the outcome and the management issues are different. We present our experience with 23 patients who sustained intracranial gunshot injuries, and identify the factors determining the outcome and management Material and Methods: From March 2016 to September 2019 data was collected from 23 cases who were treated for intracranial gunshot injuries in Department of Neurosurgery at J. N. Medical College, Aligarh. History, type of weapon used, clinical condition and radiological findings were noted. Outcome was assessed by Glasgow’s Outcome scale. Results: Overall mortality was 26.08% (6/23). Of the 4 patients in GCS (3-7) group there was 100% mortality. Of the 5 patients in GCS group (8-12) mortality was 2 and one patient in persistent vegetative stage. All patients survived in GCS group (13-15). 5 patients underwent surgery; there was one mortality in the surgical group. Better outcome was noted in single lobe involvement and trajectory involving supratentorial noneloquent areas. Conclusion: Early aggressive resuscitative measures may help in better management. GCS at presentation is the most important factor affecting outcome. CT scan offers to be an important predictor of prognosis and also help in planning the management. Suicidal wound, hypotension and midline shift has poor prognosis. We don’t recommend aggressive exploration of the bullet tract & pellet removal for every patient. Keywords: Intrac

Evaluation of zinc removal and compressive strength of self-reducing pellets composed of Electric Arc Furnace Dust

Abstract The amount of Electric Arc Furnace Dust (EAFD) is continuously increasing in mini-mill steel plants. This dust is considered a hazardous waste because of the presence of elements like lead, cadmium and chromium. Among many different treatment processes for this issue, there is the possibility of returning the EAFD back to the Electric Arc Furnace. This article presents a study of the compressive strength of self-reducing cold bonded pellets as well as their zinc removal, in an agglomerate containing EAFD, petroleum coke (PET) and Portland cement. The effects of the reductant and binder employed were discussed. Moreover, an apparatus was built to prevent zinc gas reoxidation inside an electric vertical laboratory furnace. Thus, the fraction of weight loss complemented the result of a previous study indicating the optimal content of PET source usage between 10 to 15%, in mass. Zinc removal and additional X Ray Diffraction outcomes are shown and discussed, concluding that 80% of zinc removal for this system could indicate the possibility of the EAFD reuse.

Performance evaluation of a pellet based column bed for removal of a potentially carcinogenic Polycyclic Aromatic Hydrocarbon (PAH) from water

Performance of a novel prototype of a column-bed was evaluated for the removal of a potentially toxic Polycyclic Aromatic Hydrocarbon (PAH) - Benzo(b)fluoranthene (BbF) from the water. The column-bed was prepared using the pellets fabricated from a mixture of low-cost materials: Plaster of Paris (POP), Coconut coir and Zeolite. The pellets were coated with a unique combination of bioadsorbents (Chitosan and Alginic acid) for enhanced removal, greater stability, and reusability of pellets. The pellet based column- bed showed up to 91% removal efficiency during 120 min treatment time in graded concentrations ranging from 0.01 to 10.0 ppm. Evaluation of kinetic behavior of the column was performed through linear regression analysis by fitting the data into three well-known models: Thomas, Adams-Bohart, and Yoon-Nelson. The data showed good agreement between experimental and calculated values of adsorption capacity (qe) for all the models, however Adams-Bohart model fitted best to the data obtained. This report provides a novel design of a column bed-reactor for PAH removal from water. The pelleted form of packing material for column-bed is a unique approach to enhancing the column efficiency and reusability of the materials used for column-bed preparation.

LSD1 dual function in mediating epigenetic corruption of the vitamin D signaling in prostate cancer

BackgroundLysine-specific demethylase 1A (LSD1) is a key regulator of the androgen (AR) and estrogen receptors (ER), and LSD1 levels correlate with tumor aggressiveness. Here, we demonstrate that LSD1 regulates vitamin D receptor (VDR) activity and is a mediator of 1,25(OH)2-D3 (vitamin D) action in prostate cancer (PCa).MethodsAthymic nude mice were xenografted with CWR22 cells and monitored weekly after testosterone pellet removal. Expression of LSD1 and VDR (IHC) were correlated with tumor growth using log-rank test. TRAMP tumors and prostates from wild-type (WT) mice were used to evaluate VDR and LSD1 expression via IHC and western blotting. The presence of VDR and LSD1 in the same transcriptional complex was evaluated via immunoprecipitation (IP) using nuclear cell lysate. The effect of LSD1 and 1,25(OH)2-D3 on cell viability was evaluated in C4-2 and BC1A cells via trypan blue exclusion. The role of LSD1 in VDR-mediated gene transcription was evaluated for Cdkn1a, E2f1, Cyp24a1, and S100g via qRT-PCR-TaqMan and via chromatin immunoprecipitation assay. Methylation of Cdkn1a TSS was measured via bisulfite sequencing, and methylation of a panel of cancer-related genes was quantified using methyl arrays. The Cancer Genome Atlas data were retrieved to identify genes whose status correlates with LSD1 and DNA methyltransferase 1 (DNMT1). Results were correlated with patients’ survival data from two separate cohorts of primary and metastatic PCa.ResultsLSD1 and VDR protein levels are elevated in PCa tumors and correlate with faster tumor growth in xenograft mouse models. Knockdown of LSD1 reduces PCa cell viability, and gene expression data suggest a dual coregulatory role of LSD1 for VDR, acting as a coactivator and corepressor in a locus-specific manner. LSD1 modulates VDR-dependent transcription by mediating the recruitment of VDR and DNMT1 at the TSS of VDR-targeted genes and modulates the epigenetic status of transcribed genes by altering H3K4me2 and H3K9Ac and DNA methylation. Lastly, LSD1 and DNMT1 belong to a genome-wide signature whose expression correlates with shorter progression-free survival and overall survival in primary and metastatic patients’ samples, respectively.ConclusionsResults demonstrate that LSD1 has a dual coregulatory role as corepressor and coactivator for VDR and defines a genomic signature whose targeting might have clinical relevance for PCa patients.

Depression of home cage wheel running is an objective measure of spontaneous morphine withdrawal in rats with and without persistent pain

Opioid withdrawal in humans is often subtle and almost always spontaneous. In contrast, most preclinical studies precipitate withdrawal by administration of an opioid receptor antagonist such as naloxone. These animal studies rely on measurement of physiological symptoms (e.g., wet dog shakes) in the period immediately following naloxone administration. To more closely model the human condition, we tested the hypothesis that depression of home cage wheel running will provide an objective method to measure the magnitude and duration of spontaneous morphine withdrawal. Rats were allowed access to a running wheel in their home cage for 8days prior to implantation of two 75mg morphine or placebo pellets. The pellets were removed 3 or 5days later to induce spontaneous withdrawal. In normal pain-free rats, removal of the morphine pellets depressed wheel running for 48h compared to rats that had placebo pellets removed. Morphine withdrawal-induced depression of wheel running was greatly enhanced in rats with persistent inflammatory pain induced by injection of Complete Freund's Adjuvant (CFA) into the hindpaw. Removal of the morphine pellets following 3days of treatment depressed wheel running in these rats for over 6days. These data demonstrate that home cage wheel running provides an objective and more clinically relevant method to assess spontaneous morphine withdrawal compared to precipitated withdrawal in laboratory rats. Moreover, the enhanced withdrawal in rats with persistent inflammatory pain suggests that pain patients may be especially susceptible to opioid withdrawal.

Metastatic phenotype in CWR22 prostate cancer xenograft following castration.

BackgroundCWR22 is a human xenograft model of primary prostate cancer (PCa) that is often utilized to study castration recurrent (CR) PCa. CWR22 recapitulates clinical response to androgen deprivation therapy (ADT), in that tumors regress in response to castration, but can recur after a period of time.MethodsTwo cohorts of mice, totaling 117 mice were implanted with CWR22, allowed to develop tumors, castrated by pellet removal and followed for a period of 32 and 50 weeks. Mice presenting with tumors >2.0 cm3 at the primary site, moribund appearance, or palpable masses other than the primary tumor were sacrificed prior to the endpoint of the study. Tumor tissue, serum, and abnormal lesions were collected upon necropsy and analyzed by IHC, H&E, and PCR for presence of metastatic lesions arising from CWR22.ResultsHerein, we report that CWR22 progresses after castration from a primary, hormonal therapy‐naïve tumor to metastatic disease in 20% of castrated nude mice. Histological examination of CWR22 primary tumors revealed distinct pathologies that correlated with metastatic outcome after castration.ConclusionThis is the first report and characterization of spontaneous metastasis in the CWR22 model, thus, CWR22 is a bona‐fide model of clinical PCa representing the full progression from androgen‐sensitive, primary PCa to metastatic CR‐PCa. Prostate 76:359–368, 2016. © 2015 The Authors. The Prostate published by Wiley Periodicals, Inc.

A combination of keratan sulfate digestion and rehabilitation promotes anatomical plasticity after rat spinal cord injury

Functional recovery after neuronal injuries relies on neuronal network reconstruction which involves many repair processes, such as sealing of injured axon ends, axon regeneration/sprouting, and construction and refinement of synaptic connections. Chondroitin sulfate (CS) is a major inhibitor of axon regeneration/sprouting. It has been reported that the combination of task-specific rehabilitation and CS-digestion is much more effective than either treatment alone with regard to the promotion of functional and anatomical plasticity for dexterity in acute and chronic spinal cord injury models. We previously reported that keratan sulfate (KS) is another inhibitor and has a potency equal to CS. Here, we compared the effects of KS- or CS-digestion plus rehabilitation on recovery from spinal cord injury. Keratanase II or chondroitinase ABC was locally administered at the lesion after spinal cord injury at C3/4. Task-specific rehabilitation training, i.e., a single pellet reaching task using a Whishaw apparatus, was done for 3 weeks before injury, and then again at 1–6 weeks after injury. The combination of KS-digestion and rehabilitation yielded a better rate of pellet removal than either KS-digestion alone or rehabilitation alone, although these differences were not statistically significant. The combination of CS-digestion and rehabilitation showed similar results. Strikingly, both KS-digestion/rehabilitation and CS-digestion/rehabilitation showed significant increases in neurite growth in vivo as estimated by 5-hydroxytryptamine and GAP43 staining. Thus, KS-digestion and rehabilitation exerted a synergistic effect on anatomical plasticity, and this effect was comparable with that of CS-digestion/rehabilitation. KS-digestion might widen the therapeutic window of spinal cord injury if combined with rehabilitation.

Dormant Shotgun Pellets-Are They Really Dormant?

Shotgun injuries are serious but uncommon type of injury in India. Embedded shotgun pellets have widespread functional and aesthetic implications. No specific guidelines are available as to which pellets need immediate removal. Most pellets are known to lie dormant in the body while some present with complications and warrant removal many years after injury. We hereby report a case of homicidal shotgun injury that was sustained 22 years ago and needed pellet removal due to excruciating pain.

Removal of molluscicidal bait pellets by earthworms and its impact on control of the gray field slug (Derocerus reticulatum Mueller) in western Oregon grass seed fields

Slugs are common pests of grass seed fields in western Oregon and the current focus of repeated, and often unsuccessful, efforts by growers to control them using molluscicides. Here we document rapid loss of molluscicidal bait pellets to earthworms and the resulting adverse effects on slug control. Three years of field studies were conducted at 17 locations with contrasting crops, soil types, residue levels, and tillage management programs. Baits were isolated in covered, sunken, open bottom arenas in the field to exclude removal by slugs, rodents, or birds. Forty hours of nighttime field observations and photographic documentation were collected to support the hypothesis that earthworms were removing slug bait before it had the opportunity to kill slugs. Greenhouse studies were conducted on the gray field slug (Derocerus reticulatum Mueller), in screen-topped arenas to determine the effects on mortality, seedling survival, and egg fecundity in a bait-depleting environment. Field data showed that an average of 17% of all bait pellet types were removed nightly by earthworms, with a range of 5.1–6.4 days until 100% disappearance. Individual earthworms in the field were observed removing up to three bait pellets per hour. Earthworms removed a 5% metaldehyde formulation significantly faster than either 4% metaldehyde or 1% iron phosphate pellet baits, possibly because of the smaller physical pellet size. Seedling survival in the greenhouse ≥ 65% was achieved by the highest rate of 4% metaldehyde bait pellets, the two highest rates of 7.5% metaldehyde granules, and the two highest rates of 25% metaldehyde liquid formulation. Earthworms showed no behavioral interest in the granular or liquid formulations, providing growers with attractive alternatives to the ineffectual pelleted baits currently in widespread use.

Diet Manipulation as Treatment for Elevated Serum Iron Parameters in Captive Raggiana Bird of Paradise (Paradisaea raggiana)

Elevated serum iron parameters were lowered through dietary manipulation in captive Raggiana bird of paradise (Paradisaea raggiana). Study birds were part of a captive breeding program consisting of two males and one female, captive born, 3.5-9 yr of age. Serum iron, total iron binding capacity (TIBC), percentage saturation, body weight, albumin, aspartate aminotransferase, and hematocrit were monitored at regular intervals for 2.5 yr. Routine diet consisted of a variety of fruits, vegetables, a multivitamin supplement, and a commercial low iron avian pellet, with a dietary iron content of 55 mg/kg (dry matter basis) or 1.12 mg iron/bird/day. Dietary treatment involved removal of the commercial avian pellet for 30 days at 6-to 12-mo intervals, resulting in an iron content of 42 mg/kg (dry matter basis) or 0.64 mg iron/bird/day. Average serum iron and TIBC were decreased by 75% (TIBC) to 80% (serum iron) ofpretreatment values after one 30-day treatment. Average iron saturation levels were lowered by 10% of pretreatment values after one 30-day treatment. Average hematocrit, albumin, aspartate aminotransferase, and body weight remained unchanged. No adverse effects were noted through the 2.5-yr evaluation period, and breeding behavior was undisturbed. Periodic removal of low iron commercial pellets in the diet of captive bird of paradise is a safe and effective method for lowering serum iron values without need for handling. Periodic application of this technique may be useful as a preventive tool to maintain appropriate serum iron values in avian species susceptible to iron storage disease.

Recovery from Disrupted Ultradian Glucocorticoid Rhythmicity Reveals a Dissociation Between Hormonal and Behavioural Stress Responsiveness

Ultradian release of glucocorticoids is thought to be essential for homeostasis and health. Furthermore, deviation from this pulsatile release pattern is considered to compromise resilience to stress-related disease, even after hormone levels have normalised. In the present study, we investigate how constant exposure to different concentrations of corticosterone affects diurnal and ultradian pulsatility. The rate of recovery in pulsatile hypothalamic-pituitary-adrenal (HPA) activity after withdrawal of exogenous corticosterone is also examined. Finally, the behavioural and neuroendocrine responsiveness to an audiogenic stressor is studied. Adrenally intact male rats were subcutaneously implanted with vehicle, 40% or 100% corticosterone pellets for 7 days. The continuous release of corticosterone from these implants abolished diurnal and ultradian corticosterone variation, as measured with high-frequency automated blood sampling. Pellet removal on post-surgery day 8 allowed rapid recovery of endogenous rhythms in animals previously exposed to daily average concentrations (40%) but not after exposure to high concentrations (100%) of corticosterone. Behavioural and neuroendocrine responsiveness to stress was distinctly different between the treatment groups. Audiogenic stimulation 1 day after pellet removal resulted in a similar corticosterone response in animals previously exposed to 40% corticosterone or vehicle. The 40% pellet group, however, showed less and shorter behavioural activity (i.e. locomotion, risk assessment) to noise stress compared to 100% corticosterone and vehicle-treated animals. In conclusion, unlike the animals impanted with 100% corticosterone, we find that basal HPA axis activity in the 40% group, which had mean daily levels of circulating corticosterone in the physiological range, rapidly reverts to the characteristic pulsatile pattern of corticosterone secretion. Upon reinstatement of the ultradian rhythm, and despite the fact that these animals did not differ from controls in their response to noise stress, they did show substantial changes in their behavioural response to stress.