A Quick Reference Guide for Incidental Findings on Lung Cancer Screening CT Examinations

PURPOSE

The US Preventive Services Task Force has recommended lung cancer screening (LCS) with low-dose CT (LDCT) in high-risk individuals since 2013. Because LDCT encompasses the lower neck, chest, and upper abdomen, many incidental findings (IFs) are detected. The authors created a quick reference guide to describe common IFs in LCS to assist LCS program navigators and ordering providers in managing the care continuum in LCS.

METHODS

The ACR IF white papers were reviewed for findings on LDCT that were age appropriate for LCS. A draft guide was created on the basis of recommendations in the IF white papers, the medical literature, and input from subspecialty content experts. The draft was piloted with LCS program navigators recruited through contacts by the ACR LCS Steering Committee. The navigators completed a survey on overall usefulness, clarity, adequacy of content, and user experience with the guide.

RESULTS

Seven anatomic regions including 15 discrete organs with 45 management recommendations were identified as relevant to the age of individuals eligible for LCS. The draft was piloted by 49 LCS program navigators from 32 facilities. The guide was rated as useful and clear by 95% of users. No unexpected or adverse experiences were reported in using the guide. On the basis of feedback, relevant sections were reviewed and edited.

CONCLUSIONS

The ACR Lung Cancer Screening CT Incidental Findings Quick Reference Guide outlines the common IFs in LCS and can serve as an easy-to-use resource for ordering providers and LCS program navigators to help guide management.

Thoracic point-of-care ultrasound is an accurate diagnostic modality for clinically significant traumatic pneumothorax

OBJECTIVE

There are conflicting data regarding the accuracy of thoracic point-of-care ultrasound (POCUS) in detecting traumatic pneumothorax (PTX). The purpose of our study was to determine the accuracy of thoracic POCUS performed by emergency physicians for the detection of clinically significant PTX in blunt and penetrating trauma patients.

METHODS

We conducted a retrospective institutional review board-approved study of trauma patients 15 years or older presenting to our urban Level I academic trauma center from December 2021 to June 2022. All study patients were imaged with single-view chest radiography (CXR) and thoracic POCUS. The presence or absence of PTX was determined by multidetector computed tomography (CT) or CXR and ultrasound (US) with tube thoracostomy placement.

RESULTS

A total of 846 patients were included, with 803 (95%) sustaining blunt trauma. POCUS identified 13/15 clinically significant PTXs (defined as ≥35 mm of pleural separation on a blinded overread or placement of a tube thoracostomy prior to CT) with a sensitivity of 87% (95% confidence interval [CI] 58-97), specificity of 100% (95% CI 99-100), positive predictive value of 81% (95% CI 54%-95%), and negative predictive value of 100% (95% CI 99%-100%). The positive likelihood ratio was 484 and the negative likelihood ratio was 0.1. CXR identified eight (53%) clinically significant PTXs, with a sensitivity of 53% (95% CI 27%-78%) and a specificity of 100%, when correlated with the CT. The most common reason for a missed PTX identified on expert-blinded overread was failure to recognize a lung point sign that was present on US.

CONCLUSIONS

Thoracic POCUS accurately identifies the majority of clinically significant PTXs in both blunt and penetrating trauma patients. Common themes for false-negative thoracic US in the expert-blinded overread process identified key gaps in training to inspire US education and medical education research.

Minimal Aortic Injury Detected on Computed Tomography Angiography during Initial Trauma Imaging: Single Academic Level 1 Trauma Center Experience

BACKGROUND

 Minimal aortic injury (MAI), a subtype of acute traumatic aortic injury, is being increasingly recognized with better imaging techniques. Given conservative management, the role of follow-up imaging albeit important yet has to be defined.

METHODS

 All trauma chest computed tomography angiographies (CTAs) at our center between January 2012 and January 2019 were retrospectively reviewed for presence of MAI. MAIs were generally reimaged at 24 to 72 hours and then at a 7- and 30-day interval. Follow-up CTAs were reviewed for stability, progression, or resolution of MAI, along with assessment of injury severity scores (ISS) and concomitant injuries, respectively.

RESULTS

 A total of 17,569 chest CTAs were performed over this period. Incidence of MAI on the initial chest CTA was 113 (0.65%), with 105 patients receiving follow-up CTAs. The first, second, third, and fourth follow-up CTAs were performed at a median of 2, 10, 28, and 261 days, respectively. Forty five (42.9%), 22 (21%), 5 (4.8%), and 1 (1%) of the MAIs were resolved by first, second, third, and fourth follow-up CTAs. Altogether, 21 patients showed stability (mean ISS of 16.6), and 11 demonstrated improvement (mean ISS 25.8) of MAIs. Eight patients had no follow-up CTA (mean ISS 21). No progression to higher-grade injury was observed. Advancing age decreased the odds of MAI resolution on follow-up. A possible trend (p-value 0.22) between increasing ISS and time to resolution of MAIs was noted.

CONCLUSION

 In our series of acute traumatic MAIs diagnosed on CTA imaging, there was no progression of injuries with conservative management, questioning the necessity of sequential follow-up imaging.

Pulmonary barotrauma in COVID-19: A systematic review and meta-analysis

BACKGROUND

An ever-increasing number of studies have reported an increased incidence of spontaneous pulmonary barotrauma such as pneumothorax, pneumomediastinum, and subcutaneous emphysema in patients with COVID-19. We conducted this systematic review and meta-analysis to assess the value and significance of the available data.

METHODS

A thorough systematic search was conducted to identify studies of barotrauma in hospitalized patients with COVID-19. Data analysis of case reports was done using a statistical package for the social sciences (SPSS) version 22, and meta-analysis was performed using CMA-3.

RESULTS

We identified a total of 4488 studies after thorough database searching.118 case reports and series, and 15 observational studies were included in the qualitative analysis. Fifteen studies were included in the quantitative analysis. The observational studies reported barotrauma in 4.2% (2.4-7.3%) among hospitalized patients; 15.6% (11-21.8%) among critically ill patients; and 18.4% (13-25.3%) in patients receiving invasive mechanical ventilation, showing a linear relationship of barotrauma with the severity of the disease. In addition, barotrauma was associated with a longer length of hospital stay, more extended ICU stay, and higher in-hospital mortality. Also, a slightly higher odds of barotrauma was seen in COVID-19 ARDS compared with non-COVID-19 ARDS.

CONCLUSION

COVID-19 pneumonia is associated with a higher incidence of barotrauma. It presents unique challenges for invasive and non-invasive ventilation management. Further studies are required to unravel the underlying pathophysiology and develop safer management strategies.

Flower lose, a cell fitness marker, predicts COVID-19 prognosis

Risk stratification of COVID-19 patients is essential for pandemic management. Changes in the cell fitness marker, hFwe-Lose, can precede the host immune response to infection, potentially making such a biomarker an earlier triage tool. Here, we evaluate whether hFwe-Lose gene expression can outperform conventional methods in predicting outcomes (e.g., death and hospitalization) in COVID-19 patients. We performed a post-mortem examination of infected lung tissue in deceased COVID-19 patients to determine hFwe-Lose's biological role in acute lung injury. We then performed an observational study (n = 283) to evaluate whether hFwe-Lose expression (in nasopharyngeal samples) could accurately predict hospitalization or death in COVID-19 patients. In COVID-19 patients with acute lung injury, hFwe-Lose is highly expressed in the lower respiratory tract and is co-localized to areas of cell death. In patients presenting in the early phase of COVID-19 illness, hFwe-Lose expression accurately predicts subsequent hospitalization or death with positive predictive values of 87.8-100% and a negative predictive value of 64.1-93.2%. hFwe-Lose outperforms conventional inflammatory biomarkers and patient age and comorbidities, with an area under the receiver operating characteristic curve (AUROC) 0.93-0.97 in predicting hospitalization/death. Specifically, this is significantly higher than the prognostic value of combining biomarkers (serum ferritin, D-dimer, C-reactive protein, and neutrophil-lymphocyte ratio), patient age and comorbidities (AUROC of 0.67-0.92). The cell fitness marker, hFwe-Lose, accurately predicts outcomes in COVID-19 patients. This finding demonstrates how tissue fitness pathways dictate the response to infection and disease and their utility in managing the current COVID-19 pandemic.

Forty-One Million RADPEER Reviews Later: What We Have Learned and Are Still Learning

ACR RADPEER® is the leading method of radiologic peer review in the United States. The program has evolved since its inception in 2002 and was most recently updated in 2016. In 2018, a survey was sent to RADPEER participants to gauge the current state of the program and explore opportunities for continued improvement. A total of 26 questions were included, and more than 300 practices responded. In this report, the ACR RADPEER Committee authors summarize the survey results and discuss opportunities for future iterations of the RADPEER program.

Lung cancer screening with low-dose computed tomography: an analysis of the MEDCAC decision

Lung cancer is the leading cause of cancer death in the United States and worldwide. However, among the top 4 deadliest cancers, lung cancer is the only one not subject to routine screening. Optimism for an effective lung cancer-screening examination soared after the release of the National Lung Screening Trial results in November 2011. Since then, nearly 40 major medical societies and organizations have endorsed low-dose computed tomography (LDCT) screening. In December 2013, the United States Preventive Services Task Force also endorsed LDCT. However, the momentum for LDCT screening slowed in April 2014 when the Medicare Evidence Development and Coverage Advisory Committee (MEDCAC) panel concluded that there was not enough evidence to justify the annual use of LDCT scans for the detection of early lung cancer. This article briefly reviews the epidemiology of lung cancer, the National Lung Screening Trial study results, and the growing national endorsement of LDCT from a variety of key stakeholder organizations. We subsequently analyze and offer our evidence-based counterpoints to the major assumptions underlying the MEDCAC decision.

Interaction of aluminium with bacteria isolated from wounds

The effect of aluminium as metal foil and as a weak solution of potassium aluminium sulphate on the growth of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Proteus vulgaris, has been examined over a range of pH values. Aluminium foil, and an aluminium metal film deposited by evaporation on a bonded cellulose fabric, failed to inhibit the growth of the organisms on agar plates. In contact with saline metal foil yielded trace amounts of aluminium in solution but no detectable amounts of aluminium were found in human serum which had been in prolonged contact with aluminium metal. Staph, aureus and Ps. aeruginosa were adsorbed from aqueous suspension by aluminium surfaces. Below pH 5 the growth of these organisms was inhibited by low concentrations of aluminium in aqueous solution. Preliminary measurements of the uptake of aluminium by these sensitive organisms have been made.

Dimers of the neuropeptide Y (NPY) Y2 receptor show asymmetry in agonist affinity and association with G proteins

In conditions precluding activation of G proteins, the binding of agonists to dimers of the neuropeptide Y (NPY) Y2 receptor shows two components of similar size, but differing in affinity. The dimers of all NPY receptors are solubilized as approximately 180-kDa complexes containing one G protein alpha beta gamma trimer. These heteropentamers are stable to excess agonists, chelators, and alkylators. However, dispersion in the weak surfactant cholate releases approximately 300-kDa complexes. These findings indicate that both protomers in the Y2 dimer are associated with G protein heterotrimers, but the extent of interaction depends on affinity for the agonist peptide. The G protein in contact with the first-liganded, higher-affinity protomer should have a stronger interaction with the receptor and a larger probability of activation.

Oligomerization of the heptahelical G protein coupling receptors: a case for association using transmembrane helices

The heptahelical G protein coupling receptors oligomerize extensively via transmembrane domains, in association with heterotrimeric G proteins. This provides higher affinity for agonists, conformational stability necessary for signal transduction, and protection from intracellular proteinases. The oligomerization is relevant to organismic pathophysiology and could be targeted by natural or modified agonists.

The neuropeptide Y (NPY) Y2 receptors are largely dimeric in the kidney, but monomeric in the forebrain

The neuropeptide Y(NPY) Y2 receptors are detected largely as dimers in the clonal expressions in CHO cells and in particulates from rabbit kidney cortex. However, in two areas of the forebrain (rat or rabbit piriform cortex and hypothalamus), these receptors are found mainly as monomers. Evidence is presented that this difference relates to large levels of G proteins containing the Gi alpha -subunit in the forebrain areas. The predominant monomeric status of these Y2 receptors should also be physiologically linked to large synaptic inputs of the agonist NPY. The rabbit kidney and the human CHO cell-expressed Y2 dimers are converted by agonists to monomers in vitro at a similar rate in the presence of divalent cations.

Circumferential Involvement of an Acute Type B Aortic Dissection: A Unique Case

A case of a 35-year-old woman with acute circumferential type B aortic dissection is presented. A review of the literature demonstrated that circumferential aortic dissection is limited to a small number of case reports and a small case series of type A lesions. This is the first report of a circumferential type B dissection. The case highlights the need to fully evaluate patients with acute aortic dissection and illustrates the unique data provided by transesophageal echocardiography and helical computed tomographic angiography.

Oligomerization of neuropeptide Y (NPY) Y2 receptors in CHO cells depends on functional pertussis toxin-sensitive G-proteins

Human neuropeptide Y Y2 receptors expressed in CHO cells are largely oligomeric, and upon solubilization are recovered by density gradient centrifugation as approximately 180 kDa complexes of receptor dimers and G-protein heterotrimers. A large fraction of the receptors is inactivated in the presence of pertussis toxin, in parallel with inactivation of Gi alpha subunits (with half-periods of about 4 h for both). This is accompanied by a very long-lasting loss of receptor dimers and of masked surface Y2 sites (an apparent receptor reserve pre-coupled mainly to Gi alpha subunit-containing G-proteins). However, surface Y2 receptors accessible to large peptide agonists are much less sensitive to the toxin. All surface Y2 receptors are rapidly blocked by Y2 antagonist BIIE0246, with a significant loss of the dimers, but with little change of basal Gi activity. However, both dimers and Y2 receptor compartmentalization are restored within 24 h after removal of the antagonist. In CHO cells, the maintenance and organization of Y2 receptors appear to critically depend on functional pertussis toxin-sensitive G-proteins.

Self-regulation of agonist activity at the Y receptors

Neuropeptide Y (NPY) is one of the most abundant neuropeptides, and is likely to be present at nanomolar levels over extended periods in the synaptic space of many forebrain areas. This might be linked to an evolved generalized toning activity through a number of other peptide receptors that use C-terminally amidated agonists (with LHRH and orexin receptors and GIR as examples). However, the Y1 and Y2 receptors (which constitute the bulk of Y receptors active in the neural matrix) possess subnanomolar affinities that, at saturating NPY levels, could produce excessive signaling, as well as receptor losses via repeated endocytosis. The related Y4 receptor shows an even higher agonist affinity, and faces the same problem in visceral and neural locations accessible to pancreatic polypeptide (PP). An examination of agonist peptide interaction with Y receptors shows that Y1 and Y4 receptors in particular (as located on either the intact cells, or on particulates derived from various cell types) develop a blockade dependent on ligand concentration, with the blocking ranks of [NPY]>>[peptide YY] (PYY) for the Y1, and [human PP]>>>[PYY-related Y4 agonist] for the Y4 receptor. This blockade is also echoed in a concentration-related reduction in biological activity of primary agonists (NPY and PP), resembling a partial agonism, and is influenced especially by the allosteric interactivity of agonists. With the Y2 receptor, the blocking by agonists is less pronounced, but the signaling by NPY-related peptides is apparently less than with PYY-related agonists. The extended occupancy and self-attenuation of primary agonist activity at Y receptors could represent an evolutionary solution contributing to a balancing of metabolic signaling, agonist clearance and receptor conservation.

Internalization of cloned pancreatic polypeptide receptors is accelerated by all types of Y4 agonists

Internalization of cloned rat or human Y4 receptors expressed in Chinese hamster ovary (CHO) cells increased with concentration of all types of Y4 agonists, including human and rat pancreatic polypeptides, the Y1 receptor group co-agonists possessing C-terminal TRPRY.NH2 pentapeptide, and a C-terminally amidated dimeric nonapeptide related to neuropeptide Y, GR231118. These peptides also inhibited forskolin-stimulated adenylyl cyclase activity in Y4 receptor-expressing cells, and stimulated the binding of 35S-labeled GTP-gamma-S to pertussis toxin-sensitive G-proteins in particulates from these cells. Peptide VD-11 (differing from GR231118 only by C-terminal oxymethylation) acted as a competitive antagonist in all of the above processes. Agonist-induced stimulation of the Y4 receptor internalization persisted in the presence of allosteric inhibitors of hPP binding, N5-substituted amilorides, which also were relatively little active in G-protein stimulation and cyclase inhibition by Y4 agonists. Acceleration of Y4 receptor internalization by agonists apparently is related to relaxation of allosteric constraints to ligand attachment and sequestration of the receptor-ligand complex.

Female Breast Radiation Exposure During CT Pulmonary Angiography

OBJECTIVE

The objective of our study was to estimate the effective radiation dose to the female breast during CT pulmonary angiography compared with other routine diagnostic imaging techniques.

MATERIALS AND METHODS

We retrospectively reviewed the demographic data of patients who underwent CT pulmonary angiography between May 2000 and December 2002, the diagnostic yield of those studies, and the estimated effective radiation dose to the breast incurred during CT. The estimated effective radiation dose was calculated using the ImPACT CT (Impact Performance Assessment of CT) dosimetry calculator and the CT dose index (CTDI) and was compared with the average glandular dose for two-view screening mammography.

RESULTS

During the study period, 1,325 CT pulmonary angiograms were obtained. Sixty percent (797) of the scans were obtained on female patients. The mean age of scanned females was 52.5 years (range, 15-93 years). Of the studies performed in females, 401 (50.31%) were negative, 151 (18.95%) were nondiagnostic, and 245 (30.74%) were positive for pulmonary thromboembolism. The calculated effective minimum dose to the breast of an average 60-kg woman during CT was 2.0 rad (20 mGy) per breast compared with an average glandular dose of 0.300 rad (3 mGy) for standard two-view screening mammography.

CONCLUSION

CT pulmonary angiography delivers a minimum radiation dose of 2.0 rad (20 mGy) to the breasts of an average-sized woman. This greatly exceeds the American College of Radiology recommendation of < or = 0.300 rad (3 mGy) or less for standard two-view mammography. The potential latent carcinogenic effects of such radiation exposure at this time remain unknown. We encourage the judicious use of CT pulmonary angiography and lower doses and nonionizing radiation alternatives when appropriate.

Agonist internalization by cloned Y1 neuropeptide Y (NPY) receptor in Chinese hamster ovary cells shows strong preference for NPY, endosome-linked entry and fast receptor recycling

In Chinese hamster ovary (CHO) cells expressing the cloned guinea-pig Y1 receptor, the saturable, receptor-linked internalization of NPY (NPY)-related peptides showed the rank order of human/rat neuropeptide Y (hNPY)>pig/rat peptide YY (pPYY)>=(Pro(34))human PYY>(Leu(31),Pro(34))hNPY>(Leu(31),Pro(34))hPYY>>BVD-11 (a selective Y1 antagonist). All agonists accessed similar numbers of Y1 sites in particulates from disrupted cells, with relatively small affinity variation. The rate of internalization could significantly depend on the overall interactivity of the agonist peptide (reflected in sensitivity to chaotropic agents, as well as in the level of non-saturable binding and internalization). Concentration-dependent inhibition of the agonist-driven CHO-Y1 internalization was found with filipin III (a cholesterol-complexing macrolide), and confirmed with inhibitors of clathrin lattice formation, phenylarsine oxide (PAO) and sucrose. In the concentration range affecting Y1 internalization, none of the above treatments or agents significantly alter agonist affinity for Y1 cell surface or particulate receptors. Largely similar responses to the above inhibitors were observed in CHO-Y1 cells for internalization of human transferrin. Internalization of CHO-Y1 receptor apparently is driven by NPY in strong preference to other naturally encountered agonists. At 37 degrees C, most of the internalized receptor is rapidly recycled through endosome-like membrane elements, detectable in Percoll gradients.

Blockade of pancreatic polypeptide-sensitive neuropeptide Y (NPY) receptors by agonist peptides is prevented by modulators of sodium transport. Implications for receptor signaling and regulation

Ligand binding to rodent pancreatic polypeptide-responding neuropeptide Y (NPY) receptors (here termed PP/NPY receptors), or to cloned Y4 or Y5 receptors, is selectively inhibited by amiloride, peptide or alkylating modulators of sodium transport. The PP/NPY and Y4 receptors are also selectively blocked by human or rat pancreatic polypeptide (PP) and the blocking peptides are not dissociated by high concentrations of alkali chlorides (which restore most of the binding of subtype-selective agonists to Y1 and Y2 sites). The PP/NPY receptors could also be blocked by NPY and related full-length peptides, including Y1-selective agonists (IC50 300-400 pM). The cloned Y(4) receptors from three species are much less sensitive to NPY or PYY. The sensitivity of both the PP/NPY sites and the Y(4) sites to Y2-selective peptides is quite low. The ligand attachment to PP/NPY sites is also very sensitive to peptidic Y1 antagonist ((Cys31,NVal34NPY27-36))2, which however blocks these sites at much higher molarities. Blockade of PP/NPY and Y4 sites by agonist peptides can be largely prevented by N5-substituted amiloride modulators of Na+ transport, and by RFamide NRNFLRF.NH2, but not by Ca2+ channel blockers, or by inhibitors of K+ transport. Protection of both PP/NPY and Y4 sites against blockade by human or rat pancreatic polypeptide is also afforded by short N-terminally truncated NPY-related peptides. The above results are consistent with a stringent and selective activity regulation for rabbit PP/NPY receptor(s) that may serve to differentiate agonists and constrain signaling, and could involve transporter-like interactants.

Making the transition: the role of helical CT in the evaluation of potentially acute thoracic aortic injuries

OBJECTIVE

The purpose of this study was to show that helical CT could be used at our center in lieu of routine aortography to examine patients who have had serious blunt chest trauma. We also wanted to assess the potential savings of using CT to avoid unnecessary aortography.

MATERIALS AND METHODS

The institutional review board approved the parallel imaging-CT immediately followed by aortography-of patients presenting with blunt chest trauma between August 1997 and August 1998. To screen patients for potential aortic injuries, we performed parallel imaging on 142 patients, and these patients comprised our patient population. CT examinations of the patients were reviewed for signs of injury by radiologists who were unaware of each other's interpretations and the aortographic results. Findings of CT examinations were classified as negative, positive, or inconclusive for injury. Aortography was performed immediately after CT. The technical and professional fees for both transcatheter aortography and helical CT were also compared.

RESULTS

Our combined kappa value for all CT interpretations was 0.714. The aortographic sensitivity and negative predictive value were both 100%. Likewise, the sensitivity and negative predictive value of CT were 100%. The total costs of performing aortography were estimated at approximately $402,900, whereas those for performing helical CT were estimated at $202,800.

CONCLUSION

Helical CT has a sensitivity and negative predictive value equivalent to that of aortography. Using CT to eliminate the possibility of mediastinal hematoma and to evaluate the cause of an abnormal aortic contour in a trauma patient allows us to use aortography more selectively. Avoiding the performance of unnecessary aortography will expedite patient care and reduce costs. We report the results of our experience with CT and how our center successfully made this transition in the initial examination of patients with serious thoracic trauma.

Cloned neuropeptide Y (NPY) Y1 and pancreatic polypeptide Y4 receptors expressed in Chinese hamster ovary cells show considerable agonist-driven internalization, in contrast to the NPY Y2 receptor

Guinea-pig neuropeptide Y1 and rat pancreatic polypeptide Y4 receptors expressed in Chinese hamster ovary cells were internalized rapidly upon attachment of selective peptide agonists. The Y1 and Y2, but not the Y4, receptor also internalized the nonselective neuropeptide Y receptor agonist, human/rat neuropeptide Y. The internalization of guinea-pig neuropeptide Y2 receptor expressed in Chinese hamster ovary cells was small at 37 degrees C, and essentially absent at or below 15 degrees C, possibly in connection to the large molecular size of the receptor-ligand complexes (up to 400 kDa for the internalized fraction). The rate of intake was strongly temperature dependent, with essentially no internalization at 6 degrees C for any receptor. Internalized receptors were largely associated with light, endosome-like particulates. Sucrose dose-dependently decreased the internalization rate for all receptors, while affecting ligand attachment to cell membrane sites much less. Internalization of the Y1 and the Y4 receptors could be blocked, and that of the Y2 receptor significantly inhibited, by phenylarsine oxide, which also unmasked spare cell-surface receptors especially abundant for the Y2 subtype. The restoration of Y1 and Y4 receptors after agonist peptide pretreatment was decreased significantly by cycloheximide and monensin. Thus, in Chinese hamster ovary cells the Y1 and Y4 receptors have much larger subcellular dynamics than the Y2 receptor. This differential could also hold in organismic systems, and is comparable with the known differences in internalization of angiotensin, bradykinin, somatostatin and opioid receptor subtypes.

Upregulation of pancreatic polypeptide-sensitive neuropeptide Y (NPY) receptors in estrogen-induced hypertrophy of the anterior pituitary gland in the Fischer-344 rat

Implants of diethylstilbestrol inducing anterior pituitary prolactinomas in female Fischer-344 rats produced a considerable elevation of high-affinity binding of either rat or human pancreatic polypeptide (hPP). No comparable upregulation of high-affinity binding sites was noted for the ligand [125I](Leu31,Pro34)hPYY (LP-PYY) (masked by 2 nM hPP to force selectivity for the Y1 sites), or of the Y2-selective ligand [125I]hPYY(3-36). The Y5-like sites displayed the rank order of potency of hPP = rPP, hNPY, LP-PYY > pPYY(1-36) > hNPY(2-36) > hPYY(3-36) >> aPP, similar to the previously described rabbit kidney or hypothalamic Y5-like receptors. The PP binding in the anterior pituitary was not sensitive to the Y1-selective non-peptidic antagonist BIBP-3226. The PP binding was highly sensitive to alkali metal cations, and to a N5-substituted amiloride antagonist of sodium transport, but not to a C2-guanido substituted amiloride antagonist of sodium channels. The binding was also sensitive to phospholipase C antagonist U-73122, and to alkylating alpha-adrenergic agonist chloroethylclonidine. Lactotrophs isolated in Percoll gradients after enzymic dispersion of the anterior pituitary gland retained the high-affinity PP binding. Following removal of estrogen implants, the hPP binding sites decreased to very low levels within 3 days, in parallel to the decrease of plasma prolactin.

Functional expression of three P2X(2) receptor splice variants from guinea pig cochlea

ATP has been suggested to act as a neurotransmitter or a neuromodulator in the cochlea. The responses to ATP in different cell types of the cochlea vary in terms of the rate of desensitization and magnitude, suggesting that there may be different subtypes of P2X receptors distributed in the cochlea. Recently three ionotropic P2X(2) receptor splice variants, P2X(2-1), P2X(2-2), and P2X(2-3,) were isolated and sequenced from a guinea pig cochlear cDNA library. To test the hypothesis that these different splice variants could be expressed as functional homomeric receptors, the three P2X(2) receptor variants were individually and transiently expressed in human embryonic kidney cells (HEK293). The biophysical and pharmacological properties of these receptors were characterized using the whole cell patch-clamp technique. Extracellular application of ATP induced an inward current in HEK293 cells containing each of the three splice variants in a dose-dependent manner indicating the expression of homomeric receptors. Current-voltage (I-V) relationships for the ATP-gated current show that the three subtypes of the P2X(2) receptor had a similar reversal potential and an inward rectification index (I(50 mV)/I(-50 mV)). However, the ATP-induced currents in cells expressing P2X(2-1) and P2X(2-2) variants were large and desensitized rapidly whereas the current in those cells expressing the P2X(2-3) variant was much smaller and desensitized slower. The order of potency to ATP agonists was 2-MeSATP > ATP > alpha,beta -MeATP for all three expressed splice variants. The ATP receptor antagonists suramin and PPADS reduced the effects of ATP on all three variants. Results demonstrate that three P2X(2) splice variants from guinea pig cochlea, P2X(2-1), P2X(2-2), and P2X(2-3), can individually form nonselective cation receptor channels when these subunits are expressed in HEK293 cells. The distinct properties of these P2X(2) receptor splice variants may contribute to the differences in the response to ATP observed in native cochlear cells.

Binding sites for human interferon-gamma in protocerebrum and hemolymph of tobacco hornworm (Manduca sexta) larvae differ in sensitivity to polycationic peptides

We have recently characterized specific binding sites for human interferon-gamma on particulates prepared from the protocerebrum and hemolymph of tobacco hornworm larvae, Manduca sexta ¿(Parker, M.S., Ourth, D.D., 1999. Comp. Biochem. Physiol. B 122, 155-163). The sensitivity to sulfated polysaccharides indicated an involvement of oligobasic epitopes of hIFN-gamma in the binding. In the present study, we found that polycationic peptides inhibited the binding of [125I]hIFN-gamma to particulates from either the hemolymph or the protocerebrum of Manduca sexta larvae. With amino acid homopolymers, the rank order of potency was poly-L-lysine > poly-L-arginine >> poly-L-ornithine, while the acidic side chain polymer poly-L-aspartate was not inhibitory. However, the potency of all polycationic peptides was at least three-fold greater at the hemolymph particulates. Also, acidic polysaccharides such as heparin were much more efficacious in the inhibition of hIFN-gamma binding to hemolymph relative to protocerebral particulates. The peptide polycations inhibited the binding of [125I](Leu31,Pro34)human peptide YY, a ligand selective for the Y1 subtype of the neuropeptide Y receptor, to rabbit kidney or to parietal cortex particulates with the expected rank order of poly-L-arginine > poly-L-lysine >> poly-L-ornithine, and with little cross-tissue difference in affinity. The selectivity observed with M. sexta particulates indicates a preferential involvement of oligobasic lysine-rich C-terminal sequences of IFN-gamma, while large insect tissue-related affinity differences point to involvement of diverse oligoacidic sequences in binding to protocerebrum and hemolymph sites. This study provides evidence for the presence of molecules in lepidopteran larvae that are similar in structure to vertebrate co-receptors of IFN-gamma, and adds to the characterization of these binding sites.

Ligand association with the rabbit kidney and brain Y1, Y2 and Y5-like neuropeptide Y (NPY) receptors shows large subtype-related differences in sensitivity to chaotropic and alkylating agents

The binding to rabbit kidney or hypothalamic particulates of the subtype-selective neuropeptide Y (NPY) receptor ligands [125I](Leu31,Pro34)hPYY (as Y1 site label at 2 nM human pancreatic polypeptide (hPP)), [125I]-hPYY(3-36) (Y2 label), and [125I]-hPP (Y5 label) displayed great differences in sensitivity to alkylators and chaotropic agents. Sensitivity to a nonionic chaotrope, urea, was much higher for the Y1 binding than for the Y5-like binding or the Y2 binding. The non-selective alkylator N-ethylmaleimide (NEM) and several alkylators selective for aminergic receptors were much more efficacious against the Y1 relative to the Y2 binding. Similar differences could be confirmed with the attachment of Y1 and Y2-selective tracers to CHO cells expressing the cloned guinea-pig Y1 or Y2 receptors. The Y5-like binding was quite insensitive to NEM, but sensitive to chloroethylclonidine (CEC) and prazobind, which were less potent at the Y1, and especially at the Y2 site. The unrestricted-access alkylator 2-aminoethyl methanethiosulfonate inhibited the binding to all subtypes, while the restricted-access agent 2-(trimethylammonium)ethylmethanethiosulfonate poorly inhibited the Y5-like binding, or the guanine nucleotide-insensitive Y2 binding. These results are compatible with an active conformation of the Y5-like site dependent on maintenance of a shared hydrophobic cavity. The Y2 sites resistant to guanosine polyphosphates and restricted-access alkylators were detected mainly in particulates slowly solubilized by cholate at 0-5 degrees C; these sites could be clustered.

FMRFamides exert a unique modulation of rodent pancreatic polypeptide sensitive neuropeptide Y (NPY) receptors

FMRFamide and related peptides (RFamides) were found to inhibit the association binding of iodinated human pancreatic polypeptide ([125I]hPP) to Y5-like neuropeptide Y (NPY) receptor in rodent tissues. An allosteric regulation of the activity of the rodent kidney PP-sensitive neuropeptide Y (NPY) receptor by RFamides was indicated by potency decrease with particle concentration in the inhibition of the association binding of 125I-labeled human pancreatic polypeptide (hPP) by RFamides at rabbit kidney membranes. The competition by C-terminal hexapeptide of hPP (LTRPRY.NH2) did not show such affinity change. The steady-state binding of hPP showed little sensitivity to any of the RFamides tested. The Y1-selective binding of [125I][Leu31,Pro34]hPYY (at 2 nM hPP) was much less sensitive to RFamides than the binding of [125I]hPP, albeit with some differences across tissue or cell types. The binding of Y2-selective agonist 125I-labeled human peptide YY (3-36) was quite insensitive to RFamides. The presence of a unique component in the inhibition of hPP binding by RFamides was further indicated by a degree of antagonism with phospholipase C inhibitor U-73122, and by an only limited cooperation with a N5-amiloride compound, and with alkylator chloroethylclonidine. Change of the chirality of individual residues in the FMRFamide molecule produced a significant reduction of inhibitory potency only with D-Phe in the C-terminal position. Substitution of the (C-3) L-Met by L-Leu greatly increased the inhibitory potency of RFamides relative to otherwise identical congeners. RFamides could act both as ligands of membrane neighbors of the PP receptor, and as competitors of Y5-like NPY receptor epitopes that accommodate the C-terminal aspects of agonist peptides.

Phosphorothioate oligodeoxynucleotides can selectively alter neuronal activity in the cochlea

A growing body of evidence indicates that extracellular adenosine triphosphate (ATP) may have a major role in cochlear function. Antagonists of ionotropic ATP receptors (P2X2) have significant effects on cochlear potentials and distortion product otoacoustic emissions (DPOAEs). We tested whether antisense oligodeoxynucleotides (ODNs) would mimic the functional deficiencies induced by the ATP antagonists through binding to P2X2 ATP receptor mRNA and thereby reduce the number of ATP receptors expressed in the membrane of the cells. Both a phosphorothioate ODN (S-ODN) antisense and a phosphodiester ODN (P-ODN) antisense to the P2X2 sequence and random sense ODNs containing 21 nucleotides were administered chronically (7 days) to the guinea pig cochlea via the perilymph compartment. Sound evoked cochlear potentials (cochlear microphonic; summating potential; compound action potential of the auditory nerve, CAP; latency of the first negative peak in the CAP, N1 latency) and DPOAEs were monitored to assess the effects of the ODNs. Results indicate that the phosphorothioate derivatives of both the antisense and random sense ODNs suppressed the CAP and prolonged the N1 latency with no significant effect on the other parameters. The P-ODNs had no effect. Since both the antisense and random sense S-ODNs had the same effect, we conclude that the S-ODNs affected neuronal function in a manner that did not involve binding to the ATP receptor mRNA.

Characterization of rabbit kidney and brain pancreatic polypeptide-binding neuropeptide Y receptors: differences with Y1 and Y2 sites in sensitivity to amiloride derivatives affecting sodium transport

Sites sensitive to human and rat pancreatic polypeptides (hPP and rPP) accounted for more than 30% of the specific binding of [125I](Leu31,Pro34) human peptide YY (LP-PYY) in particulates from rabbit kidney cortex, and about 10% of the specific binding in membranes from rabbit hypothalamus. The binding of [125I]hPP or [125I]rPP showed a high-affinity displacement with either hPP, rPP, LP-PYY, neuropeptide Y or peptide YY (Ki below 50 pM for all), while being quite insensitive to Y2-selective ligands. The PP binding had a high sensitivity to alkali cations and inhibitors of phospholipase C, very similar to that of LP-PYY binding 'masked' by excess cold hPP. However, as different from the Y1-like LP-PYY binding, but similar to the binding of the Y2-selective ligand [125I]human peptide YY(3-36) (hPYY(3-36)), the PP binding showed a low sensitivity to guanosine polyphosphates. The PP binding was much more sensitive to N5-substituted amiloride inhibitors of Na+ transport than the binding of LP-PYY, or that of hPYY(3-36). The inhibition of PP binding by N5-substituted amilorides was not enhanced by guanine nucleotides or by phospholipase C blockers. However, pairing of N5-substituted amilorides disproportionately increased the inhibition of hPP binding. Thus, in rabbit kidney or hypothalamus, the high-affinity PP-responding sites share some of the basic properties of the Y1 and Y2 sites, but are distinguished from both by a high sensitivity to compounds affecting sodium transport. These PP/NPY receptors could associate with membrane structures involved in the control of ion balance and osmotic responses.

Specific binding of human interferon-gamma to particulates from hemolymph and protocerebrum of tobacco hornworm (Manduca sexta) larvae

Specific binding sites for human interferon-gamma (hIFN-gamma) were found on particulates prepared from the hemolymph and protocerebrum of fifth-instar larvae of the tobacco hornworm, Manduca sexta. A portion of these sites could be solubilized in an active form by the zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate (CHAPS). A well-defined specific binding was also associated with hemolymph particulate residue after solubilization by CHAPS. About one-half of [125I]hIFN-gamma binding could be displaced by heparin. The bound hIFN-gamma could be covalently cross-linked to the binding sites using disuccinylamide suberate, and the molecular weight range of these complexes was 200-800 kDa as determined by density gradient sedimentation and gel-exclusion chromatography. Only a small fraction of the hemolymph IFN-gamma binding could be competed by another mammalian cytokine, rat prolactin (rPRL), while there was no sensitivity to rat growth hormone. The small specific rPRL binding found in Manduca hemolymph showed an affinity similar to the prolactin sites found in the liver of pregnant rats. The detergent-insoluble Manduca hIFN-gamma binding was bimodal and similar in affinity distribution to the binding found with human platelet membranes (Kdiss range 0.1-2 nM). The detergent-solubilized IFN-gamma sites were homogenous, with a Kdiss of about 1.5 nM. The IFN-gamma binding sites in Manduca tissues may therefore include molecular species similar to the known invertebrate cytokine receptors and proteoglycan co-receptors.

Characterization of Y1, Y2 and Y5 subtypes of the neuropeptide Y (NPY) receptor in rabbit kidney. Sensitivity of ligand binding to guanine nucleotides and phospholipase C inhibitors

The binding of two peptide YY/neuropeptide Y analogues selective for major subtypes of neuropeptide Y (NPY) receptors was compared in particulates from rabbit kidney cortex employing modulators of activity of G-proteins, phospholipase enzymes, and ion channels. The binding of (Leu31,Pro34)human peptide YY resembled the patterns observed previously for the brain tissue Y1 receptor, exhibiting a high sensitivity to monovalent cations, disulfide disruptors, guanosine polyphosphates and phospholipase C inhibitors. However, this binding was bimodal in response to human pancreatic polypeptide and to peptides selective for the Y2 subtype of the NPY receptor, displaying a large component pharmacologically similar to the brain Y5 receptor. This kidney Y5-like binding largely shared the sensitivity to monovalent cations, guanine nucleotides and phospholipase C inhibitors found for either the kidney or the brain Y1 receptor, and also was activated by Ca2+ ion. Both Y1- and Y5-like binding in the kidney displayed a uniformly low reactivity to a nonpeptidic Y1 antagonist, BIBP-3226, and to a receptor peptide mimetic, mastoparan analogue MAS-7. The kidney Y2 binding shared the low sensitivity to ionic environment observed for the brain Y2 subtype, and was only partially sensitive to guanine nucleotides or to MAS-7. The Y2 liganding had a sensitivity to phospholipase C inhibitors similar to the Y1/Y5 binding. This reactivity was retained in the fraction of the Y2 receptor persisting detergent solubilization in a high-affinity form, which, however, was activated rather than inhibited by G-protein agonists.

Novel variant of the P2X2 ATP receptor from the guinea pig organ of Corti

ATP functions as a neurotransmitter and a neuromodulator in various tissues by acting on metabotropic (P2Y) and ionotropic (P2X) receptors. Evidence suggests that ATP activates P2X receptors on several cell types in the organ of Corti of guinea pig including outer hair cells (OHCs), Deiters' cells, Hensen's cells, pillar cells and inner hair cells (IHCs). Determining the sequence and structure of P2X receptors in guinea pig organ of Corti is important for understanding the function of ATP in the cochlea. We screened a guinea pig organ of Corti cDNA library for P2X2 ATP receptors using rat P2X2 cDNA as a probe. We sequenced three P2X2 variants which were found to be abundant in this library. One is a novel P2X2 isoform (P2X2-3) created by a retained intron coding for an additional 27 amino acids (81 bp) in the putative extracellular domain. We have also sequenced a variant (P2X2-2) that lacks both the 81-bp sequence and a 192-bp sequence in the 3' intracellular domain. A third variant (P2X2-1) contains the intracellular 192-bp sequence but not the extracellular 81-bp sequence found in P2X2-3. The multiple transcripts arise from alternative intron and exon splicing events. In situ hybridization with a probe common to the three variants localized P2X2 to many of the cells of the organ of Corti.

Characterization of G protein and phospholipase C-coupled agonist binding to the Y1 neuropeptide Y receptor in rat brain: sensitivity to G protein activators and inhibitors and to inhibitors of phospholipase C

Binding of a Y1-subtype-selective agonist of neuropeptide Y (NPY) receptor, (Leu31,Pro34)human peptide YY (LP-PYY), to particulates from four rat brain areas (parietal cortex area 1, piriform cortex, anterior hypothalamus and hippocampus) showed a distinct response to LP-PYY and PYY, a uniformly low sensitivity to ligands selective for the Y2, Y4 and Y5 NPY receptor subtypes and high sensitivity to a Y1 site-selective antagonist, BIBP-3226. The Y1 binding was sensitive to guanine nucleotide-binding protein (G protein) agonist and antagonist nucleotides, with the rank order of guanosine 5'-O-(thiotriphosphate) (GTP gamma S) > GTP > GDP > guanosine 5'-O-(thiodiphosphate). However, guanine nucleotides did not affect about one third of the specific Y1 binding. Most of Y1 binding could be inhibited by a G protein nucleotide site/docking site receptor mimic, mastoparan analog MAS-7. In all areas examined, the Y1 binding of LP-PYY was little affected by up to 100 microM of the antagonists of K+, Na+ and Ca++ channels, protein kinase C, phospholipase A2, phospholipase D and phosphatidylinositol 3-kinase, phospholipase substrate phospholipids, steroids or detergents. However, the binding was potently inhibited by phospholipase C inhibitors (especially the aminosteroid U-73122), which also dissociated the bound Y1 ligand in steady-state conditions. U-73122 also displaced the Y1 binding insensitive to GTP gamma S. Ligand association with the brain Y1 NPY receptor thus strongly depends on activity of both G proteins and phospholipase C, implying specific interactions of these transducers/effectors with the receptor molecule in ligand binding. A portion of brain Y1 sites could be directly coupled to phospholipase(s) C.

AIDS-related bronchogenic carcinoma: fact or fiction?

OBJECTIVE

Case reviews and retrospective analyses have raised the possibility of an increased frequency of primary lung carcinoma in HIV- and AIDS-infected patients. Conclusions have often been controversial and conflicting. We conducted a population-based epidemiologic study to assess the incidence of lung neoplasms in an HIV/AIDS cohort.

MATERIALS AND METHODS

The Texas Department of Health generated descriptive data on lung neoplasms in HIV-AIDS patients whose conditions were diagnosed between 1990 and 1995. The cancer registry matched against all patients whose conditions were diagnosed during the same time interval. Relative risk was measured through standardized incidence ratios of lung neoplasms in the HIV-AIDS population as compared with that of the US population.

RESULTS

The HIV-AIDS data file included 26,181 cases. A total of 76 lung cancer cases were identified, of which 36 (47.4%) were primary lung cancers. All major histologies were represented. The observed (36)/expected (5.6) ratio (standard incidence ratio) for primary lung cancer compared to the US population was 6.5 (4.5 to 8.9, 95% confidence interval).

CONCLUSIONS

Our data indicate a 6.5-fold increased incidence of primary lung cancer in HIV- and AIDS-infected patients. We present the results of our study, a review of the work of other investigators, and address a potentially even greater public health problem in the HIV/AIDS population than previously realized.

The Hermansky-Pudlak syndrome

Hermansky-Pudlak Syndrome (HPS) is a rare, inheritable disorder characterized by the classic triad of oculo-cutaneous albinism, platelet dysfunction, and ceroid deposition. An associated complication is pulmonary fibrosis with progressive restrictive lung disease. This report discusses the lung involvement often seen in this condition correlated with radiography, computed tomography, high-resolution computed tomography, and the underlying pathology, by means of two such afflicted siblings. The elder died of respiratory failure while awaiting lung transplantation. The younger sibling is currently undergoing evaluation for transplantation.

Differences in cation sensitivity of ligand binding to Y1 and Y2 subtype of neuropeptide Y receptor of rat brain

The binding of selective ligands to the Y1 subtype of neuropeptide Y receptor in rat brain particulates was promoted by Ca2+ and also stimulated by Sr2+, but reversibly reduced by Ba2+, Mg2+, Mn2+, by the organic polycations neomycin and spermidine, and by chelating agents. The alkali monovalent cations inhibited the Ca(2+)-enabled Y1 subtype binding with some selectivity (Cs+ > or = NH4+ > Li+ > Na+, K+), with half-inhibition between 70-120 mM. The specific Y2 subtype binding was enhanced by all alkaline-earth divalent cations, Mn2+, neomycin and spermidine in the range of 0.1-10 mM, and by alkali cations at up to 100 mM, and also by Na+ salts of the chelators EGTA and EDTA. The large disparity in cation sensitivity indicates substantial differences in the structure of the binding sites of the Y1 and Y2 receptors, predictable from known distinct features of ligand epitopes and of primary structure of the receptors.

Abdominal aortic injury associated with transverse lumbar spine fracture--imaging findings

The association of abdominal aortic injury with transverse fractures of the lumbar spine is not well recognized. Three cases are presented with description of a mechanism common to both injuries that may explain this association--that of distraction and hyperflexion, such as occurs in seat-belt injuries. Whenever a transverse lumbar spine fracture following such a mechanism of injury is recognized, the co-existence of an injury to the abdominal aorta should be excluded by aortography if there is any doubt concerning the integrity of the peripheral pulses. This is best performed prior to laparotomy for any associated intraperitoneal injuries. Repeated clinical examination may detect deterioration in those cases with initially normal pulses. Ultimately, detection of the aortic injury rests on a high index of suspicion.

The effect of influenza C virus on the Purkinje cells of chick embryo cerebellum

Intra-amniotic inoculation of influenza C virus resulted in observable and quantitatively measurable changes in the Purkinje cells of chick embryo cerebellum. Purkinje cells were visualized by the Golgi-Cox procedure and prepared for statistical and computer evaluation from camera lucida drawings. Four computer-generated measurements (the area of the dendritic arbor, the perimeter of the dendritic tree, and the height and width of the cell's arborization) and two manually counted measurements (total number of branches and the number of first order branches) were made. Analysis of Purkinje cells from influenza C virus-infected embryos showed disturbances in dendritic arborization patterns and misalignment in the arrangement of the cells in the Purkinje cell layer compared to control cells. Statistical evaluation of Purkinje cell arborization showed significant decreases in all measured parameters for the influenza C virus-infected members when compared with the members of the uninfected control group.

Influence of gamma radiation on the gel rigidity index and binding capability of gelatin

Changes in the rigidity indices of gelatin gel before and after gamma irradiation were characterized by dynamic mechanical testing, and the significance of these changes on the strength of granules was evaluated. Results illustrate the difficulty of obtaining reproducible values for gels containing less than 20% gelatin. However, rigidity indices for gels with a gelatin content of 20% and higher are consistent and may provide a useful controlling factor for preparation of gelatins of more precise specifications. The data indicate that rigidity degradation kinetics of several concentrations of gelatin gel at different radiation doses are complex, showing both increasing and decreasing rates. These findings strongly suggest that doses of less than 2.0 Mrad of gamma radiation should be used in order to obtain gelatins of acceptable quality for pharmaceutical applications. The crushing strength of granules of lactose powder granulated with irradiated gelatin reveals that the binding capability of such gelatin is significantly reduced. The results obtained for various size fractions and granule hardnesses containing different binder concentrations also suggest that particle size influences the granule strength to a lesser extent than does binder concentration and its consistency.

Prospective intellectual testing in children with brain tumors

Sixteen children with brain tumors received prospective intellectual evaluations with a follow-up of 2 to 5 years. All patients were treated with surgery and radiation and 5 received chemotherapy. Most of the children remained within the normal range of intelligence, but intelligence quotient (IQ) scores declined over time. Learning disabilities were present in 15 of 16 children after radiation, and 11 required special educational services. Risk factors associated with decline in IQ appear to be young age at time of radiation and adjuvant chemotherapy.

Inimical effects of compaction speed on microorganisms in powder systems with dissimilar compaction mechanisms

Tablets were prepared from powders that were consolidated by plastic deformation and fragmentation mechanisms. Cells of Staphylococcus aureus and spores of Bacillus subtilis were incorporated in the tablets by compaction at various pressures and compression speeds. The extent of inactivation of organisms was dependent on the compression behavior of the powders, on the speed of compaction, and on the degree of densification of compacts. Scanning electron micrographs of fractured compacts revealed that particle rearrangement, fragmentation, and deformation significantly influence the "survivor". The "pressure-survivor plots" showed a linear relationship with greater inactivation in brittle material, while the extent in inactivation was reduced, and followed a nonlinear pattern in those powders exhibiting plastic deformation.

In vitro prostaglandin E2 stimulation of 45Ca mobilization from chick bone

The ability of prostaglandin E2 (PGE2) to mobilize 45Ca from chick embryo long bones was assayed in an in vitro bone culture system. Concentrations of PGE2 tested ranged from 10(-9) to 10(-5) M. The PGE2 was effective in stimulating release of 45Ca from prelabelled bones at all concentrations tested except at 10(-9) M. In addition, stimulation of 45Ca release could be produced daily for 4 consecutive days of PGE2 culture-pulsing at what appeared to be the optimal PGE2 concentration, 10(-7) M. We conclude, as in mammals, PGE2 is a potent stimulator of calcium mobilization from avian bone. The potential involvement of prostaglandins in eggshell formation is discussed.

Hypercalcemia in coccidioidomycosis

Two patients with disseminated coccidioidomycosis and hypercalcemia are presented. One patient studied showed normal levels of 25-hydroxyvitamin D with depressed levels of 1 alpha,25-dihydroxyvitamin D. The serum calcitonin level was appropriate for the level of serum calcium, and the serum parathyroid hormone level was suppressed with elevation of the nephrogenous cAMP level. Intestinal absorption of calcium was elevated at 63 percent. Hypercalcemia and hypercalciuria persisted despite a 300 mg calcium diet. An osteotropic substance similar to the humoral hypercalcemia of malignancy is postulated.