Highly Efficient and Scalable p-i-n Perovskite Solar Cells Enabled by Poly-metallocene Interfaces

Inverted p-i-n perovskite solar cells (PSCs) are easy to process but need improved interface characteristics with reduced energy loss to prevent efficiency drops when increasing the active photovoltaic area. Here, we report a series of poly ferrocenyl molecules that can modulate the perovskite surface enabling the construction of small- and large-area PSCs. We found that the perovskite-ferrocenyl interaction forms a hybrid complex with enhanced surface coordination strength and activated electronic states, leading to lower interfacial nonradiative recombination and charge transport resistance losses. The resulting PSCs achieve an enhanced efficiency of up to 26.08% for small-area devices and 24.51% for large-area devices (1.0208 cm2). Moreover, the large-area PSCs maintain >92% of the initial efficiency after 2000 h of continuous operation at the maximum power point under 1-sun illumination and 65 °C.

Habitat connectivity and resource selection in an expanding bobcat (Lynx rufus) population

Terrestrial carnivores are among the most imperiled species worldwide, yet some species are resilient and are recovering in human-dominated landscapes after decades or centuries of absence. Bobcat (Lynx rufus) populations were extirpated from much of Midwestern US in the mid-1800's, and are currently expanding and recolonizing their former range. In this study, we investigated multi-scale habitat selection for Ohio's expanding bobcat population, and examined habitat connectivity in order to evaluate the conduits for dispersal statewide. We used citizen observations collected between 1978 and 2019 and logistic regression to evaluate population-level habitat selection, and GPS telemetry data for 20 individuals collected between 2012 and 2014 and a distribution-weighted exponential Resource Selection Function to evaluate individual-level habitat selection within home ranges. At the population level, bobcats selected for higher amounts of forest and pasture (at a 50 km² scale) and herbaceous vegetation (at 15-50 50 km² scales), thus overall heterogeneous forested habitat. At individual (home range) level, bobcats selected for forested habitats with low road density and farther away from high traffic roads; they also showed weak selection for open habitat at the home range level. Male home ranges were significantly greater than female home ranges. Lastly, we used the population-level spatial outputs (i.e. habitat suitability map) to parameterize habitat connectivity models using circuit theory in the program Circuitscape. We tested three relationships between habitat suitability and resistance to movement and used a subset of data on potential dispersing individuals to evaluate which relationship performed best. All three relationships performed almost equally well, and we calculated a weighted averaged connectivity map as our final map. Habitat was highly permeable to movements between core areas of two genetically distinct subpopulations located in southeastern Ohio. We also identified potential dispersal corridors from the core areas to other regions of Ohio dominated by agriculture and suburban development via forested riparian corridors. Overall, our analysis offers new information on habitat selection and connectivity in a rebounding felid population and offers important ecological information for wildlife management strategies. We recommend that the suitability and connectivity models should be periodically updated until the population reaches an equilibrium, and be integrated with data from neighboring states for a comprehensive assessment of a conservation success story.

Alumination of aryl methyl ethers: switching between sp2 and sp3 C-O bond functionalisation with Pd-catalysis

The reaction of [{(ArNCMe)₂CH}Al] (Ar = 2,6-di-iso-propylphenyl) with aryl methyl ethers proceeded with alumination of the sp³ C-O bond. The selectivity of this reaction could be switched by inclusion of a catalyst. In the presence of [Pd(PCy₃)₂], chemoselective sp² C-O bond functionalisation was observed. Kinetic isotope experiments and DFT calculations support a catalytic pathway involving the ligand-assisted oxidative addition of the sp² C-O bond to a Pd-Al intermetallic complex.

Palladium-catalysed C-F alumination of fluorobenzenes: mechanistic diversity and origin of selectivity

A palladium pre-catalyst, [Pd(PCy₃)₂] is reported for the efficient and selective C–F alumination of fluorobenzenes with the aluminium(i) reagent [{(ArNCMe)₂CH}Al] (1, Ar = 2,6-di-iso-propylphenyl). The catalytic protocol results in the transformation of sp² C–F bonds to sp² C–Al bonds and provides a route to reactive organoaluminium complexes (2a–h) from fluorocarbons. The catalyst is highly active. Reactions proceed within 5 minutes at 25 °C (and at appreciable rates at even −50 °C) and the scope includes low-fluorine-content substrates such as fluorobenzene, difluorobenzenes and trifluorobenzenes. The reaction proceeds with complete chemoselectivity (C–F vs. C–H) and high regioselectivities (>90% for C–F bonds adjacent to the most acidic C–H sites). The heterometallic complex [Pd(PCy₃)(1)₂] was shown to be catalytically competent. Catalytic C–F alumination proceeds with a KIE of 1.1–1.3. DFT calculations have been used to model potential mechanisms for C–F bond activation. These calculations suggest that two competing mechanisms may be in operation. Pathway 1 involves a ligand-assisted oxidative addition to [Pd(1)₂] and leads directly to the product. Pathway 2 involves a stepwise C–H → C–F functionalisation mechanism in which the C–H bond is broken and reformed along the reaction coordinate, guiding the catalyst to an adjacent C–F site. This second mechanism explains the experimentally observed regioselectivity. Experimental support for this C–H activation playing a key role in C–F alumination was obtained by employing [{(MesNCMe)₂CH}AlH₂] (3, Mes = 2,4,6-tri-methylphenyl) as a reagent in place of 1. In this instance, the kinetic C–H alumination intermediate could be isolated. Under catalytic conditions this intermediate converts to the thermodynamic C–F alumination product.

A palladium pre-catalyst, [Pd(PCy₃)₂] is reported for the efficient and selective C–F alumination of fluorobenzenes with the aluminium(i) reagent [{(ArNCMe)₂CH}Al] (Ar = 2,6-di-iso-propylphenyl).

Catalyst control of selectivity in the C-O bond alumination of biomass derived furans

Non-catalysed and catalysed reactions of aluminium reagents with furans, dihydrofurans and dihydropyrans were investigated and lead to ring-expanded products due to the insertion of the aluminium reagent into a C–O bond of the heterocycle. Specifically, the reaction of [{(ArNCMe)₂CH}Al] (Ar = 2,6-di-iso-propylphenyl, 1) with furans proceeded between 25 and 80 °C leading to dearomatised products due to the net transformation of a sp² C–O bond into a sp² C–Al bond. The kinetics of the reaction of 1 with furan were found to be 1st order with respect to 1 with activation parameters ΔH^‡ = +19.7 (±2.7) kcal mol⁻¹, ΔS^‡ = −18.8 (±7.8) cal K⁻¹ mol⁻¹ and ΔG^‡_{298 K} = +25.3 (±0.5) kcal mol⁻¹ and a KIE of 1.0 ± 0.1. DFT calculations support a stepwise mechanism involving an initial (4 + 1) cycloaddition of 1 with furan to form a bicyclic intermediate that rearranges by an α-migration. The selectivity of ring-expansion is influenced by factors that weaken the sp² C–O bond through population of the σ*-orbital. Inclusion of [Pd(PCy₃)₂] as a catalyst in these reactions results in expansion of the substrate scope to include 2,3-dihydrofurans and 3,4-dihydropyrans and improves selectivity. Under catalysed conditions, the C–O bond that breaks is that adjacent to the sp²C–H bond. The aluminium(iii) dihydride reagent [{(MesNCMe)₂CH}AlH₂] (Mes = 2,4,6-trimethylphenyl, 2) can also be used under catalytic conditions to effect a dehydrogenative ring-expansion of furans. Further mechanistic analysis shows that C–O bond functionalisation occurs via an initial C–H bond alumination. Kinetic products can be isolated that are derived from installation of the aluminium reagent at the 2-position of the heterocycle. C–H alumination occurs with a KIE of 4.8 ± 0.3 consistent with a turnover limiting step involving oxidative addition of the C–H bond to the palladium catalyst. Isomerisation of the kinetic C–H aluminated product to the thermodynamic C–O ring expansion product is an intramolecular process that is again catalysed by [Pd(PCy₃)₂]. DFT calculations suggest that the key C–O bond breaking step involves attack of an aluminium based metalloligand on the 2-palladated heterocycle. The new methodology has been applied to important platform chemicals from biomass.

Non-catalysed and catalysed reactions of aluminium reagents with furans, dihydrofurans and dihydropyrans were investigated and lead to ring-expanded products due to the insertion of the aluminium reagent into a C–O bond of the heterocycle.

The partial dehydrogenation of aluminium dihydrides

The reactions of a series of β-diketiminate stabilised aluminium dihydrides with ruthenium bis(phosphine), palladium bis(phosphine) and palladium cyclopentadienyl complexes is reported.

The reactions of a series of β-diketiminate stabilised aluminium dihydrides with ruthenium bis(phosphine), palladium bis(phosphine) and palladium cyclopentadienyl complexes is reported. In the case of ruthenium, alane coordination occurs with no evidence for hydrogen loss resulting in the formation of ruthenium complexes with a pseudo–octahedral geometry and cis-relation of phosphine ligands. These new ruthenium complexes have been characterised by multinuclear and variable temperature NMR spectroscopy, IR spectroscopy and single crystal X-ray diffraction. In the case of palladium, a series of structural snapshots of alane dehydrogenation have been isolated and crystallographically characterised. Variation of the palladium precursor and ligand on aluminium allows kinetic control over reactivity and isolation of intermetallic complexes that contain new Pd–Al and Pd–Pd interactions. These complexes differ by the ratio of H : Al (2 : 1, 1.5 : 1 and 1 : 1) with lower hydride content species forming with dihydrogen loss. A combination of X-ray and neutron diffraction studies have been used to interrogate the structures and provide confidence in the assignment of the number and position of hydride ligands. ²⁷Al MAS NMR spectroscopy and calculations (DFT, QTAIM) have been used to gain an understanding of the dehydrogenation processes. The latter provide evidence for dehydrogenation being accompanied by metal–metal bond formation and an increased negative charge on Al due to the covalency of the new metal–metal bonds. To the best of our knowledge, we present the first structural information for intermediate species in alane dehydrogenation including a rare neutron diffraction study of a palladium–aluminium hydride complex. Furthermore, as part of these studies we have obtained the first SS ²⁷Al NMR data on an aluminium(i) complex. Our findings are relevant to hydrogen storage, materials chemistry and catalysis.

Abstract P5-02-03: Incidental radiographic findings at the time of breast cancer diagnosis

Background: Perioperative staging imaging to evaluate for distant metastases is frequently performed in patients with newly diagnosed breast cancer, despite clinical guidelines recommending against their routine use in stage I and II disease. In addition, recent technological advances in imaging have led to increased sensitivity for findings, many of which are unrelated to breast cancer. We assessed whether the presence of incidental findings on staging imaging is associated with a higher risk of breast cancer recurrence.

Patients and Methods: A retrospective review of staging imaging for distant metastases was performed in 340 patients with stage II or III invasive breast cancer diagnosed in 2008-2009 at a large academic medical center. Data related to patient demographics, pathology, treatment, and recurrence were abstracted from the electronic medical record. Kaplan Meier curves and Cox proportional hazards models were used to assess the association between the presence of incidental findings and time to disease recurrence.

Results: A total of 169 of 340 patients (49.7%) underwent staging evaluation for distant metastases (CT chest, CT abdomen/pelvis, bone scan, and/or PET-CT). Of these, 146 (86.4%) had at least one suspicious or indeterminate radiographic finding. To clarify these findings, 73 (43.2%) patients underwent follow-up imaging or procedures. Nineteen patients were diagnosed with metastatic disease, 18 of whom were initially thought to have stage III disease and one was thought to have stage II disease. In the 127 patients without definite evidence of metastatic disease who underwent staging imaging, 32 were diagnosed with disease recurrence. With median follow-up of 4.9 years, the presence of indeterminate or suspicious findings at diagnosis was not associated with a significant difference in time to disease recurrence, adjusted for stage, hormone receptor status, and HER2 status (HR 1.44, 95% CI 0.51-6.03, p=0.55).

Time to Disease Recurrence by Imaging ModalityImaging Modality# With Indeterminate or Suspicious Finding(s)# Without Indeterminate or Suspicious Finding(s)Hazard Ratio95% Confidence Intervalp-valueAll Patients without mets at diagnosis127231.440.51-6.030.55CT Chest83521.890.80-4.460.15CT Abdomen/Pelvis91451.380.63-3.040.43Bone Scan351231.040.44-2.460.93

Time to Disease Recurrence by Type of Radiographic AbnormalityType of Abnormal Finding# With Indeterminate or Suspicious Finding(s)# Without Indeterminate or Suspicious Finding(s)Hazard Ratio95% Confidence Intervalp-valuePulmonary nodules70661.650.76-3.580.20Liver lesions46911.720.83-3.600.15Borderline or enlarged lymph nodes201190.570.17-1.960.37

Conclusions: Staging imaging for distant metastases frequently reveals indeterminate findings, whose presence was not associated with a significant risk of disease recurrence in this analysis. Due to low yield for the diagnosis of metastases, staging imaging should not routinely be performed in stage II breast cancer patients.

Citation Format: Brothers JM, Kidwell KM, Brown RK, Henry NL. Incidental radiographic findings at the time of breast cancer diagnosis. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-02-03.

Role of FDG PET/CT in imaging of renal lesions

Focal incidental renal lesions are commonly encountered on positron emission tomography (PET)/computed tomography (CT) imaging. The vast majority of these lesions are benign. However, the interpretation of renal lesions can be problematic if the imaging criteria of simple cysts are not met. Limited literature exists on the characterisation of renal masses with metabolic imaging. The purpose of this article is to focus on the imaging features of benign and malignant renal masses with PET/CT. The lesions discussed include renal cyst, angiomyolipoma, oncocytoma, renal cell carcinoma, renal metastases and other infiltrating neoplastic processes affecting the kidney. Both the anatomical and metabolic features which characterise these benign and malignant entities are described. We emphasise the importance of viewing the CT component to identify the typical morphological features and discuss how to best use hybrid imaging for management of renal lesions. Metabolic imaging has a promising role in the imaging of renal lesions and can help prevent unnecessary biopsies and ensure optimal management of suspicious lesions.

Metal cluster chemistry: Structure and stereochemistry in the polynuclear rhodium hydrides H(n)Rh(n)[P(OR)(3)](2n)

Crystallographic analyses of x-ray and neutron diffraction data have provided a definitive structural representation of {HRh[P(O-i-C(3)H(7))(3)](2)}(2) and {HRh[P(OCH(3))(3)](2)}(3). These polynuclear hydrides are generated from square planar H(2)Rh[P(OR)(3)](2) units by edge (hydrogen atom) sharing and by vertex (hydrogen atom) sharing to form the dimeric and trimeric structures, respectively. The square-planar units are held together through four-center and three-center two-electron Rh-H-Rh bonds in the dimer and trimer, respectively. The dimer and trimer molecules each add one molecule of hydrogen to form H[(i-C(3)H(7)O)(3)P](2)RhH(3)Rh [P(O-i-C(3)H(7))(3)](2) and H(5)Rh(3)[P(OCH(3))(3)](6), respectively. NMR spectral information has served to define the stereochemical features of these polyhydrides. The significance of this chemistry in the metal cluster-metal surface analogy is described.

Physicochemical and mineralogical characterization of test materials used in 28-day and 90-day intratracheal instillation toxicology studies in rats

Two recent intratracheal instillation toxicology studies in rats clearly show that a naturally occurring quartz, with occluded crystal surfaces (quartz isolate), produced significantly less inflammatory response than a crushed reference quartz (DQ12). Respirable-size quartz isolate was isolated from bentonite parent rock, without crushing or the use of chemicals, to ensure that the surface properties of the quartz particles were unaltered. The isolation technique utilized gentle mechanical dispersion followed by sedimentation in an aqueous medium. Extensive mineralogical and chemical characterizations were undertaken to define the physicochemical properties of the test materials. The characterizations showed significant, measurable physicochemical differences between the two quartz types. These differences may help to explain the difference in toxicological response associated with these materials. The evaluation methods and resulting data that characterized the chemical and physical properties of the instillation test materials are discussed. The data presented show that such characterizations are essential if meaningful correlations are to be made between test materials and their toxicological profiles.

Changes in digital flexor tendon mechanics after endoscopic and open carpal tunnel releases in cadaver wrists

Digital flexor tendon excursion due to isolated wrist motion was measured in 5 cadaver wrists. Five sequential experimental conditions were tested: (1) intact wrists, (2) after single-incision endoscopic carpal tunnel release, (3) after addition of a distal endoscopic portal, (4) after conversion to an open palm incision, and (5) after suturing of the palm incision. Combined tendon excursion increased 27.8% after 1-incision and 29.7% after 2-incision endoscopic release; both increases were significant. A further increase in combined excursion to 43.4% over the value in intact wrists was measured after conversion to an open palm incision. Combined flexor tendon excursion after open release was significantly greater than excursion after either type of endoscopic release. Increases in excursion were also significant when flexor digitorum superficialis and flexor digitorum profundus tendons were considered separately. Excursion did not change significantly after skin suturing. These findings suggest that digital flexor tendon mechanics are closer to normal after endoscopic carpal tunnel release than after open release. It remains to be shown whether the difference is an advantage of endoscopic release over open release in the clinical setting. (J Hand Surg 2000; 25A:112-119.

The effects of exercise on ligamentous stiffness in the wrist

The purpose of this study was to determine if exercise alters wrist joint laxity, as measured by the mechanical behavior of the scaphoid bone. The load-displacement behavior of the scaphoid was studied in the palmar-dorsal direction in both wrists of 7 healthy volunteers (n = 14) before and after 2 exercise protocols (grip and push-up). When compared to the rested values, both exercise protocols significantly increased the displacement at 40 N by 47% (grip) and by 34% (push-up). Accordingly, the stiffness decreased significantly by 36% (grip) and by 32% (push-up). Partial recovery was documented after 1 hour of rest and there were no differences between any of the groups after 24 hours of rest. The increase in laxity documented during these exercise protocols reduces the ligament loads at comparable wrist positions and may thereby reduce the likelihood of traumatic ligamentous injury during participation in strenuous activity or sports.

Pulmonary dysfunction in cystic fibrosis is associated with oxidative stress

The aim of this study was to determine whether a relationship exists between the circulating concentration of antioxidants, or markers of oxidative stress, and pulmonary function in cystic fibrosis patients. Plasma was obtained from 34 patients attending a cystic fibrosis clinic. Oxidative stress was investigated by measuring the concentrations of circulating lipid hydroperoxides and malondialdehyde (lipid peroxidation) and protein carbonyls (protein oxidation). Antioxidant status was determined from the plasma concentrations of alpha-tocopherol, ascorbic acid, uric acid and total sulphydryls. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and forced mid-expiratory flow (FEF25-75) were measured in 25 of the subjects by spirometry, and expressed as percentage predicted for normal height, weight and age. Lung function decreased significantly with age and was associated with decreased plasma alpha-tocopherol, ascorbic acid and sulphydryl concentrations. The reduction in pulmonary function correlated with elevated plasma malondialdehyde, but not with lipid hydroperoxide or protein carbonyl concentrations. Patients with severe lung dysfunction (FEV1 < 50% predicted) had higher plasma concentrations of lipid hydroperoxides than those with mild-to-moderate lung dysfunction (FEV1 > 50% pred). This study provides evidence that cystic fibrosis patients have inadequate antioxidant defences to cope with the elevated oxidative stress that they regularly experience. We believe that recurring oxidative lung injury contributes to the decline in pulmonary function in these patients.

Oxidative damage to DNA in patients with cystic fibrosis

Patients with cystic fibrosis (CF) may be more susceptible to oxidative-cell injury due to impaired absorption of dietary-antioxidants. In addition, recurring pulmonary infections regularly subject them to oxidative stress. Our objective was to determine whether the concentration of urinary 8-hydroxydeoxyguanosine (oh8dG), a marker of free radical-induced DNA damage, is elevated in CF patients and to correlate its excretion with clinical status. The first morning void of urine was collected from 13 CF patients and 10 control children of similar age. To determine clinical status, forced expiratory volume (FEV1) and forced ventilatory capacity (FVC) and a Taussing-Schwachman score were obtained for each patient. Urinary oh8dG was measured by high performance liquid chromatography (HPLC) with electrochemical detection and the concentration normalized against creatinine concentration. The mean concentration (+/- SD) of urinary oh8dG was significantly higher in the CF group (2.78 +/- 1.21 vs. 1.51 +/- 0.38 nmol/mmol creatinine). A significant positive correlation was found between urinary oh8dG concentration and plasma alpha-tocopherol concentration in the CF patients (r = 0.947, p = 0.0001), suggesting that vitamin E might be involved in the excretion of oh8dG. However, no correlation was found between urinary oh8dG in CF and markers of lung function or the qualitative index of clinical status. These results confirm that patients with CF are susceptible to oxidative-induced DNA damage, although this appears to be independent of clinical status. Increased DNA damage may explain, in part, why CF patients have a higher incidence of malignancy compared to normal healthy age-matched controls.

Evidence for increased oxidative damage in patients with cystic fibrosis

Patients with cystic fibrosis (CF) may be more susceptible to oxidative cell injury than normal healthy children due to both the impaired absorption of antioxidant nutrients and the increased oxidative stress caused by chronic pulmonary infections. The purpose of this study was to examine whether markers of oxidative damage to lipids (malondialdehyde-like substances and lipid hydroperoxides) and proteins (protein carbonyls) were present in the plasma of CF patients. Mean values (+/- SD) of thiobarbituric acid-reactive substances were significantly higher in patients (6.93 +/- 1.47 mumol/L; n = 25) than in controls (5.84 +/- 0.59 mumol/L; n = 10). FFA hydroperoxides were not detected in control subjects (the detection limit of the assay was 0.02 mumol/L), but in 11 of the 33 CF patients studied they were found in a range of 0.03-0.34 mumol/L. Plasma protein carbonyl concentrations did not differ significantly between the two groups (p = 0.076), although a much wider distribution was observed in the CF patients (range 0.17-5.64 nmol/mg protein) than in the control group (range 0.24-1.55 nmol/mg protein). No correlation was found between thiobarbituric acid-reactive substances and FFA hydroperoxides or between either of these markers and protein carbonyl content. Concentrations of plasma vitamin E, vitamin C, and protein sulfhydryls were within the normal ranges in both control subjects and CF patients. The concentration of uric acid was significantly reduced (p < 0.01) in the CF group (204 +/- 96.99 mumol/L) compared with that in control subjects (352 +/- 81.11 mumol/L), but reduction in plasma levels of this antioxidant did not correlate with increased markers of free radical damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of free radicals in the pathogenesis of cystic fibrosis

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Reduced free-radical-trapping capacity and altered plasma antioxidant status in cystic fibrosis

Plasma antioxidant status and total radical-trapping antioxidant potential (TRAP) of children (n = 24) with cystic fibrosis (CF) were compared with those of children (n = 21) without the disease. Children with CF were found to have elevated plasma concentrations of ascorbic acid (94.6 +/- 58.2 mumol/L), with respect to normal children (65.6 +/- 18.8 mumol/L). Plasma uric acid (330.8 +/- 84 versus 198.0 +/- 31 mumol/L p < 0.01) and sulfhydryl group (518 +/- 43 versus 363 +/- 31 mumol/L p < 0.01) concentrations were also elevated in CF. Vitamin E levels (16.9 +/- 1.8 versus 18.4 +/- 1.3 mumol/L) were at the low end of the normal range. Despite an overall increased antioxidant array, CF patients had a reduced TRAP capacity (488 +/- 34 versus 580 +/- 79 mumol/L, p < 0.05). TRAP measurements in CF patients showed a strong negative correlation (r = 0.80, p < 0.001) with high ascorbic acid concentration, suggesting a prooxidant effect of ascorbic acid. Oral administration of ascorbic acid to adults was found to diminish TRAP activity. Concentrations of ascorbic acid similar to those seen in CF patients were attained in ascorbate-supplemented individuals, with substantial decreases in TRAP capacity. These studies suggest that high plasma ascorbic acid levels in children with CF may have a prooxidant effect. This appears to reduce the extracellular antioxidant defense of these children and may increase susceptibility to oxidative stress.

Postfracture irradiation effects on the biomechanical and histologic parameters of fracture healing

The effects of single-dose local irradiation on the biomechanical properties of closed femoral fractures were studied in 75 mature Sprague-Dawley rats. Ten days after fracture, the rats were irradiated with 900 rads at 250 kV to the entire fractured femur. At 2, 3, 4, 8, and 16 weeks after fracture, both fractured and contralateral intact femurs were recovered and evaluated biomechanically by testing to failure in torsion. Results were compared with those from a similar study involving fractures irradiated 3 days after fracture as well as nonirradiated control fractures. Fracture healing progressed faster when irradiation was delayed 10 days than when delayed 3 days, and control fractures healed more rapidly than after either delay. In the 10-day delay group, fractures showed greater strength than did those in the 3-day delay group at 8 weeks, but the strength of irradiated fractures in both groups was similarly depressed at 16 weeks, with a maximum torque well below that of control fractures. These results suggest that delaying radiation exposure of a fracture may mitigate short-term deleterious effects on fracture repair, but that long-term results may be similar to those associated with expeditious irradiation.

Detection of toxic viral-associated double-stranded RNA (dsRNA) in influenza-infected lung

While many of the molecular events in viral replication are well studied, the molecular mechanisms by which viral infections trigger such constitutional symptoms as fever and 'malaise' are unknown. The hypothesis that these viral constitutional symptoms can be triggered by the toxic action of dsRNA associated with viral replication was investigated. Total lung RNA from mice acutely infected with PR8 influenza virus, but not from sham-infected mice, was shown to induce fever and altered sleep (excess slow-wave sleep, enhanced amplitudes of electroencephalographic slow waves, and reduced rapid eye movement sleep) when injected into the rabbit brain. Viral-associated dsRNA was shown to be responsible for the rabbit responses by differential nuclease digestion. Influenza viral dsRNA was directly demonstrated in the active lung RNA preparations by reverse transcriptase-polymerase chain reaction techniques. The time course of the responses paralleled those seen in the same model inoculated with nanogram quantities of the synthetic dsRNA polyriboinosinic-polyribocytidylic acid and suggested that they were mediated by induced cytokines. A model for the role of viral-associated dsRNA in eliciting both local cytotoxicity and viral constitutional symptoms is presented.

Radionuclide evaluation of liver transplants

Orthotopic liver transplantation is now an established technique for treating patients with various forms of end stage liver disease. The number of centers performing the procedure is increasing and, as the number of transplant recipients in the population increases, many institutions performing nuclear medicine studies will be confronted with requests to evaluate these patients. While a variety of radionuclides are proving useful in this evaluation, the 99mTc iminodiacetic acid (IDA) compounds, particularly 99mTc diisopropyl IDA (DISIDA), will probably account for the majority of radionuclide evaluations of these patients because they are well suited to monitor both structural and functional changes of the graft. The primary application of radionuclide studies is focused in the postoperative period, when problems with the vascular and biliary anastomoses, rejection, infections, and bile leaks all produce alterations in radionuclide hepatobiliary studies. Abnormalities such as rejection and infection produce primarily functional, rather than structural changes and are not easily differentiated based upon the kinetics of 99mTc-DISIDA extraction and excretion by the liver, serial imaging and correlation with clinical data is necessary in such situations. Quantitative analyses of kinetic 99mTc IDA (DISIDA) studies and quantitative approaches with other compounds such as 99mTc galactosyl-neoglycoalbumin (NGA) may permit better assessments of relatively subtle changes in liver function in the posttransplant period.

Hepatic hemangiomas: evaluation by magnetic resonance imaging and technetium-99m red blood cell scintigraphy

A study was performed to evaluate and compare the sensitivity of magnetic resonance imaging (MRI) and radionuclide blood-pool scanning in the detection of hepatic hemangiomas. All patients had known hemangiomas which were first detected on either ultrasound or computed tomography. Sixteen patients with a total of 23 lesions were investigated. Eleven patients had both MRI and blood-pool scans performed. In the group studied by both modalities, 18 lesions were detected ranging in size from 1 to 11 cm. All lesions were detected by both techniques. However, two of the 18 lesions had an atypical appearance on MRI. Our experience to date indicates that the anatomic location and specific diagnosis of hemangiomas can be made with a high degree of certainty when both MRI and blood-pool scanning techniques are utilized.

Computerized chest tomography in asbestos workers suspected of having pleural disease

Forty-five computerized tomographic (CT) chest studies were performed on workers suspected of having pleural disease after being exposed to asbestos material. Ten of the 45 reviewed were court cases, and 32 workers acutely exposed at University of California-Los Angeles (UCLA) were studied with routine four views of the chest. CT confirmed the initial interpretation of chest films obtained at UCLA.

Magnetic resonance imaging artifacts: mechanism and clinical significance

Many types of artifacts may occur in magnetic resonance imaging. These artifacts may be related to extrinsic factors such as patient motion or metallic artifacts; they may be due specifically to the MR system such as power gradient drop off and chemical shift artifacts; they may occur as a consequence of general image processing techniques, as in the case of truncation artifacts and aliasing. Change in patient position, pulse sequence, or other imaging variables may improve some artifacts. Although reduction of some artifacts may require a service engineer, the radiologist has the responsibility to recognize MR imaging problems. The radiologist's knowledge of MR imaging artifacts is important to the continued maintenance of high image quality and is essential if one is to avoid confusing artifactual appearances with pathology.

Accurate demonstration of hepatic infarction in liver transplant recipients

Serial HIDA scanning has proven to be a valuable tool in the postoperative management of liver transplant patients. Previous reports have documented its efficacy in detecting biliary leakage, abscess, and rejection. We have also found HIDA scanning to be a sensitive method for detecting early hepatic infarction before ultrasonographic changes occur. Two cases are presented to demonstrate the characteristic findings seen with hepatic infarctions.

Hepatic abscess in liver transplantation. Accurate diagnosis and treatment

Serial HIDA scanning was performed on a patient following liver transplantation. During the patient's course he developed biliary obstruction that manifested as a photopenic region in the liver, on the HIDA scan which filled in on the delayed views. The patient subsequently developed a region in the superior portion of the right lobe of the liver that did not fill in with activity on delayed views. The patient was experiencing low-grade fevers and was clinically believed to have either an abscess or an episode of rejection. A gallium scan was performed revealing a photopenic defect in the same region as the HIDA. Because of the clinical suspicion of abscess, a percutaneous transhepatic drainage study was performed, revealing a large abscess cavity in the suspect area within the liver. Following the drainage the patient did well. This case illustrates the usefulness of serial HIDA scanning in patients who have received liver transplants. It also is important to note that the gallium scan was negative in this hepatic abscess. In the authors' opinions, the finding of an intrahepatic fluid collection in a septic patient that does not fill with activity on the HIDA study, should be considered the source of the infection, until proven otherwise, and should be drained regardless of the findings of other studies.

The interaction of platelet proteins with three fibroblast-derived collagenases

Three collagenases were purified from the culture medium of human skin fibroblasts using ammonium sulfate fractionation, ion-exchange chromatography and gel filtration. The cationic collagenase had a molecular weight of 42,000; two anionic collagenases had molecular weights of 63,000 and 115,000. Preincubation of the individual collagenases with purified human and bovine platelet heparin binding proteins resulted in the inhibition of the two anionic activities, but only by bovine low heparin affinity platelet protein (beta-TG). Such inhibition was dose-dependent at the microgram level, was not antagonized by heparin, and persisted even when the collagenases had been transformed into their 53,000 and 105,000 forms through treatment with p-aminophenylmercuric acetate. Neither human nor bovine high heparin affinity platelet factors (PF-4) nor human low heparin affinity platelet protein (beta-TG) were inhibitory to any of the three collagenases studied. This suggests that the ability of platelet proteins to inhibit collagenase is specifically influenced by the ionic nature of the enzyme and this inhibition is specifically dependent upon the species and type of platelet protein.

Asbestosis and the serratus anterior muscle

Twenty-seven patients with a history of asbestos exposure were reviewed at the UCLA Medical Center in December 1981. All patients were referred by the United States Department of Labor. The patients were told they had asbestosis on the basis of their history of exposure and chest radiographs taken at a local asbestos screening program and initially interpreted by a "B" reader. None of the 27 patients reviewed were found to have evidence of asbestosis either clinically or radiographically. The false-positive radiographic interpretations were due to the extrathoracic musculature (serratus anterior) mimicking intrathoracic disease. Since the study described here was done, an additional 330 patients have had their radiographs reviewed.

Pap smear screening and invasive cervical cancer

Possible failures of Pap smear screening were assessed among 63 cases of invasive cervical cancer that occurred in a group practice population between 1965 and 1975. Review of medical records revealed 33 (53 percent) cases with no history of Pap smears within two years prior to diagnosis. Among the 30 patients with recent Pap screening, 11 (17 percent) had negative smears; these could only be explained as false negatives or unusually rapid progression of disease. The remaining 19 (30 percent) had abnormal smear results, a number of whom received suboptimal follow-up care. Similar experiences have been reported from several other health care settings. Implications for preventive practices are discussed.

The use of hybridoma antibodies to probe the antigenic determinants of thyroglobulin

Using monoclonal antibodies we have begun to define the epitopes of the murine thyroglobulin molecule that elicit autoimmune responses. Based on the principle of complementation, 18 monoclonal antibodies were classified into 8 groups, defined by their reactions with the same or neighboring determinants. Further distinctions between the monoclonals were drawn from comparisons of their cross-reactions with thyroglobulins of other species and their patterns in isoelectric focusing. One low molecular weight fragment of bovine thyroglobulin, which cross-reacts extensively with thyroglobulins of other species, has been isolated and partially characterized.

Distribution and elimination of melphalan in rats and monkeys and distribution in tumors of mice bearing L1210 or P388 leukemias sensitive and resistant to this agent

Following iv injection, melphalan was eliminated monophasically from rat serum (half-life = 0.87 hour) and monkey serum (half-life = 1.9 hours) and in rat bile (half-life = 2.4 hours) and monkey urine (half-life = 1.3 hours). In rat bile and monkey urine, 2% and 20% of the dose, respectively, was excreted in 12 hours as unchanged melphalan. At each time of tissue assay (0.5-4 hours after injection), rat spleen contained less melphalan than serum, liver, or kidneys. The kidneys and bile of monkeys contained more melphalan that serum, liver, or spleen. Only a small amount of radioactivity from labeled melphalan appeared in the feces of monkeys. Melphalan reached higher concentrations in implants of P388 and L1210 leukemia cells sensitive to melphalan than in cell lines resistant to this drug. Furthermore, the amounts of radioactivity bound to macromolecules of the sensitive tumors were higher.

The broken wire suture

The body is a hostile environment for wire sutures. Although the problems of electrochemical corrosion, direct chemical attack on the suture, and inflammation produced in reaction to the suture have been largley eliminated by the use of austenitic stainless steel wires, failure of the wires may still occur due to mechano-chemical cracking -- the combined effect of insignificant stresses, usually from cold working, and insignificant chemical potentials produced by body fluids. Although stainless steel wire remains a satisfactory material for sternotomy closure or for reattaching costal cartilages, the two spectacular complications of a broken wire point out the need for care in using wire sutures. Bending, twisting, kinking and knotting must be avoided as much as possible.

Pharmacokinetics of the absorption, distribution, and elimination of melphalan in the dog

[14C]melphalan ([14C]L-PAM) was rapidly absorbed from the gut of dogs after oral dosing and reached a maximum concentration in the serum by 30 minutes. The disappearance of L-PAM (intact drug) from the serum was biphasic after iv administration, with half-lives of 14 and 66 minutes for the alpha and beta phases, respectively. The urinary excretion accounted for 44% of the total radioactivity and 25% appeared in the feces. Approximately 8% of the dose was excreted unchanged in the urine. Biliary excretion was rapid, with 11% of the dose being accounted for in the bile after 30 minutes; approximately 80% of these drug equivalents (materials containing radioactivity) was parent compound. Since large amounts of L-PAM appeared in the bile, the agent may prove to be active against cancers of the gall bladder, bile ducts, and duodenum.

A method for the measurement of L-phenylalanine mustard in the mouse and dog by high-pressure liquid chromatography

The distribution of L-phenylalanine mustard (L-PAM) was studied in dogs and mice by high-pressure liquid chromatography. Separation of L-PAM from its products of hydrolysis was accomplished with a mu-Bondapak C18 column, a solvent system composed of 2-methoxyethanol/0.1% acetic acid, and solvent programming with a step gradient. Complete separation was effected in less than 15 min. The half-life for disappearance of L-PAM from mouse blood was 41 min, whereas that from dog blood was 29 min. The monohydroxy derivative of L-PAM, L-MOH, disappeared from dog serum with a half-life of 32 min. L-MOH was not detectable in mouse tissue other than blood at times greater than 15 min after injection. In the dog at 4 hr after injection, the tissue/serum concentration ratios were greater than 1 for liver, spleen, intestine, skeletal muscle, urinary bladder and gallbladder. The concentration of L-PAM in the bile was approximately 500 times higher than that in serum.

Multiple antigenic sites on an eicosapeptide. I. Precipitin studies in the goat

Purified peptide 105-124, an antigenic determinant from the carboxy terminus ribonuclease, was found to form an immune precipitate with antibody to that region prepared by affinity chromatography from goat hyperimmune antiserum to reduced carboxymethylated ribonuclease (CM-RNase). Cm-rnase also gave an immune precipitate with the antibody. Purified antibody to another region of similar size (40-61) did not form a precipitate with CM-RNase but did co-precipitate in the presence of antibody to peptide 105-124 and CM-RNase. The precipitin reaction between antibody to peptide 105-124 and CM-RNase was inhibited by two synthetic derivatives, peptides 118-124 and ala114-RNase 114-124. Stoichiometry of the precipitin reactions of antibody to 105-124 with CM-RNase or peptide 105-124 suggested an antigen valency of three or more. Consistent with this both peptides 105-124 and ala114-RNase 114-124 elicited immediate cutaneous reactions but 118-124 did not. These findings suggest that the eicosapeptide 105-124 is multivalent since at least three antibodies can react simultaneously with it.