Trivalent nanobody-based ligands mediate powerful activation of GPVI, CLEC-2, and PEAR1 in human platelets whereas FcγRIIA requires a tetravalent ligand

BACKGROUND

Clustering of the receptors glycoprotein receptor VI (GPVI), C-type lectin-like receptor 2 (CLEC-2), low-affinity immunoglobulin γ Fc region receptor II-a (FcγRIIA), and platelet endothelial aggregation receptor 1 (PEAR1) leads to powerful activation of platelets through phosphorylation of tyrosine in their cytosolic tails and initiation of downstream signaling cascades. GPVI, CLEC-2, and FcγRIIA signal through YxxL motifs that activate Syk. PEAR1 signals through a YxxM motif that activates phosphoinositide 3-kinase. Current ligands for these receptors have an undefined valency and show significant batch variation and, for some, uncertain specificity.

OBJECTIVES

We have raised nanobodies against each of these receptors and multimerized them to identify the minimum number of epitopes to achieve robust activation of human platelets.

METHODS

Divalent and trivalent nanobodies were generated using a flexible glycine-serine linker. Tetravalent nanobodies utilize a mouse Fc domain (IgG2a, which does not bind to FcγRIIA) to dimerize the divalent nanobody. Ligand affinity measurements were determined by surface plasmon resonance. Platelet aggregation, adenosine triphosphate secretion, and protein phosphorylation were analyzed using standardized methods.

RESULTS

Multimerization of the nanobodies led to a stepwise increase in affinity with divalent and higher-order nanobody oligomers having sub-nanomolar affinity. The trivalent nanobodies to GPVI, CLEC-2, and PEAR1 stimulated powerful and robust platelet aggregation, secretion, and protein phosphorylation at low nanomolar concentrations. A tetravalent nanobody was required to activate FcγRIIA with the concentration-response relationship showing a greater variability and reduced sensitivity compared with the other nanobody-based ligands, despite a sub-nanomolar binding affinity.

CONCLUSION

The multivalent nanobodies represent a series of standardized, potent agonists for platelet glycoprotein receptors. They have applications as research tools and in clinical assays.

Validation of agent-based models of surface receptor oligomerisation

Receptor dimerisation and higher order oligomerisation regulates signalling by a wide variety of transmembrane receptors. We discuss how agent-based modelling (ABM) combined with advanced microscopy and structural studies can provide new insights into the regulation of clustering, including spatial considerations, revealing novel targets for therapeutic intervention.

Targeting platelet GPVI with glenzocimab: a novel mechanism for inhibition

Platelet glycoprotein VI (GPVI) is attracting interest as a potential target for the development of new antiplatelet molecules with a low bleeding risk. GPVI binding to vascular collagen initiates thrombus formation and GPVI interactions with fibrin promote the growth and stability of the thrombus. In this study, we show that glenzocimab, a clinical stage humanized antibody fragment (Fab) with a high affinity for GPVI, blocks the binding of both ligands through a combination of steric hindrance and structural change. A cocrystal of glenzocimab with an extracellular domain of monomeric GPVI was obtained and its structure determined to a resolution of 1.9 Å. The data revealed that (1) glenzocimab binds to the D2 domain of GPVI, GPVI dimerization was not observed in the crystal structure because glenzocimab prevented D2 homotypic interactions and the formation of dimers that have a high affinity for collagen and fibrin; and (2) the light variable domain of the GPVI-bound Fab causes steric hindrance that is predicted to prevent the collagen-related peptide (CRP)/collagen fibers from extending out of their binding site and preclude GPVI clustering and downstream signaling. Glenzocimab did not bind to a truncated GPVI missing loop residues 129 to 136, thus validating the epitope identified in the crystal structure. Overall, these findings demonstrate that the binding of glenzocimab to the D2 domain of GPVI induces steric hindrance and structural modifications that drive the inhibition of GPVI interactions with its major ligands.

Divalent nanobodies to platelet CLEC-2 can serve as agonists or antagonists

CLEC-2 is a target for a new class of antiplatelet agent. Clustering of CLEC-2 leads to phosphorylation of a cytosolic YxxL and binding of the tandem SH2 domains in Syk, crosslinking two receptors. We have raised 48 nanobodies to CLEC-2 and crosslinked the most potent of these to generate divalent and tetravalent nanobody ligands. Fluorescence correlation spectroscopy (FCS) was used to show that the multivalent nanobodies cluster CLEC-2 in the membrane and that clustering is reduced by inhibition of Syk. Strikingly, the tetravalent nanobody stimulated aggregation of human platelets, whereas the divalent nanobody was an antagonist. In contrast, in human CLEC-2 knock-in mouse platelets, the divalent nanobody stimulated aggregation. Mouse platelets express a higher level of CLEC-2 than human platelets. In line with this, the divalent nanobody was an agonist in high-expressing transfected DT40 cells and an antagonist in low-expressing cells. FCS, stepwise photobleaching and non-detergent membrane extraction show that CLEC-2 is a mixture of monomers and dimers, with the degree of dimerisation increasing with expression thereby favouring crosslinking of CLEC-2 dimers. These results identify ligand valency, receptor expression/dimerisation and Syk as variables that govern activation of CLEC-2 and suggest that divalent ligands should be considered as partial agonists.

Characterizing the binding of glycoprotein VI with nanobody 35 reveals a novel monomeric structure of glycoprotein VI where the conformation of D1+D2 is independent of dimerization

BACKGROUND

The platelet-signaling receptor glycoprotein VI (GPVI) is a promising antithrombotic target. We have previously raised a series of high-affinity nanobodies (Nbs) against GPVI and identified Nb2, Nb21, and Nb35 as potent GPVI inhibitors. The Nb2 binding site has been mapped to the D1 domain, which is directly adjacent to the CRP binding site. Ligand-binding complementary determining region 3 has only 15% conservation between all 3 Nbs.

OBJECTIVES

To map the binding sites of Nb21 and Nb35 on GPVI.

METHODS

We determined the X-ray crystal structure of the D1 and D2 extracellular domains of the GPVI-Nb35 complex. We then looked at the effects of various GPVI mutations on the ability of Nbs to inhibit collagen binding and GPVI signaling using surface binding assays and transfected cell lines.

RESULTS

The crystal structure of GPVI bound to Nb35 was solved. GPVI was present as a monomer, and the D1+D2 conformation was comparable to that in the dimeric structure. Arg46, Tyr47, and Ala57 are common residues on GPVI targeted by both Nb2 and Nb35. Mutating Arg46 to an Ala abrogated the ability of Nb2, Nb21, and Nb35 to inhibit collagen-induced GPVI signaling and blocked the binding of all 3 Nbs. In addition, Arg60 was found to reduce Nb21 inhibition but not the inhibition Nb2 or Nb35.

CONCLUSIONS

These findings reveal key residues involved in the high-affinity binding of GPVI inhibitors and negate the idea that GPVI dimerization induces a conformational change required for ligand binding.

S100A8/A9 drives the formation of procoagulant platelets through GPIbα

S100A8/A9, also known as "calprotectin" or "MRP8/14," is an alarmin primarily secreted by activated myeloid cells with antimicrobial, proinflammatory, and prothrombotic properties. Increased plasma levels of S100A8/A9 in thrombo-inflammatory diseases are associated with thrombotic complications. We assessed the presence of S100A8/A9 in the plasma and lung autopsies from patients with COVID-19 and investigated the molecular mechanism by which S100A8/A9 affects platelet function and thrombosis. S100A8/A9 plasma levels were increased in patients with COVID-19 and sustained high levels during hospitalization correlated with poor outcomes. Heterodimeric S100A8/A9 was mainly detected in neutrophils and deposited on the vessel wall in COVID-19 lung autopsies. Immobilization of S100A8/A9 with collagen accelerated the formation of a fibrin-rich network after perfusion of recalcified blood at venous shear. In vitro, platelets adhered and partially spread on S100A8/A9, leading to the formation of distinct populations of either P-selectin or phosphatidylserine (PS)-positive platelets. By using washed platelets, soluble S100A8/A9 induced PS exposure but failed to induce platelet aggregation, despite GPIIb/IIIa activation and alpha-granule secretion. We identified GPIbα as the receptor for S100A8/A9 on platelets inducing the formation of procoagulant platelets with a supporting role for CD36. The effect of S100A8/A9 on platelets was abolished by recombinant GPIbα ectodomain, platelets from a patient with Bernard-Soulier syndrome with GPIb-IX-V deficiency, and platelets from mice deficient in the extracellular domain of GPIbα. We identified the S100A8/A9-GPIbα axis as a novel targetable prothrombotic pathway inducing procoagulant platelets and fibrin formation, in particular in diseases associated with high levels of S100A8/A9, such as COVID-19.

Experimental validation of computerised models of clustering of platelet glycoprotein receptors that signal via tandem SH2 domain proteins

The clustering of platelet glycoprotein receptors with cytosolic YxxL and YxxM motifs, including GPVI, CLEC-2 and PEAR1, triggers activation via phosphorylation of the conserved tyrosine residues and recruitment of the tandem SH2 (Src homology 2) domain effector proteins, Syk and PI 3-kinase. We have modelled the clustering of these receptors with monovalent, divalent and tetravalent soluble ligands and with transmembrane ligands based on the law of mass action using ordinary differential equations and agent-based modelling. The models were experimentally evaluated in platelets and transfected cell lines using monovalent and multivalent ligands, including novel nanobody-based divalent and tetravalent ligands, by fluorescence correlation spectroscopy. Ligand valency, receptor number, receptor dimerisation, receptor phosphorylation and a cytosolic tandem SH2 domain protein act in synergy to drive receptor clustering. Threshold concentrations of a CLEC-2-blocking antibody and Syk inhibitor act in synergy to block platelet aggregation. This offers a strategy for countering the effect of avidity of multivalent ligands and in limiting off-target effects.

Katacine Is a New Ligand of CLEC-2 that Acts as a Platelet Agonist

BACKGROUND

 CLEC-2 is a platelet receptor with an important role in thromboinflammation but a minor role in hemostasis. Two endogenous ligands of CLEC-2 have been identified, the transmembrane protein podoplanin and iron-containing porphyrin hemin, which is formed following hemolysis from red blood cells. Other exogenous ligands such as rhodocytin have contributed to our understanding of the role of CLEC-2.

OBJECTIVES

 To identify novel CLEC-2 small-molecule ligands to aid therapeutic targeting of CLEC-2.

METHODS

 ALPHA screen technology has been used for the development of a high-throughput screening (HTS) assay recapitulating the podoplanin-CLEC-2 interaction. Light transmission aggregometry was used to evaluate platelet aggregation. Immunoprecipitation and western blot were used to evaluate direct phosphorylation of CLEC-2 and downstream protein phosphorylation. Autodock vina software was used to predict the molecular binding site of katacine and mass spectrometry to determine the polymeric nature of the ligand.

RESULTS AND CONCLUSION

 We developed a CLEC-2-podoplanin interaction assay in a HTS format and screened 5,016 compounds from a European Union-open screen library. We identified katacine, a mixture of polymers of proanthocyanidins, as a novel ligand for CLEC-2 and showed that it induces platelet aggregation and CLEC-2 phosphorylation via Syk and Src kinases. Platelet aggregation induced by katacine is inhibited by the anti-CLEC-2 monoclonal antibody fragment AYP1 F(ab)'2. Katacine is a novel nonprotein ligand of CLEC-2 that could contribute to a better understanding of CLEC-2 activation in human platelets.

Structure-function relationship of the platelet glycoprotein VI (GPVI) receptor: does it matter if it is a dimer or monomer?

GPVI is a critical signaling receptor responsible for collagen-induced platelet activation and a promising anti-thrombotic target in conditions such as coronary artery thrombosis, ischemic stroke, and atherothrombosis. This is due to the ability to block GPVI while having minimal effects on hemostasis, making it a more attractive target over current dual-antiplatelet therapy (DAPT) with acetyl salicylic acid and P2Y12 inhibitors where bleeding can be a problem. Our current understanding of how the structure of GPVI relates to function is inadequate and recent studies contradict each other. In this article, we summarize the structure-function relationships underlying the activation of GPVI by its major ligands, including collagen, fibrin(ogen), snake venom toxins and charged exogenous ligands such as diesel exhaust particles. We argue that contrary to popular belief dimerization of GPVI is not required for binding to collagen but serves to facilitate binding through increased avidity, and that GPVI is expressed as a mixture of monomers and dimers on resting platelets, with binding of multivalent ligands inducing higher order clustering.

Evidence that GPVI is Expressed as a Mixture of Monomers and Dimers, and that the D2 Domain is not Essential for GPVI Activation

Collagen has been proposed to bind to a unique epitope in dimeric glycoprotein VI (GPVI) and the number of GPVI dimers has been reported to increase upon platelet activation. However, in contrast, the crystal structure of GPVI in complex with collagen-related peptide (CRP) showed binding distinct from the site of dimerization. Further fibrinogen has been reported to bind to monomeric but not dimeric GPVI. In the present study, we have used the advanced fluorescence microscopy techniques of single-molecule microscopy, fluorescence correlation spectroscopy (FCS) and bioluminescence resonance energy transfer (BRET), and mutagenesis studies in a transfected cell line model to show that GPVI is expressed as a mixture of monomers and dimers and that dimerization through the D2 domain is not critical for activation. As many of these techniques cannot be applied to platelets to resolve this issue, due to the high density of GPVI and its anucleate nature, we used Förster resonance energy transfer (FRET) to show that endogenous GPVI is at least partially expressed as a dimer on resting and activated platelet membranes. We propose that GPVI may be expressed as a monomer on the cell surface and it forms dimers in the membrane through diffusion, giving rise to a mixture of monomers and dimers. We speculate that the formation of dimers facilitates ligand binding through avidity.

Adenosine and Forskolin Inhibit Platelet Aggregation by Collagen but not the Proximal Signalling Events

BACKGROUND

 The G protein-coupled receptor, adenosine A_2A, signals through the stimulatory G protein, G_s, in platelets leading to activation of adenylyl cyclase and elevation of cyclic adenosine monophosphate (cAMP) and inhibition of platelet activation.

OBJECTIVE

 This article investigates the effect of A_2A receptor activation on signalling by the collagen receptor glycoprotein (GP) VI in platelets.

METHODS

 Washed human platelets were stimulated by collagen or the GPVI-specific agonist collagen-related peptide (CRP) in the presence of the adenosine receptor agonist, 5'-N-ethylcarboxamidoadenosine (NECA) or the adenylyl cyclase activator, forskolin and analysed for aggregation, adenosine triphosphate secretion, protein phosphorylation, spreading, Ca²⁺ mobilisation, GPVI receptor clustering, cAMP, thromboxane B₂ (TxB₂) and P-selectin exposure.

RESULTS

 NECA, a bioactive adenosine analogue, partially inhibits aggregation and secretion to collagen or CRP in the absence or presence of the P2Y₁₂ receptor antagonist, cangrelor and the cyclooxygenase inhibitor, indomethacin. The inhibitory effect in the presence of the three inhibitors is largely overcome at higher concentrations of collagen but not CRP. Neither NECA nor forskolin altered clustering of GPVI, elevation of Ca²⁺ or spreading of platelets on a collagen surface. Further, neither NECA nor forskolin, altered collagen-induced tyrosine phosphorylation of Syk, LAT nor PLCγ2. However, NECA and forskolin inhibited platelet activation by the TxA₂ mimetic, U46619, but not the combination of adenosine diphosphate and collagen.

CONCLUSION

 NECA and forskolin have no effect on the proximal signalling events by collagen. They inhibit platelet activation in a response-specific manner in part through inhibition of the feedback action of TxA₂.

Development of a Combined microPET®-MR System

As evidenced by the success of PET-CT, there are many benefits from combining imaging modalities into a single scanner. The combination of PET and MR offers potential advantages over PET-CT, including improved soft tissue contrast, access to the multiplicity of contrast mechanisms available to MR, simultaneous imaging and fast MR sequences for motion correction. In addition, PET-MR is more suitable than PET-CT for cancer screening due to the elimination of the radiation dose from CT.

A key issue associated with combining PET and MR is the fact that the performance of the photomultiplier tubes (PMTs) used in conventional PET detectors is degraded in the magnetic field required for MR. Two approaches have been adopted to circumvent that issue: retention of conventional, magnetic field-sensitive PMT-based PET detectors by modification of other features of the MR or PET system, or the use of new, magnetic field-insensitive devices in the PET detectors including avalanche photo-diodes (APDs) and silicon photomultipliers (SiPMs).

Taking the former approach, we are assembling a modified microPET® Focus 120 within a gap in a novel, 1T superconducting magnet. The PMTs are located in a low magnetic field (~30mT) through a combination of magnet design and the use of fiber optic ‘bundles’.

Two main features of the modified PET system have been tested, namely the effect of using long fiber optic bundles in the PET detector, and the impact of magnetic field upon the performance of the position sensitive PMTs.

The design of a modified microPET®-MR system for small animal imaging is completed, and assembly and testing is underway.

Glenoid screw position in the Encore Reverse Shoulder Prosthesis: an anatomic dissection study of screw relationship to surrounding structures

BACKGROUND

Fixation of the baseplate to the glenoid for the Reverse Shoulder Prosthesis (DJO Surgical, Austin, TX, USA) requires secure screw purchase to avoid excessive micromotion and baseplate failure. The best screw length for fixation is unknown. In addition, excessively long screws or a plunge of the drill bit during baseplate insertion could injure surrounding structures.

METHODS

Reverse Shoulder Prosthesis baseplates were inserted in 10 fresh-frozen shoulders by use of a 6.5-mm central screw and four 5.0-mm peripheral locking screws placed 90° to the baseplate. The top superior screw was placed into the base of the coracoid, corresponding to the 1-o'clock position in a right shoulder. The distances to surrounding vital structures were recorded, screws were removed, and screw hole lengths were measured to determine the most effective lengths in different parts of the glenoid scapula.

RESULTS

The screw length was 30 mm for the superior screw holes, 28 mm for the inferior screw holes, 13 mm for the anterior screw holes, and 15 mm for the posterior screw holes. The central screw trajectory was through the anterior cortex. The anterior screw trajectory violated the subscapularis belly in all specimens. The posterior screw touched the suprascapular nerve or artery in 3 of 10 specimens.

DISCUSSION

The superior and inferior screws have the longest bony fixation. Drill bit plunge during placement of the anterior screw poses a risk to the subscapularis muscle. Drilling for the posterior screw risks injury to the suprascapular nerve and artery at the spinoglenoid notch.

CONCLUSIONS

The posterior screw should be placed with care to avoid neurovascular complications.

Management of deep infection after reverse total shoulder arthroplasty: a case series

BACKGROUND

Reverse total shoulder arthroplasty (RSA) is being increasingly used in the treatment of disabling shoulder conditions. This study reports the management of deep infections after RSA.

MATERIALS AND METHODS

Eight of 138 patients were treated for deep infection after the index procedure. A retrospective review was performed to identify risk factors, methods of management, and determine ultimate outcome. A minimum of 12-month follow-up was available in 7 of 8 patients.

RESULTS

Six infections occurred in patients who had had previous shoulder surgery. The causative bacterial organism was identified in 6 patients. Deep infection occurred in 3 patients with diabetes mellitus. Antibiotic cement was used in all cases. Six patients were managed with irrigation and debridement and retention of components. Two patients with of Staphylococcus aureus infection ultimately required resection arthroplasty. Patients managed with irrigation and debridement, intravenous antibiotics, and retention of components demonstrated good pain relief and function, without evidence of radiographic loosening. Resection resulted in pain relief but poor functional outcomes.

CONCLUSION

Limited literature is available regarding the management of deep infection in patients with RSA. Component removal after a RSA creates increased bone loss due to a cemented humeral component and glenoid baseplate with several large screws. Five of 7 patients with deep infection had undergone previous shoulder surgery. We recommend that patients should be managed with an initial irrigation and debridement, appropriate intravenous antibiotics, and component retention.

Bony adaptation of the proximal humerus and glenoid correlate within the throwing shoulder of professional baseball pitchers

BACKGROUND

Elite throwing athletes have increased proximal humeral retrotorsion (HRT) and glenoid retroversion (GRV) in their throwing shoulders compared with their nonthrowing shoulders. These adaptive morphologic changes are thought to be independently protective against shoulder injury; however, their relationship to each other is poorly understood.

PURPOSE

To determine if an association exists between HRT and GRV within the same shoulders of professional pitchers.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

The HRT and GRV measurements were determined using published techniques in asymptomatic bilateral shoulders of 32 professional pitchers (mean age, 23 years). Three measurements for each variable were averaged, and the reliability of the techniques was verified. The relationship between HRT and GRV within the same shoulders was determined with Pearson correlation coefficients. Paired t tests were used to compare HRT and GRV between the throwing and nonthrowing shoulder. Simple ratios were calculated between HRT and GRV.

RESULTS

Humeral retrotorsion and GRV were both significantly greater on the throwing side compared with the nonthrowing side (HRT: throwing = 9.0° ± 11.4° and nonthrowing = 22.1° ± 10.7°, P < .001; GRV: throwing = 8.6° ± 6.0° and nonthrowing = 4.9° ± 4.8°, P = .001). Within the same shoulders, there was a statistically significant positive association between HRT and GRV on the throwing side (r = 0.43, P = .016) but not on the nonthrowing side (r = -0.13, P = .50). The HRT:GRV ratio was 2.3:1 for throwing shoulders and 7:1 for nonthrowing shoulders.

CONCLUSION

The concurrent increases in dominant shoulder HRT and GRV were observed as a 2:1 "thrower's ratio." As this relationship was not observed on the nondominant shoulder, it suggests that bony adaptation of the proximal humerus and glenoid are coupled during skeletal development in the throwing shoulder. Longitudinal studies are needed to confirm this hypothesis.

General medical practitioners' perceived use of drug information sources with special reference to drug information centres

This study reports the current perceived use of available sources of drug information for general medical practitioners. The sample frame, of 463 GPs practising in Derbyshire, England, on January 1, 1990, provided a 74 per cent response rate to a pre-piloted questionnaire. Two printed sources, the Monthly Index of Medical Specialities and the British National Formulary (BNF) plus one personal service, fellow colleagues, were by far the most frequently used. The estimated average minimum number of days per year on which personal information services were consulted was 28.51 days compared with 63.83 days for non-personal, printed sources. Thus, if GPs are to be guided by independent sources then the BNF must be considered a prime vehicle. Drug information centres (DICs) were ranked last with 56 per cent of GPs having consulted such a source within the previous year. Use of DICs could not be predicted from GPs' characteristics or demographic data. Interviews with 101 of 106 randomly selected GPs generally confirmed questionnaire findings. However, only 41 per cent perceived themselves as users of DICs. Collation of queries from two local centres showed 25 per cent were known to be users. From interviews, discrepancies were seen to arise from accessing DICs outside the sample frame boundary plus confusion of DICs with poisons centres and hospital pharmacy departments. Thus, for use of DICs, questionnaire techniques may be unreliable unless source definition is considered. If using DICs, GPs very significantly had lower concurrent use of community pharmacists, GP colleagues and hospital consultants for general drug information

Evaluation of translocator protein quantification as a tool for characterising macrophage burden in human carotid atherosclerosis

Macrophage presence within atherosclerotic plaque is a feature of instability and a risk factor for plaque rupture and clinical events. Activated macrophages express high levels of the translocator protein/peripheral benzodiazepine receptor (TSPO/PBR). In this study, we investigated the potential for quantifying plaque inflammation by targeting this receptor. TSPO expression and distribution in the plaque were quantified using radioligand binding assays and autoradiography. We show that cultured human macrophages expressed 20 times more TSPO than cultured human vascular smooth muscle cells (VSMCs), the other abundant cell type in plaque. The TSPO ligands [3H](R)-1-(2-chlorophenyl)-N-methyl-(1-methylpropyl)-3-isoquinoline carboxamide ([3H](R)-PK11195) and [3H]N-(2,5-dimethoxybenzyl)-N-(5-fluoro-2-phenoxyphenyl)acetamide ([3H]-DAA1106) bound to the same sites in human carotid atherosclerotic plaques in vitro, and demonstrated significant correlation with macrophage-rich regions. In conclusion, our data indicate that radioisotope-labelled DAA1106 has the potential to quantify the macrophage content of atherosclerotic plaque.

Primary ACL reconstruction using allograft tissue

While bone-patellar tendon-bone (BPTB) autograft continues to be the "gold standard" and most popular graft choice for primary anterior cruciate ligament (ACL) reconstructions, the use of allograft tissues in ACL reconstruction has steadily increased over the last 2 decades. Advantages of allograft include a lack of donor-site morbidity, unlimited available sizes, shorter operative times, availability of larger grafts, smaller incisions, improved cosmesis, lower incidence of postoperative arthrofibrosis, faster immediate postoperative recovery, and less postoperative pain. Disadvantages include the potential for disease transmission and prolonged graft healing. Presented in this article are 2 techniques used at the authors' institution for primary ACL reconstruction with allograft. With the proper indications, knowledge of graft preparation and handling, and technique, allograft tissues in ACL reconstructions can provide the surgeon with clinical results equal to those of autograft reconstructions.

Exercise preconditioning upregulates cerebral integrins and enhances cerebrovascular integrity in ischemic rats

We hypothesized that exercise preconditioning strengthens brain microvascular integrity against ischemia/reperfusion injury through the tumor necrosis factor (TNF)-integrin signaling pathway. Adult male Sprague Dawley rats (n = 24) were studied in: (1) exercise (the animals run on a treadmill 30 min each day) for 3 weeks, (2) non-exercise. Six animals from each group (n = 12) were subjected to stroke, the remaining animals served as controls (n = 6 x 2). Brain infarction and edema were determined by Nissl staining. Cerebral integrin expression was detected by immunochemistry and stereological methods. In addition, we used flow cytometry to address the causal role of TNF-alpha in inducing the expression of integrins in the human umbilical vein endothelial cells under TNF-alpha or vascular endothelial growth factor (VEGF) pretreatment. Exercise reduces brain infarction and brain edema in stroke. Expressions of integrin subunit alpha(1), alpha(6), beta(1), and beta(4) were increased after exercise. Exercise preconditioning reversed stroke-reduced integrin expression. An in vitro study revealed a causal link between the gradual upregulation of TNF-alpha (rather than VEGF) and cellular expression of integrins. These results demonstrated an increase in cerebral expression of integrins and a decrease in brain injury from stroke after exercise preconditioning. The study suggests that upregulation of integrins during exercise enhances neurovascular integrity after stroke. The changes in integrins might be altered by TNF-alpha.

Imaging of cerebral blood flow and metabolism in brain injury in the ICU

The heterogeneity of the initial insult and subsequent pathophysiology has made both the study of human head injury and design of randomised controlled trials exceptionally difficult. The combination of multimodality bedside monitoring and functional brain imaging positron emission tomography (PET) and magnetic resonance (MR), incorporated within a Neurosciences Critical Care Unit, provides the resource required to study critically ill patients after brain injury from initial ictus through recovery from coma and rehabilitation to final outcome. Methods to define cerebral ischemia in the context of altered cerebral oxidative metabolism have been developed, traditional therapies for intracranial hypertension re-evaluated and bedside monitors cross-validated. New modelling and analytical approaches have been developed.

Exercise pre-conditioning reduces brain damage in ischemic rats that may be associated with regional angiogenesis and cellular overexpression of neurotrophin

There is increasing evidence that physical activity is associated with a decreased stroke risk. The purpose of this study was to determine if exercise could also reduce brain damage in rats subjected to transient middle cerebral artery (MCA) occlusion, and if the reduced brain injury is associated with angiogenesis as well as cellular expression of the nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) in regions supplied by the MCA. Adult male Sprague Dawley rats (n=36) exercised 30 min each day for 3 weeks on a treadmill on which repetitive locomotor movement was required. Then, stroke was induced by a 2-h MCA occlusion using an intraluminal filament, followed by 48 h of reperfusion. In addition to the two exercised groups of animals with or without MCA occlusion, there were two other groups of animals, with or without MCA occlusion, housed for the same duration and used as non-exercised controls. Brain damage in ischemic rats was evaluated by neurologic deficits and infarct volume. Exercise preconditioned and non-exercised brains were processed for immunocytochemistry to quantify the number of microvessels or NGF- and BDNF-labeled cells. Pre-ischemic motor activity significantly (P<0.01) reduced neurologic deficits and infarct volume in the frontoparietal cortex and dorsolateral striatum. Cellular expressions of NGF and BDNF were significantly (P<0.01) increased in cortex (neuron) and striatum (glia) of rats under the exercise condition. Significant (P<0.01) increases in microvessel density were found in striatum. Physical activity reduced stroke damage. The reduced brain damage may be attributable to angiogenesis and neurotrophin overexpression in brain regions supplied by the MCA following exercise.

Cerebrovascular pressure reactivity is related to global cerebral oxygen metabolism after head injury

BACKGROUND

After head injury, impaired cerebrovascular autoregulation has been associated with abnormally high or low cerebral blood flow. The physiological relevance of cerebral blood flow levels is difficult to assess in these patients, whose cerebral metabolic rate for oxygen (CMRO(2)) is known to be abnormal. Investigation of these relations requires quantitative measures of cerebral blood flow and CMRO(2), to allow assessment of oxygen supply and demand relations.

OBJECTIVES

To investigate the relation between dysautoregulation and global cerebral oxygen metabolism following head injury.

METHODS

Using positron emission tomography, global cerebral blood flow, CMRO(2), and oxygen extraction fraction were determined in 22 patients who were investigated in 26 examinations on days 1 to 11 (mean (SD), 3.5 (2.3)) after head injury. Cerebrovascular pressure reactivity was assessed using a pressure reactivity index, calculated as the moving linear correlation coefficient between mean arterial blood pressure and intracranial pressure. Outcome was assessed six months after injury using the Glasgow outcome scale.

RESULTS

Low CMRO(2) was associated with disturbed pressure reactivity (inverse function, R(2) = 0.21, p = 0.018) and there was a correlation between disturbed pressure reactivity and oxygen extraction fraction (quadratic function, R(2) = 0.55, p = 0.0001). There was no significant relation between pressure reactivity and cerebral blood flow. An unfavourable outcome was associated with disturbed pressure reactivity. There was no significant relation between outcome and CMRO(2) or oxygen extraction fraction.

CONCLUSIONS

There is a close relation between dysautoregulation and abnormal cerebral metabolism but not blood flow. Further studies are needed to determine whether metabolic dysfunction is a result of or a cause of disturbed pressure reactivity, and to establish if there is a relation between cerebral oxygen metabolism and outcome.

Imaging atherosclerotic plaque inflammation with [18F]-fluorodeoxyglucose positron emission tomography

BACKGROUND

Atherosclerotic plaque rupture is usually a consequence of inflammatory cell activity within the plaque. Current imaging techniques provide anatomic data but no indication of plaque inflammation. The glucose analogue [18F]-fluorodeoxyglucose (18FDG) can be used to image inflammatory cell activity non-invasively by PET. In this study we tested whether 18FDG-PET imaging can identify inflammation within carotid artery atherosclerotic plaques.

METHODS AND RESULTS

Eight patients with symptomatic carotid atherosclerosis were imaged using 18FDG-PET and co-registered CT. Symptomatic carotid plaques were visible in 18FDG-PET images acquired 3 hours post-18FDG injection. The estimated net 18FDG accumulation rate (plaque/integral plasma) in symptomatic lesions was 27% higher than in contralateral asymptomatic lesions. There was no measurable 18FDG uptake into normal carotid arteries. Autoradiography of excised plaques confirmed accumulation of deoxyglucose in macrophage-rich areas of the plaque.

CONCLUSIONS

This study demonstrates that atherosclerotic plaque inflammation can be imaged with 18FDG-PET, and that symptomatic, unstable plaques accumulate more 18FDG than asymptomatic lesions.

Hearing loss in space

BACKGROUND

Temporary and, in some cases, permanent hearing loss has been documented after long-duration spaceflights.

METHODS

We examined all existing published data on hearing loss after space missions to characterize the losses.

RESULTS

Data from Russian missions suggest that the hearing loss, when it occurs, affects mainly mid to high frequencies and that using hearing protection often might prevent the loss. Several significant questions remain about hearing loss in space. While the hearing loss has been presumed to be noise-induced, no clear link has been established between noise exposure and hearing loss during spaceflight. In one documented case of temporary hearing loss from the Shuttle-Mir program, the pattern of loss was atypical for a noise-induced loss. Continuous noise levels that have been measured on the Mir and previous space stations, while above engineering standards, are not at levels usually associated with hearing loss in ground-based studies (which have usually been limited to 8-10 h exposure periods). Attempts to measure hearing in space using threshold-based audiograms have been unsuccessful in both the American and Russian programs due to noise interference with the measurements.

CONCLUSIONS

The existing data highlight the need for reliable monitoring of both hearing and noise in long-duration spaceflight.

Hypogonadism following prostate-bed radiation therapy for prostate carcinoma

BACKGROUND

The degree of testicular damage resulting from primary treatment of prostate carcinoma by external beam radiation therapy (EBRT) to the prostate bed has not been determined. If significant testicular damage has occurred, the resulting endocrine changes may result in modified tumor behavior, contribute to postradiation impotence, and may aggravate other signs and symptoms of hypogonadism, potentially influencing a patient's choice of primary treatment for his tumor.

METHOD

Three to eight years after primary treatment for localized prostate carcinoma, serologic evaluation for hypogonadism was undertaken in 33 men who had received EBRT and in 55 similar men who had received radical prostatectomy (RP). No subjects had developed recognized tumor recurrence, and none had undergone hormonal treatment since primary therapy.

RESULTS

Among men of similar age, prior treatment with EBRT was associated with significantly more frequent hypogonadism than prior treatment with RP. In men with EBRT, total testosterone levels averaged 27.3% less, free testosterone levels 31.6% less, dihydrotestosterone levels 33.4% less, luteinizing hormone (LH) levels 52.7% greater, and follicle-stimulating hormone (FSH) levels 100% greater than those values in men who had prior treatment with RP. Differences between postradiation and postsurgical men in LH and FSH levels were most prominent in men older than 70 years.

CONCLUSIONS

Three to eight years after primary treatment for prostate carcinoma, striking hormone differences were present between men who had received EBRT to the prostate bed and those with prior RP. These differences strongly suggested that prominent and permanent testicular damage was sustained during EBRT, frequently severe enough to cause hypogonadism.

FGF-10 disrupts lung morphogenesis and causes pulmonary adenomas in vivo

Transgenic mice in which fibroblast growth factor (FGF)-10 was expressed in the lungs of fetal and postnatal mice were generated with a doxycycline-inducible system controlled by surfactant protein (SP) C or Clara cell secretory protein (CCSP) promoter elements. Expression of FGF-10 mRNA in the fetal lung caused adenomatous malformations, perturbed branching morphogenesis, and caused respiratory failure at birth. When expressed after birth, FGF-10 caused multifocal pulmonary tumors. FGF-10-induced tumors were highly differentiated papillary and lepidic pulmonary adenomas. Epithelial cells lining the tumors stained intensely for thyroid transcription factor (TTF)-1 and SP-C but not CCSP, indicating that FGF-10 enhanced differentiation of cells to a peripheral alveolar type II cell phenotype. Withdrawal from doxycycline caused rapid regression of the tumors associated with rapid loss of the differentiation markers TTF-1, SP-B, and proSP-C. FGF-10 disrupted lung morphogenesis and induced multifocal pulmonary tumors in vivo and caused reversible type II cell differentiation of the respiratory epithelium.

Are coroners' necropsies necessary? A prospective study examining whether a "view and grant" system of death certification could be introduced into England and Wales

AIMS

To determine whether the cause of death could be accurately predicted without the need for a necropsy, and thus to consider whether a "view and grant" system of issuing a cause of death could be introduced into England and Wales.

METHOD

A one year prospective necropsy study was performed incorporating 568 deaths. Before necropsy, in each case the cause of death was predicted from the available history without examination of the body, and this cause was then compared with the cause of death found at necropsy.

RESULTS

The ability of the pathologist involved in the study to predict a cause of death before necropsy, either while in the mortuary or as a paper exercise, was shown to vary between 61% and 74% of cases. After the necropsy, the number of correct predicted causes of death ranged from 39% to 46%. Ischaemic heart disease was found to be the most common and most accurately predicted cause of death. Some natural diseases were frequently misdiagnosed, whereas certain types of unnatural disease were always identified correctly.

CONCLUSIONS

This study highlights the advantages and disadvantages of a view and grant system. Although it identifies a potential use of such a system, in some cases such as natural cardiac disease, because of the potentially high diagnostic error rate, the continuation of the present system of postmortem examination as part of the coroner's enquiry is recommended.

Syntheses of the first endothelin-A- and -B-selective radioligands for positron emission tomography

We have synthesized two potential positron emission tomography (PET) radioligands for the endothelin (ET) receptor. [11C]-PD156707 was produced by O-methylation of PD169390 using [11C]iodomethane. Radiochemical conversions of the order of 74 +/- 3.2% (n = 8) were obtained. The radiochemical purity of the isolated [11C]-PD156707 was 99% and the specific activity was 538 mCi/micromol. [18F]-BQ3020 was produced from [18F]fluoride in a total radiochemical yield of 2.7 +/- 0.4% (n = 10) in 238 +/- 5 min. The radiochemical purity was 95% and specific activities of the order of 670-930 mCi/micromol were obtained.

Male adolescent exposure to endocrine-disrupting pesticides: vinclozolin exposure in peripubertal rabbits

Adolescence is a time of dramatic neuroendocrine changes that are required for sexual maturation. Hormonal mimicking or inhibiting chemicals can cause significant impairment during this critical period. Vinclozolin (Vin) has been shown to be an anti-androgen affecting male offspring in rats in utero, and its mechanism of action may be mediated by inhibition of androgenic receptor action. The majority of teenagers working on farms are male, and therefore a systemic fungicide, vinclozolin, was selected for study. The rabbit has proved to be an excellent species for modelling reproductive toxicant effects in the male and was selected as the test species. The peripubertal phase for the rabbit was determined to be between the 3rd and 4th months. A 2-month dosing period was therefore initiated at 3 months of age and carried through to the 4th month. Vin was administered by dermal application (100 mg kg(-1) in 100 microl of dimethylsulphoxide) daily. Body weights were determined weekly. The rabbits were then held until fully mature (6 months of age). Semen was collected and evaluated from sexually mature males on a weekly schedule for 5 weeks to maximize sperm output. An automated solid phase extraction procedure for monitoring exposures through isolation and quantification of Vin and its metabolic products was developed. Increased plasma levels of Vin and M2 were found throughout the experimental period. The exposed rabbits had a smaller weight gain during pubertal growth (approaching significance; P=0.059). At maturity, the accessory sex glands of the exposed animals weighed less than those of the controls (P=0.016). Surprisingly, the pooled sperm count of the exposed animals was significantly higher (P=0.017) than that of the unexposed animals. The anti-androgenic effects of Vin may have blocked the negative feedback mechanism of testosterone on the hypothalamus or pituitary gland, allowing for an increase in gonadotrophin release, and consequently increasing sperm production at puberty.

Inverted electron-hole alignment in InAs-GaAs self-assembled quantum dots

New information on the electron-hole wave functions in InAs-GaAs self-assembled quantum dots is deduced from Stark effect spectroscopy. Most unexpectedly it is shown that the hole is localized towards the top of the dot, above the electron, an alignment that is inverted relative to the predictions of all recent calculations. We are able to obtain new information on the structure and composition of buried quantum dots from modeling of the data. We also demonstrate that the excited state transitions arise from lateral quantization and that tuning through the inhomogeneous distribution of dot energies can be achieved by variation of electric field.

Redefining the functional organization of working memory processes within human lateral prefrontal cortex

It is widely held that the frontal cortex plays a critical part in certain aspects of spatial and non-spatial working memory. One unresolved issue is whether there are functionally distinct subdivisions of the lateral frontal cortex that subserve different aspects of working memory. The present study used positron emission tomography (PET) to demonstrate that working memory processes within the human mid-dorsolateral and mid-ventrolateral frontal regions are organized according to the type of processing required rather than according to the nature (i.e. spatial or non-spatial), of the information being processed, as has been widely assumed. Two spatial working memory tasks were used which varied in the extent to which they required different executive processes. During a 'spatial span' task that required the subject to hold a sequence of five previously remembered locations in working memory a significant change in blood-flow was observed in the right mid-ventrolateral frontal cortex, but not in the anatomically and cytoarchitectonically distinct mid-dorsolateral frontal-lobe region. By contrast, during a '2-back' task that required the subject to continually update and manipulate an ongoing sequence of locations within working memory, significant blood flow increases were observed in both mid-ventrolateral and mid-dorsolateral frontal regions. When the two working memory tasks were compared directly, the one that emphasized manipulation of information within working memory yielded significantly greater activity in the right mid-dorsolateral frontal cortex only. This dissociation provides unambiguous evidence that the mid-dorsolateral and mid-ventrolateral frontal cortical areas make distinct functional contributions to spatial working memory and corresponds with a fractionation of working memory processes in psychological terms.

Differences in forensic pathology practice between Scotland and England

Scotland and England are part of the United Kingdom but have separate legal systems. These legal differences have a substantial effect on forensic pathology practice, and are probably best appreciated by those pathologists who have worked on both sides of the border. This paper seeks to highlight the differences in forensic pathology practice between Scotland and England, discussing the investigation of death in both countries. It concludes that a knowledge of the Scottish procurator fiscal system of death investigation may be beneficial to those contemplating changes to the coroner system. All three authors have practised forensic pathology in Scotland and England or Wales.

Reproductive function in relation to duty assignments among military personnel

As a follow-up to the pilot study of semen quality of soldiers with various military assignments a larger, more complete study was conducted. Soldiers were recruited at Fort Hood, Texas. Thirty-three men were exposed to radar as part of their duty assignment in the Signal Corps, 57 men were involved with firing the 155 mm howitzer (potential lead exposure), and 103 soldiers had neither lead nor radar exposure and served as the comparison control group. Both serum and urinary follicle-stimulating hormone and luteinizing hormone and serum, salivary, and urine testosterone levels were determined in all men. A complete semen analysis was conducted on each soldier. For statistical analysis, the primary study variables were: sperm concentration, sperm/ejaculate, semen volume, percent normal morphology, percent motile, percent viable (both vital stain and hypoosmotic swelling), curvilinear velocity, straight-line velocity, linearity, sperm head length, width, area, and perimeter. Variables were adjusted for significant confounders (e.g., abstinence, sample age, race). No statistical differences (P < 0.05) were observed in any measurement. While these results are in agreement with two previous studies assessing soldiers firing the 155-mm howitzer, they contradict our previous report indicating that radar exposure caused a significant decrease in sperm numbers. A possible explanation is that the radar exposure in this study was that used in Signal Corps operations while the men in the previous study were using different radar as part of military intelligence operations. The data presented here in men firing the 155-mm howitzer combined with the results from the previous studies confirms that there are no deficits in semen quality in these men. The contradiction between the results of the radar exposure studies indicates that more data are needed to evaluate the relationship of military radar and male reproductive health.

Air weapon fatalities

AIMS

To describe characteristics of a series of people accidentally and deliberately killed by air powered weapons.

METHODS

Five cases of fatal airgun injury were identified by forensic pathologists and histopathologists. The circumstances surrounding the case, radiological examination, and pathological findings are described. The weapon characteristics are also reported.

RESULTS

Three of the victims were adult men, one was a 16 year old boy, and one an eight year old child. Four of the airguns were .22 air rifles, the other a .177 air rifle. Two committed suicide, one person shooting himself in the head, the other in the chest. In both cases the guns were fired at contact range. Three of the cases were classified as accidents: in two the pellet penetrated into the head and in one the chest.

CONCLUSIONS

One person each year dies from an air powered weapon injury in the United Kingdom. In addition there is considerable morbidity from airgun injuries. Fatalities and injuries are most commonly accidents, but deliberately inflicted injuries occur. Airguns are dangerous weapons when inappropriately handled and should not be considered as toys. Children should not play with airguns unsupervised.

Measurement of myocardial blood flow with oxygen-15 labelled water: comparison of different administration protocols

Positron emission tomography (PET) in conjunction with C15O2 or H215O can be used to measure myocardial blood flow (MBF) and tissue fraction (TF), i.e. the fraction of the tissue mass in the volume of the region of interest. However, with C15O2 inhalation, the tissue fraction in the septum is overestimated. Bolus injection of H215O together with arterial cannulation gives very precise results but is invasive. The purpose of this study was to develop a method which circumvents these problems. A four-parameter model with parameters for MBF, TF and spill-over fractions from both left and right ventricular cavities was developed. This method was compared with a three-parameter model (no right ventricular cavity spill-over) in both septal and non-septal regions of interest for three different administration protocols: bolus injection of H215O, infusion of H215O and inhalation of C15O2. It was found that MBF can be measured with intravenous administration of H215O without the requirement for arterial cannulation. The four-parameter protocol with bolus injection was stable in clinical studies. The four-parameter model proved essential for the septum, where it gave highly significantly better fits than did the three-parameter model (P<0.00003 in each of 15 subjects). Administration of H215O together with this four-parameter model also circumvented the problem of overestimation of TF in the septum seen with C15O2 inhalation. In addition, the radiation dose of H215O protocols is lower than that of C15O2 inhalation. Using a left atrial input curve instead of a left ventricular cavity input curve gave the same mean MBF and TF.

Male reproductive effects of lead, including species extrapolation for the rabbit model

The effects of elevated blood lead on semen quality were evaluated in the rabbit model and compared to published effects in humans. Mature, male rabbits were given lead acetate by subcutaneous injection in the dose range of 0 to 3.85 mg/kg on a Monday-Wednesday-Friday basis. In each of eight treatment groups, a dosing regimen was developed to produce blood lead levels of 0, 20, 40, 50, 70, 80, 90, and 110 microg/dL. A 5-week pre-exposure period was followed by a 15-week exposure testing period allowing for response through six cycles of the seminiferous epithelium. Semen analyses revealed that increased blood lead levels were associated with adverse changes in the sperm count, ejaculate volume, percent motile sperm, swimming velocities, and morphology. Hormonal responses were minimal. Testicular pathology revealed a dose-dependent inhibition of spermiation. For six measures of semen quality, threshold estimates ranged from 16 to 24 microg/dL. Using the species extrapolation factor derived in this study, a rabbit dose would have to be divided by 1.56 to obtain the equivalent human dose for an equal percentage decrease in sperm concentration; however, rabbits are 3.75 more sensitive in terms of absolute decrease in sperm count for a given blood lead level.

Pulmonary dysfunction in neonatal SP-B-deficient mice

Pulmonary function was assessed in newborn wild-type and homozygous and heterozygous surfactant protein B (SP-B)-deficient mice after birth. SP-B +/+ and SP-B+/- mice became well oxygenated and survived postnatally. Although lung compliance was decreased slightly in the SP-B+/- mice, lung volumes and compliances were decreased markedly in homozygous SP-B-/- mice. They died rapidly after birth, failing to inflate their lungs or oxygenate. SP-B proprotein was absent in the SP-B-/- mice and was reduced in the SP-B+/- mice, as assessed by Western analysis. Surfactant protein A, surfactant proprotein C, surfactant protein D, and surfactant phospholipid content in lungs from SP-B+/- and SP-B-/- mice were not altered. Lung saturated phosphatidylcholine and precursor incorporation into saturated phosphatidylcholine were not influenced by SP-B genotype. Intratracheal administration of perfluorocarbon resulted in lung expansion, oxygenation, and prolonged survival of SP-B-/- mice and in reduced lung compliance in SP-B+/+ and SP-B+/- mice. Lack of SP-B caused respiratory failure at birth, and decreased SP-B protein was associated with reduced lung compliance. These findings demonstrate the critical role of SP-B in perinatal adaptation to air breathing.

Rescue of SP-B knockout mice with a truncated SP-B proprotein. Function of the C-terminal propeptide

The function of the 102-amino acid C-terminal propeptide of surfactant protein B (SP-B) was analyzed by characterizing the phenotype associated with loss of expression of this peptide domain in transgenic mice. A construct encoding the signal peptide, N-terminal propeptide, and mature peptide of human SP-B (hSP-BDeltac) was cloned under the control of the 3.7-kilobase human SP-C promoter and injected into fertilized eggs of the FVB/N mouse strain. Founder mice expressing the hSP-BDeltac transgene were bred with heterozygous SP-B knockout mice (SP-B +/-). Offspring containing the transgene and one allele of mouse SP-B were identified and subsequently crossed to generate a transgenic line that expressed SP-BDeltac in a null background (SP-B(-/-)/hSP-BDeltac(+/+)). Expression of hSP-BDeltac in SP-B(-/-) mice was restricted to type II cells and resulted in a 2-fold increase in mature SP-B relative to wild type littermates. These mice survived without any evidence of respiratory problems and had normal lung function, normal alveolar surfactant phospholipid pool sizes, and typical tubular myelin indicating that the 102-residue C-terminal propeptide of SP-B is not required for normal structure and function of extracellular surfactant. However, proteolytic processing of the SP-C proprotein was perturbed resulting in the accumulation of a processing intermediate, Mr = 11,000, similar to the phenotype detected in SP-B(-/-) mice; furthermore, lamellar bodies in type II cells of SP-B(-/-)/hSP-BDeltac(+/+) mice were much larger than in the wild type animal and saturated phosphatidylcholine content in lung tissue was significantly increased although the incorporation of choline into saturated phosphatidylcholine was normal. Collectively, these results demonstrate a role for the C-terminal propeptide of SP-B in SP-C proprotein processing and the maintenance of lamellar body size. The C-terminal propeptide may be an important determinant of intracellular surfactant pool size.

Caring in full circle: the legacy of Edith Honeycutt

Edith Folsom Honeycutt, now retired, is the only staff nurse in the United States to be honored by a funded chair at a major university. In 1990, a chair of oncology nursing was established in her name at Emory University by the Metropolitan Atlanta Community Foundation. A life history method was used to examine the professional life of Edith Honeycutt through interviews and with a focus group of nurses who had worked with her. Three themes emerged: teaching by showing; expecting excellent practice; and investing in each other. A synthesized overall theme of "caring in full circle" was identified as the core descriptor. The findings of this study demonstrate how clinical education and expertise are shared and learned among staff nurses. Findings also suggest how nursing knowledge can be, and is, developed at the bedside. The connection between Emory University and Edith Honeycutt demonstrates an enduring link between a university setting and a practice arena.

Production of [11C]CH3I by single pass reaction of [11C]CH4 with I2

We report a single pass gas phase route to [11C]CH3I based on production of I from I2 at elevated temperature. I abstracts H from CH4 to yield CH3, which reacts with I2 to form CH3I. A fiber optic spectrometer was used to measure the I2 vapor concentration. [11C]CH3I yield increased with I2 concentration until excessive amounts of condensed I2 began to trap the 11C. The yield of [11C]CH3I was > 50% from [11C]CH4I; its specific activity was 12,000 Ci/mmole. The synthesis takes only 4 min after 11CH4 production and can be repeated without system cleanup.

Decreased lung compliance and air trapping in heterozygous SP-B-deficient mice

Genetic ablation of the murine SP-B gene in transgenic mice caused lethal perinatal respiratory distress in homozygous offspring, whereas heterozygous SP-B (+/-) mice survived postnatally. In adult SP-B(+/-) mice, surfactant protein B mRNA and the alveolar lavage SP-B protein were reduced by 50% compared with wild-type littermates, consistent with the inactivation of a single SP-B allele. Expression of SP-A, SP-C, and SP-D proteins was not affected in SP-B(+/-) mice. Heterozygous SP-B(+/-) mice reached maturity in numbers expected by Mendelian inheritance of a recessive gene. Lung morphology and both intracellular and extracellular phospholipid pool size and composition were unaltered in the SP-B(+/-) mice. Despite normal survival, pulmonary function studies demonstrated a consistent decrease in lung compliance in SP-B(+/-) mice. Abnormalities of inflation/deflation curves demonstrated airway collapse at low deflation pressures. Residual volumes were increased in the SP-B(+/-) mice. In summary, SP-B mRNA and SP-B protein were reduced by 50% in SP-B(+/-) mice, resulting in abnormalities of lung compliance and air trapping, suggesting a potential susceptibility to pulmonary dysfunction associated with SP-B deficiency.

Hepatitis virus infection and liver disease in injecting drug users who died suddenly

AIM

To determine the extent of liver damage resulting from infection with hepatitis B, C and D viruses (HBV, HCV and HDV) in intravenous drug users (IDUs).

METHODS

Liver sections taken at necropsy performed to investigate the cause of sudden death in 48 IDUs were scored for necroinflammatory activity and fibrosis. Evidence of infection was by detection of viral antibodies in serum, hepatitis B surface antigen (HBsAg) and HCV RNA by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Evidence of HCV infection was present in 43 (90%) of 48 serum samples. Six (12%) HBsAg positive serum samples had markers indicative of chronic HBsAg carriage, including three with antibody directed against HDV. Evidence of past HBV infection was found in 27 (69%) of 39 HBsAg negative serum samples. HIV was detected in one (2%) of 48 samples. In five (10%) of 48 samples there was no evidence of current or past infection with HCV, HBV or HIV. All 43 liver sections from HCV positive IDUs scored > or = 1 for necroinflammatory activity, whereas three IDUs without HCV scored 0. Scores for stage of fibrosis were > or = 1 in 15 (35%) of 43 and zero of five IDUs, respectively. Fibrosis scores of > or = 3 were seen only in three IDUs positive for HBV, HDV and HCV.

CONCLUSION

Inflammatory activity in the liver is present in a high proportion of IDUs in Glasgow and is strongly associated with HCV infection. Severe chronic liver damage was limited to HBsAg carriers superinfected with HDV and HCV.

The development of in vivo tracer methods to obtain new information about human disease: a study of the hallucinating brain

An outline is provided of the development of methodological strategies to address the question of focal cerebral activation during hallucinations in schizophrenic patients. In so doing, the innovation and diligence required to tailor in vivo tracer procedures to specific clinical research issues are highlighted. Attention is drawn to the complexity of methodological advances and the way in which they are based upon close scientific and technical collaboration between clinical scientists, and non-clinical scientists and research support staff.

Pathology of deaths associated with "ecstasy" and "eve" misuse

AIMS

To study the postmortem pathology associated with ring substituted amphetamine (amphetamine derivatives) misuse.

METHODS

The postmortem findings in deaths associated with the ring substituted amphetamines 3,4-methylenedioxymethyl-amphetamine (MDMA, ecstasy) and 3,4-methylenedioxyethylamphetamine (MDEA, eve) were studied in seven young white men aged between 20 and 25 years.

RESULTS

Striking changes were identified in the liver, which varied from foci of individual cell necrosis to centrilobular necrosis. In one case there was massive hepatic necrosis. Changes consistent with catecholamine induced myocardial damage were seen in five cases. In the brain perivascular haemorrhagic and hypoxic changes were identified in four cases. Overall, the changes in four cases were the same as those reported in heart stroke, although only two cases had a documented history of hyperthermia. Of these four cases, all had changes in their liver, three had changes in their brains, and three in their heart. Of the other three cases, one man died of fulminant liver failure, one of water intoxication and one probably from a cardiac arrhythmia associated with myocardial fibrosis.

CONCLUSIONS

These data suggest that there is more than one mechanism of damage in ring substituted amphetamine misuse, injury being caused by hyperthermia in some cases, but with ring substituted amphetamines also possibly having a toxic effect on the liver and other organs in the absence of hyperthermia.

Improved detection of varicella zoster infection with a spin amplification shell vial technique and blind passage

BACKGROUND

Among the methods available for the diagnosis of varicella zoster virus (VZV) infections, only tissue culture yields an isolate available for antiviral susceptibility testing or pathogenesis studies. However, conventional tube tissue culture (TC) has a low sensitivity.

OBJECTIVE

To increase the recovery rate of VZV in tissue culture.

STUDY DESIGN

Clinical specimens submitted for VZV isolation were processed by TC and rapid shell vial (SV) techniques followed by a blind passage (BP). For SV, two incubation times and two mAbs, directed against viral-early or immediate-early antigens, were compared.

RESULTS

Isolation of VZV using the SV stained at 72 h postinoculation was more sensitive (88-96%) than TC (50-67%), or the SV technique at 48 h (66-70%). It was also more rapid than TC (9.6 days). The comparison of mAbs yielded similar results in SV. Blind passage of SV at 7 days postinoculation further increased detection.

CONCLUSIONS

SV combined with BP is the method of choice for VZV isolation.

Deaths from methadone use

All deaths from methadone poisoning occurring between 1991 and 1994 in Sheffield, UK, were studied. There were 18 deaths: 17 adults (14 men, 3 women), age range of 17-45 years (mean 29), and a 3-year-old female child. Blood methadone concentrations ranged from 200 microg/l to 1863 microg/l (mean 560 microg/l). Multiple drug use was common. Ten people had been prescribed methadone, whilst eight had obtained their methadone illegally. Only 3 people were long-term methadone users. The others were probably first time users or recently new to methadone programmes. Two, including the child, were apparently forced to drink methadone. Methadone is a potent drug with serious side-effects. Naïve users are particularly at risk of death. Toxic effects may be delayed, allowing large amounts to be ingested, giving both user and medical practitioner a false sense of security. Caution should be exercised when prescribing to new patients in methadone programmes. Controlled administration of methadone may prevent overdosage and ingestion by those to whom it is not prescribed.