ABSTRACT
A range of abnormalities may acutely affect the upper limb (UL) extremity vasculature including trauma, peripheral vascular disease, and inflammatory conditions. Significant technical advances in computed tomography angiography (CTA) have led to the widespread adoption of this noninvasive modality for rapid evaluation of UL arterial abnormalities in the emergency department setting. A key advantage of CTA over traditional digital subtraction angiography (DSA) is the ability to evaluate concurrent osseous and soft tissue injuries. Accurate identification of pathology requires knowledge of normal UL arterial anatomy in addition to a high-quality study, which may be achieved with a robust CTA protocol. We describe the spectrum of imaging findings on upper limb CTA associated with various acute presentations. Traumatic vascular injuries may occur secondary to penetrating and blunt aetiologies appearing on CTA as contrast extravasation, pooling, pseudoaneurysm, occlusion, and arteriovenous fistula. Peripheral vascular disease manifests as atherosclerotic plaques with thready downstream opacification, and these may precipitate acute thromboembolic events. Inflammatory conditions affecting the UL vasculature includes large and small vessel vasculitides characterised by arterial mural thickening. The use of modalities, including ultrasound and magnetic resonance angiography (MRA), should be considered for further characterisation where appropriate.
Subject(s)
Computed Tomography Angiography , Emergency Service, Hospital , Upper Extremity , Humans , Computed Tomography Angiography/methods , Upper Extremity/blood supply , Upper Extremity/diagnostic imagingABSTRACT
Radiology currently stands at the forefront of artificial intelligence (AI) development and deployment over many other medical subspecialities within the scope of both research and clinical practice. Given this current leadership position, it is imperative that we foster collaboration and knowledge sharing to ensure the ethical, responsible and effective continued progress of AI technologies in our field, ultimately leading to enhanced patient care. To achieve this objective, three workshops have been planned through a coordinated effort by the NIHR/RCR committee. These workshops aim to convene key stakeholders including eminent academics, departmental leaders and industry partners to provide insights from their own experiences and strategies to overcome common challenges faced. In this article, we describe the outcomes from the first workshop, which addresses the topic of "facilitating the use of routine data to evaluate AI solutions". The main key insights uncovered include the need for ethical considerations, detailing of methods for data curation and storage depending on the need and requirements for de-identification. We provide resources for how to de-identify data and also a list of concerns to think about before curating your data. Finally, we address secure data-sharing methods and explore the need for quality assurances, the role of the data access committee and the patient perspectives in this task.
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BACKGROUND: A randomized trial of phenytoin in acute optic neuritis (ON) demonstrated a 30% reduction in retinal nerve fiber layer (RNFL) loss with phenytoin versus placebo. Here we present the corresponding serum neurofilament analyses. METHODS: Eighty-six acute ON cases were randomized to receive phenytoin (4-6Ā mg/kg/day) or placebo for 3Ā months, and followed up for 6Ā months. Serum was collected at baseline, 3 and 6Ā months for analysis of neurofilament heavy chain (NfH) and neurofilament light chain (NfL). RESULTS: Sixty-four patients had blood sampling. Of these, 58 and 56 were available at 3Ā months, and 55 and 54 were available at 6Ā months for NfH and NfL, respectively. There was no significant correlation between serum NfH and NfL at the time points tested. For NfH, the difference in mean placebo - phenytoin was -44Ā pg/ml at 3Ā months (PĀ =Ā 0.019) and -27Ā pg/ml at 6Ā months (PĀ =Ā 0.234). For NfL, the difference was 1.4Ā pg/ml at 3Ā months (PĀ =Ā 0.726) and -1.6Ā pg/ml at 6Ā months (PĀ =Ā 0.766). CONCLUSIONS: At 3Ā months, there was a reduction in NfH, but not NFL, in the phenytoin versus placebo group, while differences at 6Ā months were not statistically significant. This suggests a potential neuroprotective role for phenytoin in acute ON, with the lower NfH at 3Ā months, when levels secondary to degeneration of the anterior visual pathway are still elevated, but not at 6Ā months, when levels have normalized.
Subject(s)
Optic Neuritis , Phenytoin , Biomarkers , Humans , Intermediate Filaments , Neurofilament Proteins , Neuroprotection , Optic Neuritis/drug therapy , Phenytoin/therapeutic useABSTRACT
In the UK, women between 50-70 years are invited for 3-yearly mammography screening irrespective of their likelihood of developing breast cancer. The only risk adaption is for women with >30% lifetime risk who are offered annual magnetic resonance imaging (MRI) and mammography, and annual mammography for some moderate-risk women. Using questionnaires, breast density, and polygenic risk scores, it is possible to stratify the population into the lowest 20% risk, who will develop <4% of cancers and the top 4%, who will develop 18% of cancers. Mammography is a good screening test but has low sensitivity of 60% in the 9% of women with the highest category of breast density (BIRADS D) who have a 2.5- to fourfold breast cancer risk. There is evidence that adding ultrasound to the screening mammogram can increase the cancer detection rate and reduce advanced stage interval and next round cancers. Similarly, alternative tests such as contrast-enhanced mammography (CESM) or abbreviated MRI (ABB-MRI) are much more effective in detecting cancer in women with dense breasts. Scintimammography has been shown to be a viable alternative for dense breasts or for follow-up in those with a personal history of breast cancer and scarring as result of treatment. For supplemental screening to be worthwhile in these women, new technologies need to reduce the number of stage II cancers and be cost effective when tested in large scale trials. This article reviews the evidence for supplemental imaging and examines whether a risk-stratified approach is feasible.
Subject(s)
Breast Neoplasms/diagnostic imaging , Diagnostic Imaging/methods , Early Detection of Cancer/methods , Breast/diagnostic imaging , Female , Humans , RiskABSTRACT
This article reviews current limitations and future opportunities for the application of computer-aided detection (CAD) systems and artificial intelligence in breast imaging. Traditional CAD systems in mammography screening have followed a rules-based approach, incorporating domain knowledge into hand-crafted features before using classical machine learning techniques as a classifier. The first commercial CAD system, ImageChecker M1000, relies on computer vision techniques for pattern recognition. Unfortunately, CAD systems have been shown to adversely affect some radiologists' performance and increase recall rates. The Digital Mammography DREAM Challenge was a multidisciplinary collaboration that provided 640,000 mammography images for teams to help decrease false-positive rates in breast cancer screening. Winning solutions leveraged deep learning's (DL) automatic hierarchical feature learning capabilities and used convolutional neural networks. Start-ups Therapixel and Kheiron Medical Technologies are using DL for breast cancer screening. With increasing use of digital breast tomosynthesis, specific artificial intelligence (AI)-CAD systems are emerging to include iCAD's PowerLook Tomo Detection and ScreenPoint Medical's Transpara. Other AI-CAD systems are focusing on breast diagnostic techniques such as ultrasound and magnetic resonance imaging (MRI). There is a gap in the market for contrast-enhanced spectral mammography AI-CAD tools. Clinical implementation of AI-CAD tools requires testing in scenarios mimicking real life to prove its usefulness in the clinical environment. This requires a large and representative dataset for testing and assessment of the reader's interaction with the tools. A cost-effectiveness assessment should be undertaken, with a large feasibility study carried out to ensure there are no unintended consequences. AI-CAD systems should incorporate explainable AI in accordance with the European Union General Data Protection Regulation (GDPR).
Subject(s)
Artificial Intelligence/trends , Breast Neoplasms/diagnostic imaging , Image Processing, Computer-Assisted/methods , Mammography/methods , Breast/diagnostic imaging , Humans , Image Processing, Computer-Assisted/trends , Mammography/trendsABSTRACT
Sarcoidosis can affect the optic nerves by means of optic disc oedema secondary to posterior uveitis, optic disc oedema secondary to raised intracranial pressure, optic neuritis, optic atrophy secondary to compression or infiltration from a primary central nervous system lesion, and primary granuloma of the optic nerve head. The authors report the use of optical coherence tomography in assessing the response to immunosuppression in a 57-year-old woman with an optic nerve head granuloma.
ABSTRACT
BACKGROUND: Otogenic paediatric cerebral venous sinus thrombosis (CVST) is rare but has potential clinical sequelae. Its management has long been debated mainly concerning the role of surgery and the use of anticoagulant therapy. OBJECTIVE OF REVIEW: To review the current literature and examine the medical and surgical management of paediatric otogenic CVST and its clinical and radiological outcome. TYPE OF REVIEW: Systematic review. SEARCH STRATEGY: The electronic databases (MEDLINE, EMBASE, Cochrane) were searched from inception to November 2014 using text words 'cerebral venous sinus thrombosis OR cerebral venous thrombosis OR lateral sinus thrombosis OR sigmoid sinus thrombosis' AND 'otogenic OR mastoiditis OR otitis media' AND 'children OR paediatric OR pediatric'. EVALUATION METHOD: Inclusion criteria were applied by two reviewers and data extraction was carried out. The type of otological surgery (conservative versus extensive) and the use of anticoagulants with their clinical and radiological outcomes were tabulated. RESULTS: Thirty-six studies (15 case reports and 21 case series) were included with a total of 190 patients. A total of 92.1% of patients underwent otological surgery, and 69.5% had conservative surgery and 30.5% extensive otological surgery. Anticoagulants were used in 59%. A total of 79.2% of patients were reported to have had a good clinical outcome. Within this group, 56% had conservative surgery and anticoagulants. Follow-up scans were documented in 61.6% of patients and complete recanalisation was observed in 51%. Complete recanalisation was observed in 47% of those who had been anticoagulated and 55% of those who received no anticoagulation. CONCLUSIONS: Conservative otological surgery with the combination of anticoagulation was the most common treatment modality found in the group of patients with good clinical outcome. However, given the current low level of evidence, a multicentre collaborative study is needed to help establish the optimum surgical approach and the role of anticoagulation in managing paediatric otogenic CVST.
Subject(s)
Anticoagulants/therapeutic use , Disease Management , Lateral Sinus Thrombosis/drug therapy , Otitis Media/complications , Humans , Lateral Sinus Thrombosis/etiologyABSTRACT
A retrospective notes review was conducted for 50 consecutive patients who underwent shunt surgery for idiopathic intracranial hypertension (IIH). The decimal visual acuity and the mean radial degrees (MRD) of the I4e isopter of the Goldmann visual field were measured pre-operatively and after a mean follow-up period of 1123 days (range: 13-3551 days). A ventriculo-peritoneal shunt was the first procedure in 38 patients and a lumbo-peritoneal shunt in 12. The mean decimal visual acuity of the worse affected eye improved from 0.75 to 0.84, p = 0.011. The MRD score of the worse affected eye improved on average from 25.6Ā° to 35.5Ā°, p < 0.0001. In those with significant pre-operative visual impairment in their worse affected eye (defined as an MRD score ≤30Ā°), the MRD score improved on average from 10.3Ā° to 26.5Ā°, p = 0.0008. The mean number of surgical procedures for each patient was 2.8 (range: 1-15). Taking all surgical procedures into account, post-operative complications were experienced by 30 patients. At last follow-up, 28 patients still complained of headache, 8 of whom had the intervention performed primarily for headache. Shunting can improve visual function in patients with IIH. There is significant post-operative morbidity and often the need for repeated procedures. Headache also commonly remains in these patients. There is a need for a randomised controlled trial of operative interventions in IIH. Sample size calculations for such a trial to treat significant vision loss are presented.
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Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) can lead to prominent nerve hypertrophy, which can mimic other forms of neuropathy radiologically. Neuro-ophthalmological complications can also occur in CIDP, either at presentation or chronically in the disorder. This can also cause diagnostic difficulties. We report three cases of neuro-ophthalmological complications of CIDP: two cases of papilloedema and one case of proptosis. In all three cases cranial nerve hypertrophy was present. CIDP should be considered in neuro-ophthalmological presentations associated with cranial/spinal nerve root hypertrophy.
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Accumulating evidence from retrospective studies demonstrate at least non-inferior performance when using AI algorithms with different strategies versus double-reading in mammography screening. In addition, AI algorithms for mammography screening can reduce work load by moving to single human reading. Prospective trials are essential to avoid unintended adverse consequences before incorporation of AI algorithms into UK's National Health Service (NHS) Breast Screening Programme (BSP). A stakeholders' meeting was organized in Newnham College, Cambridge, UK to undertake a review of the current evidence to enable consensus discussion on next steps required before implementation into a screening programme. It was concluded that a multicentre multivendor testing platform study with opt-out consent is preferred. AI thresholds from different vendors should be determined while maintaining non-inferior screening performance results, particularly ensuring recall rates are not increased. Automatic recall of cases using an agreed high sensitivity AI score versus automatic rule out with a low AI score set at a high sensitivity could be used. A human reader should still be involved in decision making with AI-only recalls requiring human arbitration. Standalone AI algorithms used without prompting maintain unbiased screening reading performance, but reading with prompts should be tested prospectively and ideally provided for arbitration.
Subject(s)
Breast Neoplasms , Early Detection of Cancer , Humans , Female , Artificial Intelligence , Breast Neoplasms/diagnostic imaging , Prospective Studies , Retrospective Studies , State Medicine , AlgorithmsABSTRACT
BACKGROUND AND PURPOSE: The purpose of this study was to identify the incidence and prevalence of idiopathic intracranial hypertension (IIH) in Sheffield, UK. METHODS: A retrospective review of case notes was conducted to identify cases of IIH seen between 1 January 2007 and 31 December 2008. RESULTS: Sixteen (15 women and 1 man) new patients were identified to give an incidence within Sheffield of 1.56/100,000/year and 2.86/100,000/year for women. The incidence of IIH in obese women was 11.9/100,000/year. The prevalence of IIH was calculated as 10.9/100,000, and 85.7/100,000 in obese women. CONCLUSION: A higher incidence of IIH than previously reported UK data was found, which may be because of increasing obesity within the population, or improved case ascertainment.
Subject(s)
Obesity/epidemiology , Pseudotumor Cerebri/diagnosis , Pseudotumor Cerebri/epidemiology , Adult , Comorbidity , Female , Humans , Incidence , Male , Obesity/diagnosis , Prevalence , Retrospective Studies , United Kingdom/epidemiology , Young AdultABSTRACT
BACKGROUND/AIMS: Optic nerve sheath fenestration (ONSF) is a surgical intervention in the management of idiopathic intracranial hypertension (IIH) infrequently performed in the United Kingdom. Numerous surgical approaches have been described, including medial transconjunctival, lateral and endoscopic. We describe our outcomes and complications from ONSF via a supero-medial eyelid skin crease incision in patients with IIH. METHODS: We performed a retrospective review of consecutive patients undergoing ONSF for IIH between January 2011 and December 2017 by a single surgeon. RESULTS: Thirty patients were included in the analysis with a median follow-up of 14.5 months. Bilateral ONSFs were undertaken in 27 (90%). The data from one eye per patient were analysed. The mean kinetic perimetry score in mean radial degrees of the I4e isopter improved from 27.3Ā° to 35.7Ā°, p = 0.04. After removing cases with optic atrophy, the median modified FrisĆ©n grade of papilloedema improved from 2.5 to 1.0, p = 0.007. A total of 5/30 (17%) patients had complications: two (7%) had recurrence/late failure (one managed medically and one with cerebrospinal fluid [CSF] diversion surgery), one had transient cotton wool spots post-operatively, one had transient retinal haemorrhages and one patient had a transiently oval pupil. No patients had repeat ONSF, but CSF diversion surgery was subsequently carried out in 4/30 (13%) patients. CONCLUSIONS: ONSF via a supero-medial eyelid skin crease approach is effective at improving visual function in patients with IIH. The complication rates are low when compared with CSF diversion surgery and other surgical approaches for ONSF.
Subject(s)
Pseudotumor Cerebri , Decompression, Surgical , Eyelids/surgery , Humans , Optic Nerve/surgery , Pseudotumor Cerebri/surgery , Retrospective Studies , United KingdomABSTRACT
Streptococcus constellatus is an oropharyngeal commensal Gram-positive coccus, frequently associated with the respiratory tract. S. constellatus is part of the Streptococcus anginosus or milleri group, which has traditionally been considered to have propensity to cause empyema and purulent abscesses, a property that is sometimes overlooked as the severity of infections it causes may have a varying degree. In this case, we present the case of a 54-year-old male with known liver cirrhosis who developed a severe empyema during an acute liver failure episode, requiring extensive decortication and prolonged hospital admission.
ABSTRACT
The processing of asparagine-linked oligosaccharides on the alpha-chains of an immunoglobulin A (IgA) has been investigated using MOPC 315 murine plasmacytoma cells. These cells secrete IgA containing complex-type oligosaccharides that were not sensitive to endo-beta-N-acetylglucosaminidase H. In contrast, oligosaccharides present on the intracellular alpha-chain precursor were of the high mannose-type, remaining sensitive to endo-beta-N-acetylglucosaminidase H despite a long intracellular half-life of 2-3 h. The major [3H]mannose-labeled alpha-chain oligosaccharides identified after a 20-min pulse were Man8GlcNAc2 and Man9GlcNAc2. Following chase incubations, the major oligosaccharide accumulating intracellularly was Man6GlcNAc2, which was shown to contain a single alpha 1,2-linked mannose residue. Conversion of Man6GlcNAc2 to complex-type oligosaccharides occurred at the time of secretion since appreciable amounts of Man5GlcNAc2 or further processed structures could not be detected intracellularly. The subcellular locations of the alpha 1,2-mannosidase activities were studied using carbonyl cyanide m-chlorophenylhydrazone and monensin. Despite inhibiting the secretion of IgA, these inhibitors of protein migration did not effect the initial processing of Man9GlcNAc2 to Man6GlcNAc2. Furthermore, no large accumulation of Man5GlcNAc2 occurred, indicating the presence of two subcellular locations of alpha 1,2-mannosidase activity involved in oligosaccharide processing in MOPC 315 cells. Thus, the first three alpha 1,2-linked mannose residues were removed shortly after the alpha-chain was glycosylated, most likely in rough endoplasmic reticulum, since this processing occurred in the presence of carbonyl cyanide m-chlorophenylhydrazone. However, the removal of the final alpha 1,2-linked mannose residue as well as subsequent carbohydrate processing occurred just before IgA secretion, most likely in the trans Golgi complex since processing of Man6GlcNAc2 to Man5GlcNAc2 was greatly inhibited in the presence of monensin.
Subject(s)
Endoplasmic Reticulum/enzymology , Golgi Apparatus/enzymology , Immunoglobulin A/genetics , Mannosidases/metabolism , Oligosaccharides/genetics , Plasmacytoma/immunology , Protein Processing, Post-Translational , Acetylglucosaminidase , Animals , Carbonyl Cyanide m-Chlorophenyl Hydrazone/pharmacology , Cell Line , Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase , Mice , Monensin/pharmacology , Plasmacytoma/enzymology , alpha-MannosidaseABSTRACT
OBJECTIVE: Most skin lesions first present in primary care, where distinguishing rare melanomas from benign lesions can be challenging. Dermoscopy improves diagnostic accuracy among specialists and is promoted for use by primary care physicians (PCPs). However, when used by untrained clinicians, accuracy may be no better than visual inspection. This study aimed to undertake a systematic review of literature reporting use of dermoscopy to triage suspicious skin lesions in primary care settings, and challenges for implementation. DESIGN: A systematic literature review and narrative synthesis. DATA SOURCES: We searched MEDLINE, Cochrane Central, EMBASE, Cumulative Index to Nursing and Allied Health Literature, and SCOPUS bibliographic databases from 1 January 1990 to 31 December 2017, without language restrictions. INCLUSION CRITERIA: Studies including assessment of dermoscopy accuracy, acceptability to patients and PCPs, training requirements, and cost-effectiveness of dermoscopy modes in primary care, including trials, diagnostic accuracy and acceptability studies. RESULTS: 23 studies met the review criteria, representing 49 769 lesions and 3708 PCPs, all from high-income countries. There was a paucity of studies set truly in primary care and the outcomes measured were diverse. The heterogeneity therefore made meta-analysis unfeasible; the data were synthesised through narrative review. Dermoscopy, with appropriate training, was associated with improved diagnostic accuracy for melanoma and benign lesions, and reduced unnecessary excisions and referrals. Teledermoscopy-based referral systems improved triage accuracy. Only three studies examined cost-effectiveness; hence, there was insufficient evidence to draw conclusions. Costs, training and time requirements were considered important implementation barriers. Patient satisfaction was seldom assessed. Computer-aided dermoscopy and other technological advances have not yet been tested in primary care. CONCLUSIONS: Dermoscopy could help PCPs triage suspicious lesions for biopsy, urgent referral or reassurance. However, it will be important to establish further evidence on minimum training requirements to reach competence, as well as the cost-effectiveness and patient acceptability of implementing dermoscopy in primary care. TRIAL REGISTRATION NUMBER: CRD42018091395.
Subject(s)
Dermoscopy/methods , Melanoma/diagnosis , Skin Neoplasms/diagnosis , Triage/methods , Biopsy , Humans , Primary Health Care , Reproducibility of ResultsABSTRACT
Several murine monoclonal anti-human Factor VII antibodies were produced using hybridoma technology. Two noncompetitive monoclonal antibodies were used to examine by Western blotting the Factor VII cross-reactive material (CRM) in normal human plasma and three commercially available congenitally Factor VII-deficient plasmas, and to construct a facile "sandwich" immunoassay for plasma Factor VII. A second, previously undescribed, form of Factor VII CRM was detected in human plasma, which on Western blotting stained with an apparent intensity 5-8% that of Factor VII. This glycoprotein, tentatively called VII*, has a molecular weight 4,500 D less than Factor VII, lacks detectable Factor VII functional activity, does not bind to barium citrate, and is not recognized by a monoclonal antibody that recognizes Factor VII but not alpha-chymotrypsin-treated Factor VII. VII* was not proteolytically produced from Factor VII during in vitro coagulation or after infusion of human Factor VII into rabbits. As determined by Western blotting, the human hepatoma cell line, HepG2, cultured in the presence of vitamin K, secreted relatively greater levels of VII* in proportion to VII (75%) than that found in human plasma. Warfarin treatment of HepG2 cells decreased the quantity of VII secreted by 77%, whereas it only inhibited the secretion of VII* by 14%. Immunologic studies of the plasmas from a patient on chronic warfarin therapy and an individual given a short course of high dose warfarin therapy corroborated the in vitro synthetic studies obtained with HepG2 cells. The data are consistent with the production of VII* by posttranslational, proteolytic, modification of VII, that, at least in the HepG2 cells studied, occurs intracellularly. However, other mechanisms for the production of VII*, in particular, alternative RNA splicing of the transcript from a single gene, cannot be excluded.
Subject(s)
Antibodies, Monoclonal/analysis , Factor VII/immunology , Isoantigens/analysis , Animals , Antibody Specificity , Atrial Fibrillation/blood , Carcinoma, Hepatocellular/metabolism , Collodion , Cross Reactions , Electrophoresis, Polyacrylamide Gel , Factor VII/analysis , Factor VII/genetics , Factor VII Deficiency/blood , Factor VII Deficiency/genetics , Humans , Isoantigens/genetics , Isoantigens/immunology , Liver Neoplasms/metabolism , Mice , Rabbits , Warfarin/therapeutic useABSTRACT
Lymphocytes obtained from the blood of normal individuals and six patients with newly diagnosed multiple myeloma were separated into T and non-T cell populations by rosette-formation with sheep erythrocytes, and were then assayed for the presence of surface membrane Fc receptors. When compared with normal individuals, four patients with IgG myeloma had a three- to fourfold increase in T cells with IgG receptors (T gamma cells) and two patients with IgA myeloma had a two- to threefold increase in T cells with IgA receptors (T alpha cells). Patients with IgG or IgA myeloma had normal numbers of non-T lymphocytes with surface receptors for IgG and IgA, respectively. The finding that human myeloma is accompanied by elevated numbers of T cells with Fc receptors for the heavy chain class of the myeloma protein: (1) may account for the apparent "monoclonal" lymphocyte population in patients with myeloma; (b) extends to humans similar observations made in mice with secretory plasmacytomas; and (c) is of interest because T cells with Fc receptors are immunoregulatory lymphocytes.
Subject(s)
Immunoglobulin A/immunology , Immunoglobulin G/immunology , Multiple Myeloma/immunology , Receptors, Fc/analysis , T-Lymphocytes/immunology , Cell Count , HumansABSTRACT
A bone and cartilage enzyme with both 5'-nucleotide phosphodiesterase I and nucleotide pyrophosphohydrolase (NTPPPH) activity modulates physiologic mineralization and pathologic chondrocalcinosis by generating inorganic pyrophosphate. We hypothesized that, as for alkaline phosphatase, expression of an NTPPPH gene can be shared by cells from bone, cartilage, and liver and by certain leukocytes. Recently, we demonstrated the hepatocyte and murine plasma cell membrane glycoprotein PC-1 to have both 5'-nucleotide phosphodiesterase I and NTPPPH activity. We detected polypeptides cross-reactive with PC-1 in human U20S osteosarcoma cells, articular chondrocytes, homogenized human knee cartilages, human knee synovial fluids, hepatoma cells, and murine plasmacytoma cells. Constitutive low abundance PC-1 mRNA expression was detected in U20S cells and chondrocytes by a nested RNA-PCR assay and by Northern blotting. TGF beta is known to substantially increase NTPPPH activity in primary osteoblast cultures. We demonstrated that TGF beta 1 increased NTPPPH activity and the level of PC-1 mRNA and immunoprecipitable [35S]-methionine-labeled PC-1 polypeptides in U20S cells. The identification of PC-1 as an NTPPPH expressed in cells derived from bone and cartilage may prove useful in furthering the understanding of the role of NTPPPH i n physiologic and pathologic mineralization.