A high-resolution transcriptomic and spatial atlas of cell types in the whole mouse brain

The mammalian brain consists of millions to billions of cells that are organized into many cell types with specific spatial distribution patterns and structural and functional properties1-3. Here we report a comprehensive and high-resolution transcriptomic and spatial cell-type atlas for the whole adult mouse brain. The cell-type atlas was created by combining a single-cell RNA-sequencing (scRNA-seq) dataset of around 7 million cells profiled (approximately 4.0 million cells passing quality control), and a spatial transcriptomic dataset of approximately 4.3 million cells using multiplexed error-robust fluorescence in situ hybridization (MERFISH). The atlas is hierarchically organized into 4 nested levels of classification: 34 classes, 338 subclasses, 1,201 supertypes and 5,322 clusters. We present an online platform, Allen Brain Cell Atlas, to visualize the mouse whole-brain cell-type atlas along with the single-cell RNA-sequencing and MERFISH datasets. We systematically analysed the neuronal and non-neuronal cell types across the brain and identified a high degree of correspondence between transcriptomic identity and spatial specificity for each cell type. The results reveal unique features of cell-type organization in different brain regions-in particular, a dichotomy between the dorsal and ventral parts of the brain. The dorsal part contains relatively fewer yet highly divergent neuronal types, whereas the ventral part contains more numerous neuronal types that are more closely related to each other. Our study also uncovered extraordinary diversity and heterogeneity in neurotransmitter and neuropeptide expression and co-expression patterns in different cell types. Finally, we found that transcription factors are major determinants of cell-type classification and identified a combinatorial transcription factor code that defines cell types across all parts of the brain. The whole mouse brain transcriptomic and spatial cell-type atlas establishes a benchmark reference atlas and a foundational resource for integrative investigations of cellular and circuit function, development and evolution of the mammalian brain.

Augmentation of the RSNA Pulmonary Embolism CT Dataset with Bounding Box Annotations and Anatomic Localization of Pulmonary Emboli

Supplemental material is available for this article. Keywords: CT, Pulmonary Arteries, Embolism/Thrombosis, Feature Detection © RSNA, 2023.

Prognostic Value of Cardiac MRI and FDG PET in Cardiac Sarcoidosis: A Systematic Review and Meta-Analysis

Background There is no consensus regarding the relative prognostic value of cardiac MRI and fluorodeoxyglucose (FDG) PET in cardiac sarcoidosis. Purpose To perform a systematic review and meta-analysis of the prognostic value of cardiac MRI and FDG PET for major adverse cardiac events (MACE) in cardiac sarcoidosis. Materials and Methods In this systematic review, MEDLINE, Ovid Epub, CENTRAL, Embase, Emcare, and Scopus were searched from inception until January 2022. Studies that evaluated the prognostic value of cardiac MRI or FDG PET in adults with cardiac sarcoidosis were included. The primary outcome of MACE was assessed as a composite including death, ventricular arrhythmia, and heart failure hospitalization. Summary metrics were obtained using random-effects meta-analysis. Meta-regression was used to assess covariates. Risk of bias was assessed using the Quality in Prognostic Studies, or QUIPS, tool. Results Thirty-seven studies were included (3489 patients with mean follow-up of 3.1 years ± 1.5 [SD]); 29 studies evaluated MRI (2931 patients) and 17 evaluated FDG PET (1243 patients). Five studies directly compared MRI and PET in the same patients (276 patients). Left ventricular late gadolinium enhancement (LGE) at MRI and FDG uptake at PET were both predictive of MACE (odds ratio [OR], 8.0 [95% CI: 4.3, 15.0] [P < .001] and 2.1 [95% CI: 1.4, 3.2] [P < .001], respectively). At meta-regression, results varied by modality (P = .006). LGE (OR, 10.4 [95% CI: 3.5, 30.5]; P < .001) was also predictive of MACE when restricted to studies with direct comparison, whereas FDG uptake (OR, 1.9 [95% CI: 0.82, 4.4]; P = .13) was not. Right ventricular LGE and FDG uptake were also associated with MACE (OR, 13.1 [95% CI: 5.2, 33] [P < .001] and 4.1 [95% CI: 1.9, 8.9] [P < .001], respectively). Thirty-two studies were at risk for bias. Conclusion Left and right ventricular late gadolinium enhancement at cardiac MRI and fluorodeoxyglucose uptake at PET were predictive of major adverse cardiac events in cardiac sarcoidosis. Limitations include few studies with direct comparison and risk of bias. Systematic review registration no. CRD42021214776 (PROSPERO) © RSNA, 2023 Supplemental material is available for this article.

Canadian Association of Radiologists/Canadian Association of Interventional Radiologists/Canadian Society of Thoracic Radiology Guidelines on Thoracic Interventions

Thoracic interventions are frequently performed by radiologists, but guidelines on appropriateness criteria and technical considerations to ensure patient safety regarding such interventions is lacking. These guidelines, developed by the Canadian Association of Radiologists, Canadian Association of Interventional Radiologists and Canadian Society of Thoracic Radiology focus on the interventions commonly performed by thoracic radiologists. They provide evidence-based recommendations and expert consensus informed best practices for patient preparation; biopsies of the lung, mediastinum, pleura and chest wall; thoracentesis; pre-operative lung nodule localization; and potential complications and their management.

Diagnostic Accuracy of Cardiac MRI versus FDG PET for Cardiac Sarcoidosis: A Systematic Review and Meta-Analysis

Background There is limited consensus regarding the relative diagnostic performance of cardiac MRI and fluorodeoxyglucose (FDG) PET for cardiac sarcoidosis. Purpose To perform a systematic review and meta-analysis to compare the diagnostic accuracy of cardiac MRI and FDG PET for cardiac sarcoidosis. Materials and Methods Medline, Ovid Epub, Cochrane Central Register of Controlled Trials, Embase, Emcare, and Scopus were searched from inception until January 2022. Inclusion criteria included studies that evaluated the diagnostic accuracy of cardiac MRI or FDG PET for cardiac sarcoidosis in adults. Data were independently extracted by two investigators. Summary accuracy metrics were obtained by using bivariate random-effects meta-analysis. Meta-regression was used to assess the effect of different covariates. Risk of bias was assessed using the Quality Assessment Tool for Diagnostic Accuracy Studies-2 tool. The study protocol was registered a priori in the International Prospective Register of Systematic Reviews (Prospero protocol CRD42021214776). Results Thirty-three studies were included (1997 patients, 687 with cardiac sarcoidosis); 17 studies evaluated cardiac MRI (1031 patients) and 26 evaluated FDG PET (1363 patients). Six studies directly compared cardiac MRI and PET in the same patients (303 patients). Cardiac MRI had higher sensitivity than FDG PET (95% vs 84%; P = .002), with no difference in specificity (85% vs 82%; P = .85). In a sensitivity analysis restricted to studies with direct comparison, point estimates were similar to those from the overall analysis: cardiac MRI and FDG PET had sensitivities of 92% and 81% and specificities of 72% and 82%, respectively. Covariate analysis demonstrated that sensitivity for FDG PET was highest with quantitative versus qualitative evaluation (93% vs 76%; P = .01), whereas sensitivity for MRI was highest with inclusion of T2 imaging (99% vs 88%; P = .001). Thirty studies were at risk of bias. Conclusion Cardiac MRI had higher sensitivity than fluorodeoxyglucose PET for diagnosis of cardiac sarcoidosis but similar specificity. Limitations, including risk of bias and few studies with direct comparison, necessitate additional study. © RSNA, 2022 Online supplemental material is available for this article.

Combined simultaneous FDG-PET/MRI with T1 and T2 mapping as an imaging biomarker for the diagnosis and prognosis of suspected cardiac sarcoidosis

PURPOSE

To evaluate the diagnostic and prognostic significance of combined cardiac 18F-fluorodeoxyglucose (FDG) PET/MRI with T1/T2 mapping in the evaluation of suspected cardiac sarcoidosis.

METHODS

Patients with suspected cardiac sarcoidosis were prospectively enrolled for cardiac 18F-FDG PET/MRI, including late gadolinium enhancement (LGE) and T1/T2 mapping with calculation of extracellular volume (ECV). The final diagnosis of cardiac sarcoidosis was established using modified JMHW guidelines. Major adverse cardiac events (MACE) were assessed as a composite of cardiovascular death, ventricular tachyarrhythmia, bradyarrhythmia, cardiac transplantation or heart failure. Statistical analysis included Cox proportional hazard models.

RESULTS

Forty-two patients (53 ± 13 years, 67% male) were evaluated, 13 (31%) with a final diagnosis of cardiac sarcoidosis. Among patients with cardiac sarcoidosis, 100% of patients had at least one abnormality on PET/MRI: FDG uptake in 69%, LGE in 100%, elevated T1 and ECV in 100%, and elevated T2 in 46%. FDG uptake co-localized with LGE in 69% of patients with cardiac sarcoidosis compared to 24% of those without, p = 0.014. Diagnostic specificity for cardiac sarcoidosis was highest for FDG uptake (69%), elevated T2 (79%), and FDG uptake co-localizing with LGE (76%). Diagnostic sensitivity was highest for LGE, elevated T1 and ECV (100%). After median follow-up duration of 634 days, 13 patients experienced MACE. All patients who experienced MACE had LGE, elevated T1 and elevated ECV. FDG uptake (HR 14.7, p = 0.002), elevated T2 (HR 9.0, p = 0.002) and native T1 (HR 1.1 per 10 ms increase, p = 0.044) were significant predictors of MACE even after adjusting for left ventricular ejection fraction and immune suppression treatment. The presence of FDG uptake co-localizing with LGE had the highest diagnostic performance overall (AUC 0.73) and was the best predictor of MACE based on model goodness of fit (HR 14.9, p = 0.001).

CONCLUSIONS

Combined cardiac FDG-PET/MRI with T1/T2 mapping provides complementary diagnostic information and predicts MACE in patients with suspected cardiac sarcoidosis.

Why the Public Need a Say in How Patient Data are Used for Covid-19 Responses

The global coronavirus pandemic has clearly demonstrated the great urgency to collect and use patient data effectively to understand, track and manage the spread of Covid-19. The value of patient data in this pandemic is undeniable, however considerations around how - and by whom - such data should be collected, accessed and used, and for what purposes, remain to be fully debated and resolved. Who decides, and how such decisions are made remain unclear. We argue that public engagement and deliberation are essential for good governance and are key to establish and maintain a legitimate social licence for data practices around Covid-19.

Improving quality of life in vasculitis patients

Systemic vasculitis are a complex cluster of diseases with high associated morbidity. As disease-related mortality diminishes, the cumulative impact of poor health-related quality of life becomes more pertinent to patients than the initial pathological insult. In this article we explore health-related quality of life in ANCA-associated vasculitis, large-vessel vasculitis and therapeutic strategies that may enhance this critical outcome.

Multi-axis heterodyne interferometry at MHz frequencies: a short-arm measurement demonstration for LISA with off-the-shelf hardware

We report the design, construction, and operation of a multi-axis heterodyne interferometry (MAHI) system operating at MHz heterodyne frequencies, which provides a testbed for technologies to be used in the Laser Interferometer Space Antenna (LISA) space-based gravitational wave mission. The system was calibrated for measurement of the piston, pitch, and yaw of a three-axis piezo-actuated mirror, giving measured calibration values that closely match those predicted by a simulation based on Gaussian beam tracing. The piston sensitivity of the MAHI system in the LISA band was measured to be below 10  pm Hz^-1/2 for frequencies above 4 mHz and below 1  pm Hz^-1/2 for frequencies above 35 mHz. The sensitivity is limited above 2 Hz by the mechanical vibrations of the apparatus and below 1 mHz by dimensional changes caused by temperature fluctuations. Evidence points towards scattered light as the limiting noise source at intermediate frequencies. The angular sensitivity of the MAHI system was measured to be close to or below 10  nrad Hz^-1/2 for frequencies above 4 mHz and below 1  nrad Hz^-1/2 for frequencies above 100 mHz. Noise budgets for both length and angle were determined, indicating the areas in which improvements must be made in order to reach increased sensitivity. The current operating sensitivity already provides a useful testbed for LISA technologies and a potential blueprint for future ground segment equipment.

A smartphone app to communicate child passenger safety: an application of theory to practice

Child passenger safety remains an important public health problem because motor vehicle crashes are the leading cause of death for children, and the majority of children ride improperly restrained. Using a mobile app to communicate with parents about injury prevention offers promise but little information is available on how to create such a tool. The purpose of this article is to illustrate a theory-based approach to developing a tailored, smartphone app for communicating child passenger safety information to parents. The theoretical basis for the tailoring is the elaboration likelihood model, and we utilized the precaution adoption process model (PAPM) to reflect the stage-based nature of behavior change. We created assessment items (written at ≤6th grade reading level) to determine the child's proper type of car seat, the parent's PAPM stage and beliefs on selected constructs designed to facilitate stage movement according to the theory. A message library and template were created to provide a uniform structure for the tailored feedback. We demonstrate how messages derived in this way can be delivered through new m-health technology and conclude with recommendations for the utility of the methods used here for other m-health, patient education interventions.

Reducing fluxes of faecal indicator compliance parameters to bathing waters from diffuse agricultural sources: the Brighouse Bay study, Scotland

The European Water Framework Directive requires the integrated management of point and diffuse pollution to achieve 'good' water quality in 'protected areas'. These include bathing waters, which are regulated using faecal indicator organisms as compliance parameters. Thus, for the first time, European regulators are faced with the control of faecal indicator fluxes from agricultural sources where these impact on bathing water compliance locations. Concurrently, reforms to the European Union (EU) Common Agricultural Policy offer scope for supporting on-farm measures producing environmental benefits through the new 'single farm payments' and the concept of 'cross-compliance'. This paper reports the first UK study involving remedial measures, principally stream bank fencing, designed to reduce faecal indicator fluxes at the catchment scale. Considerable reduction in faecal indicator flux was observed, but this was insufficient to ensure bathing water compliance with either Directive 76/160/EEC standards or new health-evidence-based criteria proposed by WHO and the European Commission.

Predicting the effect of livestock inputs of E. coli on microbiological compliance of bathing waters

Three alternative approaches to predicting delivery of faecal indicators from livestock sources to surface water in the catchment of the River Irvine, Ayrshire, Scotland, are described. These are a soil transport model which assumes all E. coli are transported through the soil, a regression model using observed E. coli concentrations in surface waters, and a distributed catchment model (PAMIMO). Each of these is linked to a simple group of equations describing inputs of E. coli from livestock to land, transport and inactivation in the river Irvine and mixing and inactivation in the sea. The models predict E. coli content of bathing water for Irvine beach. The regression model gives the best predictions of bathing water quality. The low values predicted by the soil transport model suggests that preventing surface runoff of faecal indicators from livestock would provide an adequate solution to the problem of bathing water contamination.

Low-risk persistent gestational trophoblastic disease treated with low-dose methotrexate: efficacy, acute and long-term effects

The aim of this study was to evaluate the efficacy and toxicity of low-dose methotrexate with folinic acid rescue in a large series of consecutively treated patients with low-risk persistent gestational trophoblastic disease. Between January 1987 and December 2000, 250 patients were treated with intramuscular methotrexate (50 mg on alternate days 1, 3, 5, 7) with folinic acid (7.5 mg orally on alternate days 2, 4, 6, 8) rescue. The overall complete response rate without recurrence was 72% for first-line treatment and 95% for those who required second-line chemotherapy. Eight women (3.2%) had recurrence following remission and two (0.8%) had new moles. Two women (0.8%) died of their disease giving an overall cure of 99%. Only 10 women (4%) experienced grade III/IV toxicity during the first course of treatment and 13 women (5.2%) subsequently. Toxicity included mucositis and stomatitis, pleuritic chest pain, thrombocytopenia, uterine bleeding, abdominal pain, liver function changes, rash and pericardial effusion. A total of 59 women (23.6%) required second-line chemotherapy; 48 women had methotrexate resistance, eight had methotrexate toxicity and an empirical decision to change therapy was made in three. In all, 11 women (4.4%) had a hysterectomy before, during or after treatment; 141 women (56.4%) became pregnant following treatment: in 128 (90.7%), the outcome was successful. Methotrexate with folinic acid rescue is an effective treatment for low-risk persistent trophoblastic disease. It has minimal severe toxicity, excellent cure rates and does not appear to affect fertility.

Continuous quality improvement: educating towards a culture of clinical governance

The National Health Service in England and Wales has recently adopted a policy aimed at embedding continuous quality improvement (CQI) at all levels and across all services. The key goal is to achieve changes in practice which improve patient outcomes. This paper describes the use of a training course for multiprofessional groups of participants tailored to offer them relevant knowledge, management and team working skills, and approaches to personal and career development. These were intended to assist them in changing their practice for the benefit of patients. The participants rated the course highly in fulfilling its objectives. One cohort followed up for 6 months named changes in practice which related specifically to learning from the course. This paper shows the important contribution of multiprofessional learning to CQI and presents a useful method of evaluating links between learning and performance.

Continuous quality improvement: educating towards a culture of clinical governance

The National Health Service in England and Wales has recently adopted a policy aimed at embedding continuous quality improvement (CQI) at all levels and across all services. The key goal is to achieve changes in practice which improve patient outcomes. This paper describes the use of a training course for multiprofessional groups of participants tailored to offer them relevant knowledge, management and team working skills, and approaches to personal and career development. These were intended to assist them in changing their practice for the benefit of patients. The participants rated the course highly in fulfilling its objectives. One cohort followed up for 6 months named changes in practice which related specifically to learning from the course. This paper shows the important contribution of multiprofessional learning to CQI and presents a useful method of evaluating links between learning and performance.

Informed consent and the preregistration house officer

A survey of preregistration house officers demonstrated that less than a third had never felt compelled to obtain consent from patients for procedures they themselves did not understand. This had occurred frequently for over a fifth of respondents. Learning how to obtain informed consent is an important part of the education and training of a doctor. The wrong lessons will be learned if they feel compelled to do this when ill-equipped with relevant information about risks and alternatives.

Pediatric injuries resulting from use of all-terrain vehicles

Annually, 20,000 children are injured while operating all-terrain vehicles (ATVs). The purpose of this paper was to review child-ATV injuries in Arkansas and identify any areas in need of further investigation. An analysis of emergency-medical-service transports was done for children 0-19 years who had ATV-related injuries in Arkansas from 1998 to 1999. Prehospital-reported child-ATV emergencies were identified, separated by county, and emergency encounter rates were calculated. Our results indicate that emergency medical services (EMS) transported 319 children in Arkansas from 1998 to 1999. ATV injury information is limited in Arkansas, but available data indicate high injury rates existed for many rural counties.

Trainee satisfaction before and after the Calman reforms of specialist training: questionnaire survey

OBJECTIVES

To evaluate the impact of the Calman reforms of higher specialist training on trainee satisfaction.

DESIGN

Questionnaire surveys using portable electronic survey units, two years apart.

SETTING

Postgraduate, teaching, district general, and community NHS trusts in North Thames. North Thames deanery includes London north of the Thames, Essex, and Hertfordshire.

PARTICIPANTS

Trainees in all grades and all specialties: 3078 took part in the first survey and 3517 in the second survey.

MAIN OUTCOME MEASURES

Trainees' satisfaction with training in their current post, including educational objectives, training agreements, induction, consultant feedback, hands on experience acquired, use of log books, consultant supervision, and overall satisfaction with the post.

RESULTS

In the second survey respondents were more likely to have discussed educational objectives with their consultant, used a log book, and had useful feedback from their consultant. They were more likely to give high ratings to induction, consultant supervision, and hands on experience acquired in the post. Each of these elements was associated with increased satisfaction with the post overall. Improvements were most noticeable at the level of specialist registrar, but changes in the same direction were also seen in more junior grades.

CONCLUSIONS

After the reforms of specialist training, trainees in all grades reported greater satisfaction with their current posts. The changes required extra training time and effort from consultants.

Ectopic bone formation via rhBMP-2 delivery from porous bioabsorbable polymer scaffolds

Drug delivery devices have received considerable interest in the field of tissue engineering due to the advent of proteins that can induce proliferation and differentiation of various cells to form specific tissues and organs, for example, bone morphogenetic protein (BMP-2) for osteogenesis. In this work the delivery of a clinically relevant bioactive factor, recombinant human rhBMP-2, was tested in vivo in a rat ectopic bone induction assay. Contact radiography and radiomorphometry showed significantly more radiopacity (1798+/-183 mm2 versus. 784+/-570 mm2 radiopaque area/g scaffold) in the BMP scaffolds than controls (p < 0.002). De novo woven bone and abundant osteoid formation were confirmed from histological sections while controls contained minimal amounts of tissue. Histomorphometry revealed significantly more bone (124+/-93 mm2 versus 7+/-12 mm2) and osteoid (72+/-43 mm2 versus 20+/-21 mm2) in the BMP implants (p < 0.001). These scaffolds demonstrated the ability to deliver viable rhBMP-2 and to induce bone formation in an ectopic site.

Prevalence of clinical sinusitis in young children followed up by primary care pediatricians

OBJECTIVE

To determine the proportion of young children seen in primary care pediatric practices who meet clinical criteria for the diagnosis of sinusitis, and variations in the management of these patients' conditions.

DESIGN

Observational cohort study.

SETTINGS

Pediatric practices in the Seattle, Wash, area participating in the Puget Sound Pediatric Research Network, a regional practice-based research organization.

PATIENTS

Children, 1 to 5 years old, presenting for any reason to participating practices.

METHODS

Parents of all 1307 eligible children completed a survey specifically detailing the presence of nasal congestion or discharge and daytime cough, the duration of these symptoms, and whether the symptoms were improving. For patients meeting clinical criteria for sinusitis (nasal congestion and daytime cough persisting for > 9 days without improvement), the pediatrician recorded the presence/severity of other signs and symptoms, and the treatment prescribed. Severity of symptoms was reassessed using telephone interviews with parents at 48 to 72 hours, and again at 10 to 14 days, after the office visit. Study data were collected during 1-week to 3-week blocks at each office site during the winter months.

RESULTS

Data were collected on 1307 children; 121 had persistent respiratory symptoms meeting criteria for a diagnosis of sinusitis (9.3%, 95% confidence interval, 7.7%-10.9%). Patients who presented with cold/cough symptoms were significantly more likely to meet criteria for sinusitis than those who came for any other reason (17.3% vs 4.2%, respectively, P < .001). A physician study form was completed on 87 children with persistent symptoms; antibiotics were prescribed for 68 (78%) of these patients. Antibiotic-treated patients were more likely to have symptoms lasting longer than 29 days (P = .004) and to have purulent nasal discharge (P = .03), and were judged to be sicker at enrollment (P = .001) than untreated children. A concurrent otitis media was diagnosed in 40 (46%) of 87 patients; if the proportion of children with otitis media is excluded, 5% of children 1 to 5 years old who are seen in primary care pediatrics might be expected to receive antibiotics exclusively for a diagnosis of sinusitis. At 24 to 48 hours and at 10 to 14 days after the clinic visit, a trend was noted toward more rapid improvement among those children who were treated with antibiotics.

CONCLUSION

When the criteria are strictly adhered to, only a small proportion of young children seen during the winter months in primary care pediatric practices will be diagnosed with sinusitis.

Cartilage protective agent (CPA) Ro 32-3555, a new matrix metalloproteinase inhibitor for the treatment of rheumatoid arthritis

CPA was well tolerated at all dose levels (10-150 mg) following single oral dose administration to healthy male volunteers. There was no relationship between the intensity, duration and number of adverse events reported and the dose of CPA. There was a dose-related increase in exposure as measured by AUC0-infinity and Cmax. Administration of 10 mg CPA following food resulted in a delayed tmax, and a significant decrease in Cmax but not AUC0-infinity.

Prevention of injuries to children and adolescents

Injury prevention is one of the most important preventive health challenges for pediatricians worldwide. A science of injury control has developed. Matching a child's skill and development age is needed for anticipatory guidance. Poor children living in rural areas are at greatest risk and require continuous reinforcement. Family function relates closely to injuries and recovery from injury. Prevention involves education, legislation, environmental modification, and engineering techniques.

Modification of the mouse mitochondrial genome by insertion of an exogenous gene

Using homologous recombination in yeast we have inserted a synthetic gene encoding human ornithine transcarbamylase (sOTC), designed to allow mitochondrial (mt) translation, into the mouse mt genome. Modification of the mt genome was facilitated by its cloning into a yeast centromeric plasmid. The sOTC gene was initially flanked by 25 bp of the mt tRNA(His) gene at its 5' end and by 23 bp of the mt tRNA(Ser (AGY)) gene at its 3' end (Wheeler et al., 1996). In order to achieve homologous recombination the flanking homology was subsequently extended to 525 and 362 bp by the polymerase chain reaction (PCR). The sOTC gene was thus inserted into the cloned mt genome at a unique location between the tRNA(His) and tRNA(Ser (AGY)) genes. Positioning of the sOTC gene between these normally contiguous tRNA genes should allow its processing from the mt polycistronic transcript. The ability to modify the mammalian mt genome in this way is a valuable step towards a functional analysis of mt genetic mechanisms and possibly also towards a gene therapy approach for mt disorders.

Serum progesterone and human chorionic gonadotrophin measurements in the evaluation of ectopic pregnancy

We evaluated the clinical usefulness of measuring the serum concentrations of human chorionic gonadotrophin (HCG) and progesterone to distinguish between early viable and nonviable pregnancies. We investigated 110 women with clinical symptoms of abnormal pregnancy. A single HCG measurement did not clearly distinguish between ectopic and failing intrauterine pregnancies; an HCG value below 3,000 IU/L, together with a serum progesterone below 40 nmol/L, predicted abnormal pregnancy outcome in 97% of women (positive predictive value: 91%; negative predictive value: 95%). Serum HCG value above 3,000 IU/L or progesterones above 40 nmol/L, discriminated between an ongoing pregnancy and an abnormal pregnancy in 87% women (positive predictive value: 95%; negative predictive value: 91%) and provided reassurance of an ongoing pregnancy. Our results suggest that a combination of serum progesterone and HCG measurements provide clinically useful biochemical information which enhances the prediction of pregnancy outcome.

Latent inhibition, context specificity, and context familiarity

In two appetitive licking experiments, thirsty rats were pre-exposed on two stimuli prior to conditioning sessions in which one or both of these stimuli were paired with water. Consistent with other results, latent inhibition was disrupted when conditioning took place in a context different from that in which stimulus pre-exposure had occurred. But in animals given prior exposure to the context of stimulus pre-exposure before the start of stimulus pre-exposure, substantial and equivalent latent inhibition was evident whether or not there was a change of context between stimulus pre-exposure and conditioning. These results are discussed in terms of current theories of latent inhibition.

Physician and practice characteristics associated with judgments about breast cancer treatment

Since most cancer is treated in the local community, the judgments of primary care physicians about treatment of breast cancer are important. This study examined physician and practice characteristics associated with physician judgments about the treatment of Stage I and Stage II breast cancer. Data are combined from samples of 3,436 physicians: physicians affiliated with hospitals participating in the Community Clinical Oncology Program (CCOP) and a national sample of non-CCOP physicians. This study focused on 1,460 physicians who had seen breast cancer patients and participated in treatment decision-making. Judgments were elicited using brief vignettes. Judgments were more variable for Stage I than for Stage II treatments. Judgments consistent with the NIH Consensus Conferences on breast cancer were more likely from surgeons, physicians who participated in information networks focused on cancer, and those with more breast cancer patients. Concurrence with the consensus conference positions was less likely in older physicians and those in solo practice. These findings point to structures that reinforce quality of care, particularly those that enhance communication, such as group practice or the activities of hospital staffs, information networks, and organized continuing education.