Healthcare visits for new neurodevelopmental problems before and during the COVID-19 pandemic

BACKGROUND

The COVID-19 pandemic disrupted healthcare delivery. We hypothesized that children with neurodevelopmental problems would have reduced healthcare utilization during the pandemic compared to before the pandemic.

METHODS

We conducted a population-based study of healthcare visits for new neurodevelopmental problems among children ages 0-6 years in Ontario, Canada. Our outcome measure was rate per 1000 children-months for healthcare visits for new neurodevelopmental problems. We compared changes in monthly rates before and during the pandemic using interrupted time series analysis (ITSA).

RESULTS

The rate of new neurodevelopmental problems before the pandemic was 6.31 per 1000 children-months and during the pandemic was 6.58 per 1000 children-months. However, using ITSA, there were no differences in monthly rates of healthcare visits for new neurodevelopmental problems before and during the pandemic. The observed rate during the first 30 days of the pandemic dropped to 3.40 per 1000 children-months.

CONCLUSION

We found no significant difference in rates of healthcare visits for new neurodevelopmental problems before and during the pandemic. There was a decrease in the number of visits during the first 30 days of the pandemic compared to all months prior.

IMPACT

This study found no significant difference in rates of healthcare visits for new neurodevelopmental problems before and during the pandemic. There was a decrease in the number of visits during the first 30 days of the pandemic compared to all months prior. This study adds information on healthcare access for children during the COVID-19 pandemic. The rapid deployment of virtual healthcare delivery in Ontario, Canada may explain the fast recovery of healthcare utilization for children with neurodevelopmental problems.

School-based health care: improving academic outcomes for inner-city children-a prospective cohort quasi-experimental study

BACKGROUND

We examined whether a school-based health center model improved academic achievement compared to usual care.

METHODS

This was a quasi-experimental prospective cohort study. The primary outcome was an academic achievement. In addition, we analyzed sociodemographic characteristics and their relationship to academic achievement, and the wait time for a developmental assessment.

RESULTS

The differences in change of grades over time (from 2016/2017 to 2018/2019) were small for reading (-0.83, 95% CI -3.48, 1.82, p = 0.51), writing (-1.11, 95% CI -3.25, 1.03, p = 0.28), and math (0.06, 95% CI -3.08, 2.94, p = 0.98). The experimental arm's average wait time for developmental assessment was 3.4 months.

CONCLUSION

In this small, quasi-experimental prospective cohort study, we did not find evidence that our SBHC model improved academic achievement; however, the wait time at the SBHCs was considerably less than the provincial wait time for a developmental assessment.

TRIAL REGISTRATION

NCT04540003.

IMPACT

This study describes a unique and innovative school-based health center model. Our findings support the benefits of school-based health centers in diagnosing and treating children with developmental and mental health disorders for disadvantaged communities. This study did not find an improvement in academic achievement for school-based health center users. This study found that the wait time to developmental assessment was shorter for school-based health center users compared to the wait time reported in the community. Pandemic-associated school disruptions have highlighted the importance of accessible school-based health services for children requiring mental health and developmental assessments and care.

Direct Determination of Fission-Barrier Heights Using Light-Ion Transfer in Inverse Kinematics

We demonstrate a new technique for obtaining fission data for nuclei away from β stability. These types of data are pertinent to the astrophysical r process, crucial to a complete understanding of the origin of the heavy elements, and for developing a predictive model of fission. These data are also important considerations for terrestrial applications related to power generation and safeguarding. Experimentally, such data are scarce due to the difficulties in producing the actinide targets of interest. The solenoidal-spectrometer technique, commonly used to study nucleon-transfer reactions in inverse kinematics, has been applied to the case of transfer-induced fission as a means to deduce the fission-barrier height, among other variables. The fission-barrier height of ^{239}U has been determined via the ^{238}U(d,pf) reaction in inverse kinematics, the results of which are consistent with existing neutron-induced fission data indicating the validity of the technique.

Effect of Wearing a Face Mask on Hand-to-Face Contact by Children in a Simulated School Environment: The Back-to-School COVID-19 Simulation Randomized Clinical Trial

IMPORTANCE

Wearing a face mask in school can reduce SARS-CoV-2 transmission but it may also lead to increased hand-to-face contact, which in turn could increase infection risk through self-inoculation.

OBJECTIVE

To evaluate the effect of wearing a face mask on hand-to-face contact by children while at school.

DESIGN, SETTING, AND PARTICIPANTS

This prospective randomized clinical trial randomized students from junior kindergarten to grade 12 at 2 schools in Toronto, Ontario, Canada, during August 2020 in a 1:1 ratio to either a mask or control class during a 2-day school simulation. Classes were video recorded from 4 angles to accurately capture outcomes.

INTERVENTIONS

Participants in the mask arm were instructed to bring their own mask and wear it at all times. Students assigned to control classes were not required to mask at any time (grade 4 and lower) or in the classroom where physical distancing could be maintained (grade 5 and up).

MAIN OUTCOMES AND MEASURES

The primary outcome was the number of hand-to-face contacts per student per hour on day 2 of the simulation. Secondary outcomes included hand-to-mucosa contacts and hand-to-nonmucosa contacts. A mixed Poisson regression model was used to derive rate ratios (RRs), adjusted for age and sex with a random intercept for class with bootstrapped 95% CIs.

RESULTS

A total of 174 students underwent randomization and 171 students (mask group, 50.6% male; control group, 52.4% male) attended school on day 2. The rate of hand-to-face contacts did not differ significantly between the mask and the control groups (88.2 vs 88.7 events per student per hour; RR, 1.00; 95% CI, 0.78-1.28; P = >.99). When compared with the control group, the rate of hand-to-mucosa contacts was significantly lower in the mask group (RR, 0.12; 95% CI, 0.07-0.21), while the rate of hand-to-nonmucosa contacts was higher (RR, 1.40; 95% CI, 1.08-1.82).

CONCLUSIONS AND RELEVANCE

In this clinical trial of simulated school attendance, hand-to-face contacts did not differ among students required to wear face masks vs students not required to wear face masks; however, hand-to-mucosa contracts were lower in the face mask group. This suggests that mask wearing is unlikely to increase infection risk through self-inoculation.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04531254.

Quenching of Single-Particle Strength in A=15 Nuclei

Absolute cross sections for the addition of s- and d-wave neutrons to ^{14}C and ^{14}N have been determined simultaneously via the (d,p) reaction at 10  MeV/u. The difference between the neutron and proton separation energies, ΔS, is around -20  MeV for the ^{14}C+n system and +8  MeV for ^{14}N+n. The population of the 1s_{1/2} and 0d_{5/2} orbitals for both systems is reduced by a factor of approximately 0.5 compared with the independent single-particle model, or about 0.6 when compared with the shell model. This finding strongly contrasts with results deduced from intermediate-energy knockout reactions between similar nuclei on targets of ^{9}Be and ^{12}C. The simultaneous technique used removes many systematic uncertainties.

First Exploration of Neutron Shell Structure below Lead and beyond N=126

The nuclei below lead but with more than 126 neutrons are crucial to an understanding of the astrophysical r process in producing nuclei heavier than A∼190. Despite their importance, the structure and properties of these nuclei remain experimentally untested as they are difficult to produce in nuclear reactions with stable beams. In a first exploration of the shell structure of this region, neutron excitations in ^{207}Hg have been probed using the neutron-adding (d,p) reaction in inverse kinematics. The radioactive beam of ^{206}Hg was delivered to the new ISOLDE Solenoidal Spectrometer at an energy above the Coulomb barrier. The spectroscopy of ^{207}Hg marks a first step in improving our understanding of the relevant structural properties of nuclei involved in a key part of the path of the r process.

A multicentre assessment of prostate MRI quality and compliance with UK and international standards

AIM

To assess prostate magnetic resonance imaging (MRI) image quality and compliance with technical standards between centres in the South West region of the UK.

MATERIALS AND METHODS

Fifteen imaging sites in the region submitted seven consecutive anonymised MRI studies. These were assessed by two experienced radiologists in consensus. Overall, subjective image quality for T2-weighted imaging (T2W), diffusion weighted imaging (DWI), and dynamic contrast enhancement (DCE) was scored on a five-point Likert scale. Five additional quality parameters were also assessed visually, including image noise, motion, artefact, and distortion. The degree of compliance by each site with 21 published technical standards was also assessed.

RESULTS

Ninety-four MRI examinations were reviewed from across all sites (mean 6.3 scans per site, range 5-7). Mean compliance with technical standards was 63% (range 38-86%). Forty-seven percent of sites did not perform DCE. One site used a 3 T scanner. The percentage of patients with overall quality scores of ≥3 (diagnostically acceptable) were 68% for T2W, 81% for DWI, and 60% for both T2W and DWI. Ninety-three percent of the 45 patients who underwent DCE had diagnostically acceptable studies. By scanner age, the percentage of patients with diagnostically acceptable T2W scores was 53% for scanners ≥7 years and 80% when <7 years (p=0.006). Comparing individual sites, the mean overall quality scores were 2.9 (range 2.2-4.2) for T2W, 3.2 (1.8-4.7) for DWI, and 3.4 (2.5-4.7) for DCE.

CONCLUSION

There is wide variation in compliance with recognised technical standards and image quality across sites. If MRI is to replace biopsy in selected low-risk patients, improvements in image quality may be required.

The integration of transabdominal ultrasound simulators into an ultrasound curriculum

Introduction

Simulation is increasingly used throughout medicine. Within ultrasound, simulators are more established for learning transvaginal and interventional procedures. The use of modern high-fidelity transabdominal simulators is increasing, particularly in centres with large trainee numbers. There is no current literature on the value of these simulators in gaining competence in abdominal ultrasound. The aim was to investigate the impact of a new ultrasound curriculum, incorporating transabdominal simulators into the first year of training in a UK radiology academy.

Methods

The simulator group included 13 trainees. The preceding cohort of 15 trainees was the control group. After 10 months, a clinical assessment was performed to assess whether the new curriculum resulted in improved ultrasound skills. Questionnaires were designed to explore the acceptability of simulation training and whether it had any impact on confidence levels.

Results

Trainees who had received simulator-enriched training scored higher in an objective clinical ultrasound assessment, which was statistically significant (p = 0.0463). End confidence scores for obtaining diagnostic images and demonstrating pathology were also higher in the simulation group. All trainees stated that transabdominal simulator training was useful in early training.

Conclusions

This initial study shows that embedded into a curriculum, transabdominal ultrasound simulators are an acceptable training method that can result in improved ultrasound skills and higher confidence levels. Using simulators early in training could allow trainees to master the basics, improve their confidence, enabling them to get more educational value from clinical ultrasound experience while reducing the impact of training on service provision.

Can ultrasound help to manage patients with scrotal trauma?

Traumatic injuries to the scrotum are uncommon but, when they do occur, frequently lead to serious complications. Early complications include testicular infarction, necrosis and abscess formation; in the longer-term trauma may result in testicular atrophy and subfertility. Early surgical intervention in patients with testicular rupture can significantly improve the clinical outcome and reduce the need for delayed orchidectomy. However, clinical examination of the scrotum following trauma is difficult and frequently inaccurate; this may result in incorrect triage of patients for surgical exploration. Scrotal ultrasound can reliably assess scrotal injuries and diagnose testicular rupture with a high level of accuracy. Additionally, ultrasound can provide important information regarding testicular perfusion, which can further inform decisions on surgical management. This article reviews the sonographic findings that may be encountered in patients with scrotal trauma, with an emphasis on blunt trauma. It describes the pivotal role that ultrasound can play in the accurate triage of these patients to surgical or conservative management.

Single-photon emission CT using (99m)Tc-dimercaptosuccinic acid (DMSA) for characterization of suspected renal masses

OBJECTIVE

A retrospective analysis of the clinical utility of (99m)Tc-dimercaptosuccinic acid (DMSA) single photon emission CT (SPECT) for characterization of suspected renal masses.

METHODS

15 patients who had undergone (99m)Tc-DMSA SPECT were identified, and 13 patients also had SPECT/CT. (99m)Tc-DMSA uptake in the renal lesion was characterized semiquantitatively. Other imaging tests, histology and clinical data were available for correlation.

RESULTS

(99m)Tc-DMSA was not taken up in all five renal masses with histological confirmation of malignancy (uptake 7-19% of normal renal tissue); in two further masses, which were clinically likely to be malignant; and in one indeterminate mass (lack of sufficiently long follow-up). No renal malignancy was identified in any of the seven patients whose renal masses had normal (99m)Tc-DMSA uptake (41-130%).

CONCLUSION

Although caution with regard to applying those results in clinical practice must be advised, owing to the retrospective nature of this report and the small number of patients included, it seems that (99m)Tc-DMSA SPECT shows a clinically useful diagnostic accuracy for distinguishing true renal masses (which in many cases require surgery) from pseudomasses.

ADVANCES IN KNOWLEDGE

(99m)Tc-DMSA SPECT is a clinically useful adjunct test for characterization of suspected renal masses.

Shape coexistence in the neutron-deficient even-even (182-188)Hg isotopes studied via coulomb excitation

Coulomb-excitation experiments to study electromagnetic properties of radioactive even-even Hg isotopes were performed with 2.85  MeV/nucleon mercury beams from REX-ISOLDE. Magnitudes and relative signs of the reduced E2 matrix elements that couple the ground state and low-lying excited states in Hg182-188 were extracted. Information on the deformation of the ground and the first excited 0+ states was deduced using the quadrupole sum rules approach. Results show that the ground state is slightly deformed and of oblate nature, while a larger deformation for the excited 0+ state was noted in Hg182,184. The results are compared to beyond mean field and interacting-boson based models and interpreted within a two-state mixing model. Partial agreement with the model calculations was obtained. The presence of two different structures in the light even-mass mercury isotopes that coexist at low excitation energy is firmly established.

Testicular microlithiasis an ultrasound dilemma: survey of opinions regarding significance and management amongst UK ultrasound practitioners

OBJECTIVE

To establish whether there is a consensus regarding the significance of testicular microlithiasis and a strategy for managing patients with this condition, amongst ultrasound practitioners in the UK.

METHODS

An electronic questionnaire was distributed to 1482 members of the British Medical Ultrasound Society (BMUS), requesting information from ultrasound practitioners involved in scrotal ultrasound about their interpretation of the risk associated with testicular microlithiasis and their departmental or personal recommendations for managing patients with this condition.

RESULTS

Responses were obtained from 221 BMUS members. Analysis demonstrated a wide variation in the significance attributed to the discovery of testicular microlithiasis and the risk of subsequent development of testicular germ cell tumours. There was also great variation in strategies for management of patients with testicular microlithiasis, including the need for surveillance ultrasound, amongst ultrasound practitioners regardless of their job description.

CONCLUSION

Lack of consensus shown by this study highlights significant differences across the UK in managing patients with testicular microlithiasis and validates the importance of guidance currently being formulated by the European Society of Urogenital Radiology.

ADVANCES IN KNOWLEDGE

We believe that this is the first survey to be conducted amongst imaging specialists in the UK regarding testicular microlithiasis and demonstrates that there is currently no uniform practice in managing patients with this condition.

Quenching of cross sections in nucleon transfer reactions

Cross sections for proton knockout observed in (e,e'p) reactions are apparently quenched by a factor of ∼0.5, an effect attributed to short-range correlations between nucleons. Here we demonstrate that such quenching is not restricted to proton knockout, but a more general phenomenon associated with any nucleon transfer. Measurements of absolute cross sections on a number of targets between 16O and 208Pb were analyzed in a consistent way, with the cross sections reduced to spectroscopic factors through the distorted-wave Born approximation with global optical potentials. Across the 124 cases analyzed here, induced by various proton- and neutron-transfer reactions and with angular momentum transfer ℓ=0-7, the results are consistent with a quenching factor of 0.55. This is an apparently uniform quenching of single-particle motion in the nuclear medium. The effect is seen not only in (d,p) reactions but also in reactions with A=3 and 4 projectiles, when realistic wave functions are used for the projectiles.

Test of sum rules in nucleon transfer reactions

The quantitative consistency of nucleon transfer reactions as a probe of the occupancy of valence orbits in nuclei is tested. Neutron-adding, neutron-removal, and proton-adding transfer reactions were measured on the four stable even Ni isotopes, with particular attention to the cross section determinations. The data were analyzed consistently in terms of the distorted wave Born approximation to yield spectroscopic factors. Valence-orbit occupancies were extracted, utilizing the Macfarlane-French sum rules. The deduced occupancies are consistent with the changing number of valence neutrons, as are the vacancies for protons, both at the level of <5%. While there has been some debate regarding the true "observability" of spectroscopic factors, the present results indicate that empirically they yield self-consistent results.

Digital tomosynthesis--a new lease of life for the intravenous urogram?

OBJECTIVES

Digital tomosynthesis is a new digital technique based on conventional X-ray tomography. It acquires multiple low-dose projections during a single sweep of the X-ray tube, which are reassembled to provide high-resolution slices at different depths. Suggested uses include visualisation of pulmonary nodules, mammography, angiography, dental imaging and delineation of fractures. This study aims to evaluate its potential role as part of an intravenous urogram (IVU) by assessing the diagnostic quality in imaging the kidneys in clinical practice.

METHODS

100 renal units from consecutive traditional IVU studies were retrospectively compared with 101 renal units imaged using digital tomosynthesis. These were scored for visualisation of the renal outline and collecting system, presence of a renal cyst or mass and overall diagnostic quality. Radiation doses were calculated.

RESULTS

46.5% of traditional IVUs were found to be of diagnostic quality. The IVUs with digital tomosynthesis were of diagnostic quality in 95.5%. This represents a highly statistically significant difference (p<0.0001). There was also a statistically significant dose reduction, with a mean reduction of 56%, for the samples studied.

CONCLUSION

Digital tomosynthesis offers a significant increase in the percentage of diagnostic quality tests for assessing renal pathology, compared with traditional IVU, and significantly reduces radiation. It also offers considerable advantages in ease and speed of imaging. For these reasons, in any situation where IVU is still being used to assess the kidneys, digital tomosynthesis is likely to be of considerable benefit in improving diagnostic quality.

A training simulator for ultrasound-guided percutaneous nephrostomy insertion

Increasing trainee numbers and changes to working patterns have resulted in a scarcity of training opportunities for training-grade doctors wishing to learn nephrostomy tube insertion techniques. A method of introducing trainees to the skills required to perform percutaneous nephrostomy in a safe, non-threatening environment, without risk to patients, is desirable. Commercial and biological nephrostomy phantoms are available, but they are expensive and not widely available, and a cheap, safe, valid alternative is desirable. We describe a simple technique for producing a gelatin-based phantom, which we suggest has face and content simulator validity. The use of this nephrostomy phantom could optimise existing clinical training opportunities through familiarisation with nephrostomy technique and equipment, and development of the psychomotor skills required for successful nephrostomy insertion prior to undertaking supervised procedures on patients.

First experiment with HELIOS: the structure of 13B

A first experiment is reported that makes use of a new kind of spectrometer uniquely suited to the study of reactions with radioactive beams in inverse kinematics, the helical orbit spectrometer, HELIOS. The properties of some low-lying states in the neutron-rich N=8 nucleus 13B were studied with good resolution. From the measured angular distributions of the (d,p) reaction and the relative spectroscopic factors, spin and configuration assignments of the first- and third-excited states of this nucleus can be constrained.

Initial clinical experience of an ultrasonic strain imaging system with novel noise-masking capability

Quasistatic strain imaging is a form of elastography that can produce qualitative images of tissue stiffness with only software modifications to conventional ultrasound hardware. Unlike current commercial offerings, the novel strain-imaging system that is the subject of this paper displays regions of signal decorrelation using an overlaid colour mask and can also produce three-dimensional (3D) strain images. In illustrative studies of the breast, testis and thyroid, the colour mask is seen to reduce the potential to misinterpret noise as meaningful stiffness information, and also helps to differentiate cystic and solid lesions. High-quality imaging of the testis in vivo demonstrates that 3D strain imaging is feasible.

Structure of 240Pu: evidence for octupole phonon condensation?

The expanded level structure of 240Pu available from the present study highlights the role of strong octupole correlations in this nucleus. In addition to a delayed alignment in the yrast band, the observations include the presence of both I(+)-->(I-1)(-) and I(-)-->(I-1)(+)E1 transitions linking states of the yrast and negative-parity bands at high spin and the presence of an additional even-spin, positive-parity band deexciting exclusively to the negative-parity sequence. The observations appear to be consistent with expectations based on the recently proposed concept of octupole phonon condensation.

MRI appearances of acute idiopathic scrotal oedema in an adult

Acute idiopathic scrotal oedema is an uncommon cause of acute painless scrotal swelling that is usually seen in children. Traditionally, ultrasound has been used to help establish the diagnosis in the appropriate clinical setting. We report the MRI appearances of acute idiopathic scrotal oedema in a 51-year-old male with associated involvement of the penis.

Nuclear structure relevant to neutrinoless double beta decay: 76Ge and 76Se

The possibility of observing neutrinoless double beta decay offers the opportunity of determining the effective neutrino mass if the nuclear matrix element were known. Theoretical calculations are uncertain, and measurements of the occupations of valence orbits by nucleons active in the decay can be important. The occupation of valence neutron orbits in the ground states of 76Ge (a candidate for such decay) and 76Se (the daughter nucleus) were determined by precisely measuring cross sections for both neutron-adding and removing transfer reactions. Our results indicate that the Fermi surface is much more diffuse than in theoretical calculations. We find that the populations of at least three orbits change significantly between these two ground states while in the calculations, the changes are confined primarily to one orbit.

Polycystic kidneys: a cautionary story

We describe the imaging appearances of a patient with bilateral, synchronous, multiloculated renal cell carcinoma with a predominantly cystic nature. The patient had progressive chronic renal failure. He was initially erroneously diagnosed as having autosomal dominant polycystic kidney disease (ADPKD) on the basis of the imaging findings. We believe this to be the first report describing bilateral synchronous renal carcinomas replacing the renal parenchyma imitating ADPKD.

Effect of a triaxial nuclear shape on proton tunneling: the decay and structure of 145Tm

Gamma rays deexciting states in the proton emitter 145Tm were observed using the recoil-decay tagging method. The 145Tm ground-state rotational band was found to exhibit the properties expected for an h{11/2} proton decoupled band. In addition, coincidences between protons feeding the 2{+} state in 144Er and the 2{+}-->0{+} gamma-ray transition were detected, the first measurement of this kind, leading to a more precise value for the 2{+} excitation energy of 329(1) keV. Calculations with the particle-rotor model and the core quasiparticle coupling model indicate that the properties of the pi{11/2} band and the proton-decay rates in 145Tm are consistent with the presence of triaxiality with an asymmetry parameter gamma approximately 20 degrees .

Isospin symmetry of odd-odd mirror nuclei: identification of excited states in N=Z-2 48Mn

Excited states have been observed in the N=Z-2 odd-odd nucleus 48Mn for the first time. Through comparison with the structure of 48V, a first high-spin study of an odd-odd mirror pair has been achieved. Differences between the T=1 analogue states in this pair have been interpreted in terms of Coulomb effects, with the aid of shell-model calculations in the full pf valence space. Unlike other mirror pairs, the energy differences have been interpreted almost entirely as due to a monopole effect associated with smooth changes in radius (or deformation) as a function of angular momentum. In addition, the large energy shift between analogue negative-parity states is interpreted in terms of the electromagnetic spin-orbit interaction in nuclei.

Evidence for nontermination of rotational bands in 74Kr

Three rotational bands in 74Kr were studied up to (in one case one transition short of) the maximum spin I(max) of their respective single-particle configurations. Their lifetimes have been determined using the Doppler-shift attenuation method. The deduced transition quadrupole moments reveal a modest decrease, but far from a complete loss of collectivity at the maximum spin I(max). This feature, together with the results of mean field calculations, indicates that the observed bands do not terminate at I = I(max).

Is the nuclear spin-orbit interaction changing with neutron excess?

The difference in the energies of the lowest states corresponding to the two nodeless single-particle orbitals outside the Z=50 closed proton shell, h(11/2) and g(7/2), increases with neutron excess. We have measured the Sn(alpha,t) reaction for all seven stable even Sn isotopes and found that the spectroscopic factors are constant for these two states, confirming their characterization as single-particle states. The trend in energies is consistent with a decrease in the nuclear spin-orbit interaction. A similar trend, also suggesting a decreasing spin-orbit splitting, is seen in the energies of the neutron single-particle states outside the N=82 core, i(13/2) and h(9/2).

Alignment delays in the N = Z nuclei (72)Kr, (76)Sr, and (80)Zr

The ground state rotational bands of the N = Z nuclei (72)Kr, (76)Sr, and (80)Zr have been extended into the angular momentum region where rotation alignment of particles is normally expected. By measuring the moments of inertia of these bands we have observed a consistent increase in the rotational frequency required to start pair breaking, when compared to neighboring nuclei. (72)Kr shows the most marked effect. It has been widely suggested that these "delayed alignments" arise from np-pairing correlations. However, alignment frequencies are very sensitive to shape degrees of freedom and normal pairing, so the new experimental observations are still open to interpretation.

Equilibrium folding properties of the yeast prion protein determinant Ure2

The yeast non-Mendelian factor [URE3] propagates by a prion-like mechanism, involving aggregation of the chromosomally encoded protein Ure2. The [URE3] phenotype is equivalent to loss of function of Ure2, a protein involved in regulation of nitrogen metabolism. The prion-like behaviour of Ure2 in vivo is dependent on the first 65 amino acid residues of its N-terminal region which contains a highly repetitive sequence rich in asparagine. This region has been termed the prion-determining domain (PrD). Removal of as little as residues 2-20 of the protein is sufficient to prevent occurrence of the [URE3] phenotype. Removal of the PrD does not affect the regulatory activity of Ure2. The C-terminal portion of the protein has homology to glutathione S -transferases, which are dimeric proteins. We have produced the Ure2 protein to high yield in Escherichia coli from a synthetic gene. The recombinant purified protein is shown to be a dimer. The stability, folding and oligomeric state of Ure2 and a series of N-terminally truncated or deleted variants were studied and compared. The stability of Ure2, DeltaGD-N, H2O, determined by chemical denaturation and monitored by fluorescence, is 12.1(+/-0.4) kcal mol-1at 25 degrees C and pH 8.4. A range of structural probes show a single, coincident unfolding transition, which is invariant over a 550-fold change in protein concentration. The stability is the same within error for Ure2 variants lacking all or part of the prion-determining domain. The data indicate that in the folded protein the PrD is in an unstructured conformation and does not form specific intra- or intermolecular interactions at micromolar protein concentrations. This suggests that the C-terminal domain may stabilise the PrD against prion formation by steric means, and implies that the PrD does not induce prion formation by altering the thermodynamic stability of the folded protein.

Marrow versus infection in the Charcot joint: indium-111 leukocyte and technetium-99m sulfur colloid scintigraphy

This study evaluated the role of combined leukocyte/marrow scintigraphy in the assessment of the neuropathic or Charcot joint.

METHODS

Seventeen patients with (111)In-labeled leukocyte accumulation in 20 radiographically confirmed Charcot joints underwent 99mTc-sulfur colloid marrow scintigraphy. Studies demonstrating labeled leukocyte accumulation without corresponding activity on marrow images were classified as positive for osteomyelitis. Six of the patients also underwent three-phase bone scintigraphy. Bone scans were interpreted as positive for osteomyelitis when focal hyperperfusion, focal hyperemia and focal bony uptake on delayed images were present. Bone images were also interpreted together with labeled leukocyte images using two different criteria for a positive study. One criterion was the presence of labeled leukocyte activity in a region demonstrating abnormal activity on the bone scan, which was more intense than adjacent marrow activity or marrow activity in the corresponding region of the contralateral foot. The second criterion was either a spatially incongruent distribution of the two tracers or hyperintense activity on the leukocyte study, as compared to the bone scan.

RESULTS

Leukocyte/marrow studies were positive for osteomyelitis in 4 of the 20 neuropathic joints. Osteomyelitis was present in three of the four joints, whereas in the fourth, infection was confined to overlying soft tissues. None of the 16 neuropathic joints with negative leukocyte/marrow scans were infected. In one patient who underwent below-the-knee amputation, histological analysis confirmed the presence of hematopoietically active marrow corresponding to areas of congruent activity on the leukocyte and marrow images. Three-phase bone scintigraphy was positive in all six neuropathic joints studied; osteomyelitis was present in two of them. Using the first criterion, leukocyte/bone imaging was also positive in all six. Using the second criterion, leukocyte/bone imaging was positive in the two infected neuropathic joints, as well as in three uninfected ones. Leukocyte/marrow scintigraphy was positive in both infected joints and negative in the four without infection.

CONCLUSION

Labeled leukocyte accumulation in the uninfected Charcot joint does occur and is related, at least in part, to hematopoietically active marrow. Leukocyte/marrow scintigraphy is a reliable way to differentiate between marrow and infection as the cause of labeled leukocyte accumulation in the neuropathic joint and, in this series, was superior to both three-phase bone scintigraphy and combined leukocyte/bone scintigraphy.

Radioisotopes and their use in the diagnosis and management of thyroid disease

The use of radioactive isotopes in thyroid evaluation and therapy gives important information in the endocrine assessment of the aged. Thyroid uptake imaging can be used to establish a hypothyroid or hyperthyroid state and can determine the functional status of a palpable nodule. Investigational agents, such as T1 201m DMSA, MIBG, FDG, and Gallium are reviewed in relation to the evaluation of neoplasia. A detailed discussion of thyroid carcinoma ablation and subsequent radioiodine therapy is described, as are radiation safety procedures as they relate to the elderly.

Demonstration of supernumerary tracheal bronchus by computed tomographic scanning and magnetic resonance imaging

A bronchus arising directly from the trachea is an infrequent congenital anomaly which usually represents the displaced origin of a normal bronchus. Rarely, a true supernumerary tracheal bronchus occurs supplying an associated tracheal lobe. The case is described of a patient in whom a supernumerary tracheal bronchus and tracheal lobe was demonstrated by computed tomographic scanning and magnetic resonance imaging.