Abnormal dopamine transporter imaging in pure autonomic failure: a potential biomarker of central nervous system involvement

BACKGROUND AND PURPOSE

Pure autonomic failure (PAF) is a rare progressive neurodegenerative disease characterized by neurogenic orthostatic hypotension at presentation, without other neurological abnormalities. Some patients may develop other central neurological features indicative of multiple system atrophy or a Lewy body disorder. There are currently no biomarkers to assess possible central nervous system involvement in probable PAF at an early stage. A possibility is to evaluate the nigrostriatal dopaminergic degeneration by imaging of dopamine transporter with DaTscan brain imaging. The objective was to evaluate subclinical central nervous system involvement using DaTscan in PAF.

METHODS

We retreospectively reviewed pure autonomic failure patients who were evaluated at the Autonomic Unit between January 2015 and August 2021 and underwent comprehensive autonomic assessment, neurological examination, brain magnetic resonance imaging and DaTscan imaging. DaTscan imaging was performed if patients presented with atypical features which did not meet the criteria for Parkinson's disease or multiple system atrophy or other atypical parkinsonism.

RESULTS

In this cohort, the median age was 49.5 years at disease onset, 57.5 years at presentation, and the median disease duration was 7.5 years. Five of 10 patients had an abnormal DaTscan without neurological features meeting the criteria of an alternative diagnosis. Patients with abnormal DaTscan were predominantly males, had shorter disease duration and had more severe genitourinary symptoms.

DISCUSSION

Degeneration of nigrostriatal dopaminergic neurons measured using DaTscan imaging can present in patients with PAF without concurrent signs indicating progression to widespread α-synucleinopathy. It is advocated that DaTscan imaging should be considered as part of the workup of patients with emerging autonomic failure who are considered to have PAF.

Chest radiograph classification and severity of suspected COVID-19 by different radiologist groups and attending clinicians: multi-reader, multi-case study

OBJECTIVES

To quantify reader agreement for the British Society of Thoracic Imaging (BSTI) diagnostic and severity classification for COVID-19 on chest radiographs (CXR), in particular agreement for an indeterminate CXR that could instigate CT imaging, from single and paired images.

METHODS

Twenty readers (four groups of five individuals)-consultant chest (CCR), general consultant (GCR), and specialist registrar (RSR) radiologists, and infectious diseases clinicians (IDR)-assigned BSTI categories and severity in addition to modified Covid-Radiographic Assessment of Lung Edema Score (Covid-RALES), to 305 CXRs (129 paired; 2 time points) from 176 guideline-defined COVID-19 patients. Percentage agreement with a consensus of two chest radiologists was calculated for (1) categorisation to those needing CT (indeterminate) versus those that did not (classic/probable, non-COVID-19); (2) severity; and (3) severity change on paired CXRs using the two scoring systems.

RESULTS

Agreement with consensus for the indeterminate category was low across all groups (28-37%). Agreement for other BSTI categories was highest for classic/probable for the other three reader groups (66-76%) compared to GCR (49%). Agreement for normal was similar across all radiologists (54-61%) but lower for IDR (31%). Agreement for a severe CXR was lower for GCR (65%), compared to the other three reader groups (84-95%). For all groups, agreement for changes across paired CXRs was modest.

CONCLUSION

Agreement for the indeterminate BSTI COVID-19 CXR category is low, and generally moderate for the other BSTI categories and for severity change, suggesting that the test, rather than readers, is limited in utility for both deciding disposition and serial monitoring.

KEY POINTS

• Across different reader groups, agreement for COVID-19 diagnostic categorisation on CXR varies widely. • Agreement varies to a degree that may render CXR alone ineffective for triage, especially for indeterminate cases. • Agreement for serial CXR change is moderate, limiting utility in guiding management.

Does relative renal function improve after intervention for chronic ureteric obstruction?

Introduction

Unilateral renal function often deteriorates with chronic ureteric obstruction. Our objectives were to determine the change in relative renal function (RRF) by MAG3 renography after intervention for ureteric obstruction, and to identify clinical/epidemiological factors which influence long-term outcomes.

Material and methods

We identified 228 patients from 2006 to 2017 who underwent MAG3 renography before and after intervention for unilateral ureteric obstruction. Patients were grouped into categories preoperatively - with normal RRF (43–57%) through mild (29–42%), moderate (15–28%) and severe (<15%) impairment of RRF. Patient demographics, types of obstructive uropathy and intervention employed were analysed. Each group was assessed for the absolute change in RRF and change in RRF category postoperatively.

Results

The mean patient age was 50.4 years (SD 16.7), and 62.3% were female. Overall, the mean pre- and post-intervention RRF of the obstructed kidney did not differ significantly (32.30% vs. 32.20%, P = 0.835). Most patients remained in their preoperative RRF group: 85.9% of normal, 67.4% of mild, 64.4% of moderate and 73.3% of patients with severe RRF impairment did not change category.

Patients with mildly impaired preoperative RRF showed a significant worsening postoperatively (36.37% vs. 34.58%, P = 0.024). The other three groups showed no significant change in RRF following intervention.

Multivariate logistic regression analysis showed no statistically significant association between type of intervention, age, gender or diagnosis and improvement in postoperative RRF category.

Conclusions

Our results show that RRF does not improve significantly after intervention for ureteric obstruction. The aim should therefore be to maintain existing renal function and relieve symptoms.

Metastatic malignancy mimics: a rare case of traumatic splenosis mimicking intra-abdominal malignancy

We present a case of a patient, undergoing imaging for an unrelated presentation, whose adolescent abdominal trauma had caused an unrecognised disseminated intra-abdominal splenosis, resulting in an imaging presentation on CT that suggested intra-abdominal malignancy. The lack of correlative symptoms of disseminated malignancy, in addition to imaging findings suggesting previous upper abdominal trauma, led to a suggestion that the intra-abdominal lesion might represent spleen tissue. A denatured red cell scan with radio-labelled technetium-99m, allowed this tissue to be confirmed as splenic in nature, and an invasive, and potentially risky biopsy was averted.

Quantifying center of pressure variability in chondrodystrophoid dogs

The center of pressure (COP) position reflects a combination of proprioceptive, motor and mechanical function. As such, it can be used to quantify and characterize neurologic dysfunction. The aim of this study was to describe and quantify the movement of COP and its variability in healthy chondrodystrophoid dogs while walking to provide a baseline for comparison to dogs with spinal cord injury due to acute intervertebral disc herniations. Fifteen healthy adult chondrodystrophoid dogs were walked on an instrumented treadmill that recorded the location of each dog's COP as it walked. Center of pressure (COP) was referenced from an anatomical marker on the dogs' back. The root mean squared (RMS) values of changes in COP location in the sagittal (y) and horizontal (x) directions were calculated to determine the range of COP variability. Three dogs would not walk on the treadmill. One dog was too small to collect interpretable data. From the remaining 11 dogs, 206 trials were analyzed. Mean RMS for change in COPx per trial was 0.0138 (standard deviation, SD 0.0047) and for COPy was 0.0185 (SD 0.0071). Walking speed but not limb length had a significant effect on COP RMS. Repeat measurements in six dogs had high test retest consistency in the x and fair consistency in the y direction. In conclusion, COP variability can be measured consistently in dogs, and a range of COP variability for normal chondrodystrophoid dogs has been determined to provide a baseline for future studies on dogs with spinal cord injury.

Incidence of extrinsic compression of the internal jugular vein in unselected patients undergoing CT angiography

BACKGROUND AND PURPOSE

Little is known about how commonly the internal jugular vein is compressed by extrinsic structures in the upper neck. The purpose of this paper was to identify the frequency and cause of external compression of the superior segment of the internal jugular vein.

MATERIALS AND METHODS

Retrospective review of CT angiograms of the neck was performed in 108 consecutive patients. Axial source images were evaluated for moderate (>50%) or severe (>80%) stenosis of the internal jugular vein on the basis of external compression. The cause of extrinsic compression was also recorded. In cases with stenosis, the presence of ipsilateral isoattenuated collateral veins was recorded and considered representative of collateral flow.

RESULTS

Moderate stenosis was seen in 33.3% of right and 25.9% of left internal jugular veins. Severe stenosis was seen in 24.1% of right and 18.5% of left internal jugular veins. The most common causes of extrinsic compression included the styloid process and the posterior belly of the digastric muscle. In patients with severe internal jugular vein stenosis, 53.8% of right sides and 55% of left sides had associated condylar collaterals.

CONCLUSIONS

Extrinsic compression of the superior segment of the internal jugular vein is a common finding in unselected patients, often caused by the styloid process or the posterior belly of the digastric muscle. Presence of severe stenosis is not universally associated with collateral formation.

Solitary fibrous tumor of the buccal space: treatment with percutaneous cryoablation

Solitary fibrous tumors are rare spindle cell neoplasms that typically occur in the thorax but have been described in various locations within the abdomen and head and neck region. The most common extrapleural site is the oral cavity, but these tumors have been also described in the orbit, nasopharynx, paranasal sinuses, salivary glands, and larynx. We describe a case of a solitary fibrous tumor of the buccal space successfully treated with percutaneous CT-guided cryoablation.

Family-centred care for children in hospital

BACKGROUND

Family-centred care (FCC) is a widely used model in paediatrics, and is felt instinctively to be the best way to provide care to children in hospital. However, its effectiveness has not been measured.

OBJECTIVES

The primary objective of this review was to assess the effects of family-centred models of care for hospitalised children when compared to standard or professionally-centred models of care, on child, family and health service outcomes.

SEARCH STRATEGY

We searched: MEDLINE (1966 to February 2004); the Cochrane Central Register of Controlled Trials (CENTRAL), (The Cochrane Library, Issue 2, 2004); CINAHL (1982 to February 2004); PsycINFO (1972 to February 2004); ERIC (1982 to February 2004); Sociological Abstracts (1963 to February 2004); Social Work Abstracts (1977 to February 2004); and AMI (Australasian Medical Index) (1966 to February 2004).

SELECTION CRITERIA

We searched for randomised controlled trials (RCTs) or quasi-randomised controlled trials including cluster randomised trials and controlled clinical trials (CCTs), and controlled before and after studies (CBAs), in which family-centred care models are compared with professionally-centred models of care for hospitalised children (aged up to 12 years). Studies also had to meet criteria for family-centredness and methodological quality. In order to assess studies for the degree of family-centredness, this review utilised a modified rating scale based on a validated instrument.

DATA COLLECTION AND ANALYSIS

Two review authors undertook the searches, and three authors independently assessed trial quality and extracted data. We contacted study authors for additional information.

MAIN RESULTS

No studies met inclusion criteria, and hence no analysis could be undertaken. Five studies came close to inclusion. Three of these studies were excluded primarily because of inadequate or unclear blinding of outcome assessment, while for one study the age group was outside the parameters of this review. One study met most criteria, but the children were aged up to 18 years. We contacted the study authors who kindly provided a subset analysis, but on further examination the study also proved to have inadequate blinding procedures and so was not included. It was not possible to undertake any subset analysis of populations. Of the other studies identified through the search, 13 met some of the inclusion criteria but were reports of qualitative research and are reviewed elsewhere.

AUTHORS' CONCLUSIONS

This review has highlighted the dearth of high quality quantitative research about family-centred care. A much more stringent examination of the use of family-centred care as a model for care delivery to children and families in health services is needed.

Multiple paternity and mating patterns in the American alligator,Alligator mississippiensis

Eggs were sampled from 22 wild American alligator nests from the Rockefeller Wildlife Refuge in south-west Louisiana, along with the females guarding the nests. Three nests were sampled in 1995 and 19 were sampled in 1997. Females and offspring from all clutches were genotyped using five polymorphic microsatellite loci and the three nests from 1995 were also genotyped using one allozyme locus. Genotypes of the hatchlings were consistent with the guarding females being the mothers of their respective clutches. Multiple paternity was found in seven of the 22 clutches with one being fathered by three males, and the remaining six clutches having genotypes consistent with two males per clutch. Paternal contributions of multiply sired clutches were skewed. Some males sired hatchlings of more than one of the 22 clutches either as one of two sires of a multiple paternity clutch, as the sole sire of two different clutches, or as the sole sire of one clutch and one of two sires of a multiply sired clutch. There was no significant difference between females that had multiple paternity clutches and those that had singly sired clutches with respect to female total length (P = 0.844) and clutch size (P = 0.861). Also, there was no significant correlation between genetic relatedness of nesting females and pairwise nest distances (r2 = 0.003, F1,208 = 0.623, P = 0.431), indicating that females in this sample that nested close to one another were no more related than any two nesting females chosen at random. Eleven mutations were detected among hatchlings at the five loci over the 22 clutches. Most of these mutations (eight of 11) occurred at Ami(mu)-17, the only compound microsatellite locus of the five used in this study, corresponding to a mutation rate of 1.7 x 10-3. Finally, most of the mutations (82%) were homoplasious, i.e., mutating to an allelic state already present in this Louisiana population.

Differential destabilization of repetitive sequence hybrids in fluorescence in situ hybridization

A method for painting a chromosome or chromosome region by fluorescence in situ hybridization (FISH) without blocking DNA is described. Both unique sequence and repetitive sequence components of a fluorescently labeled probe are hybridized under low-stringency conditions, but the chromosomes are washed in such a manner that repetitive sequences are differentially removed, while region-specific unique sequence fragments remain bound to the target chromosomes. We refer to this differential retention and removal of probe components as differential stability FISH.

CT of the brain: a comparison of transportable and fixed-platform scanners

OBJECTIVE

The purpose of this study was to determine whether an in-hospital transportable CT scanner can provide diagnostic brain images and to compare the quality of these images with those from a conventional fixed-platform CT scanner.

SUBJECTS AND METHODS

Twenty-seven patients with known or suspected intracranial pathology underwent imaging on a transportable scanner and a fixed-platform scanner within 1 hr of each other. Images from each CT examination were evaluated independently by two neuroradiologists who were unaware of patient history. Conspicuousness of intracranial pathology and normal anatomy were rated on a 5-point scale (1 point, optimal; 5 points, poor or not visualized). Statistical comparisons were made using nonparametric tests.

RESULTS

Seven CT scans were interpreted as showing normal findings and 20 scans revealed intracranial pathology on both CT scanners. Image quality was higher on the fixed scanner (average rating, 2.42 points; SE = .12) than on the transportable scanner (average rating, 3.10 points; SE = .12) (p = .001). Depiction of the cerebellum, midbrain, and supratentorial gray-white matter was better on the fixed scanner (p < .05). However, we found no significant differences in detection of intracranial pathology between scanners. Both radiologists found images from both scanners to be diagnostic in all 27 patients.

CONCLUSION

Images of the brain on the transportable CT scanner were less clear than those on a fixed scanner. However, images from the transportable CT scanner were diagnostic in 27 consecutive patients. The implications of this finding are important for the provision of CT services for critically ill patients who cannot be transported to the radiology department.

Hybridization-based karyotyping of mouse chromosomes: hybridization-bands

We have developed a method, which we have named hybridization-banding, to identify simultaneously all chromosomes in a mouse metaphase spread. The method uses a combination of hybridization probes labeled with a single fluor to yield a simple, unique, readily identifiable hybridization pattern on each chromosome. The method is superior to Giemsa- or fluorescence-based banding methods for chromosome identification because the hybridization patterns are simpler and easier to identify, and unique patterns can be designed at will for each chromosome. Analysis can be performed with a standard fluorescence microscope, and images can be recorded on film with an ordinary 35-mm camera, making the method useful to many investigators. The method can also be applied to any species for which chromosomes and probes can be prepared.

Application of in situ PCR to yeast cells for screening YAC libraries

We have used in situ PCR technology in yeast cells with the ultimate goal of cloning and screening genomic yeast artificial chromosome (YAC) libraries. The target sequences in YAC clones were amplified "in situ" in yeast cells by the same set of microsatellite primers used in solution-based PCR screening. The method is fast and sensitive and obviates the steps required for individual isolation of DNAs from hundreds to thousands of YAC clones and thus has an advantage over conventional solution-based PCR screening. This approach can conceivably be applied to the products of automated robotic workstations.

Mus and Peromyscus chromosome homology established by FISH with three mouse paint probes

Fluorescence-labeled DNA probes constructed from three whole house mouse (Mus domesticus) chromosomes were hybridized to metaphase spreads from deer mouse (Peromyscus maniculatus) to identify homologies between the species. Mus Chr 7 probe hybridized strongly to the ad-centromeric two-thirds of Peromyscus Chr 1q. Most of Mus 3 probe hybridized principally to two disjunct segments of Peromyscus Chr 3. Mus Chr 9 probe hybridized entirely to the whole Peromyscus Chr 7. Three Peromyscus linkage groups were assigned to chromosomes, based on linkage homology with Mus. The data also are useful in interpretation of chromosomal evolutionary history in myomorphic rodents.

MR imaging of implanted depth and subdural electrodes: is it safe?

This study evaluates the safety of imaging chronic epilepsy patients with intracranial depth and subdural electrodes by magnetic resonance (MR). To identify an epileptogenic focus, the precise location of the electrode contacts is necessary, and MR can provide this information. However, many neurosurgeons and neuroradiologists are hesitant to scan patients by MR with these implanted, metallic electrodes for fear of electrode displacement, current induction or heating secondary to the strong magnetic field. In the present study, the subdural electrodes were made of stainless steel with either stainless steel or platinum contacts. The depth electrodes were made of either platinum or a nickel-chromium alloy (nichrome). We reviewed 98 cases in which patients with implanted depth electrodes, subdural electrodes, or both underwent MR scanning. A total of 143 depth electrodes, 688 subdural strips, and 38 subdural grids were implanted in the 98 procedures. MR scanning was performed on a 1.5-T unit and consisted of T1, T2, and/or spoiled gradient echo pulse sequences. There were no documented complications related to the MR scans. Based on this study and a review of the literature, we feel that MR imaging can safely localize intracranial electrodes.

Analysis of large and small colony L5178Y tk-/- mouse lymphoma mutants by loss of heterozygosity (LOH) and by whole chromosome 11 painting: detection of recombination

Analysis of 122 spontaneous large and small colony mutants derived from L5178Y tk +/- mouse lymphoma cells at 28 heteromorphic microsatellite loci on chromosome 11 showed that extensive loss of heterozygosity (LOH) is common in both large colony and small colony mutants, eliminating most chromosome 11 loci as candidates for a putative growth control locus. These results, in conjunction with historical cytogenetic data, suggest that a putative growth control locus lies distal to the thymidine kinase (Tk1) gene, near the telomere. Thirty seven mutants were hybridized with a chromosome 11-specific whole chromosome painting probe for analysis of rearrangements. Generally, painting confirmed earlier observations that large colony mutants are karyotypically normal, whereas small colony mutants frequently have detectable rearrangements. A point probe distal to Tk1 revealed no evidence of chromosome breakage in small colony mutants that appeared normal on whole 11 painting and had no LOH. Therefore, the molecular difference between large and small colony mutants remains unknown. Models to explain large and small colony mutants consistent with our findings are presented, including loss of a putative growth control gene, differential mechanisms of chromosome breakage/repair and second site mutations as explanations for small colony mutants. Painting revealed translocations and aneuploidy and showed that non-disjunction was not a common explanation for complete LOH. The most common finding was that large regions of LOH do not result from deletions, demonstrating that these cells can detect recombination events as well as previously observed chromosomal rearrangements, deletions and point mutations.

Monte carlo simulation of a single-molecule detection experiment

The physical and instrumental processes that occur in experiments for the detection of individual fluorescent molecules in solution are described, with emphasis on their incorporation into a quantitative Monte Carlo simulation. The simulation is applied to the conditions of a past experiment [Appl. Opt. 34, 3208 (1995)], which utilizes a sheath flow system for high detection efficiency, and it generates comparable results, while helping to identify experimental limitations. The simulation indicates that the use of low dead-time electronics and appropriate selection of experimental parameters should enable detection at more rapid rates for applications in which large numbers of molecules are to be efficiently counted.

Evaluation of orthodontic relapse using the cubic spline function

A sample of 72 orthodontically treated patients was reexamined many years out of retention. They had been treated either by the extraction of four premolars or without extractions. The average number of years between the end of treatment and the taking of follow-up records was 20, with a range of 12 to 35 years. Some conventional measurements were studied such as intertooth widths, arch perimeter, and incisor irregularity. In addition, a new method for comparison of arch form at different stages of treatment, which uses the cubic spline function, was used. Cases were grouped into extraction and nonextraction, and statistics were used to test the differences between the two groups. Correlations between the spline variables and conventional variables were computed, and multiple regression analysis was carried out using the spline variables as dependent variables. Some treatment and relapse changes were independent of whether the case was treated with extractions or not, whereas other trends were unique to one treatment group. The correlation analysis revealed strong relationships between variables that measured changes during the same treatment stage. There were also moderate correlations between some of the spline variables and the traditional measurements. Multiple regression analysis was used to account for changes in some spline variables, however, the usefulness of the model as a predictor is limited.

Slow ventricular conduction in mice heterozygous for a connexin43 null mutation

To characterize the role of the gap junction protein connexin43 (Cx43) in ventricular conduction, we studied hearts of mice with targeted deletion of the Cx43 gene. Mice homozygous for the Cx43 null mutation (Cx43 -/-) die shortly after birth. Attempts to record electrical activity in neonatal Cx43 -/- hearts (n = 5) were unsuccessful. Ventricular epicardial conduction of paced beats, however, was 30% slower in heterozygous (Cx43 -/+) neonatal hearts (0.14+/-0.04 m/s, n = 27) than in wild-type (Cx43 +/+) hearts (0.20+/-0.07 m/s, n = 32; P < 0.001). This phenotype was even more severe in adult mice; ventricular epicardial conduction was 44% slower in 6-9 mo-old Cx43 -/+ hearts (0.18+/-0.03 m/s, n = 5) than in wild-type hearts (0.32+/-0.07 m/s, n = 7, P < 0.001). Electrocardiograms revealed significant prolongation of the QRS complex in adult Cx43 -/+ mice (13.4+/-1.8 ms, n = 13) compared with Cx43 +/+ mice (11.5+/-1.4 ms, n = 12, P < 0.01). Whole-cell recordings of action potential parameters in cultured disaggregated neonatal ventricular myocytes from Cx43 -/+ and +/+ hearts showed no differences. Thus, reduction in the abundance of a major cardiac gap junction protein through targeted deletion of a Cx43 allele directly leads to slowed ventricular conduction.

Spatially organized response zones in rat olfactory epithelium

Electroolfactogram recordings were made with a four-electrode assembly from the olfactory epithelium overlying the endoturbinate bones facing the nasal septum. In this study we tested whether odors of different chemical structures produce maximal responses along longitudinally oriented regions following the olfactory receptor gene expression zones described in the literature. The distribution of responses along the dorsal-to-ventral direction of this epithelium (i.e., across the expression zones) was tested in two types of experiments. In one, four electrodes were fixed along the dorsal-to-ventral axis of one turbinate bone. In the other, four electrodes were placed in corresponding positions on four turbinate bones and moved together up toward the top of the bone. These experiments compared the odorants limonene and alpha-terpinene, which are simple hydrocarbons, with carvone and menthone, which differ from the hydrocarbons by the presence of ketone groups. All responses were standardized to an amyl acetate or ethyl butyrate standard. The responses to limonene and alpha-terpinene were often larger for the ventral electrodes. The responses to carvone and menthone were largest for the dorsal electrodes. Intermediate electrodes gave responses that were intermediate in amplitude for these odors. The possibility that direction of air flow caused the observed response distributions was directly tested in experiments with odor nozzles placed in two positions. The relatively larger dorsal responses to carvone and relatively larger ventral responses to limonene were present despite odor nozzle position. We conclude that the responses to this set of odors vary systematically in a fashion parallel to the four gene expression zones. The odorant property that governs this response distribution may be related to the presence of oxygen-containing functional groups. Certain odors evoked larger responses at the intermediate electrode sites than at other sites. Cineole was the best example of this effect. This observation shows that not all oxygen-containing functional groups produce the same effect. Although we cannot exclude other possible mechanisms, these three response gradients may be produced by the four receptor expression zones described for many of the putative olfactory receptor genes. Therefore many of the receptors in each zone may share common properties. It remains to be determined whether this zonal input is significant in central odor processing. However, the correlation of odor chemical properties with the structure of receptor molecules in each zone may provide significant leads to structure-function relationships in vertebrate olfaction.

Identification of a heteromorphic microsatellite within the thymidine kinase gene in L5178Y mouse lymphoma cells

The objective of this work is to identify a heteromorphism within the thymidine kinase (Tk1) gene which can be used to assay for allele loss by means of PCR. Intron F of mouse Tk1 contains two (CA)n microsatellite sequences separated by 107 bp of non-repetitive sequence. We tested this region for heteromorphism in L5178Y mouse lymphoma cells. A PCR primer pair designated Agl1 yielded products of 396 and 194 bp from L5178Y tk+/- genomic DNA. The 194-bp product resulted from a secondary binding site between the two (CA)n repeats for the forward Ag11 primer and was not produced from tk-/- mutants that had lost the functional Tk1b allele. Agl2 primers produced two PCR products of 523 and approximately 440 bp and Agl3 primers produced products of 579 and approximately 500 bp. In both these cases, the difference in product size was approximately equal, indicating that Intron F is approximately 80 bp shorter in the non-functional Tk1a allele than in Tk1b. This heteromorphism forms the basis for an assay for allele loss by means of PCR. Agl1 and Agl3 primers yielded additional products of 91 and 274 bp, respectively, consistent with sizes expected from the mouse Tk1 pseudogenes (Tk1-ps). Our conclusions drawn from an analysis of 122 mutants for Tk1b loss using Agl2 primers agreed with previous analysis of the NcoI heteromorphism. Thus, a simple PCR-based analysis can identify Tk1b loss in the L5178Y mouse lymphoma cells.

Olfactory marker protein (OMP) gene deletion causes altered physiological activity of olfactory sensory neurons

Olfactory marker protein (OMP) is an abundant, phylogentically conserved, cytoplasmic protein of unknown function expressed almost exclusively in mature olfactory sensory neurons. To address its function, we generated OMP-deficient mice by gene targeting in embryonic stem cells. We report that these OMP-null mice are compromised in their ability to respond to odor stimull, providing insight to OMP function. The maximal electroolfactogram response of the olfactory neuroepithelium to several odorants was 20-40% smaller in the mutants compared with controls. In addition, the onset and recovery kinetics following isoamyl acetate stimulation are prolonged in the null mice. Furthermore, the ability of the mutants to respond to the second odor pulse of a pair is impaired, over a range of concentrations, compared with controls. These results imply that neural activity directed toward the olfactory bulb is also reduced. The bulbar phenotype observed in the OMP-null mouse is consistent with this hypothesis. Bulbar activity of tyrosine hydroxylase, the rate limiting enzyme of catecholamine biosynthesis, and content of the neuropeptide cholecystokinin are reduced by 65% and 50%, respectively. This similarity to postsynaptic changes in gene expression induced by peripheral olfactory deafferentation or naris blockade confirms that functional neural activity is reduced in both the olfactory neuroepithelium and the olfactory nerve projection to the bulb in the OMP-null mouse. These observations provide strong support for the conclusion that OMP is a novel modulatory component of the odor detection/signal transduction cascade.

Relation of chemical structure to spatial distribution of sensory responses in rat olfactory epithelium

1. Electroolfactogram (EOG) recordings were made in three configurations from the rat olfactory epithelium. Each configuration compared recordings in the dorsomedial recess of the epithelium with recordings in ventral or lateral parts of the epithelium. Most comparisons were made with simultaneous recordings. The exception was a series in which the dorsal recess and lateral space between the base of two turbinate bones were directly exposed for odor application and recording. The spatial distributions of maximal responses were largely independent of recording configuration. 2. Simultaneous recordings compared dorsomedial and lateral sites in the epithelium during stimulation with a series of 50 odorants. The odorants that evoked larger responses in the lateral sites were usually compounds that lacked oxygen containing functional groups (such as the carbonyl group). This was true for straight chain and cyclic alkanes, for terpine compounds, and for aromatic compounds. The major exception was cineole, a bicyclic compound. All compounds containing ketone groups evoked larger dorsomedial responses. The responses of aldehydes and esters depended upon whether they were attached to aliphatic or aromatic chains. 3. In the three types of preparation, the sites responding best to ketones were in the same expression zone of the epithelium according to published maps for the rat and mouse. The sites responding best to odors without functional groups were in the far lateral or ventral region and corresponded to one of the two most lateral and ventral expression zones. This fact suggests that the receptors in these regions have a preference for particular chemical properties. This level of analysis cannot determine whether all receptors in each zone have a stronger response to certain properties of these odorants or whether each zone contains different proportions of receptors with these properties.

Chromosome Microdissection-Based Techniques for Genome Analysis

It is now possible to start at a cytogenetically defined position in any eucaryotic genome and proceed toward isolation and identification of candidate genes known to map to that position, taking advantage of the new PCR amplification technology to produce position-specific DNA. The starting material for this very useful exercise is DNA microdissected from standard cytogenetic preparations. Here we describe techniques for acquiring useful samples of such DNA and strategies for the use of chromosome region-specific DNA for gene discovery projects.

Selection of hybrids by affinity capture (SHAC): a method for the generation of cDNAs enriched in sequences from a specific chromosome region

We have established a method for preparing cDNA sublibraries enriched in sequences from specific chromosome regions, called selection of hybrids by affinity capture (SHAC). This procedure can be described in two stages. In the first stage, a particular chromosome region, in this study mouse chromosome 11, was microdissected, followed by PCR amplification with a universal degenerate primer. This material is referred to as the "target" DNA. In the second stage, a mouse liver cDNA library with unique linker-adapter ends, referred to as the "source" cDNA, was hybridized to the biotin-labeled target DNA prepared during the first stage. The resulting DNA duplexes were captured by streptavidin-coated magnetic beads. The cDNAs were released from their biotin-labeled target homologs by alkaline denaturation and recovered by PCR amplification. These cDNAs were referred to as the SHACcDNAs. Specificity of the SHACcDNA to chromosome 11 was verified by FISH analysis. To examine representation of the SHACcDNA, we confirmed the presence of seven genes or single-copy DNA segments known to be localized on mouse chromosome 11, using a dot blot assay. In addition, a second round of SHAC was performed to achieve even higher specificity for the resulting chromosome 11 SHACcDNA. The SHAC technology should facilitate construction of cytogenetically defined cDNA libraries and should assist in the fields of gene discovery and genome mapping.

Effects of Medicare's prospective payment system on service use by depressed elderly inpatients

OBJECTIVE

To determine the effects of Medicare's prospective payment system (PPS) on hospital care, changes in length of stay and intensity of clinical services received by 2,746 depressed elderly patients in 297 acute care general medical hospitals were studied.

METHODS

A pre-post design was used, and differences in sickness at admission were controlled for. Data on length of stay and use of specific clinical services were obtained from the medical record using a medical record abstraction form. Care provided on units exempt from PPS was compared with care provided in nonexempt units.

RESULTS

After implementation of PPS, the average length of stay fell by up to three days within the different types of acute care settings studied, but this decline was partially offset by proportionately more admissions to psychiatric units, which had longer lengths of stay. Intensity of clinical services increased after PPS implementation, especially in nonexempt psychiatric units.

CONCLUSION

Despite financial incentives for hospitals to reduce clinical services under PPS, its implementation was not associated with a marked decline in length of stay, when averaged across all treatment settings, and was associated with an increase in the intensity of many clinical services used by depressed elderly patients in general hospitals.

Gap junction protein phenotypes of the human heart and conduction system

INTRODUCTION

Gap junction channels are major determinants of intercellular resistance to current flow between cardiac myocytes. Alterations in gap junctions may contribute to development of arrhythmia substrates in patients. However, there is significant interspecies variation in the types and amounts of gap junction subunit proteins (connexins) expressed in disparate regions of mammalian hearts. To elucidate determinants of conduction properties in the human heart, we characterized connexin phenotypes of specific human cardiac tissues with different conduction properties.

METHODS AND RESULTS

The distribution and relative abundance of Cx37, Cx40, Cx43, Cx45, and Cx46 were studied immunohistochemically using monospecific antibodies and frozen sections of the sinoatrial node and adjacent atria. AV node and His bundle, the bundle branches, and the left and right ventricular walls. Patterns of expression of these connexins in the human heart differed from those in previous animal studies. Sinus node gap junctions were small and sparse and contained Cx45 and apparently smaller amounts of Cx40 but no Cx43. AV node gap junctions were also small and contained mainly Cx45 and Cx40 but, unlike the sinus node, also expressed Cx43. Atrial gap junctions were larger than nodal junctions and contained moderate amounts of Cx40, Cx43, and Cx45. Junctions in the bundle branches were the largest in size and contained abundant amounts of Cx40, Cx43, and Cx45. Gap junctions in ventricular myocardium contained mainly Cx43 and Cx45; only a very small and amount of ventricular Cx40 was detected in subendocardial myocyte junctions and endothelial cells of small to medium sized intramural coronary arteries. Minimal Cx37 and Cx46 immunoreactivity was detected between occasional atrial or ventricular myocytes.

CONCLUSIONS

The relative amounts of individual connexins and the number and size of gap junctions vary greatly in specific regions of the human heart with different conduction properties. These differences likely play a role in regulating cardiac conduction velocity. Differences in the connexin phenotypes of specific regions of the human heart and experimental animal hearts must be considered in future experimental or modeling studies of cardiac conduction.

Mouse chromosome-specific painting probes generated from microdissected chromosomes

Using degenerate primer amplification of chromosomes microdissected from banded cytogenetic preparations, we constructed both whole chromosome painting probes for mouse Chromosomes (Chrs) 1, 2, 3, and 11 and a centromere probe that strongly paints most mouse centromeres. We also amplified a Robertsonian translocation chromosome microdissected from unstained preparations to construct a painting probe for Chrs 9 and 19. The chromosome probes uniformly painted the respective chromosomes of origin. We demonstrated the utility of the Chr 11 probe in aberration analysis by staining mutants that we had previously identified as containing a Chr 11 translocation, and in some mutant cell lines we observed chromosome rearrangements not previously detected in stained cytogenetic preparations. The technology of microdissection and amplification applies to all mouse chromosomes or to specific subchromosomal regions and will be useful in mouse genetics, in aberration analysis, and for chromosome identification.

Quality of care for depressed elderly patients hospitalized in the specialty psychiatric units or general medical wards

BACKGROUND

Studies to assess quality of care have become increasingly important for research and policy purposes.

OBJECTIVE

To evaluate the difference in quality of care between elderly depressed patients hospitalized in specialty psychiatric units and those hospitalized in general medical wards.

METHODS

We reviewed retrospectively the medical charts of 2746 patients with depression hospitalized in 297 general medical hospitals in five different states. Quality of care was assessed by clinical review of explicit and implicit information contained in the medical records of patients in specialty psychiatric units (n = 1295) and general medical wards (n = 1451). We also used other secondary data sources to determine postdischarge outcomes.

RESULTS

We found that (1) a higher percentage of admissions on the psychiatric units were considered appropriate, (2) overall psychological assessment was better on the psychiatric unit, (3) patients were more likely to receive psychological services on the psychiatric wards but more likely to receive traditional general medical services on medical wards, (4) there were more inpatient general medical complications on the psychiatric wards, and (5) implicit measures of clinical status at discharge were better for those on the psychiatric unit.

CONCLUSIONS

Although limited by reliance on medical record abstraction and a retrospective study design, our data indicate that the quality of care for the psychological aspects of the treatment of depression may be better on psychiatric units, while the quality of general medical components of care may be better on general medical wards.

Localisation of ventricular tachycardia substrates by analysis of the surface QRS recorded during ventricular tachycardia

BACKGROUND

Analysis of the surface ECG can predict the locations of pacing foci but is of limited value for locating arrhythmogenic substrates causing ventricular tachycardia because of the effects of myocardial infarction, ischaemia, and bundle branch block on ventricular activation.

AIM

To determine whether analysis of the initial 60 ms segment of the surface QRS improves the accuracy of the ECG for predicting ventricular tachycardia origin we correlated the locations of 37 arrhythmogenic areas present in 20 patients with the 3D vectors of the ventricular tachycardias generated by each respective area.

METHODS

The 3D vector of each ventricular tachycardia morphology was calculated from the integrals of the initial 60 ms of the surface vectorcardiogram and from the entire QRS recorded in each lead of the Frank orthogonal lead vectorcardiogram. Sixty eight-morphologies of ventricular tachycardia were mapped using simultaneous recordings from 60 catheter electrodes.

RESULTS

Ventricular tachycardias with 3D vectors directed inferiorly and posteriorly or superiorly and anteriorly were more likely to originate from the septum, P = 0.04, whereas tachycardias directed superiorly and to the right were more likely to originate from the inferior wall and the cardiac apex, P = 0.001. However, the same arrhythmogenic area could generate multiple ventricular tachycardias with different 3D vectors. In addition, ventricular tachycardias with similar 3D vectors were generated by arrhythmogenic areas in the septal, apical and inferior walls. The variances of the mean 3D vectors of ventricular tachycardias originating from each of 12 different cardiac regions were no different when based on the initial 60 ms of the surface QRS than on the entire surface QRS.

CONCLUSION

Analysis of the surface ECG provides only an approximate guide to the locations of arrhythmogenic areas generating ventricular tachycardia even when analysis is restricted to the initial forces in the surface QRS. Therefore, detailed mapping is needed to accurately determine the number and location of arrhythmogenic areas.

Rapid and efficient detection of single chromophore molecules in aqueous solution

The first experiments on the detection of single fluorescent molecules in a flowing stream of an aqueous solution with high total efficiency are reported. A capillary injection system for sample delivery causes all the dye molecules to pass in a diffusion-broadened stream within a fast-moving sheath flow, through the center of the tightly focused laser excitation beam. Single-molecule detection with a transit time of ~1 ms is accomplished with a high-quantum-efficiency single-photon avalanche diode and a low dead-time time-gating circuit for discrimination of Raman-scattered light from the solvent.

Regional distribution of rat electroolfactogram

1. Electroolfactorgram (EOG) recordings were made from different regions of the rat olfactory epithelium to test for spatial distribution of odor responses. 2. The EOG recordings showed spatial distribution of the odor responses in the olfactory epithelium. While some odorants (amyl acetate, anisole, and ethyl butyrate) were more effective in evoking responses in the dorsal recess near the septum, other odorants (including limonene, cineole, cyclooctane, and hexane) were more effective in the lateral recesses among the turbinate bones. These differences were seen as statistically significant odorant-by-position interactions in analysis of variance. 3. Comparisons of recordings along the anteroposterior dimension of the epithelium produced smaller differences between the odor responses. These were not significant for 3-mm distances, but were statistically significant for 5- to 6-mm distances along the dorsomedial epithelium. 4. The latencies were significantly longer in the lateral recesses than in the medial region. This probably reflects a more tortuous air path along the turbinate bones to the lateral recesses. 5. The olfactory receptor cells were activated by antidromic stimulation via the nerve layer of the olfactory bulb. The population spikes evoked from the olfactory receptor cells could be suppressed by prior stimulation with odorants that evoked strong EOG responses. This collision of the antidromic action potentials with the odor-evoked action potentials indicates that the same population of receptor cells was activated in both cases. 6. The flow rate and duration of the artificial sniff were varied systematically in some experiments. The differential distribution of response sizes was present at all flow rates and sniff durations. Some odors (e.g., amyl acetate and anisole) produced increased responses in the epithelium of the lateral recesses when flow rates or sniff durations were high. We suggest that these changes may reflect the sorptive properties of the nasal membranes on these odors. The responses to other odors (e.g., hexane or limonene) were not greatly affected by flow rate or sniff duration. 7. Taken with existing anatomic data, the results indicate that the primary olfactory neurons that project axons to glomeruli in different parts of the olfactory bulb are responsive to different odors. The latency differences between responses at medial and lateral sites are large enough to be physiologically significant in the generation of the patterned responses of olfactory bulb neurons.

The molecular basis of anisotropy: role of gap junctions

Electrical activation of the heart requires transfer of current from one discrete cardiac myocyte to another, a process that occurs at gap junctions. Recent advances in knowledge have established that, like most differentiated cells, individual cardiac myocytes express multiple gap junction channel proteins that are members of a multigene family of channel proteins called connexins. These proteins form channels with unique biophysical properties. Furthermore, functionally distinct cardiac tissues such as the nodes and bundles of the conduction system and atrial and ventricular muscle express different combinations of connexins. Myocytes in these tissues are interconnected by gap junctions that differ in tissue-specific manner in terms of their number, size, and three-dimensional distribution. These observations suggest that both molecular and structural aspects of gap junctions are critical determinants of the anisotropic conduction properties of different cardiac tissues. Expression of multiple connexins also creates the possibility that "hybrid" channels composed of more than one connexin protein type can form, thus greatly increasing the potential for fine control of intercellular ion flow and communication within the heart.

Cardiac intercellular communication: consequences of connexin distribution and diversity

Gap junctions contain channels which allow the exchange of ions and small molecules between adjacent cells. In the heart, these channels are crucial for normal intercellular current flow and the propagation of action potentials throughout the myocardium. Molecular cloning studies have demonstrated that these channels are formed by members of a family of related proteins called connexins each containing conserved and unique regions. There are several consequences of this multiplicity of connexins. Multiple connexins are expressed in differing, but sometimes overlapping, distributions within cardiovascular and other tissues. Connexin40, connexin43, and connexin45 are all found in cardiac myocytes, but their abundance differs in specialized cardiac regions with disparate conductive properties. Individual connexins form channels with differing voltage-dependence, conductance, and permeability properties, as demonstrated by functional expression of the cloned sequences. Connexins differ in their modification by phosphorylation, which may contribute to physiological regulation of intercellular communication. Expression of multiple connexins may lead to the formation of multiple channel types in a single tissue or cell and potentially allows mixing to form heterotypic and/or heteromeric channels. Thus, multiple connexins may contribute to the differences in intercellular resistance in cardiac regions with differing conductive properties and possibly may allow differences in the signalling molecules that pass between cells.

Simultaneous mapping of the tricuspid and mitral valve annuli at electrophysiological study

BACKGROUND

Mapping of the right free wall in patients with accessory pathways is difficult compared with that of the left free wall where the coronary sinus permits stable and accurate location of the electrodes used for endocardial mapping. Furthermore, the sequential roving catheter method is less satisfactory than multiple simultaneous electrode recordings spanning the circumference of the valve annulus. A new method for mapping the tricuspid annulus is described.

METHODS

Mapping was performed in nine patients with a suspected right free wall accessory pathway or an atriofascicular connection. The tricuspid annulus was mapped using a specially shaped 1 cm interelectrode 10 pole catheter positioned in the right atrium immediately above the annulus. The coronary sinus was mapped with a 5 mm interelectrode 10 pole catheter and a 2 mm interelectrode 10 pole catheter recorded His bundle activity. Catheter positions were confirmed by multiplane fluoroscopy. Electrograms were digitised and recorded simultaneously using a custom computerised mapping system. The position of the multielectrode catheter around the tricuspid annulus relative to that of the coronary arteries was examined by coronary angiography in three patients.

RESULTS

Seven right free wall and two posterior septal accessory pathways, and three atriofascicular connections were detected. Ventricular activation adjacent to both valve annuli was mapped in five patients with pre-excitation. The locations of eight of the nine accessory pathways and the three atriofascicular connections were confirmed at operative mapping. One right free wall accessory pathway in a patient with Ebstein's anomaly was not detected at operative mapping. No additional accessory pathways were found at operative mapping or routine 6 month postoperative electrophysiological study, or during a mean (SD) clinical follow up of 22 (7) months. The tricuspid annulus catheter was located during coronary angiography at a mean (SD) of about 2.5 (0.7) cm above and parallel to the right coronary artery in the right atrioventricular groove.

CONCLUSIONS

This new catheter technique permits rapid detailed mapping of atrial and ventricular activation around the tricuspid annulus with a resolution of at least < or = % 1 cm, depending on the number and spacing of electrodes in each catheter. The technique was accurate as judged by mapping at surgery. This method is simple and safe compared with that of others for mapping the right free wall via the right coronary artery. It should facilitate detection and ablation of right free wall accessory pathways and atriofascicular connections.

Modulation of connexin43 expression: effects on cellular coupling

INTRODUCTION

Gap junctions connect cardiac myocytes allowing propagation of action potentials. They contain intercellular channels formed by multiple different connexin proteins. The arrangement and type of gap junctions and the types, function, and interaction of connexin proteins determine intercellular resistance and can thereby influence conduction velocity and the potential for reentrant arrhythmias. Our goal was to develop genetically manipulable models to test the effects of altering expression of a major cardiac connexin (connexin43) on intercellular coupling and expression of other connexin proteins.

METHODS AND RESULTS

BHK cells that are poorly coupled and BWEM cells that are well coupled were stably transfected with plasmids containing connexin43 cDNA in antisense and sense orientations. RNA blots confirmed expression of the transfected transcripts. Immunoblots showed that connexin43 protein was reduced in the BHK antisense transfectants and increased in the BHK sense transfectants compared to the parental cells. It was not detectably changed in the BWEM antisense transfectant line compared to the BWEM parental cells. Transfection of connexin43 cDNA did not affect production of connexin45 mRNA and protein nor did transfection induce expression of other previously unexpressed connexin mRNAs. Cell coupling was assessed by intercellular diffusion of microinjected Lucifer yellow in confluent cell populations. Lucifer yellow passed to a mean of 3 +/- 3 neighboring parental BHK cells, to 8 +/- 8 neighbors in the sense connexin43 transfected BHK cells, and to only 2 +/- 2 neighbors in the antisense connexin43 transfected BHK cells (P < 0.05). In contrast, dye transfer did not differ significantly between the parental BWEM cells (mean transfer = 19 +/- 14 cells) and the BWEM connexin43 antisense transfectants (mean transfer = 15 +/- 12 cells) (P = 0.20).

CONCLUSIONS

These data demonstrate that stable transfection with connexin43 cDNA constructs can result in detectable changes in connexin43 expression and cellular coupling without inducing compensatory changes in the cell's connexin phenotype and, therefore, may provide a basis for future attempts at specifically modulating connexin expression and intercellular resistance in cardiac tissues.

Expression of multiple gap junction proteins in human fetal and infant hearts

Mammalian cardiac myocytes express multiple gap junction channel proteins or connexins. Expression patterns of the avian homologues of the mammalian cardiac connexins change during cardiac morphogenesis in association with changes in the electrophysiologic properties of intercellular junctions in chick cardiac myocytes. To determine whether expression of cardiac connexins is developmentally regulated in humans, we characterized connexin mRNA and protein content and distribution in hearts of 11 human fetuses (74 to 122 d gestational age), seven children (0.5 mo to 3 y of age), and two adults. Northern blot analysis identified transcripts of connexin40 (Cx40), connexin43 (Cx43), and connexin45 (Cx45) genes in all hearts analyzed. Cx40 mRNA was approximately 5-fold more abundant in samples from fetal hearts than in hearts of children or adults. However, fetal samples used for RNA extraction included atrial as well as ventricular myocardium, whereas samples from children and adults were exclusively ventricular. Northern analysis of adult human right atrial appendages revealed abundant Cx40 mRNA, thus suggesting that the greater amount of Cx40 signal seen on Northern blots from fetal hearts could have been attributable to atrial contributions. Neither Cx43 nor Cx45 mRNA varied significantly in amount in samples from the different developmental stages analyzed. Immunofluorescence identified abundant Cx43 in the known distribution of gap junctions in myocytes in sections of all hearts. Cx45 staining was inconspicuous in fetal hearts but was readily apparent in cardiac myocytes in hearts of older subjects. In contrast, Cx40 staining in the ventricle was confined to mural coronary arteries, apparently in endothelial cells, whereas in the atrium Cx40 staining at myocyte junctions was abundant.(ABSTRACT TRUNCATED AT 250 WORDS)

Distinct gap junction protein phenotypes in cardiac tissues with disparate conduction properties

OBJECTIVES

We sought to characterize the connexin phenotypes of selected regions of the canine heart with different conduction properties to determine whether variations in connexin expression might contribute to the differences in intercellular resistance and conduction velocity that occur in different cardiac tissues.

BACKGROUND

Gap junctions connect cardiac myocytes, allowing propagation of action potentials. Intercellular channels with different electrophysiologic properties are formed by different connexin proteins.

METHODS

To determine which connexins were likely to be expressed in the sinus node, atrioventricular (AV) node and atrial and ventricular myocardium, messenger ribonucleic acids (RNAs) from each of these sites were hybridized with probes for connexin26, connexin31, connexin32, connexin37, connexin40, connexin43, connexin45, connexin46 and connexin50. Immunostaining with monospecific antibodies to connexin40, connexin43 and connexin45 was used to delineate the distribution of connexins in frozen sections of these different cardiac tissues.

RESULTS

Only messenger RNAs coding for connexin40, connexin43 and connexin45 were detected by Northern blot analysis. By immunohistochemical staining, junctions in the sinus and AV nodes and proximal His bundle were virtually devoid of connexin43 but contained both connexin40 and connexin45. Gap junctions in the distal His bundle and the proximal bundle branches stained intensely for connexin40 and connexin43 and to a lesser extent for connexin45. Atrial gap junctions showed abundant staining of connexin43, connexin40 and connexin45. Ventricular gap junctions were characterized by abundant staining of connexin43 and connexin45 and much less staining of connexin40.

CONCLUSIONS

Although most cardiac gap junctions contain connexin40, connexin43 and connexin45, the relative amounts of each of these connexins vary considerably in cardiac tissues with different conduction properties.

Simultaneous 60-electrode mapping of ventricular tachycardia using percutaneous catheters

OBJECTIVES

We developed a new approach for mapping ventricular tachycardia at electrophysiologic study using simultaneous recordings from up to 60 catheter electrodes.

BACKGROUND

Good results for surgical or catheter ablation of ventricular tachycardia are limited by the ability to detect and completely map all of the underlying arrhythmogenic areas. Currently, catheter mapping of all configurations of ventricular tachycardia is impossible or unsatisfactory in at least 60% of patients because of poorly tolerated rapid rates, nonsustained ventricular tachycardia or multiple configurations.

METHODS

Twenty-four patients with recurrent ventricular tachycardia refractory to antiarrhythmic drugs were studied using up to six percutaneous decapolar catheters introduced into the ventricles. Left ventricular maps of ventricular tachycardia were achieved by two to three transseptal catheters, two to three transaortic catheters, a coronary sinus catheter and right ventricular catheters. Simultaneous endocardial maps of either right or left ventricles were possible with a resolution of approximately 1 to 2 cm. Up to 60 electrograms were digitized and recorded simultaneously using a custom-computerized mapping system.

RESULTS

Successful maps of 73 ventricular tachycardia configurations were obtained in 22 patients. The mapping procedure failed in two patients because of inability to catheterize the left ventricle in one and inability to induce monomorphic ventricular tachycardia in the other. The mean (+/- SD) ventricular tachycardia cycle length was 285 +/- 53 ms (range 215 to 470). A total of 39 separate arrhythmogenic areas (median 1, interquartile [25% to 75%] range 1 to 3/patient) were detected, of which 21 (54%) were in the left ventricular free wall, 17 (44%) were in the ventricular septum, and 1 (2%) was in the right ventricular outflow tract. Ten patients (45%) had at least two arrhythmogenic areas. Thirteen patients subsequently underwent operation. All but one of the arrhythmogenic areas found at surgical mapping had been identified at preoperative catheter mapping. Complications of the preoperative mapping procedure occurred in four patients, with complete resolution in three and minor long-term sequelae in the other.

CONCLUSIONS

This technique permits detailed catheter mapping of all types of monomorphic ventricular tachycardias, including those leading to hemodynamic collapse, and should enable better choice and direction of surgical or catheter ablation.

Loss of heterozygosity in spontaneous and chemically induced tumors of the B6C3F1 mouse

The B6C3F1 mouse is used worldwide to gauge the carcinogenic hazard posed by chemicals to humans. An assessment of the ability of this rodent model to predict human neoplasia requires an evaluation of similarities and differences in the genetics of tumor formation between these two species. We examined 142 spontaneous and chemically-induced liver tumors isolated from the B6C3F1 mouse for losses of heterozygosity (LOH) at 78 polymorphic loci and compared these results to genetic changes known to occur in human hepatocellular carcinoma. Approximately a third of the 142 mouse tumors exhibited LOH, suggesting that tumor suppressor gene inactivation may be involved in the formation of mouse liver tumors. Most of the LOH observed was restricted to seven chromosome sites and most of the tumors that underwent LOH lost alleles from only one of those seven sites. The relatively few losses seen in these mouse tumors distinguished them from clinical stage human tumors in that, in the mouse tumors, interstitial deletions appeared more frequently than losses of whole chromosomes. Only four mouse tumors lost a whole chromosome. LOH occurred at loci of the mouse genome syntenic to areas of the human genome known to harbor the Wilms', retinoblastoma, APC, MCC and DCC tumor suppressor genes; these genes have never been associated with hepatocellular carcinomas. Losses observed on chromosomes 5 and 8 (syntenic to human chromosomes 4 and 16) suggest tumor suppressor genes that are common to hepatocellular carcinomas from both species, while losses on chromosome 9 suggest involvement of a previously unidentified tumor suppressor gene.

Can the electrophysiologic study predict treatment outcome in patients with sustained ventricular tachyarrhythmias unrelated to coronary artery disease?

Sustained ventricular tachyarrhythmias unrelated to coronary artery disease are uncommon. Currently there are no clear guidelines to aid selection of the most appropriate treatment strategy. Therefore, factors potentially predictive of arrhythmia recurrence and death and the ability of the electrophysiologic study to predict treatment outcome in patients with spontaneous sustained ventricular tachyarrhythmias unrelated to coronary artery disease were examined in 41 medically treated patients followed for a median of 25 (range 1-76) months. Examined factors were: syncope associated with the spontaneous arrhythmia, the morphology and cycle length of the presenting arrhythmia, underlying ventricular function, cardiac pathology, and the results of drug assessment at electrophysiologic study. Random variability in the ease of arrhythmia induction at electrophysiologic study was measured for the group as a whole and was allowed for in prediction of an effective drug response. The 95% confidence intervals for variability in the ease of repeat arrhythmia induction at the same study were < or = 1 extrastimulus and for variability in the ease of repeat arrhythmia inductions at different studies were < or = 2 extrastimuli. Poisson regression models were used for data analysis. Arrhythmia recurrence was most likely in: (1) patients on treatment not predicted to be anti-arrhythmic at electrophysiologic study; (2) patients whose treatment was not assessable at electrophysiologic study because the arrhythmia was not reliably inducible; (3) patients with impaired ventricular function; and (4) re-entered patients whose arrhythmia had recurred on previously allocated therapy. The risk of arrhythmia recurrence decreased with time from hospital assessment. All five deaths occurred in patients with impaired ventricular function.

CONCLUSIONS

drug efficacy should be tested at electrophysiologic study in patients with reproducibly inducible clinical arrhythmias. Treatment not proven to be anti-arrhythmic at electrophysiologic study is usually ineffective. Patients with ventricular dysfunction are at highest risk of death from arrhythmia recurrence and should be considered for an implantable defibrillator, arrhythmia surgery, or heart transplantation if drug treatment is not predicted to be effective or is not assessable at electrophysiologic study.

Quality of care for depressed elderly pre-post prospective payment system: differences in response across treatment settings

We evaluated the quality of care for depressed elderly patients (n = 2,746) hospitalized in general medical hospitals (n = 297) before or after implementation of Medicare's Prospective Payment System, focusing on whether the response to time period differed for hospitals that in the post-PPS period had no psychiatric unit, an exempt psychiatric unit, or a nonexempt unit, and by ward placement within hospitals with psychiatric units. Quality of care increased over time, and for most measures of quality of care the level of improvement did not differ significantly across different types of hospitals or by ward placement. The intensity of use of therapeutic services, such as rehabilitation, occupation, or recreation therapy, increased over time, particularly in nonexempt psychiatric units and hospitals without psychiatric units, such that these locations caught up some over time in the level of use of these services to the level for exempt psychiatric units. Several outcomes of care improved over time, and the degree of improvement in the rate of inpatient medical and psychiatric complications and other outcomes was significantly greater for psychiatric units that were exempt post-PPS than for nonexempt treatment locations.

Quality of care for hospitalized depressed elderly patients before and after implementation of the Medicare Prospective Payment System

OBJECTIVE

The authors evaluated the impact of Medicare's Prospective Payment System on aspects of quality of care and outcomes for depressed elderly inpatients in acute-care general medical hospitals.

METHOD

The depressed elderly inpatients (N = 2,746) were hospitalized in 297 acute-care general medical hospitals. The authors used a retrospective before-and-after design, controlling for differences over time in sickness at admission. Quality of care and outcomes were assessed through clinical review of explicit and implicit information in the medical records; secondary data sources provided information on postdischarge outcomes.

RESULTS

After implementation of the prospective payment system 1) a higher percentage of patients had clinically appropriate acute-care admissions; 2) the initial assessment of psychological status by the treating provider was more complete; 3) the quality of psychotropic medication management, as rated by the study psychiatrists, improved; 4) the rates of any inpatient medical or psychiatric complication, of discharge to another hospital or a nursing home, and of inpatient readmission declined; and 5) there was no marked change in the percentage of patients rated by study clinicians as having acceptable overall clinical status at discharge or the rate of mortality 1 year after admission.

CONCLUSIONS

After the implementation of the Medicare Prospective Payment System, the quality of care for depressed elderly inpatients improved and there was no marked increase in adverse clinical outcomes. Despite these gains, after implementation the quality of care was moderate at best and over one-third of the patients had unacceptable clinical status at discharge.

Tears of the anterior cruciate ligament: primary and secondary signs at MR imaging

To investigate primary and secondary signs of anterior cruciate ligament (ACL) tear at magnetic resonance (MR) imaging, the authors retrospectively reviewed 103 MR imaging examinations obtained in 99 patients, the original interpretations of these examinations, clinical records, and arthroscopy reports. Fifty cases of arthroscopy-documented complete ACL tear were included. The primary signs of ACL tear (ie, abnormal ACL morphologic features or signal intensity) had respective sensitivity and specificity values of 96% (48 of 50 examinations) and 94% (50 of 53) on sagittal images and 92% (46 of 50) and 83% (43 of 52) on coronal images. As a secondary sign of ACL tear, bone bruise involving the lateral compartment of the knee was found in 40% (20 of 50) of cases of ACL tear and in 4% (2 of 53) of cases of normal ACL. The mean curvature of the posterior cruciate ligament was increased (0.40 vs 0.27; P < .0001) in cases of ACL tear. An abnormal appearance of the ACL on sagittal images remains the single most sensitive and specific sign of ACL tear.

Accuracy of various methods of localization of the orifice of the coronary sinus at electrophysiologic study

The coronary sinus (CS) orifice is an important reference point for determining electrode and, thereby, accessory pathway location at electrophysiologic study. The reliability of fluoroscopic landmarks used to identify the CS orifice is not known. This study compared the accuracy of several fluoroscopic landmarks for identifying the CS orifice with the location defined by radiopaque contrast injection of the CS. Forty patients were studied. Radiographic markers of the CS orifice that were examined included: (1) the point at which the CS catheter prolapsed during advancement, (2) the point of maximum convexity of the CS catheter when a superior vena caval approach was used, (3) the right side of the ventricular septum, and (4) the relation to the underlying vertebrae. The least-significant difference method of multiple comparisons was used for statistical analysis. The point at which the CS catheter prolapsed was the most accurate noncontrast method for determining the location of the CS orifice (p less than 0.05), but was possible without the use of excessive force in only 48% of patients. The point of catheter prolapse was a median of 1 mm (range 0 to 11) from the true location of the os. Errors with other examined landmarks ranged up to 3 cm. Identification of the CS orifice is best performed by radiopaque contrast injection. The point of prolapse during catheter advancement in the CS is an accurate alternative when contrast injection is not feasible. Other noncontrast fluoroscopic landmarks are less reliable and are best avoided.(ABSTRACT TRUNCATED AT 250 WORDS)