Non-contrast CT at comparable dose to an abdominal radiograph in patients with acute renal colic; impact of iterative reconstruction on image quality and diagnostic performance

OBJECTIVES

The aim was to assess the performance of low-dose non-contrast CT of the urinary tract (LD-CT) acquired at radiation exposures close to that of abdominal radiography using adaptive statistical iterative reconstruction (ASiR).

METHODS

Thirty-three patients with clinically suspected renal colic were prospectively included. Conventional dose (CD-CT) and LD-CT data sets were contemporaneously acquired. LD-CT images were reconstructed with 40 %, 70 % and 90 % ASiR. Image quality was subjectively and objectively measured. Images were also clinically interpreted.

RESULTS

Mean ED was 0.48 ± 0.07 mSv for LD-CT compared with 4.43 ± 3.14 mSv for CD-CT. Increasing the percentage ASiR resulted in a step-wise reduction in mean objective noise (p < 0.001 for all comparisons). Seventy % ASiR LD-CT images had higher diagnostic acceptability and spatial resolution than 90 % ASiR LD-CT images (p < 0.001). Twenty-seven calculi (diameter = 5.5 ± 1.7 mm), including all ureteric stones, were correctly identified using 70 % ASiR LD-CT with two false positives and 16 false negatives (diameter = 2.3 ± 0.7 mm) equating to a sensitivity and specificity of 72 % and 94 %. Seventy % ASiR LD-CT had a sensitivity and specificity of 87 % and 100 % for detection of calculi >3 mm.

CONCLUSION

Reconstruction of LD-CT images with 70 % ASiR resulted in superior image quality than FBP, 40 % ASIR and 90 % ASIR. LD-CT with ASIR demonstrates high sensitivity and specificity for detection of calculi >3 mm.

TEACHING POINTS

• Low-dose CT studies for urinary calculus detection were performed with a mean dose of 0.48 ± 0.07 mSv • Low-dose CT with 70 % ASiR detected calculi >3 mm with a sensitivity and specificity of 87 % and 100 % • Reconstruction with 70 % ASiR was superior to filtered back projection, 40 % ASiR and 90 % ASiR images.

Patient and provider attitudes towards monitored naltrexone treatment of alcohol dependence in schizophrenia

OBJECTIVE

To describe the attitudes of patients and their mental health providers regarding participation in a controlled trial of directly monitored naltrexone (NTX) treatment for alcohol dependence in schizophrenia.

METHOD

Ninety participants with schizophrenia and their providers were asked to report opinions of treatment with oral NTX or placebo 3 times per week for 12 weeks, motivational counseling (MI), and voucher-based incentives (VBI) for attendance.

RESULTS

Seventy-nine percent of participants "liked the study a lot," and 94% reported that it was helpful. Study components rated as helpful by participants were: VBI (95% of participants), meeting with staff 3 times per week (84%), reporting alcohol use (82%), MI (82%), reporting psychiatric symptoms (73%), breath alcohol testing (72%), and study medication (57%). Benefits reported by patients were: feeling better mentally (67%), drinking less (52%), feeling better physically (49%), and stopping drinking (27%). Seventy percent of providers reported that the study was helpful. Benefits noted by providers included: reduced drinking (33%), better treatment adherence (32%), stopping drinking (23%), and reduced psychiatric symptoms (22%). Patient/provider responses agreed on helpfulness with stopping or reducing drinking.

CONCLUSIONS

Most participants with schizophrenia liked participating in a clinical trial of directly observed naltrexone treatment for alcohol dependence, and found incentives for attendance, frequent staff contact and monitoring of drinking, and motivational counseling to be the most helpful. Most participants reported improvement in mental health and reduced drinking. Mental health providers also reported that the study was helpful, but they did not describe the same degree of benefit as did patients.

NDRG2, a novel regulator of myoblast proliferation, is regulated by anabolic and catabolic factors

Skeletal muscle tissue undergoes adaptive changes in response to stress and the genes that control these processes are incompletely characterised. NDRG2 (N-myc downstream-regulated gene 2), a stress- and growth-related gene, was investigated in skeletal muscle growth and adaption. While NDRG2 expression levels were found to be up-regulated in both differentiated human and mouse myotubes compared with undifferentiated myoblasts, the suppression of NDRG2 in C2C12 myoblasts resulted in slowed myoblast proliferation. The increased expression levels of the cell cycle inhibitors, p21 Waf1/Cip1 and p27 Kip1, and of various muscle differentiation markers in NDRG2-deficient myoblasts indicate that a lack of NDRG2 promoted cell cycle exiting and the onset of myogenesis. Furthermore, the analysis of NDRG2 regulation in C2C12 myotubes treated with catabolic and anabolic agents and in skeletal muscle from human subjects following resistance exercise training revealed NDRG2 gene expression to be down-regulated during hypertrophic conditions, and conversely, up-regulated during muscle atrophy. Together, these data demonstrate that NDRG2 expression is highly responsive to different stress conditions in skeletal muscle and suggest that the level of NDRG2 expression may be critical to myoblast growth and differentiation.

Radiographic and clinical changes of the patellar tendon after tibial plateau leveling osteotomy 94 cases (2000-2003)

Patellar tendon thickening (PTT) and patellar tendinosis (PTS) have been discussed in the veterinary literature as a post-operative complication of tibial plateau leveling osteotomy (TPLO). The purpose of this study was to define radiographic PTT, determine the frequency of and risk factors for PTT and PTS, and describe the clinical and histopathological findings of PTS after TPLO. We hypothesized that the location of the osteotomy alters forces placed on the patelloar tendon resulting in PTT or PTS. Radiographs and medical records from 83 dogs undergoing 94 TPLO procedures were retrospectively evaluated. Two months post-operatively, 19 dogs (20.2%) had a normal patellar tendon or mild PTT, 51 (54.3%) had moderate PTT, and 24 (25.5%) had severe PTT. Seven of the 24 dogs (7.4%) with severe PTT had clinical signs consistent with PTS. Only dogs with severe PTT developed PTS (p < 0.0001). The risk factors for the development of PTT include: a cranial osteotomy, a partially intact cranial cruciate ligament (CCL) in conjunction with a cranial osteotomy, and post-operative tibial tuberosity fracture. The only risk factor identified for the development of PTS was a partially intact CCL. Four dogs with PTS improved with conservative therapy and one improved with surgical treatment. Two dogs had tendon biopsies with histopothological review that showed tendon degeneration with lack of inflammation. As only the dogs with severe PTT develop PTS, a caudal osteotomy for the prevention of PTT and subsequent PTS is recommended.

Real-time RT-PCR analysis of housekeeping genes in human skeletal muscle following acute exercise

Studies examining gene expression with RT-PCR typically normalize their mRNA data to a constitutively expressed housekeeping gene. The validity of a particular housekeeping gene must be determined for each experimental intervention. We examined the expression of various housekeeping genes following an acute bout of endurance (END) or resistance (RES) exercise. Twenty-four healthy subjects performed either a interval-type cycle ergometry workout to exhaustion (∼75 min; END) or 300 single-leg eccentric contractions (RES). Muscle biopsies were taken before exercise and 3 h and 48 h following exercise. Real-time RT-PCR was performed on β-actin, cyclophilin (CYC), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and β2-microglobulin (β2M). In a second study, 10 healthy subjects performed 90 min of cycle ergometry at ∼65% of V̇o2 max, and we examined a fifth housekeeping gene, 28S rRNA, and reexamined β2M, from muscle biopsy samples taken immediately postexercise. We showed that CYC increased 48 h following both END and RES exercise (3- and 5-fold, respectively; P < 0.01), and 28S rRNA increased immediately following END exercise (2-fold; P = 0.02). β-Actin trended toward an increase following END exercise (1.85-fold collapsed across time; P = 0.13), and GAPDH trended toward a small yet robust increase at 3 h following RES exercise (1.4-fold; P = 0.067). In contrast, β2M was not altered at any time point postexercise. We conclude that β2M and β-actin are the most stably expressed housekeeping genes in skeletal muscle following RES exercise, whereas β2M and GAPDH are the most stably expressed following END exercise.

A multilevel modelling approach to analysis of patient costs under managed care

The growth of the managed care model of health care delivery in the USA has led to broadened interest in the performance of health care providers. This paper uses multilevel modelling to analyse the effects of managed care penetration on patient level costs for a sample of 24 medical centres operated by the Veterans Health Administration (VHA). The appropriateness of a two level approach to this problem over ordinary least squares (OLS) is demonstrated. Results indicate a modicum of difference in institutions' performance after controlling for patient effects. Facilities more heavily penetrated by the managed care model may be more effective at controlling costs of their sicker patients.

On measuring the hospital cost/quality trade-off

This paper explores the relationship between cost and quality of hospital care. A total operating cost function is estimated for 137 US Department of Veterans Affairs hospitals for 1988-1993 using three rate-based measures of quality as regressors. The high likelihood of the existence of measurement error in quality in the cross section leads to the application of novel instrumental variable techniques. Results suggest that mortality and readmission indices are adjusted inadequately for illness severity. The measure on the failure to follow up inpatient discharges with outpatient care, however, appears to increase cost. The results of this paper underscore a number of practical difficulties and challenges facing government or other systems in evaluating the relative performance of their hospitals.

Identification of Gas6 as a ligand for Mer, a neural cell adhesion molecule related receptor tyrosine kinase implicated in cellular transformation

Mer/Nyk/Eyk is an orphan receptor tyrosine kinase expressed at high levels in monocytes and cells derived from epithelial and reproductive tissues. Overexpression of Mer has been associated with lymphoid malignancies. Here we identify Gas6, the product of a growth arrest specific gene, as a ligand for Mer. Gas6 has previously been shown to activate both Axl and Rse/Tyro3, two other receptor tyrosine kinases in the same family as Mer. The apparent relative association and dissociation rate constants of Gas6 for soluble Axl, Rse/Tyro3 and Mer were compared using surface plasmon resonance. Gas6 was shown to induce rapid phosphorylation of Mer expressed in several different types of cells. We also observed a transient activation of p42 MAP kinase following activation of Mer by Gas6. Thus, Gas6 exerts its biological effects through multiple receptor tyrosine kinases.

Pharmacokinetics, tissue distribution, and expression efficiency of plasmid [33P]DNA following intravenous administration of DNA/cationic lipid complexes in mice: use of a novel radionuclide approach

The pharmacokinetics, tissue distribution, and efficacy of a systemic gene transfer method were examined in male BALB/c mice (6-8 weeks old) using 33P-labeled plasmid DNA for luciferase. The DNA was delivered via tail vein injection in saline ([33P]DNA) or in a cationic lipid formulation ([33P]DNA/lipid). One group of mice received approximately equal to 1-3 microCi (45 micrograms of DNA) of either formulation, and mice were euthanized at 2 and 20 min, and 1 and 24 h postdose (2 mice/time point). Blood and plasma radioactivity were quantified, and whole body autoradiographic (WBAR) images were obtained from 20-microns whole body sections. A tissue distribution (TD) study was conducted in a second group of mice, which received approximately equal to 4-6 microCi (45-60 micrograms of DNA) of [33P]DNA/lipid. Mice were euthanized at 1.5 h (1 mouse; [33P]DNA/lipid) or 24 h (2 mice/ group), and organ radioactivity and luciferase expression were measured in lung, liver, kidney, spleen thymus, and parotid salivary gland by direct quantitation methods. Microautoradiography (MAR) was performed on a third group of mice (n = 2), which received 3 microCi (45 micrograms of DNA) of [33P]DNA/lipid and were euthanized at 24 h postdose. For WBAR, the [33P]DNA/lipid tissue distribution (% dose equiv/g) at 2 min was lung >> liver > spleen (red pulp) > kidney (cortex); at 24 h the ranking was spleen (red pulp) > liver > lung, kidney (cortex). The [33P]DNA organ distribution observed at 2 min was liver >> spleen (red pulp) > lung, blood > kidney (cortex); at 24 h the ranking was liver, spleen (red pulp) > kidney (cortex) > lung, blood. High levels of radioactivity in bone (cortical, marrow, growth plate) in both groups may represent uptake of the 33P-labeled test articles by the cellular component of the bone marrow, particularly macrophages, as well as deposition of [33P]phosphate in the bone matrix following metabolism of the [33P]DNA. In the luciferase component of the study, no expression was observed in the [33P]DNA group at 24 h. The [33P]- DNA/lip group exhibited expression as early as 1.5 h in the lung; at 24 h, expression was seen in all the organs examined. Microautoradiography of 24-h tissue samples revealed radioactivity in hepatic Kupffer cells, reticuloendothelial system cells in the marginal zone of the spleen, and diffusely along alveolar septae with scattered accumulations in alveolar macrophages. The results of the WBAR, TD, MAR, and luciferase assay show that the use of cationic lipids significantly altered the biodistribution and resulting expression of the DNA plasmid. Further, 33P (0.25 MeV beta, half-life = 25 days) was shown to be an excellent radionuclide for quantitative WBA and MAR, providing sharp images with less personal hazard and greater ease of handling than 32P (1.71 MeV beta, half-life = 14.3 days).

A telecommunications system for monitoring and counseling patients with hypertension. Impact on medication adherence and blood pressure control

This study was conducted to evaluate the effect of automated telephone patient monitoring and counseling on patient adherence to antihypertensive medications and on blood pressure control. A randomized controlled trial was conducted in 29 greater Boston communities. The study subjects were 267 patients recruited from community sites who were >or= 60 years of age, on antihypertensive medication, with a systolic blood pressure (SBP) of >or= 160 mm Hg and/or a diastolic blood pressure (DBP) of >or= 90 mm Hg. The study compared subjects who received usual medical care with those who used a computer-controlled telephone system in addition to their usual medical care during a period of 6 months. Weekly, subjects in the telephone group reported self-measured blood pressures, knowledge and adherence to antihypertensive medication regimens, and medication side-effects. This information was sent to their physicians regularly. The main study outcome measures were change in antihypertensive medication adherence, SBP and DBP during 6 months, satisfaction of patient users, perceived utility for physicians, and cost-effectiveness. The mean age of the study population was 76.0 years; 77% were women; 11% were black. Mean antihypertensive medication adherence improved 17.7% for telephone system users and 11.7% for controls (P = .03). Mean DBP decreased 5.2 mm Hg in users compared to 0.8 mm Hg in controls (P = .02). Among nonadherent subjects, mean DBP decreased 6.0 mm Hg for telephone users, but increased 2.8 mm Hg for controls (P = .01). For telephone system users, mean DBP decreased more if their medication adherence improved (P = .03). The majority of telephone system users were satisfied with the system. Most physicians integrated it into their practices. The system was cost-effective, especially for nonadherent patient users. Therefore, weekly use of an automated telephone system improved medication adherence and blood pressure control in hypertension patients. This system can be used to monitor patients with hypertension or with other chronic diseases, and is likely to improve health outcomes and reduce health services utilization and costs.

Cost allocation patterns between hospital inpatient and outpatient departments

OBJECTIVE

This study examines changes in hospitals' cost allocation patterns between inpatient and outpatient departments in response to the implementation of the prospective payment system. DATA SOURCES AND STUDY SETTINGS: The analysis was carried out using data for 3,961 hospitals obtained from the Medicare Cost Reports and from the American Hospital Association for the years 1984 through 1988.

STUDY DESIGN

A total operating cost function was estimated on the two outputs of discharges and outpatient visits. The estimation results were instrumental in disaggregating costs into inpatient and outpatient components. This was done cross-sectionally for each of the five years.

PRINCIPAL FINDINGS

Comparison of this cost breakdown with that of hospital revenue provides evidence of distinct patterns in which nonteaching, rural, and small hospitals increasingly allocated greater costs to outpatient departments than did large, urban, and teaching hospitals.

CONCLUSIONS

The results suggest that small rural hospitals turned to the outpatient side in the face of tough economic challenges over the period of study. Because differences in cost allocation patterns occur by particular hospital category, analyses that rely on accounting cost or revenue data in order to identify cost differences among those same categories may come to erroneous conclusions. In particular, because teaching hospitals apportion costs more heavily on the inpatient side, cost allocation differences cause upward bias in the PPS medical education adjustment.

"Occult" hepatitis B virus as source of infection in liver transplant recipients

Hepatitis B virus (HBV) infection almost always recurs after liver transplantation in patients who were surface antigen (HBsAg) positive before surgery but apparent de novo acquisition of infection in a transplant setting has not previously been reported. We have used sensitive techniques to elucidate the origin of such infections in patients in a California transplantation programme. We tested post-transplant serum from 207 patients who had been HBsAg negative and found 20 to be HBsAg positive. The origin of infection was identified in 7 patients, being occult pre-transplant infection in 5 and occult infection in the donor in 2. No pre-transplant patient nor donor with demonstrable HBV DNA had serological markers of hepatitis B. Post-transplant HBV DNA was present in serum from 19 patients. Analysis of the variable pre-S region of HBV demonstrated 100% sequence homology between recipient liver and post-transplant serum (2 patients) and between donor serum and recipient post-transplant serum (2). There was only 84% homology between the 2 different patients infected with subtype adw. 19 patients are alive, 9 without histological evidence of hepatitis (mean follow-up 33 months), and survival was significantly greater than that of a group with recurrent HBV infection. Apparent acquisition of HBV infection with liver transplantation is not rare, and may be due to occult pre-transplant infection or occult infection in the donor. The post-transplant outcome of this infection tends to be benign but our findings do underscore the clinical relevance of HBV infection in the absence of serological markers.

Measuring inpatient and outpatient costs: a cost-function approach

In this article, the authors estimate a multiple-output cost function for a sample of 2,235 hospitals during the period 1984-88 to disaggregate total costs into inpatient and outpatient components. The results suggest that outpatient cost growth is roughly proportional to that of inpatient cost, despite much higher relative growth in revenues and utilization on the outpatient side. The stability in the outpatient/inpatient cost ratio implies that the increase in the outpatient-to-inpatient utilization ratio was offset by a decline in their relative unit costs.

Characterization of a candidate bcl-1 gene

The t(11;14)(q13;q32) translocation has been associated with human B-lymphocytic malignancy. Several examples of this translocation have been cloned, documenting that this abnormality joins the immunoglobulin heavy-chain gene to the bcl-1 locus on chromosome 11. However, the identification of the bcl-1 gene, a putative dominant oncogene, has been elusive. In this work, we have isolated genomic clones covering 120 kb of the bcl-1 locus. Probes from the region of an HpaII-tiny-fragment island identified a candidate bcl-1 gene. cDNAs representing the bcl-1 mRNA were cloned from three cell lines, two with the translocation. The deduced amino acid sequence from these clones showed bcl-1 to be a member of the cyclin gene family. In addition, our analysis of expression of bcl-1 in an extensive panel of human cell lines showed it to be widely expressed except in lymphoid or myeloid lineages. This observation may provide a molecular basis for distinct modes of cell cycle control in different mammalian tissues. Activation of the bcl-1 gene may be oncogenic by directly altering progression through the cell cycle.

Cloning of the t(11;14)(q13;q32) translocation breakpoints from two human leukemia cell lines

The t(11;14)(q13;q32) translocation has been associated with several subtypes of human leukemia and lymphoma. It has been proposed that this translocation activates a proto-oncogene designated BCL1. In an effort to better understand the mechanism by which this translocation leads to malignancy, we have studied this translocation in two human cell lines. MO1094 and MO2058 were derived from patients with prolymphocytic variants of chronic lymphocytic leukemia. Southern blotting of the MO2058 cell line documented that the translocation linked the Jh region in the immunoglobulin heavy chain gene to the previously described BCL1 major translocation cluster (MTC). Using the polymerase chain reaction, we cloned this translocation and showed that the chromosome 11 breakpoint was within 7 bp of two other samples reported previously. Southern blotting of the MO1094 cell line suggested that the translocation in this cell line might link Jh sequences to a new region in the BCL1 locus on chromosome 11. Therefore, the MO1094 breakpoint was cloned from a genomic library. Comparison with normal cloned DNA from the BCL1 locus showed that the chromosome 11 breakpoint occurred 24 kb telomeric of the MTC. This work reinforces the concept that translocation breakpoints in the BCL1 locus are scattered over at least 63 kb.

Risk for occupational transmission of human immunodeficiency virus type 1 (HIV-1) associated with clinical exposures. A prospective evaluation

OBJECTIVES

To summarize the results of a 6-year, ongoing, prospective study of the risk for human immunodeficiency virus type 1 (HIV-1) transmission among health care workers, and to estimate the magnitude of the risk for HIV-1 infection associated with different types of occupational exposures.

DESIGN

Prospective cohort study; the median follow-up for employees sustaining parenteral exposures was 30.2 months (range, 6 to 69 months).

SUBJECTS

Health care workers at the Clinical Center, National Institutes of Health, including those reporting parenteral and nonparenteral occupational exposures to HIV-1.

MEASUREMENTS AND MAIN RESULTS

One thousand three hundred and forty-four clinical health care workers reported 179 percutaneous and 346 mucous membrane exposures to fluids from HIV-1-infected patients during a 6-year period. Responding to a supplementary questionnaire, 559 of these workers reported 2712 cutaneous exposures to blood from HIV-1-infected patients and more than 10,000 cutaneous exposures to blood from all patients during a 12-month period. Occupational transmission of HIV-1 occurred in a single worker after a parenteral exposure to blood from an HIV-1-infected patient. No infections occurred after either mucous membrane or cutaneous exposures to blood from HIV-1-infected patients. Use of newer diagnostic technologies (for example, antigen detection, gene amplification) has not resulted in the identification of occupationally transmitted seronegative infections.

CONCLUSIONS

Combining our results with those of other prospective studies, the risk for HIV-1 transmission associated with a percutaneous exposure to blood from an HIV-1-infected patient is approximately 0.3% per exposure (95% CI, 0.13% to 0.70%); the risks associated with occupational mucous membrane and cutaneous exposures are likely to be substantially smaller. These data support the use of barrier precautions and suggest a need for strategies that change health care providers' attitudes and behaviors.

A survey of homeless adults in urban emergency shelters

Following a review of several studies of homeless populations, the authors describe a survey of 68 homeless adults in eight urban emergency shelters in Hennepin County, Minnesota. The results indicated impressive rates of mental illness, alcoholism, minor criminality, and chronic medical and dental problems. More significant, the authors believe, both for the homeless and for public policy planners, is that a majority of the interviewees were disconnected from supportive social networks and were underutilizing medical and welfare programs for which they were eligible. Almost 40 percent of those with chronic health problems were receiving no medical care, and only 6 percent were receiving mental health services, although more than 50 percent needed such care. The authors compare the findings with those of studies discussed in the literature review.