Laboratory equipment maintenance contracts

The increasing level of technical sophistication and complexity found in clinical laboratory instrumentation today more than ever demands careful attention to maintenance service needs. The time-worn caution for careful definition of requirements for acquisition of a system should also carry over to acquisition of maintenance service. Guidelines are presented for specifications of terms and conditions for maintenance service from the perspective of the laboratorian in the automated clinical laboratory.     

Lack of a co-promoting effect of a 60 Hz magnetic field on skin tumorigenesis in SENCAR mice

It has been proposed that extremely low frequency (ELF) magnetic fields may enhance tumorigenesis through a co-promotional mechanism. This hypothesis has been further tested using the two-stage model of mouse skin carcinogenesis, i.e. 12-O-tetradecanoylphorbol-13-acetate (TPA)- induced promotion of skin tumors in mice initiated by a single subcarcinogenic dose of 7,12-dimethylbenz[a]anthracene. Experimentation described herein utilized the SENCAR mouse and examined the effect of a magnetic field on skin tumor promotion induced by three different doses of TPA within its dose-response range, i.e. 0.85, 1.70 or 3.40 nmol, administered twice per week. SENCAR mice (56/treatment group) were exposed to a 60 Hz magnetic field having a flux density of 2 mT for 6 h/day for 5 days/week and compared with mice exposed to the ambient magnetic field. Tumor incidence and multiplicity were monitored weekly for 23 weeks of TPA promotion. Statistical evaluation of the effects of the magnetic field on tumor incidence and multiplicity did not reveal any statistically significant effects; thus, within the sensitivity limits imposed by the animal model and the exposure parameters employed, no promotional or co-promotional effect of a 2 mT magnetic field on skin tumor development in SENCAR mice could be demonstrated.      

Ectopic splenomegaly in Felty's syndrome

A 50-year-old woman with Felty's syndrome, who presented with "menopausal" symptoms, was found to have a large pelvic mass on physical exam. Computed tomography of the pelvis led to an incorrect diagnosis of malignancy, while radionuclide imaging using Tc-99m sulfur colloid confirmed the diagnosis of ectopic splenomegaly.     

Scintigraphic evaluation of liver transplant function

Since the initiation of liver transplantation at our institution 9 yr ago, 73 patients ranging in age from 8 mo to 64 yr have undergone this procedure. In the immediate postoperative period and at various times thereafter as deemed necessary, radionuclide studies were performed using one of the iminodiacetic acid (IDA) derivatives labeled with 99mTc. Initially, these studies were performed using labeled PIPIDA with a shift to diisopropyl IDA when this latter agent became available. The IDA agent is administered as a bolus so that the "flow" and "pooling" may be viewed immediately after injection. This is followed by sequential imaging at various times up to 24 hr, with optional graphic tracings of hepatic and bowel patterns of uptake and clearance of radioactivity. An analysis of the initial portion of the IDA scan yields useful information regarding the arterial and portal venous supply of the liver. The rapidity of hepatic concentration and excretion provides a direct measure of hepatocyte function which is particularly helpful when used sequentially to follow the response of the liver to therapy for rejection or infection. The study is also used to assess the biliary system for obstruction or leaks.     

Aerosol penetration ratio: a new index of ventilation

Superimposition of nuclear medicine scintigrams and standard radiographs provides a unique opportunity for merging functional information intrinsic to nuclear medicine images with the high resolution anatomic detail of radiographs. A newly developed image processing system allows the merging of two separate films of greatly varying sizes to form a single composite image. Subsequent quantitative analysis of the composite image may be performed. Using the superimposition technique, [99mTc]DTPA aerosol ventilation scans (4.5 X 4.5 cm) were superimposed upon chest radiographs (35.6 X 43.2 cm) in 17 cystic fibrosis (CF) patients. Subsequent quantification of the area of nuclear scan ventilation and the radiographic lung area was then performed. A new quantitative radiologic index of ventilation, the aerosol penetration ratio (APR), was defined. Linear correlation of aerosol penetration ratio with residual volume (RV) as percent of total lung capacity (TLC) measured by body plethysmography was good. We conclude that the APR has validity as a physiologic parameter which localized regional excessive residual volume and correlates well with RV/TLC, the "gold standard" pulmonary function index of obstructive airway disease.     

Collaborative Initiatives in the Care of Early Stage Breast Cancer: Reduction in Variation of Breast-Conserving Therapy

Abstract: Breast-conserving therapy (BCT) has survival results comparable to those obtained with modified radical mastectomy (MST). However, studies suggest variations in the rates of breast-conserving therapy that are not explained by comorbidities or age. The Virginia Health Quality Center collaborated with 40 Virginia hospitals to address patterns of breast cancer treatment. Medicare Peer Review Organization data files were used to identify all Medicare beneficiaries with a primary diagnosis of breast cancer from January 1, 1992, through June 30, 1993. Explicit chart review was performed on a random sample of patients with early stage disease receiving either BCT or MST. At baseline, the BCT rate was 21.1% after controlling for access to radiation facilities, medical conditions, and demographic variables. Hospitals with the highest rates of appropriate BCT served as resources for the project. We provided data on BCT rates to 40 participating hospitals. Hospitals then submitted comprehensive plans to address the performance of BCT. A four-step cooperative improvement intervention was employed to initiate and sustain changes at the hospital level. Interventions included individual hospital feedback, dissemination of model cancer care processes at high-performing institutions, and integration of oncology services for breast cancer treatment decisions. One year after implementation, the overall BCT rate in Virginia increased to 25.5%. Hospitals with the lowest BCT rates increased their average rate from 6.6% to 21.2%. Middle tercile hospitals increased BCT rates by 10%. Variation between the lowest and highest terciles was reduced to 9%. Variation in BCT rates can be reduced by a collaborative program centered on addressing processes of care for breast cancer treatment for Medicare patients with early stage disease.     

Colonic wall thickness, pancreatic enzyme dose and type of preparation in cystic fibrosis

Increased colonic wall thickness has been reported in patients exposed to large doses of high strength pancreatic enzyme preparations who did not develop fibrosing colonopathy. This has been interpreted as evidence for a spectrum of subclinical disease. The relation between sonographically measured colonic wall thickness and pancreatic enzyme preparation and dose was studied in 86 children with cystic fibrosis (CF). Colonic wall thickness of a control group was also measured. The average thickness in all colonic regions was higher in the CF group (overall average range 0.7-2.5 mm v 0.6-1.4 mm in the control group). There was no significant relation between colonic wall thickness and age, sex, total dose of lipase, or copolymer. Apart from one patient with an early colonic stricture, none of those exposed to high doses of lipase, or the methacrylic acid copolymer Eudragit L30 D55, showed evidence of subclinical damage to the colon. The reproducibility of the sonographic measurements was poor.     

Chemical hazards in radiology

A variety of chemicals are used in medical imaging as developer and fixer ingredients, germicides, and cleaning agents. Glutaraldehyde, a potent sensitizer, may cause occupational skin and respiratory diseases in exposed individuals. Poor ventilation, unsafe practices, and lack of hazard recognition may contribute to occupational asthma and other respiratory disease in susceptible medical imaging personnel. Failure to respond effectively to initial health complaints and reduce exposure levels can have serious consequences for affected employees. It is therefore important for occupational safety and health professionals to alert health facility managers to potential dangers and to recommend effective intervention strategies. When problems are identified, a multidisciplinary team approach is the best method for evaluating and controlling hazards. This team should include industrial hygienists, safety staff, occupational medicine physicians, mechanical and ventilation engineers, personnel specialists, and medical imaging staff. A thorough hazard assessment, medical diagnosis, and administrative personnel actions are critical to effective problem identification and correction. In the case of chemical sensitization, removal of the affected employee may be necessary. By working with designers and equipment installers to monitor compliance with appropriate codes and manufacturers' specifications, hazards can be prevented. We present additional operations, ventilation, and design improvements to reduce chemical exposures to radiology employees.     

Suppression of arylamine toxicity in the Fischer-344 rat following ingestion of a complex mixture.

The toxic effects of a mixture of 2-aminoanthracene (2-AA), benzanthracene (BA), and dinitropyrene isomers (DNP), and the toxic effects of these compounds individually, were investigated in the Fischer-344 rat following dietary exposure via a powdered basal diet. Animals were sacrificed at 14-, 30-, and 80-days of dietary exposure. Exposure to dietary 2-AA alone induced anorexia, cachexia, variable mortality, and altered serum chemistry profiles in the F-344 rat. Reduced lymphocyte counts were also shown in rats exposed to 2-AA. A temporal pattern of effect of 2-AA dietary exposure was observed in the progression of hepatic lesions in exposed animals. Dietary exposure to either DNP isomers or BA at a 10-fold higher concentration in the diet, relative to 2-AA, did not induce detectable toxic responses. However, exposure of rats to a mixture of 2-AA, BA, and DNP isomers (100 mg/kg, 1.0 g/kg, and 1.0 g/kg of diet, respectively) resulted in the attenuation of toxic effects when compared to exposure of F-344 rats to 2-AA alone. These results indicate that the toxic effects of 2-AA are suppressed by co-administration of DNP and BA and suggest that compound interactions need to be considered when predicting the toxic potential of specific environmental pollutants.