Biomedical subjects
Publications and source records attributed to S J White.
Fourteen patients with disease of the spinal cord were imaged with fluid-attenuated inversion-recovery (FLAIR) sequences in which the inversion time was chosen to substantially reduce or null the signal from CSF. Lesions were seen with greater conspicuity than with conventional contrast-enhanced and -unenhanced T1- and T2-weighted sequences in 11 cases.
The application of newer imaging modalities such as ultrasound, CT, and MR imaging has made a major contribution to the understanding of pediatric hip disorders. Multiplanar imaging has been a major advancement in the depiction of the complex hip joint anatomy. Direct visualization of cartilage in the immature joint is now possible with MR imaging. Sophisticated computer software programs allow three-dimensional reconstruction of the joint from CT and MR data. Manipulation of three-dimensional images allows preoperative simulation of proposed surgical reorientation of hips with deformity resulting from dysplasia and Legg-Calvé-Perthes disease.
Nemaline myopathy (NEM) is a neuromuscular disorder characterized by the presence, in skeletal muscle, of nemaline rods composed at least in part of alpha-actinin. A candidate gene and linkage approach was used to localize the gene (NEM1) for an autosomal dominant form (MIM 161800) in one large kindred with 10 living affected family members. Markers on chromosome 19 that were linked to the central core disease gene, a marker at the complement 3 locus, and a marker on chromosome 1 at the alpha-actinin locus exclude these three candidate genes. The family was fully informative for APOA2, which is localized to 1q21-q23. NEM1 was assigned to chromosome 1 by close linkage for APOA2, which is localized to 1q21-q23. NEM1 was assigned to chromosome 1 by close linkage to APOA2, with a lod score of 3.8 at a recombination fraction of 0. Recombinants with NGFB (1p13) and AT3 (1q23-25.1) indicate that NEM1 lies between 1p13 and 1q25.1. In total, 47 loci were investigated on chromosomes 1, 2, 4, 5, 7-11, 14, 16, 17, and 19, with no indications of significant linkage other than to markers on chromosome 1.
One hundred and eighty children undergoing CT examination were randomly allocated to receive meglumine diatrizoate, iohexol, or iopamidol as their i.v. contrast agent. Minor side effects were detected in 85% of children receiving meglumine diatrizoate, in 18% of those receiving iohexol, and in 36% of those receiving iopamidol. Because many of these minor side effects cause patient motion or delay scanning after contrast medium injection, they potentially degrade image quality. These findings are an indication for the use of low osmolarity contrast agents for i.v. use in pediatric CT imaging.
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Linkage was shown between the myotonic dystrophy locus (DM) and a highly polymorphic AC repeat marker within the kallikrein (KLK1) locus (Z = 3.00, theta = 0.0). Linkage between KLK1 and the highly polymorphic AC repeat marker within the apolipoprotein C2 (APOC2) locus, which had been established in normal families, was confirmed in myotonic dystrophy families (Z = 4.37, theta = 0.11). These highly polymorphic AC repeat markers flank DM on chromosome 19. The gene order is cen-APOC2 (0.03) DM (0.08) KLK1-qter with recombination frequencies shown in parentheses. Genotypes for the AC repeat markers can be determined simultaneously by multiplex PCR and separation of the two base pair differences between adjacent alleles on sequencing gels. In informative families, this approach provides rapid diagnosis and is more accurate than methods using markers restricted to the proximal side of the myotonic dystrophy gene.
To evaluate use of a digital photostimulable phosphor imaging system in the neonatal nursery, 150 newborns were divided into three groups of 50. In the first two groups, screen-film and computed radiographs of the chest were obtained at the same radiation exposure; in the third group, computed radiographs were obtained with a 50% dose reduction (half-exposure computed radiographs). All images were blindly evaluated by three readers who scored the quality of visualization of the mediastinum, lung, bone, soft tissues, and endotracheal and nasogastric tubes, and also image density. No statistical differences in visualization of tubes existed among the three groups. Visualization of the mediastinum, lung, bones, and soft tissues was statistically significantly better on computed radiographs than on half-exposure computed radiographs; visualization of the lungs, bones, and soft tissues was statistically significantly better on screen-film radiographs than half-exposure computed radiographs. Image density was statistically better on computed and half-exposure computed radiographs than on screen-film radiographs.
This study evaluates iohexol as a contrast agent in the gastrointestinal tract in children. In the first part of the study, iohexol in concentrations of 180 and 300 mg l/ml was compared in double-blind manner with barium. Sixty-four patients were studied. No significant difference in changes of blood pressure and pulse rate was found between the three groups of patients studied. Diarrhea was significantly more common in the children receiving iohexol than in children receiving barium. The diarrhea was not due to previously identified high-risk factors in the children, nor was it due to concurrent medication. When image quality was assessed in each anatomic region of the gastrointestinal tract, fewer nondiagnostic ratings occurred with barium than with iohexol. With barium, fewer ratings of poor mucosal coating and slightly fewer ratings of suboptimal contrast density occurred. The second part of the study was an open evaluation of iohexol 180 mg l/ml in 18 patients in whom barium was clinically contraindicated. Three of 53 assessments were nondiagnostic. Mucosal coating was poor in 6%, and contrast density was suboptimal in 8% of patients. The results of this study indicate that barium is the preferred contrast agent for routine evaluation of the gastrointestinal tract in children. Good-quality images can be obtained, however, with iohexol in concentrations of 180 or 300 mg l/ml, and iohexol is an excellent contrast agent for evaluation of the gastrointestinal tract in those patients in whom barium is relatively or absolutely contraindicated.
We present two cases of growth plate injury of the hand and wrist in young patients with renal rickets and osteodystrophy but no history of antecedent trauma. The postulated mechanism of injury is subclinical biomechanical stress on the involved extremity superimposed on the already weakened metaphysis and growth plate. Thus, the findings may be viewed as an insufficiency injury to the metaphysis and growth plate. Physicians should be aware that, in the absence of unusual athletic activity, epiphysiolysis of the upper extremity is uncommon and requires a search for underlying metabolic bone disease.
The effects of the 'loop diuretics' bumetanide, furosemide and piretanide on fluid reabsorption from the rat proximal convoluted tubule have been tested to assess whether a Na(+)-Cl- cotransport mechanism can support fluid reabsorption from this nephron segment. Proximal convoluted tubules were perfused in vivo at 25 nl min-1 with chloride Ringer solutions containing [3H]inulin. Fluid reabsorptive rate (Jv) was 2.05 +/- 0.07 nl mm-1 min-1 (n = 115) from control chloride Ringer. Bumetanide at 10(-6) and 10(-5) M reduced Jv by about 40%. Bumetanide at 10(-7) M, furosemide (10(-4) and 10(-5) M) and piretanide (10(-4) and 10(-5) M) had no effect on Jv. At 10(-3) M, furosemide and piretanide reduced Jv by about 45%. The results show that luminal application of loop diuretics lowers fluid reabsorption from the proximal convoluted tubule and the order of potency for inhibiting reabsorption is bumetanide greater than furosemide identical to piretanide. The specificity of the loop diuretics at their effective concentrations needs to be confirmed, however, before attribution of a role for Na(+)-Cl- co-transport in the support of proximal tubule fluid reabsorption.
Recently we have examined six children with the diagnosis of choledochal cyst who demonstrate a greater spectrum of biliary involvement than expected. Classically choledochal cysts have been divided into types and subtypes based on the configuration of common bile duct dilatation; however, this simplified information is misleading since surgical management is dependent on the exact extent of intrahepatic and extrahepatic biliary abnormalities. The pre-operative ultrasound examination must be meticulous to provide enough pertinent anatomic details. Much of the intrahepatic anatomy is not visualized at surgery nor on the operative cholangiograms where reflux of contrast into the intrahepatic ducts may not be consistently achieved.
We compared a new dual-screen, dual-emulsion film system for X-ray mammography with a widely used single-screen, single-emulsion combination for routine contact mammography in 100 patients with a variety of mammographic findings. By using a five-point rating scale (1 = poor, 5 = excellent), four blinded readers found the conventional combination superior in density (by 0.46 points on the rating scale), resolution (by 0.64 points), contrast (by 0.46 points), visibility of calcification (by 0.50 points), visibility of soft-tissue masses (by 0.37 points), and overall quality (by 0.47 points). No difference was seen in the graininess of the films. In our study, the conventional system was consistently found to be slightly better than the dual-screen, dual-emulsion combination. The dual-emulsion mammograms required more careful scrutiny, particularly for detection of faint microcalcifications.
The effect of a bar-code system on personnel time requirements and data-entry accuracy in an existing automated controlled substances inventory system was determined. In the previous system, technicians used a keyboard and alphanumeric codes to enter into the computer data about the physical transfer of controlled substances among hospital areas. A system for barcode data entry was adapted for use with the existing procedure. After learning to use the bar-code system, four experienced technicians entered data by the keyboard method for eight days and the bar-code method for eight days during a 32-day study period. The amount of time required to enter all transactions and the accuracy of data entry were measured. Mean data-entry times for the keyboard and bar-code methods were not significantly different, most likely because of the greater number of manipulations needed for bar-code data entry. The mean percentage error associated with the bar-code method (0.79%) was significantly less than the error associated with the keyboard method (1.53%). For this particular computer system in which bar-code data entry was adapted to existing procedures, use of bar codes to enter controlled substances inventory data was not substantially faster but was more accurate than a traditional key-board data-entry method.
We examined radiographs of 12 Egyptian royal mummies obtained by two of the authors (W.R. and J.E.H.) and never before published. These radiographs demonstrate findings not previously described in Egyptian mummies, including congenital lunate-triquetral fusion and destructive skeletal lesions not explainable on the basis of vandalism by tomb robbers. Antemortem fractures, degenerative joint disease, and arterial vascular calcification were also seen. In 11 of the 12 cases, there was chondrocalcinosis of intervertebral discs or menisci, probably an artifact of embalming. Visceral packing and skeletal deformity due to wrapping were observed, as well. Radiology provides important paleopathologic and archeologic information for the accurate, comprehensive study of Egyptian mummies.
The effects of the anion transport inhibitor DIDS (4,4'-diisothiocyano-stilbene-2,2'-disulphonate) on fluid reabsorption by the rat proximal convoluted tubule were investigated by the stationary microperfusion (split-drop) method. Addition of 10(-5) mol 1-1 DIDS to luminal and capillary perfusates in the presence of peritubular bicarbonate (25 mmol 1-1) increased the reabsorptive half-time (t 1/2) from 35.1 +/- 4.5 to 57.0 +/- 6.2 s, corresponding to a decrease in fluid reabsorption (Jv) from 1.33 +/- 0.06 to 0.89 +/- 0.09 nl min-1 mm-1. Omission of bicarbonate per se from the peritubular capillaries reduced Jv to 0.41 +/- 0.03 nl min-1 mm-1 and this reabsorptive flux was completely inhibited by the addition of 2 mmol 1-1 NaCN to both the luminal and peritubular perfusates. In the absence of bicarbonate, the addition of DIDS at either 10(-4) or 10(-5) mol 1-1 to both lumen and capillary perfusates had no significant effect on either t 1/2 or Jv. These results show that the inhibitory action of DIDS on fluid reabsorption is dependent on the presence of bicarbonate. However, the proximal tubule also reabsorbs water in the absence of bicarbonate by a mechanism that is dependent on cellular metabolism, but is insensitive to DIDS at the concentrations used in this study.
Personnel time and costs associated with computer-assisted instruction (CAI) and traditional "one-on-one" instruction in basic computer drug-order entry procedures were compared. Both programs consisted of an introduction to the training session, familiarization of users with the computer hardware and keyboard, and step-by-step instructions in unit dose and intravenous admixture order-entry procedures. The CAI module was developed by a pharmacist with no prior programming experience. It was designed to be used side-by-side with the actual inpatient pharmacy computer system. Fifth-year pharmacy students in their clinical clerkship rotation served as the study population. The personnel (both subject and pharmacy supervisor) time and costs associated with each method were evaluated for significant differences by a two-tailed Student's t test. Of 21 subjects who participated in this study, 11 received CAI and 10 received traditional instruction. CAI was associated with significantly less mean total personnel time (99.64 +/- 18.78 minutes) than one-on-one instruction (133.60 +/- 22.89 minutes). Mean total salary expense was significantly lower for CAI ($13.03 +/- 2.15) than for one-on-one instruction ($28.79 +/- 4.91). Program development time for the CAI module was 18.5 hours longer than that for the one-on-one program. The CAI module cost $1577.77 more to develop than the one-on-one program; however, 24 new employees would be required to offset development costs if the hardware were already available and 100 new employees if hardware had to be purchased. Computer-assisted instruction of new employees in computer order-entry procedures can be a cost-effective alternative to traditional training methods.(ABSTRACT TRUNCATED AT 250 WORDS)
Thirty-four Duchenne and Becker muscular dystrophy families were initially ascertained from South Australia. These have been tested systematically with the DNA probes XJ1.1 and pERT87-15. DNA results from 21 informative families have been combined with results of CK testing. Pedigree analysis was carried out using the computer program LINKAGE to provide risk figures to potential female carriers. This simple approach separated potential carriers into low or high risk classes (familial cases) or low or moderate risk classes (isolated cases). No prenatal diagnoses were carried out. The detection of deletions in two probands out of 34 makes possible definitive prenatal diagnosis in those families. For the remaining families, prenatal diagnosis could only be offered in terms of a probability statement after linkage analysis. Risk figures presented from hypothetical pedigrees demonstrated that prenatal diagnosis by linkage usually provided reasonable reliability only where informative flanking markers are used.
Hospital pharmacy directors were surveyed in September 1987 about staff pharmacist turnover, recruitment, and retention. Questionnaires were mailed to pharmacy directors at 541 hospitals in the United States. Three hundred thirty-nine questionnaires were returned (62.7% usable response rate); more than 50% of the questionnaires sent to each geographic region were completed. Only 129 respondents reported difficulty filling vacant staff pharmacist positions within the past 12 months, although 320 believed there is a pharmacist shortage. Seventy-eight reported having positions that remained unfilled for three to six months. For more than 90% of the vacant positions, two-thirds of the duties were in drug distribution. Five hundred thirty-three pharmacists were reported to have left their positions in the past 12 months; the directors said salary and working hours were the reasons most often given, and that 47.5% left to work at other hospitals and 13.1% at chain community pharmacies. National advertisements and the use of professional recruitment agencies were the recruitment methods most frequently mentioned, and salary increases, recognition through feedback from management, and participation in management decisions were the methods most commonly mentioned for retaining pharmacists. Salary was the most frequently reported reason for hospital pharmacist turnover, and nearly half of the pharmacists leaving their positions went to other hospitals.