Diffraction tomography by a method of image projections

A method of three-dimensional diffraction tomography based on image projections is derived. Inversion methods based on projections generally are inaccurate due to the spreading nature of the scattered wave. By backpropagating the field onto a single plane in the image region, diffraction effects are reduced and a projection of the weakly scattering object is generated. Consequently, conventional X-ray inversion techniques may be used to image the object. The relationship between the backpropagated field and the projection is derived both for high frequency incident waves and low spatial frequency scatterers. The generalized image kernel allows the use of curved or misaligned recording surfaces. Numerical results are included.     

Transplantation for adults with congenital heart disease.

Heart transplantation is a recognised treatment for end-stage heart failure of any cause including congenital heart disease. Congenital heart disease has contributed relatively little to the adult heart transplant activities in the past two decades. However, this is likely to change as an increasing number of children with congenital heart disease reach adulthood because of the advances in paediatric cardiology and surgery. Some of these grown-ups with congenital heart disease (GUCH patients) will need transplantation for late myocardial dysfunction either secondary to uncorrected lesions, or despite previous repair or palliative surgery. These patients are managed along the same clinical principles as those with cardiac failure of other aetiologies, despite the lack of any evidence to support this approach. Nevertheless, they introduce new challenges. First, some may have pulmonary vascular disease and require heart-lung transplantation, or lung transplantation combined with repair of their cardiac defects. Second, those with failing Fontan circulation are usually much sicker than other transplant candidates, with protein-losing enteropathy along with renal and hepatic dysfunction. Third, a suitable donor organ may not be found due to elevated levels of antibodies in response to previous blood transfusions and possibly the previous implantation of homografts. Fourth, the operation may be technically difficult because of the presence of adhesions secondary to previous operations, collaterals, and unusual anatomy. Fifth, postoperative care may be complicated because of predisposition to bleeding, infection and pulmonary hypertension, and the presence of residual aortopulmonary collaterals resulting in a significant left-to-right shunt. Despite a higher early mortality, the overall results of heart transplantation so far have been encouraging with survivals similar to that of adults with acquired heart disease and that of the paediatric population. However, this may change as the proportion of high-risk patients (failing Fontans) increases. GUCH patients with Eisenmenger's syndrome may be offered lung transplantation with repair of the cardiac defect or heart-lung transplantation. However, because of the limited success of these approaches, and improved management of pulmonary hypertension, patient selection remains difficult.     

Pneumothorax and other lung diseases: effect of altered resolution and edge enhancement on diagnosis with digitized radiographs

Prior studies have shown that pneumothorax is one of the more difficult entities to diagnose with digitized radiography. This study was designed to test whether increasing resolution from 1.25 to 2.5 line pairs per millimeter (lp/mm) and image processing (edge enhancement from unsharp masking) would increase accuracy and confidence in the diagnosis of pneumothorax, as well as normal cases and other forms of lung disease. Conventional radiographs were digitized with use of a laser reader and then reformatted as film hard copy. Eleven observers read 35 cases reformatted in three different ways (1.25 lp/mm, 2.5 lp/mm, 1.25 lp/mm unsharp mask). The images with finer resolution (2.5 lp/mm) and unsharp mask images were superior to those with coarser resolution (1.25 lp/mm) for the diagnosis of pneumothorax. There was no difference in diagnostic accuracy for normal patients. For abnormalities other than pneumothorax, the unsharp mask images were significantly worse. Confidence in the diagnosis of pneumothorax and other abnormalities was highest with the finest resolution (2.5 lp/mm).     

Characterization of antibody and selection of alternative drug therapy in hydrochlorothiazide-induced immune hemolytic anemia

The authors report the clinical and laboratory findings of a patient who had severe immune hemolytic anemia due to hydrochlorothiazide (HCTZ). In this case, the HCTZ antibody reacted not only with other thiazide and thiazide-like drugs, but also with a chemically unrelated diuretic, ethacrynic acid. These results indicate that HCTZ antibody activity is not restricted solely to the thiazides and imply that therapy with any of the reactive drugs would be contraindicated for this patient. The serologic screening for drug reactivity may be useful for selecting alternative therapy for patients with drug-induced immune hemolytic anemia.     

An effective treatment of comminuted fractures of the distal radius

One hundred cases of comminuted fracture of the distal radius were treated by a simple uniform method consisting of distraction by an external fixator for 3 weeks followed by functional bracing. During the application of the external fixator, autogenous cancellous bone chips were taken from the iliac crest and packed into the fracture site to realign the juxtaarticular fragments and to fill up the bone gap. Complications have been minimal. The results, after an average follow-up period of 20 months, taking into consideration subjective assessment of pain, objective measurement of wrist motion, and radiologic angles, have been excellent.     

Surgical Management of Marfan Syndrome in Children

Between August 1983 and January 1991, seven patients with Marfan syndrome underwent surgery for severe cardiovascular complications. The mean age at presentation was 5.7 months (range 4 to 9 months) in the infant group (n = 3), and 13.3 years (range 10 to 16 years) in a group of older children (n = 4). The primary indications for surgery in the infant group (performed at a mean of 3 years after diagnosis) were ascending aortic aneurysm with valvar regurgitation in one patient, and severe mitral valve prolapse with regurgitation in two. In the older group, surgical indications (performed at a mean of 2.8 years after diagnosis) were ascending aortic aneurysm with valvar regurgitation in three patients and acute aortic dissection in one. For aortic surgery, a composite valved conduit was used in four patients, and an aortic homograft in one. For mitral valve surgery, mechanical prostheses were used. Ail patients survived the primary operation. Over a mean follow-up of 17.5 patient-years (range 1 to 9 years), two patients in the infant Marfan group went on to further successful surgery (prosthetic mitral valve replacement and aortic root repair with aortic homograft) at a mean interval of 4.3 years after the Initial surgery. Our results suggest that the major cardiovascular risk factors of Marfan syndrome in the young, even in those diagnosed during infancy, have been favorably changed by surgery with an encouraging medium-term outlook. The correct timing of surgery is aided by echocardiography. (J Card Surg 1994;9:50–54)     

Delayed primary wound closure using skin tapes for advanced appendicitis in children. A prospective, controlled study.

In a 3-year period, 63 consecutive patients with advanced perforated (n=53) and gangrenous (n=10) appendicitis were allocated to undergo either immediate wound closure or delayed primary wound closure after emergency appendectomy. The incidence of wound infection between delayed primary wound closure and immediate wound closure was similar (24.0% and 21.1%, respectively). The duration for complete healing of infected wounds was slightly shorter in the group undergoing delayed primary wound closure (mean +/- SD, 24.3 +/- 9.2 days) than in the group undergoing immediate wound closure (mean +/- SD, 32.6 +/- 16.5 days), but the difference was not significant. However, healing of noninfected wounds was significantly prolonged in the group undergoing delayed primary wound closure (mean +/- SD, 19.3 +/- 10.1 days) compared with the group undergoing immediate wound closure (mean +/- SD, 7.0 +/- 0 days). The latter had been shown to associate with more nonseptic wound complications and therefore required longer rehabilitation. Our study showed that delayed primary closure did not offer additional advantage over immediate closure in the treatment of wounds associated with advanced appendicitis in children.     

Inhibition of 2-nitropropane-induced rat liver DNA and RNA damage by benzyl selenocyanate

We observed that pretreatment of male F344 rats with benzyl selenocyanate, a versatile organoselenium chemopreventive agent in several animal model systems, decreases the levels of DNA and RNA modifications produced in the liver by the hepatocarcinogen 2- nitropropane. To clarify the mechanisms involved, we pretreated male F344 rats with either benzyl selenocyanate, its sulfur analog benzyl thiocyanate, phenobarbital or cobalt protoporphyrin IX; the latter is a depletor of P450. We then determined (1) the ability of liver microsomes to denitrify 2-nitropropane, (2) effects on 2-nitropropane- induced liver DNA and RNA modifications and (3) amount of nitrate excreted in rat urine following administration of the carcinogen. Pretreatment with benzyl selenocyanate or phenobarbital increased the denitrification activity of liver microsomes by 217 and 765%, respectively, increased liver P4502B1 by 31- and 435-fold, respectively, decreased the levels of 2-nitropropane-induced modifications in liver DNA (29-70% and 17-30%, respectively) and RNA (67-85% and 30-50%, respectively), and increased the 24-h urinary excretion of nitrate by 157 and 209%, respectively. Pretreatment with benzyl thiocyanate had no significant effect on any of these parameters. Pretreatment with cobalt protoporphyrin IX decreased liver P4502B 1 by 87%, decreased the denitrification activity of liver microsomes by 76%, decreased the 24 h urinary excretion of nitrate by 88.5%, but increased the extent of 2-nitropropane-induced liver nucleic acid modifications by 17-67%. These results indicate that the metabolic sequence from 2-nitropropane to the reactive species causing DNA and RNA modifications does not involve the removal of the nitro group. Moreover, they suggest that benzyl selenocyanate inhibits 2-NP-induced liver nucleic acid modifications in part by increasing its detoxication through induction of denitrification, although it is evident that other mechanisms must also be involved.      

Isotypic analysis of humoral immune responses in rhesus monkeys to an adult microsomal antigen of Schistosoma mansoni: an indicator of successful treatment

A study was undertaken to examine the potential role of immunodiagnostic methods in determining successful chemotherapy in schistosomiasis. Fifteen rhesus monkeys were infected with 1,500 Schistosoma mansoni (Puerto Rico strain) cercariae, and 10 of the monkeys were then treated with a curative dose of praziquantel 13 weeks after infection. Five monkeys remained untreated. One monkey was not successfully cured, as confirmed by the presence of both male and female worms at the time of perfusion. Serum samples were longitudinally collected and specific Ig isotypes were quantified with an adult microsomal antigen of S. mansoni using the FAST-ELISA. Specific isotypes were detected with monoclonal antibodies specific for each human Ig isotype, followed by a peroxidase-conjugated anti-mouse Ig. Longitudinally, all monkeys showed similar isotype patterns. Isotypes increased for the first nine weeks following infection, and then began to decrease. Ten to 14 days following treatment, all isotypes increased. The Ig isotype responses of all monkeys followed classic patterns of isotype expression. A ratio of pretreatment (week 13) IgG1 absorbance values to post-treatment IgG1 absorbance values was generated for each monkey. All successfully treated monkeys, determined to be worm-free by perfusion, had IgG1 ratios at week 53 greater than 2.4 (range 2.4-181). The untreated monkeys and the single monkey that was a treatment failure had IgG1 ratios less than 2.1 (range 0.09-2.05) for the same time period.