Cerebral Oximetry Monitoring in Extremely Preterm Infants

BACKGROUND

The use of cerebral oximetry monitoring in the care of extremely preterm infants is increasing. However, evidence that its use improves clinical outcomes is lacking.

METHODS

In this randomized, phase 3 trial conducted at 70 sites in 17 countries, we assigned extremely preterm infants (gestational age, <28 weeks), within 6 hours after birth, to receive treatment guided by cerebral oximetry monitoring for the first 72 hours after birth or to receive usual care. The primary outcome was a composite of death or severe brain injury on cerebral ultrasonography at 36 weeks' postmenstrual age. Serious adverse events that were assessed were death, severe brain injury, bronchopulmonary dysplasia, retinopathy of prematurity, necrotizing enterocolitis, and late-onset sepsis.

RESULTS

A total of 1601 infants underwent randomization and 1579 (98.6%) were evaluated for the primary outcome. At 36 weeks' postmenstrual age, death or severe brain injury had occurred in 272 of 772 infants (35.2%) in the cerebral oximetry group, as compared with 274 of 807 infants (34.0%) in the usual-care group (relative risk with cerebral oximetry, 1.03; 95% confidence interval, 0.90 to 1.18; P = 0.64). The incidence of serious adverse events did not differ between the two groups.

CONCLUSIONS

In extremely preterm infants, treatment guided by cerebral oximetry monitoring for the first 72 hours after birth was not associated with a lower incidence of death or severe brain injury at 36 weeks' postmenstrual age than usual care. (Funded by the Elsass Foundation and others; SafeBoosC-III ClinicalTrials.gov number, NCT03770741.).

Comparing the diagnostic efficacy of full field digital mammography with digital breast tomosynthesis using BIRADS score in a tertiary cancer care hospital

Introduction

Breast cancer is one of the leading cancers in females worldwide, and its incidence has been rising at an exponential pace in the last 10 years even in India. Mammography has been the mainstay for detection of breast cancer over decades and has gradually advanced from screen film to full-field digital mammography. Recently, tomosynthesis has evolved as an advanced imaging investigation for early diagnosis of breast lesions in both diagnostic and screening settings.

Aim of Study

To compare and evaluate the impact of digital breast tomosynthesis (DBT) compared to full-field digital mammography (FFDM) in the interpretation of BIRADS score in both diagnostic and screening settings.

Settings and Design

A 1-year prospective longitudinal study was conducted in the Department of Radio-diagnosis in our institute using Hologic Selenia Dimensions for mammography as well as tomosynthesis.

Materials and Methods

One hundred women known or suspected (opportunistic screening) for breast cancer were evaluated either with FFDM alone or both FFDM and DBT. Sensitivity, specificity, positive predictive value, negative predictive value, and P value were used to assess the various diagnostic criteria in our study.

Results

Addition of DBT to FFDM results in a statistically significant increase in the sensitivity, specificity, and positive predictive value, and a statistically significant decrease in the false positive rates. Similar results were noted in both diagnostic and screening cases. It was observed that, in most cases, i.e. a total of 47, DBT did not change the BIRADS scoring; however, its addition increased the diagnostic confidence. BIRADS was upgraded and downgraded in 14 and 31 cases, respectively, with the addition of DBT to FFDM. New lesions were seen with addition of DBT to FFDM in 8 cases.

Conclusion

Addition of DBT to FFDM results in increase in sensitivity, specificity, positive predictive value, and a statistically significant decrease in false positive rates in both diagnostic and screening cases. As addition of tomosynthesis results in a significant decrease in recall rate, it should be added, at least, in all screening mammography programs.

Occupational exposure and tuberculosis among medical residents in a high-burden setting: an open-cohort study

SETTING

Postgraduate (PG) residency programme of a tertiary care teaching hospital in southern India.

OBJECTIVE

To estimate the incidence of tuberculosis (TB) among PG residents, determine the frequency of exposure to infectious TB patients and assess whether particular specialties were associated with higher risk of exposure and incident TB.

DESIGN

We assembled an open cohort of PG residents who were on the academic rolls for more than 3 months at any time between December 2011 and January 2013. We collected data both retrospectively and prospectively using two surveys-an entry survey at study initiation or entry into the cohort, and an exit survey at residency completion or study closure.

RESULTS

Among 398 PG residents enrolled in the study, we identified five cases of incident TB during a cumulative follow-up period of 10 962 person-months. The incidence rate was 547 per 100 000 person-years, which was 3.1 times the incidence in the general population. Nearly two thirds (n = 257, 65%) of the residents were exposed to at least one infectious patient. Across the three specialty-based risk strata, there was an ordered increase in the median number of exposures (P < 0.001) and evaluation for presumptive TB (P = 0.024), as well as a trend towards higher incident TB.

CONCLUSION

TB incidence is significantly higher among PG residents than in the general population.

Anterior abdominal wall abscess with epididymo-orchitis: an unusual presentation of acute pancreatitis

Pancreatitis indicates inflammation of the pancreas. Clinically acute pancreatitis typically presents as upper abdominal pain mostly in epigastric region, nausea, vomiting and elevated levels of amylase and lipase. Depending upon severity of acute pancreatitis patient may presents with minimal symptoms to more severe signs of acute abdomen like generalized guarding and rigidity. Inspite of absence of disease-specific signs and symptoms for acute pancreatitis, diagnosis is usually not difficult using a combination of clinical, laboratory and radiological findings. Sometimes pancreatitis may presents atypically, which may be misleading in the management especially when typical presentation of pancreatitis as described above is absent. We have described a case of pancreatitis where patient presented with anterior abdominal wall abscess with epididymo-orchitis because of tracking of pancreatic fluid into the retroperitoneum till scrotum. Patients presentation may be different depending upon complication occurred during the course of pancreatitis. After reviewing the literature we found very few cases in which you may not get a clue to diagnose pancreatitis because of atypical presentation. In the described case, patient managed conservatively with percutaneous drainage of the abscess by pigtail catheter placement and scrotal support for epididymoorchitis. This avoided unnecessary exploration in above patient.

More than meets the eye: digital fraud in dentistry

INTRODUCTION

Digital photographs play a substantial role in the presentation and validation of clinical cases for documentation and research purposes in esthetically oriented professions such as dentistry. The introduction of sophisticated cameras and "easy to use" computer software readily available on today's market has enabled digital fraud to emerge as a common and widely used practice. Hence, it is essential that both dentists and editorial circles are aware and cautious with regard to the possibility of digital fraud.

MATERIALS AND METHODS

A set of 10 routine "pre-" and "post" treatment dental procedure photographs were taken and randomly manipulated using standard desktop software. A team of 10 dental professionals were selected and each one of them was individually requested to review and evaluate the authenticity of the photographs.

RESULTS

An assessment of expert opinion revealed an overall sensitivity of 60% and a sensitivity of 15% in correctly identifying a manipulated photograph, which is considered low. Furthermore, there was poor interobserver agreement.

CONCLUSION

Advanced technology that is easily available has resulted in adept digital fraud that is difficult to detect. There is a need for awareness among both dental practitioners and the editorial circle regarding misrepresentation due to image manipulation. It is therefore necessary to follow a skeptical approach in the assessment of digitalized photos used in research and as a part of clinical dentistry.

Use of a modified anterior inclined plane in the treatment on the dentoskeletal Class II division 2 patient

Class II malocclusions are seen due to the underdevelopment of the mandible in most of the cases. To compensate for the mandible retrusive position, there is flaring of the lower anterior teeth or retroclination of the central incisors as a compensatory mechanism seen in Class II division 2 type of malocclusion. This case report evaluates the skeletal and dental changes when a 12-year-old female patient with Class II div 2 malocclusion was treated with a modified anterior inclined plane. The postreatment data suggested that there were no significant changes in the vertical skeletal parameters. The upper central incisors were significantly realigned by proclination along with retroclination of the lateral incisors. There was significant increase in the mandibular length. The results revealed that the modified anterior inclined plane showed good results in the treatment of a case of Class II div 2 malocclusion.

Melanotic neuroectodermal tumor of infancy: discussion of a case and a review of the imaging findings

Melanotic neuroectodermal tumor of infancy (MNTI) is an uncommon melanin-containing mesenchymal tumor of neural crest origin. What make this tumor unique and interesting is its characteristic predilection for anterior maxilla (premaxilla) and the presence of pigment melanin which gives the tumor distinct clinicopathological, immunohistochemical, ultrastructural and imaging features. Although first described almost a century ago, to the authors’ knowledge, only a few hundred cases of MNTI have been reported worldwide in the English medical literature. The pool of documented radiological findings is even more sparse as not more than a dozen cases could be abstracted from an Internet search of the radiology literature. We document a case of MNTI and describe the imaging findings with intent to contribute to its small but accruing radiological data.

Report of a case of pericardial mesothelioma with liver metastases responding well to pemetrexed and platinum-based chemotherapy

Pericardial mesothelioma remains a disease with a bleak prognosis. We report the case of a patient with metastases to liver and good response to pemetrexed and carboplatin-based combination chemotherapy and consequent prolonged progression-free survival.

Effect of early mobilisation on grip strength, pinch strength and work of hand muscles in cases of closed diaphyseal fracture radius-ulna treated with dynamic compression plating

AIMS

The purpose of the study was to objectively determine the effects of early mobilisation in terms of grip strength and work of hand muscles in cases of closed diaphyseal fracture radius - ulna treated with dynamic compression plating.

SUBJECTS AND METHODS

Fifty normal subjects and Twenty-one patients, (Eleven patients treated with early active and resistive goal directed mobilisation and Ten control group) were assessed for pinch strength and grip strength on Pinch Dynamometer and Jamar Dynamometer and work of hand muscles on Ergograph. Standardised positions of the equipments and patients were maintained throughout the study.

RESULTS

Results showed highly significant reduction in performance in patients treated with early mobilisation as compared to normal subjects in their first assessment (Fourth week post operatively). These patients showed significant improvement in successive assessments (sixth & eighth post operative week) on exercising in between these assessments.

CONCLUSIONS

There are significant effects on grip strength and work of hand muscles in patients treated with that early active and resistive goal directed mobilisation.

Late onset schizophrenia versus early onset schizophrenia : a comparison of clinical features

Patients of late onset schizophrenia (LOS) (13 subjects), early onset schizophrenia (EOS) current age above 40 years (15 subjects) and early onset schizophrenia (EOS)- current age at or below 40 years (15 subjects) were compared. The LOS group differed from the two EOS groups only in having higher score on the item 'persecutory delusions'. The findings do not support the diagnostic validity of LOS.

Life events and social support in married schizophrenics

Life events are associated with relapse in schizophrenia. However, the role and interplay of marriage and social support have not been explored in research on schizophrenia, especially stable patients. Life events and social support were assessed in two groups comprising 30 married and an equal number of unmarried patients of schizophrenia. The time frame for these assessments was a period of 6 months prior to such evaluation. The married group reported higher stress score and greater number of undesirable life events. Negative correlation was present for social support with number of undesirable life events in the sample as a whole. Hence, it is concluded that marriage leads to experiencing more stress but there are other psychosocial variables mitigating the same and preventing relapse.

Potent in vitro and in vivo inhibitors of platelet aggregation based upon the Arg-Gly-Asp sequence of fibrinogen. (Aminobenzamidino)succinyl (ABAS) series of orally active fibrinogen receptor antagonists

Our initial orally active fibrinogen receptor antagonist benzamidinopentanoyl (BAP) series which was discovered through truncation of our i.v. antiplatelet agent (SC-52012) demonstrated modest oral activity in canine studies (ethyl [5-(4-amindinophenyl)pentanoyl]-3-amino-3-(3-pyridyl)propionate, 1e). Introduction of an amide bond adjacent to the benzamidine led to a novel series with an (aminobenzamidino)succinyl (ABAS) Arg-Gly surrogate that had improved in vitro potency (5-17 times) relative to the BAP series. Four ester prodrug/acid active metabolite pairs (2a/2e, 60a/60e, 62a/62e, 63a/63e) from the ABAS series which varied in their 3-substituent on the beta-amino ester "aspartate mimetic" were prepared in enantiomerically enriched form (> 95:5), and they were evaluated in canine studies for their ability to block collagen-induced aggregation in platelet-rich plasma, the elimination profile (t1/2 beta-phase), repeated oral dosing studies, and oral systemic availability. Of the four ester prodrug/acid active metabolite pairs, 2e/2a (SC-54684A/SC-54701A) has the most favorable properties in the above studies with an IC50 = 67 +/- 5 nM (dog platelet-rich plasma, collagen), t1/2 beta = 1.6 h (ester) and 6.5 h (acid), no adverse effects upon repeated dosing, and a drug oral systemic availability of 62% (area under curve (AUC) of acid 2a (drug) following ig administration of ester 2e (prodrug, 2.5 mg/kg) divided by AUC of acid 2a (drug) following i.v. administration of ester 2e (prodrug, 2.5 mg/kg) as determined by HPLRC). In further pharmacokinetic studies using nonlabeled 2e/2a, the oral systemic availability (ester 2e ig/ester 2e i.v.) of 2e was measured to be in the range of 44.7-53.0%. The more biologically relevant oral systemic availability (ester 2e ig/acid 2a i.v.) of 2e was found to be in the range of 22.0-26.4%. A pharmacophore model based on inhibitors from several different benzamidine classes including 2a (ABAS class) was developed using a combination of molecular modeling (MM2) and pharmacophore identification (APOLLO) methods.

An enzyme-linked immunosorbent assay for complement regulatory proteins and membrane-bound immunoglobulins on intact red blood cells

We have developed an ELISA technique to examine RBC-bound molecules in autoimmune disorders. In particular, the technique has enabled us to investigate the role of some complement regulatory proteins in immune complex transport and to suggest that decay accelerating factor (DAF) may be involved in this process. In both autoimmune haemolytic anaemia (AHA) and systemic lupus erythematosus (SLE) a sub-set of individuals was identified, on the basis of patterns of complement receptor 1 (CR1) expression on RBC. In these patients, CR1 identified using the monoclonal antibody E11 was low or absent whereas CR1 identified using a DAKO monoclonal antibody (C3RTo5) was present at normal levels.

Fungal colonization in gastric ulcers

Until now studies on fungal colonization of gastric ulcers were retrospective involving small series of patients. This prospective study of 50 patients with gastric ulcers (25 benign and 25 malignant) revealed colonization by Candida in 17 (34%) cases. There was no significant difference in colonization between benign and malignant ulcers. Follow up revealed no difference in healing of ulcers with or without fungal colonization.

Takayasu arteritis: initial and long-term follow-up in 16 patients after percutaneous transluminal angioplasty of the descending thoracic and abdominal aorta

PURPOSE

To analyze results of percutaneous transluminal angioplasty (PTA) for stenosis of the descending thoracic and/or abdominal aorta caused by Takayasu arteritis (TA).

MATERIALS AND METHODS

Subjects were 16 patients (12 female and four male, aged 6-46 years) with symptoms of hypertension or severe bilateral lower limb claudication. Total aortography revealed stenotic lesions in the descending thoracic aorta in five, in the abdominal aorta in 10, and in both vessels in one patient. Involvement of arch vessels in four patients and of the renal artery in four patients was also noted. Double-balloon angioplasty was performed in eight patients.

RESULTS

Initial technical and clinical success was 100%. The maximum follow-up period was 52 months (mean, 21 months 2 weeks). Ankle-brachial index as determined with Doppler ultrasound improved considerably in 10 patients. Three patients had symptoms of restenosis during follow-up. Cumulative patency rate by life-table analysis was 67%.

CONCLUSION

PTA has a definite role in the management of TA in view of its procedural simplicity, cost-effectiveness, and results compared with surgical revascularization procedures.

Comparison of technetium-99m pyrophosphate and technetium-99m DTPA aerosols for SPECT ventilation lung imaging

Although [99mTc] diethylenetriaminepentaacetic acid (DTPA) is currently the most widely used radioaerosol, rapid alveolar clearance limits its usefulness for single photon emission computed tomography (SPECT) ventilation lung imaging. Previous research has shown that [99mTc]phosphate compounds have high alveolar deposition and slow clearance and thus provide suitable aerosols for pulmonary ventilation studies. We have compared the pulmonary retention and blood levels of [99mTc]pyrophosphate (PYP) and [99mTc]DTPA in eight normal nonsmoking male volunteers. These two radioaerosols have comparable pulmonary deposition. Technetium-99m PYP, however, has a much slower pulmonary clearance which allows sufficient time (20 or more minutes) for SPECT data acquisition using a single-headed rotating gamma camera. While the radiation absorbed dose to the lungs for [99mTc]PYP (0.31 rad/mCi) is greater than for [99mTc]DTPA (0.11 rad/mCi), it is at a clinically acceptable and safe level.

Accurate diagnosis of renal transplant rejection by indium-111 platelet imaging despite postoperative cyclosporin therapy

Previous reports indicate that In-111 platelet scintigraphy (IPS) is a reliable test for the early diagnosis of acute post-operative renal transplant rejection (TR). However, the recent introduction of cyclosporin for post-transplantation immunosuppression requires that the diagnostic efficacy of IPS once again be established. Therefore, a prospective IPS study of 73 post-operative renal transplant recipients was conducted. Fourty-nine patients received cyclosporin and 24 patients did not receive this drug. Between these two patient groups, there were no significant differences in the diagnostic sensitivities (0.86 vs 0.80) and specificities (0.93 vs 0.84) with which TR was identified. We conclude that during the first two weeks following renal transplantation the cyclosporin treatment regimen used at our institution does not limit the reliability of IPS as a test for TR.

Early diagnosis of acute postoperative renal transplant rejection by indium-111-labeled platelet scintigraphy

A prospective evaluation of 111In-labeled platelet scintigraphy (IPS) for the early diagnosis of acute postoperative renal transplant rejection (TR) was undertaken. The results of IPS were compared with in vitro biochemical tests, the clinical finding of graft tenderness, and combined [99mTc]DTPA and [131I]orthoiodohippurate scintigraphy. With a sensitivity of 0.93 and a specificity of 0.95, IPS provided otherwise unavailable diagnostic information. Furthermore, postoperative IPS was a good predictor of long-term allograft survival.

Effect of Sn(II) ion concentration and heparin on technetium-99m red blood cell labeling

While convenience and economy favor the use of in vivo methods for labeling red blood cells (RBCs) with [99mTc]pertechnetate, previous reports suggested that patient medication such as heparin might interfere and thus result in inferior quality images. In this study, using a canine model, the role of stannous Sn(II) ion in in vivo and in vitro labeling of RBCs both in the presence and absence of a therapeutic dose of heparin was investigated. Our results showed that Sn(II) ion concentration of 20 micrograms/kg body weight levels provided better than 80% in vivo labeling efficiency enabling high quality blood-pool images even in the presence of therapeutic doses of heparin.

A simple method to quantitate iodine-124 contamination in iodine-123 radiopharmaceuticals

Iodine-123 (123I) produced by the 124Te(p,2n)123I reaction contains several percent 124I radionuclidic contamination at the time of imaging. Since 124I degrades the quality of the images and causes unnecessary radiation absorbed dose to the patient, it is important to know the amount present in radiopharmaceuticals at the time of administration. A simple approach is described which uses a radionuclide dose calibrator and lead shield. The sample is assayed both shielded and unshielded and the ratio of readings depends uniquely upon the percent 124I present. The technique can be adopted for any type of dose calibrator, sample container, and Pb shield, but use of the numeric constants reported here should be restricted to the specified equipment.

Splenic phagocytic function after partial splenectomy and splenic autotransplantation

We investigated splenic reticuloendothelial activity after splenic preservation procedures to determine their effect upon the phagocytic function of the spleen. We performed the following procedures in Sprague-Dawley rats: sham laparotomy, total splenectomy, hemisplenectomy, subtotal splenectomy, or total splenectomy with intraperitoneal splenic autotransplantation. At nine weeks after operation, phagocytic function of the spleen was determined by measuring radiocolloid uptake. Mean (+/- SEM) splenic phagocytic indices for sham laparotomy (41.2 +/- 2.9), hemisplenectomy (44 +/- 2.9), and subtotal splenectomy (43.2 +/- 5.2) were similar; however, the phagocytic index was reduced markedly after autotransplantation (15.8 +/- 2.2). These data demonstrate that the phagocytic function of the spleen after hemisplenectomy and subtotal splenectomy correlates highly with the weight of the splenic remnant; however, phagocytic function after autotransplantation remains reduced even after accounting for differences in splenic weight.

Concentration of In-111-oxine-labeled autologous leukocytes in noninfected and nonrejecting renal allografts: concise communication

Autologous leukocytes labeled with In-111 oxine (ILL) concentrated in the renal allografts of eight patients for whom transplant rejection, infection, or acute tubular necrosis (ATN) could be excluded. All patients had good-to-adequate renal function at the time of ILL scintigraphy, and none developed rejection or renal transplant failure during a 1-mo follow-up period. It is concluded that normally functioning renal allografts without evidence of rejection, infection, or ATN often will concentrate ILL. When a baseline study is not available for comparison, this phenomenon limits the value of ILL scintigraphy as a diagnostic test for transplant rejection or infection.

Noninvasive radioisotopic technique for detection of platelet deposition in mitral valve prostheses and quantitation of visceral microembolism in dogs

A noninvasive technique has been developed in the dog model for imaging, with a gamma camera, the platelet deposition on Björk-Shiley mitral valve prostheses early postoperatively. At 25 hours after implantation of the prosthesis and 24 hours after intravenous administration of 400 to 500 microCi of platelets labeled with indium-111, the platelet deposition in the sewing ring and perivalvular cardiac tissue can be clearly delineated in a scintiphotograph. An in vitro technique was also developed for quantitation of visceral microemboli in brain, lungs, kidneys, and other tissues. Biodistribution of the labeled platelets was quantitated, and the tissue/blood radioactivity ratio was determined in 22 dogs in four groups: unoperated normal dogs, sham-operated dogs, prosthesis-implanted dogs, and prosthesis-implanted dogs treated with dipyridamole before and aspirin and dipyridamole immediately after operation. Fifteen to 20% of total platelets were consumed as a consequence of the surgical procedure. On quantitation, we found that platelet deposition on the components of the prostheses was significantly reduced in prosthesis-implanted animals treated with dipyridamole and aspirin when compared with prosthesis-implanted, untreated dogs. All prosthesis-implanted animals considered together had a twofold to fourfold increase in tissue/blood radioactivity ratio in comparison with unoperated and sham-operated animals, an indication that the viscera work as filters and trap platelet microemboli that are presumably produced in the region of the mitral valve prostheses. In the dog model, indium-111-labeled platelets thus provide a sensitive marker for noninvasive imaging of platelet deposition on mechanical mitral valve prostheses, in vitro evaluation of platelet microembolism in viscera, in vitro quantitation of surgical consumption of platelets, and evaluation of platelet-inhibitor drugs.

Indium-111 tropolone, a new tracer for platelet labeling

Platelets have been labeled with a new neutral, lipid-soluble metal complex of indium 111 (111In) and tropolone. Unlike oxine, which is soluble in ethyl alcohol, tropolone is soluble in isotonic saline. Platelet labeling with 111In tropolone can be performed in both acid-citrate-dextrose (ACD) plasma and ACD saline within two hours. Labeling efficiency has been 80% to 90%. 111In tropolone in ACD saline and ACD plasma at tropolone concentrations of 5 and 10 micrograms/ml, respectively, and incubation of the platelets with the tracer at room temperature for 20 minutes were optimal conditions for labeling. The authors have developed an ACD-saline kit for convenient preparation of 111In-labeled platelets. No adverse effect of 111In tropolone on platelets has been observed in studies of biodistribution, recovery, and survival of platelets in rabbits and dogs.

Comparative evaluation of red cell-labeling parameters of three lipid-soluble- 111In-chelates: effect of lipid solubility on membrane incorporation and stability constant on transchelation

A rabbit red cell model was used to determine the cell labeling properties of three lipid-soluble 111In-complexes: 111In-oxine, 111In-acetylacetone, and 111In-tropolone. Partition coefficients (olive oil/buffer) were measured to determine the lipid solubility and were 3.54, 7.93, and 18.18 for 111In-oxine, 111In-acetylacetone, and 111In-tropolone respectively. The effect of the concentration of these three chelating agents on labeling efficiencies was studied. The factors influencing the labeling efficiencies of these complexes such as cell density, time of incubation, influence of temperature, pH, effect of plasma proteins, and citrate ion concentration in the cell-labeling medium were studied. Labeling yields as high as 95.15 +/- 4.15% were achieved with 111In-tropolone after a 10-min incubation at 37 degrees C. The optimum pH for cell labeling was 6.5. Excess citrate ion (greater than 3.02 mg/ml) and small amounts of plasma proteins (greater than 10 microliter/ml) decreased the labeling efficiencies in all three cases. Distribution of these 111In-complexes in membrane, membrane fragments, and hemoglobin was studied after hemolysis. In spite of the higher lipid solubility of 111In-tropolone, the transchelation capacity appears to be similar to that of 111In-oxine. 111In-acetylacetone had the highest transchelation capacity.

Indium-111 tropolone, a new high-affinity platelet label: preparation and evaluation of labeling parameters

Platelets were isolated with a new neutral, lipid-soluble metal complex of indium-111 and tropolone. Unlike oxine, which must be dissolved in ethyl alcohol, tropolone is soluble saline. Platelet labeling with In-111 tropolone can be performed in both acid-citrate-dextrose (ACD)-plasma and ACD-saline media within two hours' time. Labeling efficiency has been 80-90% in ACD-saline and 60-70% in the ACD-plasma medium. Optimum concentrations for the labeling of platelets with In-111 tropolone were 5 micrograms/ml in ACD-saline and 10 micrograms/ml in ACD-plasma, using a 15-min incubation at room temperature. A kit formulation for convenient routine preparation of In-111-labeled platelets has been developed. Seven parameters of platelet labeling were studied: concentration of tropolone, citrate, plasma proteins, and calcium ions; also platelet density, temperature, and pH of incubation medium. Their effects on the mechanism of platelet labeling with lipid-soluble tracers are discussed.