Failure of ablation of a mediastinal parathyroid adenoma by repeated contrast staining

In a patient with primary hyperparathyroidism an attempt was made to ablate a middle mediastinal parathyroid gland by forceful staining with radiographic contrast material. The gland was stained on two separate occasions, two weeks apart. Both times the serum calcium level temporarily fell to the normal range but reverted to abnormal levels. The patient ultimately required surgery for correction of hypercalcemia. The mechanism of staining and possible reasons for failure as well as potential complications are discussed.     

Gallium-67 lung uptake: conjugate-view technique

A conjugate-view technique is derived for calculation of absolute gallium-67 (Ga-67) uptake from scintillation-camera images. The technique combines counts of posterior and anterior images of the lung with an attenuation correction obtained from cobalt-57 (Co-57) transmission imaging. The formulation is such that the effects of Compton scatter build-up are accounted for. Studies utilizing a canine model indicated that, normally, more activity is located in the chest wall than in the lungs. The quantitative technique must therefore accurately account for a variety of Ga-67 distributions, including that in the chest wall. Calculations were performed using a three-component model comparing results obtained with the conjugate-view approach to the actual uptake. These calculations suggest that an assumption of uniform activity distribution allows an accuracy of approximately +/- 10% over a broad range of body-part thicknesses and uptake by the lungs. It was concluded that the conjugate-view technique is necessarily approximate but can provide clinically useful results.     

Platelet Functions in Cardiopulmonary Bypass Surgery

Background

Haemorrhage after Cardio Pulmonary Bypass (CPB) Surgery is a well recognised complication that leads to significant morbidity and mortality. The incidence varies between 5-25% depending upon the clinical situation. Several factors are implicated as causative but none have been precisely proved.

Methods

Our study was an attempt to evaluate the haemostatic defect with particular reference to platelet function abnormalities during cardio pulmonary bypass surgery, in order to reduce the morbidity and mortality associated with post CPB haemorrhage. Flow cytometric evaluation of different platelet glycoproteins like GPIb/IX, GPIIb/IIIa and GMP-140 was done.

Results

The marker expression showed deregulation during surgery which returned to base after bypass was terminated. In contrast, the cases with bleeding showed significant variation. P-Selectin (GMP 140) expression decreased progressively till 3^rd post-operative day showing lack of activation of platelets in cases of severe bleeding.

Conclusion

Longer duration of CPB initiates plasmin generation through heparin, which raises the PAI-1-tPA complex and thereby down regulating the functions of platelets. This suggests a link between duration of CPB, bleeding, platelet dysfunction and fibrinolysis. Hence serial estimations of the levels of GMP-140 and tPA can predict severe bleeding.Key Words: CardioPulmonary Bypass, Platelet dysfunction, flowcytometry, platelet glycoproteins, haemorrhage     

Immunohistologic dissection of the human kidney using monoclonal antibodies

Nine murine monoclonal antibodies which detect differentiation antigens of the human kidney are described. Immunofluorescence and immunoperoxidase studies demonstrate that these antigens are expressed by different cell types comprising the nephron. Monoclonal antibody MA99 detects a glycoprotein complex of the glomerular basement membrane. Monoclonal antibody S4 detects a glycoprotein of 160,000 daltons (gp160) expressed by glomerular and proximal tubular epithelial cells. Monoclonal antibodies S23, S27 and S6 immunoprecipitate a glycoprotein of 120,000 daltons (gp120) found on cells of the proximal tubule and portions of Henle's loop. Monoclonal antibody C26 identifies a glycoprotein of 40,000 daltons (gp40) expressed by cells of the distal and collecting tubules. Monoclonal antibodies M2 and S8 are specific for A and B blood group antigens, respectively, found on cells of the collecting tubule in individuals of the respective blood type. This panel of antibodies is useful in the study of normal renal embryogenesis, microanatomy and physiology as well as pathological processes including tumors.     

Cutting balloon angioplasty for resistant venous anastomotic stenoses

Conventional angioplasty of stenoses at the venous anastomosis has been demonstrated to be an important endovascular adjunct to mechanical thrombectomy of clotted arteriovenous dialysis grafts. In some cases, however, severe venous anastomosis stenosis is resistant to angioplasty. Cutting balloon angioplasty may have an advantageous role in these difficult situations in order to avoid surgical revision. In this series of 350 patients receiving percutaneous, endovascular declotting procedures, 9 patients had high-grade venous anastomotic stenoses (opening less than 2 mm) that could not be remedied with either conventional or high-pressure noncompliant peripheral angioplasty balloons. These nine patients had the lesions opened with the use of 4 mm x 10 mm cutting balloons and placement of self-expanding nitinol stents at the venous anastomosis during the same angiography procedure. Patients were followed for patency and functionality of the graft. In all cases, immediate technical success occurred. Among these patients, the vessels have remained patent for as long as 20 months of follow-up and grafts have remained functional. Cutting balloon angioplasty may have a potential therapeutic role in resistant venous anastomotic stenoses.     

Response of LNCaP spheroids after treatment with an alpha-particle emitter (213Bi)-labeled anti-prostate-specific membrane antigen antibody (J591)

A theoretical drawback to alpha-particle therapy with 213Bi is the short range of the particle track coupled with the short half-life of the radionuclide, thereby potentially limiting effective cytotoxicity to rapidly accessible, disseminated individual tumor cells (e.g., as in leukemia). In this work, a prostate carcinoma spheroid model was used to evaluate the feasibility of targeting micrometastatic clusters of tumor cells using 213Bi-labeled anti-prostate-specific membrane antigen (PSMA) antibody, J591. In prostate cancer, vascular dissemination of tumor cells or tumor cell clusters to the marrow constitutes an important step in the progression of this disease to widespread skeletal involvement, an incurable state. Such prevascularized clusters are ideal targets for radiolabeled antibodies because the barriers to antibody penetration that are associated with the capillary basal lamina have not yet formed. Beta- and gamma-emitting radionuclides such as 131I, which are widely used in radioimmunotherapy, are not expected to be effective when targeting single cells or small cell clusters. This is because the range of the emissions is one to two orders of magnitude greater than the target size, and the energy deposited per traversal is insufficient to produce any significant radiobiological effect. Spheroids of the prostate cancer cell line, LNCaP-LN3, were used as a model of prevascularized micrometastases; their response to an anti-PSMA antibody, J591, radiolabeled with the alpha-particle emitter 213Bi (T(1/2), 45.6 min.) has been measured. The time course of spheroid volume reductions was found to be sensitive to the initial spheroid volume. J591 labeled with 0.9 MBq/ml 213Bi resulted in a 3-log reduction in spheroid volume on day 33, relative to control, for spheroids with an initial diameter of 130 microm; 1.8 MBq/ml were required to achieve a similar response for spheroids with an initial diameter of 180 microm. Equivalent spheroid responses were observed after 12 Gy of acute external beam photon irradiation. Monte Carlo-based microdosimetric analyses of the 213Bi decay distribution in individual spheroids of 130-microm diameter yielded an average alpha-particle dose of 3.7 Gy to the spheroids, resulting in a relative biological effectiveness factor of 3.2 over photon irradiation. The activity concentrations used in the experiments were clinically relevant, and this work supports the possibility of using 213Bi-labeled antibodies not only for disseminated single tumor cells, as found in patients with leukemia, but also for micrometastatic tumor deposits up to 180 microm in diameter (1200 cells).