Computer graphics for digitally formatted images

The increasing use of digitally formatted imaging systems requires high-quality interactive gray-scale computer raster graphics systems for the management, display, and analog film recording of digital image and alphanumeric information. These systems are a combination of computer hardware and software and implement a set of graphics protocols. This paper describes a set of interactive graphics protocols that has been developed for clinical use.     

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     

Modulation of hypoglycemia-induced increases in plasma epinephrine by estrogen in the female rat

Clinical studies have demonstrated that estrogen replacement therapy suppresses stress-induced increases in plasma catecholamines. The present study determined whether normal circulating levels of estrogen can modulate hypoglycemia-induced increases in plasma epinephrine (EPI). In anesthetized female rats, insulin-induced hypoglycemia (0.25 U/kg) increased plasma EPI concentration to a significantly greater extent in 14-day ovariectomized (OVEX) rats compared to that in sham-operated controls. In 17beta-estradiol (E2)-replaced OVEX rats, the hypoglycemia-induced rise in plasma EPI was reduced significantly when compared to that in vehicle-replaced OVEX rats. OVEX and E2 replacement had no effect on tyrosine hydroxylase or phenylethanolamine N-methyltransferase mRNA levels in the adrenal medulla. In isolated adrenal medullary chromaffin cells, agonist-induced increases in intracellular Ca2+ were unaffected by 48-hr exposure to 10 nM E2. In contrast, acute (3-min) exposure to micromolar concentrations of E2 dose-dependently and reversibly inhibited agonist-induced Ca2+ transients. In addition, in OVEX rats, a constant infusion of E2 significantly reduced the insulin-induced increase in plasma EPI concentration compared to that in vehicle-infused controls. These data demonstrate that physiologic levels of circulating E2 can modulate hypoglycemia-induced increases in plasma EPI. This effect seems independent of steroid influence on adrenal medullary secretion or biosynthesis. In contrast, acute exposure to high levels of E2 can also suppress hypoglycemia-induced increases in plasma epinephrine, due at least in part to inhibition of stimulus-secretion coupling.