The effect of hematocrit, fibrinogen concentration and temperature on the kinetics of clot formation of whole blood.

BACKGROUND: Dynamic mechanical analysis of blood clots can be used to detect the coagulability of blood. OBJECTIVE: We investigated the kinetics of clot formation by changing several blood components, and we looked into the clot "signature" at its equilibrium state by using viscoelastic and dielectric protocols. METHODS: Oscillating shear rheometry, ROTEM, and a dielectro-rheological device was used. RESULTS: In fibrinogen- spiked samples we found the classical high clotting ability: shortened onset, faster rate of clotting, and higher plateau stiffness. Electron microscopy explained the gain of stiffness. Incorporated RBCs weakened the clots. Reduction of temperature during the clotting process supported the development of high moduli by providing more time for fiber assembly. But at low HCT, clot firmness could be increased by elevating the temperature from 32 to 37°C. In contrast, when the fibrinogen concentration was modified, acceleration of clotting via temperature always reduced clot stiffness, whatever the initial fibrinogen concentration. Electrical resistance increased continuously during clotting; loss tangent (D) (relaxation frequency 249 kHz) decreased when clots became denser: fewer dipoles contributed to the relaxation process. The relaxation peak (Dmax) shifted to lower frequencies at higher platelet count. CONCLUSION: Increasing temperature accelerates clot formation but weakens clots. Rheometry and ROTEM correlate well.

Visual acuity after vitrectomy and epiretinal membrane peeling with or without premacular indocyanine green injection.

PURPOSE: To compare postoperative visual acuity of eyes operated for an epiretinal membrane (ERM), with or without intraoperative intraocular indocyanine green (ICG) injection. METHODS: Retrospective study of 75 pseudophakic eyes with epiretinal membrane operated by vitrectomy-peeling. In 20 cases operated in 2001 and 2002 (Group 1), ICG diluted in 5% glucose solution was injected intraoperatively into the vitreous. In another group of 55 cases operated between 1996 and 1999 (Group 2), ICG was not used. RESULTS: The mean visual acuity was 0.32(+1) and 0.32(+2) preoperatively, 0.4(+2) and 0.5 at 1 month, and 0.63 and 0.63(+2) on the final examination in Groups 1 and 2, respectively. Visual acuities were not significantly different between the two groups. CONCLUSIONS: Premacular injection of ICG during vitrectomy to facilitate epiretinal membrane peeling did not appear to compromise postoperative improvement of visual acuity. However, its use is questioned since it did not yield better postoperative results and because potential toxic adverse reactions could not be excluded by this study.

Effect of liver transplantation on hepatic glucose metabolism in a patient with type I glycogen storage disease.

BACKGROUND: In type I glycogenosis, mutation of the glucose-6-phosphatase gene results in absent glucose-6-phosphatase activity in liver cells leading to fasting hypoglycemia. Liver transplantation is expected to normalize glucose homeostasis. METHODS: Endogenous glucose production (6,6 2H2 glucose) was measured after an overnight fast and during exogenous 13C-labeled glycerol infusion in a patient with glycogenosis type I 24 months after liver transplantation and in a group of healthy subjects. RESULTS: Compared with healthy subjects, the glycogenosis patient had normal fasting glucose production and glucose and insulin concentrations after liver transplantation, but mildly elevated plasma glucagon concentrations. Gluconeogenesis from exogenous glycerol (13C glucose synthesis) was similar and did not lead to enhancement of glucose production in both healthy controls and the patient. CONCLUSIONS: Liver glucoregulatory function is restored by orthotopic liver transplantation in type I glycogenosis.

Autoimmune retinal dysfunction in sarcoid chorioretinopathy.

BACKGROUND: Visual loss, photophobia and night-blindness in a middle-aged patient with a previous history of cancer are highly suggestive of cancer-associated retinopathy. HISTORY AND SIGNS: A 63-year-old man complained of slowly progressive bilateral visual loss, photophobia and night-blindness. His past medical history was remarkable for surgical and medical treatment of a carcinoma of the base of his tongue nine years earlier. Visual acuity was 0.3 RE and 0.15 LE, with constricted visual field in both eyes. Ocular examination and fluorescein angiography were non-relevant. Electroretinography revealed diffuse cone and rod dysfunction. ICG angiography showed multiple small widespread hyperfluorescent spots. A chest CT scan revealed multiple focal lesions which were biopsied. Histological diagnosis was sarcoidosis. THERAPY AND OUTCOME: Upon systemic steroid therapy, visual function gradually improved, and ICG anomalies disappeared. Vision recovered to 1.0 RE and 0.8 LE with normal visual field in both eyes. CONCLUSION: Sarcoidosis may present as an autoimmune retinal dysfunction with photophobia and night blindness as the presenting symptoms.