Embryonic stem cell-derived T cells induce lethal graft-versus-host disease and reject allogenic skin grafts upon thymic selection.

Efficient differentiation of embryonic stem cells (ESC) into hematopoietic progenitor cells (HPCs) is crucial for the establishment of stem cell-based therapies targeting the treatment of immunological and hematological disorders. However, so far, it has not been possible to induce long-term survival of murine ESC-derived HPCs without the overexpression of HoxB4, a homeobox transcription factor that confers self-renewal properties to hematopoietic cells. Yet it has not been feasible to generate T cells from HoxB4-expressing HPCs, a problem that has been attributed to HoxB4. Here, we show that Notch1 signaling in HoxB4-transduced ESCs leads to efficient derivation of T cells that survive long term. These T cells display a normal T-cell Vß repertoire, respond to mitogen stimulation and induce lethal graft-versus-host disease. Thymic selection in fetal thymic organ cultures (FTOCs) allowed negative selection and generation of T cells tolerant to 'self' and capable of rejecting MHC-mismatched skin allografts. Our data show that ESC-derived T cells, despite high expression of HoxB4, are fully immunocompetent.

Acute computed tomography findings in patients with acute confusion of non-traumatic aetiology / Hallazgos agudos con tomografía computarizada en pacientes con confusión aguda de etiología no traumática

BACKGROUND: A retrospective review was undertaken of all patients referred for computed tomography (CT) scans of the head for acute onset of confusion, not consequent on head trauma, during the period June 1, 2004 to May 31, 2007. METHOD: Data were obtained by Microsoft Word search of the reports of the Radiology Department of the University Hospital of the West Indies, Kingston, Jamaica. Two hundred and twenty-one patients were reviewed: 103 men and 118 women. The mean age of the sample was 64 years; 168 patients (76%) were 50 years old or older. RESULT: Computed tomography scans were reported normal in 170 (76.9%) patients; 45 patients (20.4%) had definite acute intracranial CT findings. Findings were equivocal in three patients (1.4%) and unavailable for three (1.4%); 23.2% and 15.6% of patients above and below the age of 50 years respectively showed acute abnormalities on CT. The most common acute finding on CT scan was an ischaemic infarct (68%). Other abnormalities included intracerebral haemorrhage and metastases 6.2% each, toxoplasmosis and primary brain tumour 4.2% each and subdural haematoma and meningitis 2.1% each. The diagnoses of toxoplas-mosis were made based on appearances typical of toxoplasmosis on CT scans in patients whose request stated that they were HIV positive. CONCLUSION: In the sample reviewed, most patients who presented with acute confusion were above the age of 50 years. Overall, 20.4% of patients from all age groups had acute abnormalities on CT with a relative higher proportion, 23.2% versus 15.6% of those over 50 years, having acute pathology. The most common abnormality was an ischaemic infarct. This finding is similar to that in developed countries and unlike that seen in other developing countries where infectious aetiologies predominate.

ANTECEDENTES: Durante el período de junio, 2004 a mayo 31, 2007, se llevó a cabo una revisión retrospectiva de todos los pacientes remitidos para escaneos mediante tomografía computarizada (TC escáner) de la cabeza, en casos de ataques de confusión aguda, no originados por traumas en la cabeza. MÉTODO: Los datos fueron obtenidos mediante búsqueda con Microsoft Word de los informes del Departamento de Radiología del Hospital Universitario de West Indies, Kingston, Jamaica. Se revisaron doscientos veintiún pacientes: 103 hombres y 118 mujeres. La edad promedio de la muestra fue 64 años; 168 pacientes (76%) tenían 50 años de edad o más. RESULTADO: Los escaneos mediante tomografía computarizada fueron reportados como un procedimiento normal en 170 (76.9%) pacientes; 45 pacientes (20.4%) tuvieron hallazgos agudos intracraneales definidos por TC. Los hallazgos fueron equívocos en tres pacientes (1.4%) y no disponibles en tres (1.4%); 23.2% y 15.6% de los pacientes por encima y por debajo de la edad de 50 años respectivamente, mostraron anormalidades agudas en la TC. El hallazgo agudo más común con el escaneo de TC fue el infarto isquémico (68%). Otras anormalidades incluyeron hemorragias intracerebrales y metástasis, 6.2% respectivamente; toxoplasmosis y tumor primario del cerebro, 4.2% respectivamente, y hematoma subdural y meningitis, 2.1% respectivamente. CONCLUSIÓN: En la muestra revisada, la mayoría de los pacientes que presentaron confusión aguda se hallaban por encima de 50 años de edad. En general, 20.4% de los pacientes de todos los grupos etarios presentaban anormalidades agudas en la TC en una proporción relativamente más alta, siendo el caso que el 23.2% frente al 15.6% de aquéllos por encima de 50 años, presentaban patologías agudas. La anormalidad más común fue el infarto isquémico. Este hallazgo es similar al de los países desarrollados, y diferente al que se observa en otros países en vías de desarrollo, dónde predominan las etiologías infecciosas.

Acute computed tomography findings in patients with acute confusion of non-traumatic aetiology.

BACKGROUND: A retrospective review was undertaken of all patients referred for computed tomography (CT) scans of the head for acute onset of confusion, not consequent on head trauma, during the period June 1, 2004 to May 31, 2007. METHOD: Data were obtained by Microsoft Word search of the reports of the Radiology Department of the University Hospital of the West Indies, Kingston, Jamaica. Two hundred and twenty-one patients were reviewed: 103 men and 118 women. The mean age of the sample was 64 years; 168 patients (76%) were 50 years old or older. RESULT: Computed tomography scans were reported normal in 170 (76.9%) patients; 45 patients (20.4%) had definite acute intracranial CT findings. Findings were equivocal in three patients (1.4%) and unavailable for three (1.4%); 23.2% and 15.6% of patients above and below the age of 50 years respectively showed acute abnormalities on CT The most common acute finding on CT scan was an ischaemic infarct (68%). Other abnormalities included intracerebral haemorrhage and metastases 6.2% each, toxoplasmosis and primary brain tumour 4.2% each and subdural haematoma and meningitis 2.1% each. The diagnoses of toxoplasmosis were made based on appearances typical of toxoplasmosis on CT scans in patients whose request stated that they were HIV positive. CONCLUSION: In the sample reviewed, most patients who presented with acute confusion were above the age of 50 years. Overall, 20.4% of patients from all age groups had acute abnormalities on CT with a relative higher proportion, 23.2% versus 15.6% of those over 50 years, having acute pathology. The most common abnormality was an ischaemic infarct. This finding is similar to that in developed countries and unlike that seen in other developing countries where infectious aetiologies predominate.

Co(2+):YSGG saturable absorber Q switch for infrared erbium lasers.

Passive Q switching of Er:glass (1.53 microm) with a new, robust, solid-state saturable absorber, Co(2+):Y(3)Sc(2)Ga(3)O(12), has been demonstrated. Q-switched pulses of 20 ns and 4 mJ of energy were obtained. An absorption cross section of 5 x 10(-20) cm(2) was measured. Preliminary results for a Co(2+):Y(3)Al(5)O(12) saturable absorber Q switch are also discussed.

Dy(2+):CaF(2) saturable-absorber Q switch for the ruby laser.

Passive Q switching of a flash-lamp-pumped ruby laser has been demonstrated with a Dy(2+):CaF(2) saturable absorber at room temperature. Typically a single Q-switched pulse of 4.5 mJ and 94 ns was observed. At 694 nm, the ground-state absorption cross section and the excited-state absorption cross section of the Dy(2+):CaF(2) absorber were found to be 1.2 × 10(-18) cm(2) and 0.9 × 10(-18) cm(2) respectively, with a four-level slow-relaxing saturable-absorber model.

Dual Q switching and laser action at 1.06 and 1.44 microm in a Nd(3+):YAG-Cr(4+):YAG oscillator at 300 K.

We report what is to our knowledge the first dual operation comprising laser action and Q switching of Cr(4+):YAG pumped intracavity by a Nd:YAG laser. This technique produced dual 1.06- and 1.44-microm pulses with 35- and 200-ns pulse widths, respectively. The Nd:YAG rod was pumped by a 1-ms flash-lamp pulse, resulting in a train of 1.06- and 1.44-microm pulse pairs at approximately a 30-kHz rate.