[Progressive multifocal leukoencephalopathy (PML) in chronic lymphatic leukemia (CLL). Review of the literature and case report]. / Progressive multifokale Leukoenzephalopathie (PML) bei chronisch lymphatischer Leukämie (CLL). Literaturübersicht und Fallbeschreibung.

Progressive multifocal leukoencephalopathy (PML) is an infectious disease of the central nervous system caused by the JC virus. Progressive multifocal leukoencephalopathy represents a reactivation of the JC virus after long-standing immunosuppression. Also, PML plays an important role as an opportunistic infection in patients with AIDS. The average time of survival in patients with PML in combination with chronic lymphatic leukemia (CLL) (n = 17 in the literature) is 4.3 months, and therapeutic options are not established. We report the case of a patient with CLL and PML. Clinical symptoms are slight hemiparesis of the right side, mainly appearing as a disturbance of motor function. In MRI, a typical subcortical lesion was shown, and JC virus DNA was positive in the CSF by PCR. Because of first positive results in treatment of PML in patients with AIDS, therapy with cidofovir was started. After treatment for 16 months, symptoms are stable, the PML-induced lesions in MRI are in regression, and JC virus DNA is not detectable in the CSF.

Process optimization of a continuous airlift tower-loop reactor.

Based on the experimental investigations with H. polymorpha and Methylomonas M 15 in bench-scale airlift tower-loop reactors, a general distributed parameter model was developed and used to simulate to cultivation process in a 40-m-high production reactor. This general model was simplified with regard to the gas phase and loop balances and was employed to optimize cell productivity and/or profit in a 20-m-high pilot-plant airlift tower-loop reactor. Maximum cell productivity always occurs in the oxygen-transfer-limited growth range. In case of a high "penalty factor" for nonconsumed substrate, maximum profit is attained at the boundary between substrate and oxygen-transfer-limited growth. Oxygen-transfer limitation exists in the lower half of the tower, whereas in the upper half, substrate limitation prevails. The longitudinal dissolved oxygen concentration passes a minimum in this case as has been determined experimentally in the bench-scale column. The simulation results agree fairly well with the data measured in the pilot plant.

Identification of mass-transfer parameters and process simulation of SCP production process in airlift tower reactors with an external loop.

A distributed parameter model for simulation of SCP-production processes in tower reactors with an outer loop was developed by considering substrate, cell, and CO(2) balances in the liquid phase, and O(2) and CO(3) balances in the ges phase and taking into account variations of dissolved oxygen concentration, pressure, and k(L)a along the column, as well as double substrate Monod kinetics. This model was used to describe the cultivation of Hansenula polymorpha in a tower-loop reactor (height 275 cm, diameter 15 cm). Parameter identification and process simulation were carried out by a hybrid computer. The variation of identified mass transfer parameters with fermentation time and operation mode is considered employing ethanol and glucose substrate, respectively. Relationships among k(L)a, substrate concentration, and superficial gas velocity were developed to facilitate the layout and simulation of pilot-plant reactors.