Use of X-ray tomography to map crystalline and amorphous phases in frozen biomaterials.

The outcome of both cryopreservation and cryosurgical freezing applications is influenced by the concentration and type of the cryoprotective agent (CPA) or the cryodestructive agent (i.e., the chemical adjuvants referred to here as CDA) added prior to freezing. It also depends on the amount and type of crystalline, amorphous and/or eutectic phases formed during freezing which can differentially affect viability. This work describes the use of X-ray computer tomography (CT) for non-invasive, indirect determination of the phase, solute concentration and temperature within biomaterials (CPA, CDA loaded solutions and tissues) by X-ray attenuation before and after freezing. Specifically, this work focuses on establishing the feasibility of CT (100-420 kV acceleration voltage) to accurately measure the concentration of glycerol or salt as model CPA and CDAs in unfrozen solutions and tissues at 20 degrees C, or the phase in frozen solutions and tissue systems at -78.5 and -196 degrees C. The solutions are composed of water with physiological concentrations of NaCl (0.88% wt/wt) and DMEM (Dulbecco's Modified Eagle's Medium) with added glycerol (0-8 M). The tissue system is chosen as 3 mm thick porcine liver slices as well as 2 cm diameter cores which were either imaged fresh (3-4 h cold ischemia) or after loading with DMEM based glycerol solutions (0-8 M) for times ranging from hours to 7 days at 4 degrees C. The X-ray attenuation is reported in Hounsfield units (HU), a clinical measurement which normalizes X-ray attenuation values by the difference between those of water and air. NaCl solutions from 0 to 23.3% wt/wt (i.e. water to eutectic concentration) were found to linearly correspond to HU in a range from 0 to 155. At -196 degrees C the variation was from -80 to 95 HU while at -78.5 degrees C all readings were roughly 10 HU lower. At 20 degrees C NaCl and DMEM solutions with 0-8 M glycerol loading show a linear variation from 0 to 145 HU. After freezing to -78.5 degrees C the variation of the NaCl and DMEM solutions is more than twice as large between -90 and +190 HU and was distinctly non-linear above 6 M. After freezing to -196 degrees C the variation of the NaCl and DMEM solutions increased even further to -80 to +225 HU and was distinctly non-linear above 4 M, which after modeling the phase change and crystallization process is shown to correlate with an amorphous phase. In all tissue systems the HU readings were similar to solutions but higher by roughly 30 HU, as well as showing some deviations at 0 M after storage, probably due to tissue swelling. The standard deviations in all measurements were roughly 5 HU or below in all samples. In addition, two practical examples for CT use were demonstrated including: (1) glycerol loading and freezing of tissue cores and, (2) a mock cryosurgical procedure. In the loading experiment CT was able to measure the permeation of the glycerol into the sample at 20 degrees C, as well as the evolution of distinct amorphous vs. crystalline phases after freezing to -196 degrees C. In the mock cryosurgery example, the iceball edge was clearly visualized, and attempts to determine the temperature within the iceball are discussed. An added benefit of this work is that the density of these frozen samples, an essential property in measurement and modeling of thermal processes, was obtained in comparison to ice.

[Complications after high dose therapy and autologous stem cell transplantation. Retrospective study of an unselected patient sample]. / Komplikationen nach Hochdosistherapie und autologer Stammzelltransplantation. Retrospektive Untersuchung an einem nicht selektionierten Patientenkollektiv.

BACKGROUND: High-dose therapy (HDT) with autologous blood stem cell transplantation (ASCT) has become the therapy of choice for patients with specific hematologic neoplasms. Although pancytopenia after HDT with stem cell support is of relatively short duration, complications may be severe and life-threatening. In unselected patients with hematologic and solid tumor malignancies, only few data have been published regarding complications. We therefore analyzed the rate of infection and toxicity in patients with different neoplasms undergoing HDT and ASCT. PATIENTS AND METHODS: From 6/96 to 12/99 42 patients received 54 HDT and ASCT (nine tandem transplants and one triple transplant). The median age was 55 years (range 25-74 years) with equal sex distribution. 30 patients suffered from hematologic malignancies and twelve from solid tumors. RESULTS: Infections were the major cause for complications followed by mucositis, pain and diarrhea. In four patients a positive cytomegalovirus polymerase chain reaction (CMV-PCR) was detected. In two patients this positive test result was accompanied by clinical symptoms of CMV infection. One patient developed lung fibrosis due to busulfan (WHO 4 degrees) and additionally a veno-occlusive disease (VOD) of the liver (WHO 4 degrees). Two patients (4%) died due to CMV pneumonia and multiple organ failure after idiopathic pneumonia, respectively. Four patients developed secondary neoplasms (two patients myelodysplastic syndromes, two patients solid tumors). Three of them had been heavily pretreated. We further analyzed whether the following parameters had an influence on the rate of complications: tumor diagnosis (hematologic vs. solid), number of pretreatment protocols (< 2 vs. > or = 2), CD34+ cell count (< median CD34+ cell count vs. > or = median CD34+ cell count), age (< or = 55 years vs. > 55 years), mucositis (WHO 1-2 degrees vs. 3-4 degrees) and conditioning regimen (myeloablative vs. myelosuppressive). The infection rate was higher in patients receiving myeloablative therapy compared to patients with myelosuppressive conditioning and the platelet count recovery was slower. In patients receiving a higher CD34+ cell count, time until platelets reached > 50/nl was shorter than in patients with a lower CD34+ cell count. Patients with > or = 2 pretreatment protocols had a higher infection rate than patients with < 2 pretreatments. Patients suffering from severe mucositis (WHO 3-4 degrees) exhibited a slower platelet recovery and a higher infection rate. No difference was noted in the complication rate for the other parameters (tumor diagnosis, age). CONCLUSION: Complication rate and mortality in this heterogeneous patient group were not different from the data of other authors describing selected patients receiving a uniform conditioning regimen or having a distinct disease. The complication rate is influenced by the number of pretreatment protocols, conditioning regimens and the number of transplanted CD34+ cells.

Impact resistance of materials for guards on cutting machine tools--requirements in future European safety standards.

Guards on machine tools are meant to protect operators from injuries caused by tools, workpieces, and fragments hurled out of the machine's working zone. This article presents the impact resistance requirements, which guards according to European safety standards for machine tools must satisfy. Based upon these standards the impact resistance of different guard materials was determined using cylindrical steel projectiles. Polycarbonate proves to be a suitable material for vision panels because of its high energy absorption capacity. The impact resistance of 8-mm thick polycarbonate is roughly equal to that of a 3-mm thick steel sheet Fe P01. The limited ageing stability, however, makes it necessary to protect polycarbonate against cooling lubricants by means of additional panes on both sides.

Chédiak-Higashi-Steinbrinck syndrome (CHS) in a 27-year-old woman--effects of G-CSF treatment.

Chédiak-Higashi-Steinbrinck syndrome (CHS) is a rare autosomal recessive disorder which is usually lethal in early childhood. Diagnostic hallmark is the occurrence of giant inclusion bodies in peripheral leukocytes and their bone marrow precursors. We report on a 27-year-old female patient who was admitted for treatment of a skin abscess. She recovered after intravenous antibiotic treatment and surgical incision. Hematological investigation was initiated because of a persisting neutropenia of 15%, with a leukocyte count initially in the normal range but subsequent leukopenia. Case history revealed recurrent skin infections from childhood on, regularly requiring surgical intervention. One year prior to admission a neuropathy had been diagnosed, while a partial albinism had been known for years. Microscopic examinations of peripheral blood and bone marrow aspirate smears were diagnostic for CHS. Additionally, a secondary antibody deficiency was found. Normalization of the white blood cell count, including the differential count, was observed following initiation of G-CSF treatment. Functional assessment of phagocytosis and oxidative burst activity of granulocytes revealed normal results before and after stimulation with G-CSF, however, natural killer cell activity was only weak, with slight improvement after G-CSF treatment in vivo. Cytogenetic analysis showed a normal female karyotype. Although the haploidentical brother of the patient may serve as an allogeneic stem cell donor, transplantation has been postponed because of further deterioration of her already existing CHS-specific neurological impairment. Nevertheless, while receiving G-CSF maintenance treatment our patient experienced no further infectious episodes within 6 months after diagnosis of CHS.