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PubMed1991

Contamination during in vitro processing of bone marrow for transplantation: clinical significance.

We determined the prevalence and clinical significance of positive microbiologic cultures obtained from 194 consecutive bone marrow harvests intended for infusion in 188 consecutive adult bone marrow transplant patients. Microbiologic cultures were obtained at harvest, after manipulation in vitro (for ABO imcompatibility or purging procedures), and at the time of thawing and infusion (after earlier cryopreservation). Only one of 194 marrow harvests was culture-positive intra-operatively (from an ABO-compatible allogeneic marrow that was infused without manipulation). None of 39 other allogeneic marrows (including 21 ABO-incompatible marrows which were manipulated in vitro) and none of 154 autologous marrows (including 40 which were purged in vitro) grew bacteria or fungi. On the other hand, 12 of 153 (8%) bone marrow samples were positive for micro-organisms after thawing at the time of infusion. The predominant organisms cultured were gram negative bacilli (including five Pseudomonas sp.), probably introduced during the thawing process in a water bath. In only one of 13 contaminated marrows was the same organism(s) (Pseudomonas picketti and Pseudomonas paucimobilis) recovered in vivo during the transplant course. This patient experienced a bacteremia which was eradicated without sequelae. Contamination of marrow can occur during the procurement and in vitro handling processes. With proper sterile technique bone marrow infusion does not pose a significant infectious risk for the immunocompromised transplant patient.

Adolescent↗
PubMed2006

Whole-blood leukoreduction filters are a source for cryopreserved cells for phenotypic and functional investigations on peripheral blood lymphocytes.

BACKGROUND: Leukoreduction of blood is now widely performed by blood banks, and the possibility of recovering 10(8) to 10(9) white blood cells (WBCs) from leukoreduction filters, which are usually discarded, represents a promising source for normal human cells. Previous studies with these filters to prepare WBCs have performed their experimentation with fresh cells only. Whether these filter-derived cells could also be used to prepare frozen cell banks to facilitate work organization and open new avenues for their utilization as references in physiological studies and clinical investigations was investigated. STUDY DESIGN AND METHODS: Blood samples or whole-blood leukoreduction filters were obtained, after informed consent, from volunteers or blood donors, respectively. The proportions of CD3+, CD14+, CD16+, CD19+, and CD45+ cells within peripheral blood mononuclear cells (PBMNCs) were determined by flow cytometry from all samples. B cells were isolated and their functional responses were evaluated in vitro. RESULTS: The yield of PBMNCs recovered from whole-blood leukoreduction filters was lower (50%) than the one with fresh blood samples but still provided 2 x 10(8) to 4 x 10(8) PBMNCs per unit. After one cycle of freezing-thawing, the proportions of B- and T-cell populations were similar to normal blood values. Purified B cells issued from whole-blood leukoreduction filters displayed normal phenotypes and functions. CONCLUSION: Leukoreduction filters represent a valuable source of PBMNCs. These cells could be easily recovered to prepare frozen cell banks useful in basic phenotypic and functional analyses involving the main subsets of B cells and the global T-cell population.

Antigens, CD↗
PubMedDate not supplied

A morphometric comparison of the nuclear morphology of fresh and frozen-thawed human zona-bound and unbound sperm.

The role of sperm nuclear morphology in zona binding and the effect of cryopreservation on sperm nuclear morphology have been investigated using objective criteria. The nuclear dimensions of fresh and frozen-thawed sperm heads that had been prepared by the swim-up (SU) technique, and bound to human oocytes in vitro, were measured using a computer-assisted image analyzer. These were compared with each other and also to sperm in the SU samples and those that had not bound to the zona pellucida. The unbound (UB) sperm and SU sperm had very similar nuclear morphology. In contrast, the nuclear morphology of the zona-bound (ZB) sperm differed significantly (P < 0.05) from that of the SU and UB sperm. These differences were found specifically between area, breadth, and roundness in the SU and ZB sperm preparations, and between area and roundness in the UB and ZB sperm preparations; the ZB sperm had smaller but rounder nuclei than either the SU or UB sperm. In addition, the frozen-thawed sperm in the SU and UB groups showed a trend towards smaller nuclei than the corresponding fresh groups, whereas the frozen-thawed ZB sperm had significantly (P < 0.05) smaller nuclear dimensions than the fresh ZB sperm. From the present study it appears that the ZB sperm are a morphologically distinct population, although it is not yet clear whether these differences reflect functional events that occur in the sperm head during its maturation or changes at the level of the sperm's DNA after the initial stage of zona binding.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Nucleus↗
PubMed2000

Semen treatment with progesterone and/or acetyl-L-carnitine does not improve sperm motility or membrane damage after cryopreservation-thawing.

OBJECTIVE: To assess the effects of progesterone and acetyl-L-carnitine used before semen cryopreservation-thawing on sperm motility parameters and plasma membrane integrity. DESIGN: Prospective cohort study. SETTING: Academic tertiary center. PATIENT(S): Subfertile men undergoing semen evaluation. INTERVENTION(S): Before cryopreservation, spermatozoa were incubated with water-soluble progesterone (1 and 10 microM), acetyl-L-carnitine (2.5, 5, 10, and 20 mM), or both (progesterone, 1 microM; and acetyl-L-carnitine, 5 mM). MAIN OUTCOME MEASURE(S): Postthaw change of motility parameters (computer-assisted measurements) and vitality-membrane integrity (examined with eosin-Y staining and annexin V-Cy3 binding assay). RESULT(S): There were no statistically significant differences between control samples and samples treated with progesterone and/or acetyl-L-carnitine for cryosurvival rate, motility parameters, or membrane integrity. The percentages of postthaw cells identified as live showed significantly different results with use of the eosin-Y staining and annexin V binding assay. CONCLUSION(S): Neither progesterone nor acetyl-L-carnitine seemed to prevent cryodamage assessed by motility changes or membrane integrity in human spermatozoa of subfertile men. Annexin V binding, a reflection of membrane translocation of phosphatidylserine, provided more distinct information about postfreezing membrane integrity changes than eosin-Y staining.

Acetylcarnitine↗
PubMed1999

Retroviral marking and transplantation of rhesus hematopoietic cells by nonmyeloablative conditioning.

The ability to engraft significant numbers of genetically modified hematopoietic stem and progenitor cells without the requirement for fully myeloablative conditioning therapy is a highly desirable goal for the treatment of many nonmalignant hematologic disorders. The aims of this study were to examine, in nonhuman primates (rhesus), (1) the effects of pretreatment of host animals with cytokines (G-CSF and SCF), i.e., before nonmyeloablative irradiation, on the degree and duration of neo gene marking of circulating leukocytes after autologous cell reinfusion and (2) to compare transduction of primitive hematopoietic target cells in the presence of our standard transduction cytokine combination of IL-3, IL-6, and stem cell factor (SCF) and in the presence of an alternative combination containing SCF, G-CSF, and the thrombopoietin analog MGDF. Cytokine-mobilized rhesus peripheral blood progenitor/stem cells (PBSCs) were enriched for CD34+ cells and transduced with neo vectors (either G1Na or LNL6) for 96 hr in cultures containing rhIL-3, rhIL-6, and rhSCF or MGDF, rhSCF, and rhG-CSF and cryopreserved. Four animals underwent minimal myeloablative conditioning with 500 cGy irradiation with or without pretreatment with SCF and G-CSF, followed by reinfusion of the cryopreserved cells on the subsequent day. Neutrophil nadirs (< or =500/mm3) were 0-3 days in duration; there were no significant periods of severe thrombocytopenia. Marking of circulating granulocytes and mononuclear cells was extensive and durable in all animals (exceeding 12% in the mononuclear cells of one animal) and persisted beyond the final sampling time in all animals (up to 33 weeks). No difference in extent or duration of marking was attributable to either cytokine presensitization of recipients prior to irradiation, or to the substitution of MDGF and G-CSF for IL-3 and IL-6 during transduction.

Animals↗
PubMedDate not supplied

Serum total gangliosides and TA90-IC levels: novel immunologic markers in colorectal cancer.

BACKGROUND: Because of the challenge in defining prognostic markers predictive of recurrence or progression, carcinoembryonic antigen (CEA) remains the most frequently used marker in colorectal cancer, despite its low sensitivity. We hypothesized that TA90-IC status and serum ganglioside levels might be useful markers and might be of prognostic significance in colorectal cancer. METHODS: Serum samples from 68 patients undergoing surgical treatment for histologically proven colorectal cancer were analyzed for the presence of CEA, serum gangliosides, and TA90-IC. Forty-one patients had node-negative disease, whereas 27 patients had limited metastatic disease. The intent was curative resection, even for patients with metastatic disease. Cryopreserved serum specimens were analyzed in a blinded fashion for total serum ganglioside levels (by an assay that detects lipid-associated sialic acids), for CEA, and for TA90-IC (by a murine monoclonal antibody-based enzyme-linked immunosorbent assay). A positive value for TA90-IC levels was defined as an optical density (OD) of more than 0.410 at 405 nm. RESULTS: Serum ganglioside levels were elevated more frequently than CEA concentrations (84% vs 44%). The combination of serum ganglioside and CEA values was more sensitive (88%) than CEA value alone (44%) in identifying patients with early-stage colorectal cancer. TA90-IC levels were elevated more frequently than CEA concentrations (56% vs 32%). The combination of TA90-IC and CEA values was more sensitive (72%) than CEA value alone (32%) in identifying patients with advanced-stage colorectal cancer. At an enzyme-linked immunosorbent assay cutoff level of 0.410, 15 (56%) patients had positive TA90-IC values. Fourteen patients alive with residual disease had a median OD TA90-IC level of 0.879, and only three patients had levels below the OD cutoff value of 0.410. Thirteen patients with no evidence of disease had a median level of 0.277, and only four patients had OD levels > or = 0.410. TA90-IC was significantly higher in the alive with residual disease patients than those rendered no evidence of disease (P = 0.02). CONCLUSIONS: We speculate that a multiple-marker analysis that combines CEA values with serum ganglioside and TA90-IC values may be more sensitive than CEA value alone for detecting colorectal cancer. The potential prognostic significance of TA90-IC status in advanced disease warrants further investigation.

Adult↗
PubMed2005

Birth of live Spanish ibex (Capra pyrenaica hispanica) derived from artificial insemination with epididymal spermatozoa retrieved after death.

As a consequence of increasing limitations to maintaining genetic variability in endangered wildlife species, methods of assisted reproduction widely used in domestic animals are being applied to nondomestic species. However, practical efforts have met limited success to date. The Spanish ibex (Capra pyrenaica hispanica) is a wild caprine originating exclusively in the mountains of Spain. This study was designed to evaluate the fertilizing capability of cryopreserved Spanish ibex epididymal spermatozoa recovered postmortem. For this purpose, we have previously evaluated the effect of time elapsed between death and sperm recovery on spermatic parameters, and the fertilization ability of frozen-thawed spermatozoa using heterologous in vivo fertilization by intrauterine insemination in domestic goat (Capra hircus). The time of death significantly affected most sperm quality parameters (motility, viability and intact acrosomes). The fertility obtained by heterologous artificial insemination was 18.7%, and only goats inseminated with spermatozoa recovered within 8h after death became pregnant. Our findings showed that heterologous in vivo fertilization is a useful method to evaluate the fertilizing capacity of sperm samples in rare or wild species. Sperm samples, with verified fertilization ability in the previous trial, were used to inseminate a total of six ibex females. Inseminations resulted in one pregnancy. The study demonstrated for the first time the feasibility of applying artificial insemination in Spanish ibex.

Animals↗
PubMed1991

Analysis of bismuth in serum and blood by electrothermal atomic absorption spectrometry using platinum as matrix modifier.

Bismuth-containing medicines have been used for years, but there is a lack of clinically applicable methods for measuring bismuth in body fluids. We describe a sensitive, accurate and precise method for analysis of bismuth in blood and serum, which is suitable both for monitoring purposes and for further investigations into the biokinetics and safety of bismuth. Bismuth was quantitated with electrothermal atomic absorption spectrometry with Zeeman background correction. In the furnace programme a cool-down step was introduced and platinum was used as a matrix modifier. Recovery for 40 micrograms/l is 93.7 +/- 4.6% (mean +/- SD) from serum and 92.8 +/- 5.4% from blood; within-day precision (n = 10) at 40 micrograms/l is 3.2% for serum and 4.2% for blood. Day-to-day precision at 40 micrograms/l (n = 10) was 4.5% for serum and 4.0% for blood. The detection limit is 0.7 microgram/l for serum and 1.0 microgram/l for blood. Blood samples have to be collected in glass tubes and stored at -20 degrees C.

Animals↗
PubMed2006

Effect of post-thaw dilution with autologous prostatic fluid on dog semen motility and sperm acrosome status.

The aim of this study was to evaluate the effect of post-thaw dilution with autologous prostatic fluid on motility parameters, longevity and acrosome status of frozen-thawed dog spermatozoa. After semen collection, seminal plasma was separated by centrifugation and stored frozen until use. Sperm pellets were diluted in two steps with an egg yolk-Tris extender to a final concentration of 5% glycerol and 0.5% Equex STM Paste. After thawing, semen was diluted 1:2 either with Tris buffer or with the autologous prostatic fluid. Motility was evaluated using a phase contrast microscope and a computer-assisted motility analyser system immediately after thawing and at hourly intervals up for 4h at 38 degrees C. The status of acrosomes was assessed with Spermac stain at thawing and after 2 h of incubation. Motility and straight line velocity were initially higher in prostatic fluid-diluted samples (0 h and 0 and 1h, respectively), but decreased to values similar to those of Tris-diluted samples in a time-dependent manner. In contrast, both the curvilinear velocity and amplitude of lateral head displacement were lower in prostatic fluid-diluted samples (1 and 3 h and 0, 1 and 3 h, respectively). The dilution did not have any significant effect on the percentage of acrosome-intact spermatozoa at either thawing or after 2 h. The pattern of motility of prostatic fluid-diluted samples suggests a reduction in hyperactivated motility with time, even though prostatic fluid neither prolonged spermatozoa longevity nor had any effect on the status of spermatozoa acrosomes.

Acrosome↗
PubMed2005

Comparison of soluble thrombomodulin, von Willebrand factor, tPA/PAI-1 complex, and high-sensitivity CRP concentrations in serum, EDTA plasma, citrated plasma, and acidified citrated plasma (Stabilyte) stored at -70 degrees C for 8-11 years.

The aim was to define the most suitable specimen collection tubes for measurements of soluble Thrombomodulin (sTM), von Willebrand factor (vWF), and tPA/PAI-1 complex concentrations, and in particular whether the strongly acidic citrate additive in Stabilyte plasma would give significantly improved long-term stability of any of these analytes. We measured these analytes in paired specimens from 34 subjects, sampled 8-11 years before analysis, in serum, EDTA plasma, citrated plasma, and acidified citrated plasma (Stabilyte). Results were evaluated by regression analysis and Bland-Altman plots. All associations were linear across a wide assay range. Soluble TM was found to be highly unstable in serum as well as in EDTA plasma and to some extent even in ordinary citrate plasma: acidified citrate plasma is necessary to preserve sTM immunoreactivity in long-term storage. For hsCRP the slopes were not significantly different from that predicted by the dilution effect (0.83-0.86) of the citrate additive and there was no appreciable intercept. vWF values were comparable in citrate and acidified citrate plasma but serum and EDTA plasma samples yielded lower than expected results. For tPA/PAI-1 complex, Stabilyte tubes gave systematically lower results than the other tubes, with serum and EDTA plasma scoring the highest values, suggesting that in vitro increase in complex levels takes places upon blood collection and/or storage. We conclude that Stabilyte plasma is the specimen collection tube of choice for biobank projects aiming to measure fibrinolytic factors as well as several other analytes in the clotting system, such as soluble thrombomodulin and von Willebrand factor, in addition to the inflammatory marker hs-CRP. Indeed, using acidified Stabilyte plasma as the single medium would substantially simplify sampling for many epidemiological studies.

Biomarkers↗
PubMed2003

Effects of dead spermatozoa on motion characteristics and membrane integrity of live spermatozoa in fresh and cooled-stored equine semen.

The aim of this study was to determine if dead spermatozoa reduced motility or membrane integrity of live spermatozoa in fresh and cooled-stored equine semen. Three ejaculates from each of three stallions were centrifuged and virtually all seminal plasma was removed. Spermatozoa were resuspended to 25 x 10(6) spermatozoa/ml with EZ-Mixin CST extender and 10% autologous seminal plasma, then divided into aliquots to which 0 (control), 10, 25, 50, or 75% (v/v) dead spermatozoa were added. Dead spermatozoa preparations contained 25 x 10(6) spermatozoa/ml and 10% seminal plasma from pooled ejaculates of the three stallions, in EZ-Mixin CST extender. Spermatozoa were killed in the pooled ejaculates by repeated freezing and thawing, then stored at -20 degrees C until warmed to 37 degrees C and mixed with aliquots of fresh spermatozoa to be cooled and stored in an Equitainer for 24h. Motion characteristics (% total motility (MOT), % progressive motility (PMOT), and mean curvilinear velocity (VCL)) for fresh and 24h cooled samples were determined using a computerized spermatozoal motion analyzer. The presence of up to 75% dead spermatozoa did not adversely affect MOT or PMOT of live spermatozoa in either fresh or cooled-stored semen. However, VCL and the percentage of membrane-intact spermatozoa were reduced compared to control samples when 75% (v/v) dead spermatozoa were added. Membrane integrity, as assessed by staining with carboxyfluoresein diacetate-propidium iodide, was highly correlated (r>0.8; P<0.001) with MOT and PMOT in both fresh and cooled-stored semen samples. Results of this study have application to the processing of both cooled and frozen equine semen.

Animals↗
PubMed2001

What's happening? The quality of methylene blue treated FFP and cryo.

It is currently unclear to what degree methylene blue in combination with removal, of cells from plasma, by filter, can directly influence the loss of active components of plasma and whether the co-precipitation of FVIII/vWf with fibrinogen/fibronectin is affected by combined methylene blue and light treatment (MBLT). These questions are investigated using the Fenwal system. Our results indicate that up to 15% of the FVIII and IX are lost due to exposure of plasma to filters and methylene blue (MB). The illumination leads to a further 10-15% loss of all other major clotting factors. Factor XI appears to be highly sensitive to the MBLT-process, while inhibitors of the coagulation system are less affected. MBLT did not grossly influence the distribution of fVIII/vWf:Ag between cryoprecipitate and cryosupernatant using a paired control/test protocol, although the fVIII/vWf recovery is reduced in MBLT samples. The three commercially available MBLT processes differ in terms of operational aspects. These may have some impact on overall quality/safety and bioequivalency.

Anti-Infective Agents↗
PubMed1999

Quality assurance in measuring the elemental composition of the alga Fucus vesiculosus.

Algae are increasingly used for the purpose of environmental biomonitoring, for instance in the long-term program of the Federal Environmental Specimen Bank of Germany. Therefore, for the studies presented here, freeze-dried samples of Fucus vesiculosus collected from the North Sea shores were analyzed for a broad range of elements by instrumental neutron activation analysis (INAA), while inductively coupled plasma atomic emission spectrometry (ICP-AES) and mass spectrometry (ICP-MS) were carried out on digests. The entire analytical procedures, including field sampling, cleaning of material, sample handling, determination of blanks and instrumental parameters, are described. Certified reference materials analyzed in parallel with real samples and intermethod comparisons were used for assuring the accuracy of the analytical data. Reproducibility of INAA measurements was between 4 and 6% depending on the element considered. Possible sources of uncertainty and variation of the contaminant origins are discussed. Boundary conditions for the performance of algae sampling within environmental monitoring programs and the application of this marine bioindicator for the purpose of controlling time-dependent and local differences in element patterns are presented.

Cryopreservation↗
PubMed1994

Enterotoxigenicity, hemolytic activity and antibiotic resistance of Aeromonas spp. isolated from freshwater prawn marketed in Dhaka, Bangladesh.

Aeromonas spp. were isolated from gills, swimmerets, eggs, stomachs and ventral muscles of freshwater prawns (Macrobrachium malcolmsonii) available in the local fish market of Dhaka, Bangladesh. The density of Aeromonas spp. on these different body parts of the prawn samples ranged from 1.1 +/- 0.2 x 10(4) to 1.5 +/- 0.16 x 10(7) cfu per gram. The viable counts of aeromonads, fecal coliforms (FC) and Escherichia coli gradually increased in prawn samples when stored at 4 C. At -20 C, the viable counts gradually decreased and became zero on the 12th day of storage. The isolation of A. sobria (56%) was more frequent than that of A. hydrophila (31%) and A. caviae (13%). In the rabbit ileal loop (RIL) model, fluid accumulation induced by live cultures and cell-free culture filtrates of 11 strains ranged from 0.5 to 1.5 and 0.5 to 1.7 ml/cm of gut, respectively. Of 11 enterotoxigenic strains, 7 were A. sobria and 4 were A. hydrophila. Enterotoxigenicity correlated with hemolytic activity on blood agar. All enterotoxigenic strains were uniformly sensitive to chloramphenicol and gentamicin and resistant to novobiocin and vancomycin. Isolation of enterotoxigenic and antibiotic-resistant Aeromonas from these prawn samples indicates possible public health problems for their handlers as well for raw prawn consumers.

Aeromonas↗
PubMed2004

Assessing HER-2 status in fresh frozen and archival cytological samples obtained by fine needle aspiration cytology.

Determination of HER-2 status is an essential prerequisite in considering a patient's eligibility for anti-HER-2 therapy; few studies have focused on its evaluation on cytological material. We present a new method of assessing HER-2 status on cytological samples, by fluorescence in situ hybridization (FISH) with an automated detection system, using fresh frozen (FF) and May-Grunwald-Giemsa (MGG) stained smears, and we evaluate the reliability of HER-2 determination on fine needle aspiration cytology (FNAC). The pre-treatment protocol for FF smears is easier and faster than for MGG stained slides. However, with the described procedure, FISH is also feasible on archival MGG stained slides. We conclude that with this method, cytological samples obtained by FNAC, either FF or MGG, are a reliable option for assessing HER-2 status.

Biopsy, Fine-Needle↗
PubMed1996

Light damage in rod outer segments: the effects of fixation on ultrastructural alterations.

PURPOSE: In this electron microscopical study, we compared effects of chemical fixation versus cryofixation on the ultrastructure of acute rod outer segment alterations in the rat retina. METHODS: The alterations were induced by toxic levels of diffuse white light. Albino rats were exposed to 2000 lux for 30 min. Samples from one eye of each animal were fixed by high pressure freezing and samples from the other eye were fixed by standard glutaraldehyde procedures. RESULTS: Light exposed retina showed major differences in their rod outer segments, inner segments and photoreceptor synaptic regions in chemical fixation. In particular gross vesiculations of outer segment membranes were produced in light exposed experiments. In contrast, in cryo-fixed samples such prominent changes were not observed in outer segment membranes. There was, however, occasional formation of small vesicles and a reduction of the cilium diameter in response to light damage. In the dark adapted control group the morphology of chemically fixed and cryo-fixed photoreceptors was similar. CONCLUSIONS: We conclude, that cryo-fixed samples better represent the living state of the retina, because high pressure freezing is a purely physical method and acts much faster than chemical fixation.

Animals↗
PubMed1993

Lupus anticoagulant testing: effect of the platelet count on the activated partial thromboplastin time.

The activated partial thromboplastin time (APTT) is often used as a test to diagnose patients with lupus anticoagulants. It is recommended that platelet-poor plasma be used in the APTT test. In this study the effects of residual platelet contamination on lupus anticoagulant and antiphospholipid antibody testing are described. In fresh samples the residual platelet contamination has no significant effect whereas in frozen samples the effect of residual platelet contamination can have a significant effect on the APTT testing.

Antibodies, Antiphospholipid↗
PubMed1995

Correlation of relaxometry and histopathology: the transplantable human glioblastoma SF295 grown in athymic nude mice.

Human glioblastomas of the brain are characterized by a wide range of proton relaxation rates in vitro (1/T1 and 1/T2) and heterogeneous appearance in magnetic resonance imaging. It was previously found that their 1/T1 values vary widely at magnetic field strengths much below imaging fields, even at the same water content. In the present study, we measure 1/T1 at different magnetic field strengths (NMRD profile) for a specific transplantable, human glioblastoma (SF295), grown subcutaneously in athymic nude mice, to search for histologic characteristics that might correlate with the variability of 1/T1 at low fields (1/T1L). Using a field-cycling relaxometer, NMRD profiles were obtained for 32 fresh, histologically characterized, tumor specimens, 7 to 24 days post implantation of cryopreserved SF295 fragments. Tumor volume, dry weight, and pH of specimens were determined, the extent of hemorrhage and necrosis rated, and specimen location within the tumor recorded. A statistically significant increase in the average 1/T1 was found with increasing level of necrosis at 0.0024 T and below, possibly reflecting progressive protein aggregation in samples with up to 40% necrosis. This correlation was not significant at imaging fields. Although pH was increased in central necrosis, neither pH, dry weight, sample location, nor fresh hemorrhage could explain the changes in 1/T1L. The variability of 1/T1L among SF295 samples is much reduced compared to that of fresh surgical specimens of human glioblastomas of the brain. The heterogeneous appearance of glioblastomas in MRI may have a histologic correlate which reflects molecular changes involved with induction of cell death and necrosis. Further investigations may identify the factors responsible for affecting 1/T1L (hypoxia, radiation, chemotherapy).

Animals↗