Basal tissue factor expression in endothelial cell cultures is caused by contaminating smooth muscle cells. Reduction by using chymotrypsin instead of collagenase

A discrepancy exists between basal tissue factor (TF) expression found in endothelial cell cultures and the failure to detect TF in unpertubated endothelial cells in vivo. We demonstrated that basal TF expression in endothelial cell cultures originated from contaminating cells. These cells were ultrastructurally and flowcytometrically identified as smooth muscle cells. The cell cultures had been obtained from collagenase-treated human umbilical cord vessels. Histologic studies revealed that after collagenase treatment the basement membrane was digested and underlying structures were disrupted at some areas of the vein. We selected chymotrypsin as an alternative for the isolation of endothelial cells. Using chymotrypsin, the endothelial lining was selectively lost leaving the basement membrane undisturbed. Furthermore, use of chymotrypsin instead of collagenase minimized the level of basal TF activity. Taken together, we demonstrated that basal TF expression in endothelial cell cultures is caused by contaminating smooth muscle cells. This contamination can strongly be reduced using chymotrypsin instead of collagenase for isolation of endothelial cells.     

Ventral pallidal GABA-A receptors regulate prepulse inhibition of acoustic startle

Prepulse inhibition (PPI) of the acoustic startle reflex occurs when a weak auditory stimulus is presented 30-500 ms before the startling stimulus. Previous studies have shown that PPI is modulated by GABAergic projections from the ventral striatum to the ventral pallidum (VP). To evaluate the anatomical and pharmacological substrates of pallidal modulation of PPI, we measured PPI after intrapallidal infusion of GABA-B and GABA-A antagonists. Intrapallidal infusion of the GABA-B antagonist, 2-OH-saclofen (0.025-0.10 microgram), did not significantly alter PPI, startle amplitude or peak startle latency. Infusion of the GABA-A antagonist, picrotoxin (0.02-0.08 microgram), into the medial or central VP significantly reduced PPI; this effect appeared somewhat weaker after picrotoxin infusion into the lateral VP and was absent after infusion into the adjacent fundus striatum (FS). There was no significant effect of picrotoxin infusion into any of the VP sites or FS on startle amplitude or peak startle latency. Thus, ventral striato-pallidal GABAergic modulation of PPI appears to be mediated solely by GABA-A receptors and this modulatory substrate is predominantly distributed across the medial and central portions of the VP.     

The impact of posttraumatic seizures on 1-year neuropsychological and psychosocial outcome of head injury

This study examined the relationship of posttraumatic seizures and head injury severity to neuropsychological performance and psychosocial functioning in 210 adults who were prospectively followed and assessed 1 year after moderate to severe traumatic head injury. Eighteen percent (n = 38) of the patients experienced 1 or more late seizures (i.e., seizures occurring 8 or more days posttrauma) by the time of the 1-year followup. As expected, the head injured patients who experienced late posttraumatic seizures were those with the most severe head injuries, and they were significantly more impaired on the neuropsychological and psychosocial measures compared to those who remained seizure free. However, after the effects of head injury severity were controlled, there were no significant differences in neuropsychological and psychosocial outcome at 1 year as a function of having seizures. These findings suggest that worse outcomes in patients who develop posttraumatic seizures up to 1 year posttrauma largely reflect the effects of the brain injuries that cause seizures, rather than the effect of seizures.     

Long-term results of preoperative radiation therapy alone for stage T3 and T4 rectal cancer

BACKGROUND: There has been a resurgence of interest in the use of preoperative radiation therapy, with or without chemotherapy, for locally advanced rectal cancer. The purpose of this study was to analyse the time course and pattern of failure for 74 patients with clinical stage T3 or T4 (cT3-4) rectal cancer treated with preoperative radiation therapy for whom long-term follow-up was available. METHODS: Seventy-four patients with cT3-4 rectal cancer received a median of 45.0 Gy radiation alone followed by surgery 4-8 weeks later. Median follow-up was 90 months; two-thirds of patients were followed for at least 60 months. RESULTS: Following radiation therapy the pathological stage was 4 per cent pT0, 26 per cent pT1-2 and 70 per cent pT3-4. Thirty-two per cent had involved lymph nodes. The actuarial 5-year rates of local control, freedom from distant metastasis and disease-specific survival were 80, 64 and 73 per cent respectively. The corresponding 10-year rates were 73, 51 and 50 per cent. Median times to detection of local and distant recurrence were 34 and 24 months respectively. Eighty per cent of local recurrences were detected within 54 months; 80 per cent of distant recurrences were detected within 57 months. CONCLUSION: In this analysis, the time to detection of both local and distant recurrences following preoperative radiation therapy for advanced rectal cancer was surprisingly long. Almost 5 years (57 months) of follow-up were required to detect 80 per cent of all failures. The 5-year local control rate of 80 per cent compares favourably with that achieved by more aggressive chemoradiation regimens for fixed cancers; however, the high distant failure rate with radiation therapy alone suggests that adjuvant systemic therapy should be investigated.     

Propofol or midazolam for sedation and early extubation following cardiac surgery

PURPOSE: The purpose of this randomized, double-blind study was to evaluate the efficacy of midazolam and propofol for postoperative sedation and early extubation following cardiac surgery. METHODS: ASA physical status II-III patients scheduled to undergo elective first-time cardiac surgery with an ejection fraction > 45% were eligible. All patients received a standardized sufentanil/isoflurane anaesthesia. During cardiopulmonary bypass 100 micrograms.kg-1.min-1 propofol was substituted for isoflurane. Upon arrival in the Intensive Care Unit (ICU), patients were randomized to either 10 micrograms.kg-1.min-1 propofol (n = 21) or 0.25 microgram.kg-1.min-1 midazolam (n = 20). Infusion rates were adjusted to maintain sedation within a predetermined range (Ramsay 2-4). The infusion was terminated after four hours. Patients were weaned from mechanical ventilation and their tracheas extubated when Haemodynamic stability, haemostasis, normothermia and mental orientation were confirmed. Haemodynamic measurements, arterial blood gas tensions and pulmonary function tests were recorded at specified times. RESULTS: There were no differences between the two groups for the time spent at each level of sedation, number of infusion rate adjustments, amount of analgesic and vasoactive drugs, times to awakening and extubation. The costs of propofol were higher than those of midazolam. There were no differences in haemodynamic values, arterial blood gas tensions and pulmonary function. CONCLUSION: We conclude that midazolam and propofol are safe and effective sedative agents permitting early extubation in this selected cardiac patient population but propofol costs were higher.     

Proteolysis as a probe of thermal unfolding of cytochrome c

This paper provides a risk-based approach for establishing threshold accountability values for radioactive sealed sources based on current scientific information and realistic assumptions. Although this paper focuses specifically on accountability thresholds, the methodology provided can be easily modified to determine risk-based exemption and licensing thresholds.     

Use of a simple light absorbance assay to measure lymphocyte proliferation

The proliferative response of human lymphocytes to stimuli such as foreign histocompatibility antigens or mitogens is generally assessed by measuring the amount of tritiated thymidine which the cells incorporated in culture. In this paper, the possibility of assessing lymphocyte proliferation and viability by an empirical assay, using measurement of light absorbance on a ELISA reader in the yellow wave length (450 nm/air-550 nm/air), has been studied. The correlation of these measurements with a colormetric viability assay using MTS/PMS, with tritiated thymidine incorporation and with trypan blue exclusion viability counting, was determined. The results showed that the light absorbance assay correlated well with cell proliferation during 48-120 hours culture period and with cell viability after a 72 hour period. The MTS/PMS colormetric assay as well as trypan blue exclusion cell counting confirmed that the light absorbance assay was not merely caused by dead cells. This data confirm that the light absorbance assay is sufficiently sensitive to low levels of proliferation to allow detection of such responses at least as effectively as thymidine incorporation. The light absorbance assay procedure avoids the expense, time and hazards associated with scintillation counting, and is simple to perform without the necessity for reagents and preparative steps required by other assays.