Dose characteristics of in-house-built collimators for stereotactic radiotherapy with a linear accelerator

Dose characteristics of a stereotactic radiotherapy unit based on a standard Varian Clinac 4/100 4 MV linear accelerator, in-house-built Lipowitz collimators and the SMART stereotactic radiotherapy treatment planning software have been determined. Beam collimation is constituted from the standard collimators of the linear accelerator and a tertiary collimation consisting of a replaceable divergent Lipowitz collimator. Four collimators with isocentre diameters of 15, 25, 35 and 45 mm, respectively, were constructed. Beam characteristics were measured in air, acrylic or water with ionization chamber, photon diode, electron diode, diamond detector and film. Monte Carlo simulation was also applied. The radiation leakage under the collimators was less than 1% at 50 mm depth in water. Specific beam characteristics for each collimator were imported to SMART and dose planning with five non-coplanar converging 140 degrees arcs separated by 36 degrees angles was performed for treatment of a RANDO phantom. Dose verification was made with TLD and radiochromic film. The in-house-built collimators were found to be suitable for stereotactic radiotherapy and patient treatments with this system are in progress.     

Guanylyl cyclase inhibition reduces contractility and decreases cGMP and cAMP in isolated rat hearts

Objectives of the current studies were to characterize the pattern of GnRH secretion in the cerebrospinal fluid of the bovine third ventricle, determine its correspondence with the tonic and surge release of LH in ovariectomized cows, and examine the dynamics of GnRH pulse generator activity in response to known modulators of LH release (suckling; neuropeptide Y [NPY]). In ovariectomized cows, both tonic release patterns and estradiol-induced surges of GnRH and LH were highly correlated (0.95; p < 0.01). Collectively, LH pulses at the baseline began coincident with (84%) or within one sampling point after (100%) the onset of a GnRH pulse, and all estradiol-induced LH surges were accompanied by corresponding surges of GnRH. A 500- microg dose of NPY caused immediate cessation of LH pulses and lowered (p < 0.001) plasma concentrations of LH for at least 4 h. This corresponded with declines (p < 0.05) in both GnRH pulse amplitude and frequency, but GnRH pulses were completely inhibited for only 1.5-3 h. In intact, anestrous cows, GnRH pulse frequency did not differ before and 48-54 h after weaning on Day 18 postpartum, but concentrations of GnRH (p < 0.05) and amplitudes of GnRH pulses (4 of 7 cows) increased in association with weaning and heightened secretion of LH. We conclude that the study of GnRH secretory dynamics in third-ventricle CSF provides a reasonable approach for examining the activity and regulation of the hypothalamic pulse generator in adult cattle. However, data generated using this approach must be interpreted in their broadest context. Although strong neurally mediated inhibitors of LH pulsatility (suckling; NPY) had robust effects on one or more GnRH secretory characteristics in CSF, only high doses of NPY briefly abolished GnRH pulses. This implies that the GnRH signal received at the hypophyseal portal vessels under these conditions may differ quantitatively or qualitatively from those in CSF, and theoretically would be undetectable or below a biologically effective threshold when LH pulses are absent.     

Fibronectin in host defense: implications in the diagnosis, prophylaxis and therapy of infectious diseases

A polymerase chain reaction (PCR) was developed for the detection of Clostridium botulinum type A, a cause of human botulism. A two primer set and an oligonucleotide detection probe were used to specifically detect Cl. botulinum type A neurotoxin gene (BoNT/A). After 40 cycles of amplification, detection of a 798 bp amplified DNA fragment was carried out by agarose gel electrophoresis and Southern blot hybridization. This assay was able to detect 12.5 fg of purified target DNA or five bacteria per reaction. The sensitivity in artificially contaminated food samples after an 18 h enrichment step ranges from 10 to 10(3) bacteria per g according to the type of food samples. No cross-reactions were observed with the other Cl. botulinum toxinotypes and other bacteria found routinely in food. This PCR method may provide a suitable and rapid alternative to standard techniques for detection of Cl. botulinum type A in food samples.     

Alveolar epithelial fluid transport: basic mechanisms and clinical relevance

New evidence indicates that alveolar fluid clearance is driven by active sodium transport across the alveolar epithelium. Several in vivo as well as some in vitro studies indicate that vectorial sodium transport drives fluid clearance across the alveolar epithelium. This transport process can be upregulated by both catecholamine-dependent and catecholamine-independent mechanisms. Water transport appears to move across the alveolar epithelium primarily via transcellular water channels, recently termed aquaporins. Under some conditions, net alveolar fluid clearance continues even in the presence of acute lung injury. It is now possible to study the rate and mechanisms of alveolar fluid clearance in patients with either hydrostatic or increased permeability pulmonary edema. In addition, it may be possible to increase the rate of alveolar fluid clearance and hence the resolution of pulmonary edema in some patients, using aerosolized beta-adrenergic agonist therapy.     

Adjuvant intraperitoneal chemotherapy with carbon-adsorbed mitomycin in patients with gastric cancer: results of a randomized multicenter trial of the Austrian Working Group for Surgical Oncology

PURPOSE: Previous studies have demonstrated a beneficial effect of intraperitoneally applied mitomycin bound to activated carbon particles (M-CH) in preventing intraabdominal recurrence following curative surgery for gastric cancer. The Austrian Working Group for Stomach Cancer, a subgroup of the Austrian Working Group for Surgical Oncology, initiated a multicentric phase III trial to evaluate the safety and efficacy of this treatment regimen. PATIENTS AND METHODS: A total of 91 patients with a radically resected gastric cancer infiltrating the serosal surface were randomly assigned to receive either 50 mg mitomycin bound to a solution of 375 mg carbo adsorbens intraperitoneally before closure of the abdominal wound (n = 46) or served as a surgical control group (n = 45). Postoperative complications and recurrence-free and overall survival were evaluated to analyze the risks and benefits of this treatment. RESULTS: After a median observation period of 597 days (range, 72 to 1,096), a significantly higher postoperative complication rate was observed in the M-CH group (35%) compared with the control group (16%) (P < .02). In accordance with this finding, the postoperative (60 days) mortality rate was also significantly elevated in the M-CH group (11% v 2% in the control group). Since analysis of overall and recurrence-free survival failed to show any beneficial effect of M-CH therapy, the protocol committee decided to stop further recruitment of patients onto this study. CONCLUSION: Adjuvant intraperitoneal therapy of gastric cancer by mitomycin bound to activated carbon particles is associated with an increased rate of postoperative complications. However, no benefit for prognosis following radical resection of locally advanced tumors was observed in this multicenter phase III trial.     

Varicella serology among school age children with a negative or uncertain history of chickenpox

Four phenylethanoids isolated from the stems of Cistanche deserticola, acteoside (1), 2'-acetylacteoside (2), isoacteoside (3) and tubuloside B (4), significantly suppressed NADPH/CCl4-induced lipid peroxidation in rat liver microsomes. Addition of them to primary cultured rat hepatocytes efficiently prevented cell damage induced by exposure to CCl4 or D-galactosamine (D-GalN). Acteoside (1) further showed pronounced anti-hepatotoxic activity against CCl4 in vivo.     

Pro-caspase-3 is a major physiologic target of caspase-8

The apoptotic signal triggered by ligation of members of the death receptor family is promoted by sequential activation of caspase zymogens. We show here that in a purified system, the initiator caspases-8 and -10 directly process the executioner pro-caspase-3 with activation rates (kcat/Km) of 8.7 x 10(5) and 2.8 x 10(5) M-1 s-1, respectively. These rates are of sufficient magnitude to indicate direct processing in vivo. Differentially processed forms of caspase-3 that accumulate during its activation have similar rates of activation, activities, and specificities. The pattern and rate of caspase-8 induced activation of pro-caspase-3 in cytosolic extracts was the same as in a purified system. Moreover, immunodepletion of a putative intermediary in the pathway to activation, pro-caspase-9, was without consequence. Taken together these data demonstrate that the initiator caspase-8 can directly activate pro-caspase-3 without the requirement for an accelerator. The in vitro data thus help to deconvolute previous in vivo transfection studies which have debated the role of a direct versus indirect transmission of the apoptotic signal generated by ligation of death receptors.     

Injuries as a result of California earthquakes in the past decade

The devastating effects of earthquakes have been demonstrated repeatedly in the past decade, through moderate and major earthquakes such as the October 1987 Whittier Narrows earthquake (5.9 on the Richter scale), the October 1989 Loma Prieta earthquake (7.1) and the January 1994 Northridge earthquake (6.7). While 'official' tallies of injuries and deaths are reported for each event, the numbers vary from report to report. For Northridge, the number of injuries vary between 8,000 and 12,000; the number of deaths from 33 to 73 (Peek-Asa et al., 1997; Durkin, 1996). While official estimates are commonly reported following disasters, the study of actual numbers, types and causes of casualties has not developed. In this paper, we identify the numbers and risk factors for injuries within community-based samples across three earthquakes in urban California. We first report the numbers and types of injuries in each earthquake and then identify risk factors specifically associated with the Northridge earthquake.