Mixed venous oxygen saturation in abdominal aortic surgery: intraoperative hypothermia and vasodilator therapy implications

This prospective study was designed to test the hypothesis that intraoperative hypothermia occurring during abdominal aortic surgery and vasodilator therapy used to avoid severe consequences of aortic clamping could both disturb the mixed venous oxygen saturation signal (SVO2). Twenty high risk surgical patients, ASA physical status II or III, were catheterized with the standard pulmonary artery catheter; SVO2 was determined by direct spectrophotometric measurements of oxygen haemoglobin concentration of serial samples. The relationships between SVO2, haemodynamic, metabolic variables and core temperature were analyzed. Haemodynamic values and oxygen transport were stable while inadequate tissue oxygenation occurred. A significant correlation was found between SVO2 and CI (r = 0.59, p less than 0.01), SVO2 and SVRI (r = -0.4, p less than 0.01), SVO2 and CT (r = -0.46, p less than 0.01), SVO2 and VO2 (r = -0.76, p less than 0.001). SVO2 and Qs/Qt (r = 0.83, p less than 0.001), SVO2 and EO2 (r = -0.75, p less than 0.001. No correlation was observed between SVO2 and lactacidemia (r = 0.04, p less than 0.05). Satisfactory haemodynamic stability and oxygen transport steady-state were the main conditions for a significant correlation between SVO2 and haemodynamic factors. However, there was no correlation between SVO2 and inadequate tissue oxygenation. SVO2 reflected only oxygen extraction. Intraoperative hypothermia provided an increased haemoglobin affinity for oxygen. Vasodilator therapy which allowed a decrease in systemic vascular resistance produced an increase in the left-right shunt and in venous oxygen admission. Thus hypothermia and vasodilator therapy could be both responsible for the elevated SVO2 occurring during infrarenal abdominal aortic surgery.     

Immunoregulatory markers in rats carrying Dunning R3327 H, G, or MAT-LyLu prostatic adenocarcinoma variants

The Dunning R3327 tumor represents a system for studying prostate cancer in Copenhagen X Fischer rats. Animals bearing variant sublines (H, G, and MAT-LyLu) differing in growth rate, differentiation, hormone responsiveness, and metastatic ability were assayed for three immunological markers. Spleens were passed through a tissue sieve, and mononuclear cells were obtained by Ficoll-Hypaque centrifugation. These were assayed for leukocytic subsets using monoclonal antibodies. An adherent population was isolated and evaluated using thin-layer chromatography for conversion of radiolabeled arachidonic acid to E series prostaglandins. Finally, sera from these animals were assayed for levels of circulating immune complexes using polyethylene glycol precipitation. Data from 52 rats bearing the various tumors were obtained, correlated with subline aggressiveness, and compared to 15 controls. Each tumor group demonstrated significantly lower helper/suppressor T-cell ratios than controls, probably due to general tumor presence. In addition, the most aggressive R3327 MAT-LyLu variant had significantly increased prostaglandin E synthesis by adherent spleen cells compared to the H or G sublines and significantly increased levels of circulating immune complexes relative to the H subline. G subline values for both prostaglandin E and circulating immune complexes levels were intermediate, suggesting that these markers correlate better with tumor aggressiveness than helper/suppressor T-cell ratios.     

Outbreak of Pichia anomala infection in the pediatric service of a tertiary-care center in Northern India

An outbreak of nosocomial fungemia due to the unusual yeast, Pichia anomala occurred in the pediatric wards of our hospital over a period of 23 months (April 1996 to February 1998). A total of 379 neonates and children (4.2% admissions) were infected. The probable index case was admitted to the pediatric emergency ward, with subsequent transmission to the premature nursery, pediatric intensive care units, and other children wards. Carriage on the hands of health care personnel was likely to be responsible for dissemination of the fungus. The outbreak could only be controlled after a health education campaign to improve hand-washing practices was instituted and after nystatin-fluconazole prophylaxis to all premature neonates and high-risk infants was introduced. In a case-control study, we identified a lower gestational age, a very low birth weight (<1,500 g), and a longer duration of hospital stay as significant risk factors associated with P. anomala fungemia in premature neonates. We conducted a culture prevalence survey of 50 consecutive premature neonates and found that 28% were colonized with P. anomala at a skin or mucosal site on the date of delivery and that 20% of these neonates subsequently developed P. anomala fungemia. We performed multilocus enzyme electrophoresis on 40 P. anomala outbreak isolates (including patient and health care workers' hand isolates), and the results suggested that these isolates were identical. Our study highlights the importance of P. anomala as an emerging nosocomial fungal pathogen.     

The missions of medical schools: the pursuit of health in the service of society

Mission statements and role documents of medical schools in the United Kingdom, United States, Canada and Australia have been examined on their Internet Web sites and categorised in purpose, content and presentation. The format and content are highly variable, but there is a common vision of three integral roles, namely, education, advancement of knowledge and service to society. Other frequent themes include tradition and historical perspective, service for designated communities, and benchmarking to accreditation standards. Differences in content reflect variable interpretation of the notion of "mission", and local or national characteristics such as institutional affiliations, the types, levels and organisation of medical education, relationships with health systems, and extent of multi-professional education. Outcomes data and measures of medical school performance referenced to the institution's stated missions are rarely encountered.     

Activated Ras/JNK driven Dilp8 in imaginal discs adversely affects organismal homeostasis during early pupal stage in Drosophila,a new checkpoint for development

Background

Dilp8-mediated inhibition of ecdysone synthesis and pupation in holometabolous insects maintains developmental homeostasis through stringent control of timing and strength of molting signals. We examined reasons for normal pupation but early pupal death observed in certain cases.

Results

Overexpression of activated Ras in developing eye/wing discs inhibited Ptth expression in brain via upregulated JNK signaling mediated Dilp8 secretion from imaginal discs, which inhibited ecdysone synthesis in prothoracic gland after pupariation, leading to death of ~25- to 30-hour-old pupae. Inhibition of elevated Ras signaling completely rescued early pupal death while post-pupation administration of ecdysone to organisms with elevated Ras signaling in eye discs partially rescued their early pupal death. Unlike the earlier known Dilp8 action in delaying pupation, hyperactivated Ras mediated elevation of pJNK signaling in imaginal discs caused Dilp8 secretion after pupariation. Ectopic expression of certain other transgene causing pupal lethality similarly enhanced pJNK and early pupal Dilp8 levels. Suboptimal ecdysone levels after 8 hours of pupation prevented the early pupal metamorphic changes and caused organismal death.

Conclusions

Our results reveal early pupal stage as a novel Dilp8 mediated post-pupariation checkpoint and provide further evidence for interorgan signaling during development, wherein a peripheral tissue influences the CNS driven endocrine function.

     

P300 and Long-Term Memory: Latency Predicts Recognition Performance

The study-test paradigm was used to investigate memory acquisition processes and the effects of repetition on long-term recognition memory. In this procedure, subjects are presented with a list of words (“targets”) to be memorized (Study series). They are later tested for recognition on a word list comprised of the target words mixed randomly with an equal number of new, distractor words (Test series). Both reaction time and the P300 component of the event-related brain potential were used as measures of processing time. During the Study series, large P300s were elicited despite a word category probability of 1.0. When the words from the Study series were divided on the basis of recognition performance, words that were subsequently recognized elicited P300s with shorter latencies than unrecognized words. P300 amplitude to words in the Study series increased with repetition while maintaining a constant latency. During the Test series, P300 latency and reaction time decreased with repetition for both target and distractor words. P300 amplitude to all words increased substantially over Test repetitions with target words eliciting larger P300s than distractor words. Words that were recognized more consistently during the Test series elicited larger and earlier P300s than words that were recognized less consistently. The P300 amplitude and latency results from both the Study and Test series are interpreted as reflecting the increased discriminability of the target words as the memory trace increases in strength.