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Biomedical subjects

N Kessaris

Publications and source records attributed to N Kessaris.

11 recordsLinked to original sources
PubMed2004

Risk-adjusted prediction of operative mortality in oesophagogastric surgery with O-POSSUM.

INTRODUCTION: The present study was designed to develop a dedicated oesophagogastric model for the prediction of risk-adjusted postoperative mortality in upper gastrointestinal surgery (O-POSSUM). METHODS: Using 1042 patients undergoing oesophageal (n = 538) or gastric (n = 504) surgery between 1994 and 2000 the Portsmouth predictor equation for mortality (P-POSSUM) scoring system was compared with a standard logistic regression O-POSSUM model and a multilevel O-POSSUM model using the following independent factors: age, physiological status, mode of surgery, type of surgery and histological stage. RESULTS: The overall mortality rate was 12.0 per cent (elective mortality rate 9.4 per cent and emergency mortality rate 26.9 per cent). P-POSSUM overpredicted mortality (14.5 per cent), particularly in the elective group of patients. The multilevel model offered higher discrimination than the single-level O-POSSUM and P-POSSUM models (area under receiver-operator characteristic curve 79.7 versus 74.6 and 74.3 per cent). When observed to expected outcomes were evaluated, the multilevel O-POSSUM model was found to offer better calibration (Hosmer-Lemeshow chi(2) statistic 10.15 versus 10.52 and 28.80). CONCLUSION: The multilevel O-POSSUM model provided an accurate risk-adjusted prediction of death from oesophageal and gastric surgery for individual patients. In conjunction with a multidisciplinary approach to patient management, the model may be used in everyday practice for perioperative counselling of patients and their carers.

Adult↗
PubMed2003

Evaluation of POSSUM and P-POSSUM scoring systems in patients undergoing colorectal surgery.

BACKGROUND: The Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (POSSUM) and Portsmouth POSSUM (P-POSSUM) equations were derived from a heterogeneous general surgical population and have been used successfully as audit tools to provide risk-adjusted operative mortality rates. Their applicability to high-risk emergency colorectal operations has not been established. METHODS: POSSUM variables were recorded for 1017 patients undergoing major elective (n = 804) or emergency (n = 213) colorectal surgery in ten hospitals. Subgroup analysis was performed to investigate the predictive capability of POSSUM and P-POSSUM in emergency and elective surgery and in patients in different age groups. RESULTS: The overall operative mortality rate was 7.5 per cent (POSSUM-estimated mortality rate 8.2 per cent; P-POSSUM-estimated mortality rate 7.1 per cent). In-hospital deaths increased exponentially with age. Both scoring systems overpredicted mortality in young patients and underpredicted mortality in the elderly (P < 0.001). Death was underpredicted by both systems for emergency cases, significantly so at a simulated emergency caseload of 47.9 per cent (P < 0.05). CONCLUSION: There is a lack of calibration of POSSUM and P-POSSUM systems at the extremes of age and high emergency workload. This has important implication in clinical practice, as consultants with a high emergency workload may seem to underperform when these scoring systems are applied. Recalibration or remodelling strategies may facilitate the application of POSSUM-based systems in colorectal surgery.

Adult↗
PubMed2001

Ventral neurogenesis and the neuron-glial switch.

In the developing spinal cord, neuroepithelial precursors at different positions along the dorsal-ventral axis generate distinct neuronal and glial subtypes. For example, one group of ventral precursors generates neurons followed by oligodendrocytes. A spate of recent articles, including several in this issue of Neuron, are devoted to the mechanisms governing neuronal and glial subtype specification in the ventral cord. We review these studies and discuss the nature of the ventral neuron-oligodendrocyte switch.

Animals↗
PubMed2001

The role of mini-fragment screw fixation in volar dislocations of the proximal interphalangeal joint.

Palmar fracture-dislocations of the proximal interphalangeal (PIP) joint are uncommon injuries, which can be associated with long-term complications if sub-optimally treated. We report two cases of palmar fracture-dislocations of the PIP joint treated by open reduction and internal fixation using a single mini-fragment screw. The long term results of hand and finger function were excellent.

Accidental Falls↗
PubMed1994

Polymerase chain reaction fails to incriminate exogenous retroviruses HTLV-I and HIV-1 in rheumatological diseases although a minority of sera cross react with retroviral antigens.

OBJECTIVES: To investigate the presence of antibodies to HTLV and HIV retroviral antigens in the rheumatological diseases rheumatoid arthritis (RA), polymyositis/dermatomyositis (PM/DM), primary Sjögren's syndrome (pSS), and systemic lupus erythematosus (SLE), and to use polymerase chain reaction (PCR) to seek these exogenous retroviruses in proviral form in cellular DNA from these patients. METHODS: Thirty patients with active RA, 13 with PM, 14 with pSS and five with SLE were recruited and their sera tested for antibodies to HTLV-I in enzyme linked immunosorbent assay (ELISA) and Western blot analysis. Seropositivity to HIV-1 was also sought. DNA was extracted from peripheral blood lymphocytes, synovial tissue and muscle biopsies and tested by polymerase chain reaction using consensus primers for HTLV-I and HIV-1. RESULTS: In HTLV-I ELISA, nine rheumatological sera (4/30 RA, 3/13 PM/DM and 2/5 SLE patients) were considered positive; 14 from pSS patients and 30 from normal subjects were negative. In a control group which included osteoarthritis, Crohn's disease and bacterial endocarditis patients, only two of 80 proved positive in this system. Validation of these sera by Western blotting generally revealed weak reactivity against a variety of HTLV-I antigens. PCR of genomic DNA derived from patients' peripheral blood mononuclear cells did not reveal the presence of HTLV-I and HIV-1 target sequences. CONCLUSIONS: This study shows that PCR precludes HTLV-I and HIV-1 infection as causative agents in these rheumatological diseases although a minority of patients possess antibodies that are weakly cross-reactive with retroviral antigens.

Adolescent↗
PubMed1993

Rectal thermoluminescent dosimeter measurements using the MicroSelectron High Dose Rate afterloader in postoperative intravaginal radiation cases.

PURPOSE: The purpose of this study is twofold: First, to measure the dose distribution along the anterior and posterior rectal wall, compare them to the prescribed dose and establish the rectal length receiving the maximum dose. Second, to carry out in-phantom dose measurements in order to confirm that the dose planned is in fact the dose delivered. METHODS AND MATERIALS: The dose distribution along the anterior and posterior rectal wall was measured for a group of 25 Gynecologic cases treated with a vaginal cylinder, using the MicroSelectron High Dose Rate system. The method of measurement employed flexible vinyl rectal probes (1 or 2 cm diameter). Two fine plastic tubes, each containing 15 Thermo Luminescent Dosimeters rods, were attached along the probe on opposite sides to measure the anterior and posterior rectal wall dose distributions. RESULTS: The dose distribution exhibited a sharp peak covering a rectal length from one to two centimeters. The peak doses for the anterior rectal wall ranged from 60% to 110% of prescribed dose. In-phantom measurements used layers of phantom material that contained a special source tube for the Iridium-192 source as well as Thermoluminescent Dosimeter tube(s) positioned at 1 cm distance from the source tube. The afterloader was programmed to deliver 300 cGy at 1 cm along its treatment length. CONCLUSION: The Thermo Luminescent Dosimeters measurements showed good agreement with the doses expected on the basis of the treatment plan.

Brachytherapy↗
PubMed1978

Hyperthermia and low dose-rate irradiation.

Hyperthermia combined with 60Co gamma irradiation was studied using V79 hamster cells cultured in vitro. Modest hyperthermia (41 degrees C for 6 hrs.) enhanced the cell killing produced by acute exposure to radiation. The same treatment enhanced the effect of low dose-rate irradiation (200 rads/hr.) even more. The sequence in which modest hyperthermia was combined with low dose-rate irradiation was important. Maximal enhancement was observed when hyperthermia was followed by irradiations. The probable explanation is that, by damaging the repair system, prior heat renders the cells unable to repair sublethal damage during subsequent low dose-rate irradiation.

Animals↗