Postoperative hypoalbuminemia as a risk factor for surgical site infection after oral cancer surgery

OBJECTIVES

Postoperative surgical site infection (SSI) is a frequent postoperative complication in patients with oral cancer and significantly affects patient recovery and medical expenses. The aim of this study was to examine the predictors of SSI in patients undergoing major surgery for oral or oropharyngeal squamous cell carcinoma (OSCC) and to determine the relationship between perioperative albumin and the development of SSI.

SUBJECTS AND METHODS

In 337 consecutive patients who underwent clean-contaminated surgery for OSCC, serum albumin, glucose, and hemoglobin levels were perioperatively measured. Differences between the groups were examined using Fisher's exact test, Mann-Whitney U-test, and multiple logistic regression analysis.

RESULTS

Surgical site infection was detected in 88 (26.1%) patients with median time to development of 10 (2-25) days. Multiple logistic regression analysis showed that only postoperative serum albumin < 2.5 g dl(-1) was an independent variable predictive of SSI (P = 0.003). The duration of hospital stay was negatively correlated with postoperative albumin (R(2) = -0.302, P < 0.001).

CONCLUSION

Early postoperative hypoalbuminemia <2.5 g dl(-1) is an independent risk factor for the development of SSI in patients undergoing oral cancer surgery. Clinicians should be aware of the implications of postoperative hypoalbuminemia and consider more intensive postoperative care in these patients.

Noncancer health events as a leading cause of competing mortality in advanced head and neck cancer

BACKGROUND

The survival of patients with head and neck squamous cell carcinoma (HNSCC) can be affected by noncancer health events (NCHE) as well as by index cancer progression and second primary cancer (SPC). This study aimed to investigate the risk factors for NCHE and noncancer mortality (NCM) in patients with advanced-stage HNSCC.

PATIENTS AND METHODS

This cohort study involved 600 consecutive patients with overall stage III to IV HNSCC who were treated between 2001 and 2010 at our tertiary referral hospital. NCHE was defined as re-admission (i.e. after the primary treatments for the index tumors) due to noncancer-related causes. The incidences of NCHE and NCM and their risk factors were analyzed by using cumulative incidence and cause-specific hazard functions.

RESULTS

During a median follow-up period of 54 months, 224 (37.3%) and 55 (9.2%) of the 600 patients had NCHE and NCM, respectively. The 5-year index cancer mortality, SPC mortality, and NCM rates were 23.8%, 4.2%, and 8.9%, respectively. Multivariate analyses revealed that body mass index <20 kg/m(2) (P = 0.018), Charlson comorbidity index (CCI) ≥1 (P < 0.001), tumor recurrence (P < 0.001), SPC occurrence (P < 0.001), and initial chemotherapy (P = 0.049) were independent NCHE predictors. Older age (P < 0.001), CCI ≥1 (P = 0.008), tumor recurrence (P < 0.001), and SPC occurrence (P = 0.047) were independent NCM predictors. Patients with respiratory NCHE were at a higher risk of NCM than patients with other NCHE types (P < 0.001).

CONCLUSIONS

One or more comorbidities, tumor recurrence, and SPC occurrence were independent predictors of both NCHE and NCM. Patients with respiratory NCHE had a particularly high risk of NCM.

Early peripheral blood and T-cell chimerism dynamics after umbilical cord blood transplantation supported with haploidentical cells

Single-unit umbilical cord blood (CB) SCT is limited by low total nucleated cell (TNC) dose. Co-infusion of CD34+ cells from a third party HLA-mismatched donor, known as dual or haplo-cord transplant, reduces the period of post-transplant neutropenia and related complications. The aim of this study was to analyze the value of early post-transplant peripheral blood (PB) and T cell chimerism after 28 dual transplants regarding CB engraftment. Cumulative incidence of myeloid engraftment at 30 days was 93% with a median time to engraftment of 14 days (10-29). Patients who developed CB graft failure (n=5) showed very low percentages of CB cells on days +14, +21 and +28 with decreasing dynamics. On the other hand, percentages of CB cells in patients who achieved CB engraftment increased over time. Interestingly, such patients showed two distinct chimerism dynamics in PB, but all of them showed a predominance of CB T cells early after SCT with increasing dynamics over time. Early post-transplant chimerism dynamics in PB and T cells predicts CB graft failure enabling rapid therapeutic measures to be applied. On the other hand, early increasing percentages of CB T cells correlates with ultimate CB engraftment.

Higher-contrast requirements for recognizing low-pass-filtered letters

Kwon and Legge (2011) found that high levels of letter recognition accuracy are possible even when letters are severely low-pass filtered (0.9 cycles per letter). How is letter recognition possible with such severe reduction in the spatial resolution of stimulus letters? Clues may come from understanding the possible interaction between contrast and spatial resolution in letter recognition. Here, we asked what the effect is on the contrast threshold for detecting and recognizing letters as the spatial-frequency cutoff of letters is reduced (in cycles per letter). We measured contrast thresholds of seven normally sighted subjects for detecting and recognizing single letters of the English alphabet. The letters were low-pass filtered with several cutoff frequencies (0.9-3.5 cycles per letter, including unfiltered letters). We found that differences in contrast thresholds between detection and recognition increased substantially with decreasing cutoff frequency. We also incorporated the human contrast sensitivity function into an ideal observer model and found qualitatively good agreement between the pattern of performance for the model and our human subjects. Our findings show that the human visual system requires higher contrast for letter recognition when spatial resolution is severely limited. Good agreement between the model and human subjects shows that the greater contrast requirement for recognizing low-pass letters is due to a reduction in the information content of the letters rather than a change in human visual processing. The reduction in stimulus information may be due to increasing stimulus similarity associated with a reduction in spatial-frequency cutoff.

336 QUANTITATIVE ANALYSIS OF TETRACYCLINE-INDUCIBLE EXPRESSION OF THE GREEN FLUORESCENT PROTEIN GENE IN TRANSGENIC CHICKENS

The use of transgenic farm animals as bioreactors to address the growing demand for biopharmaceuticals, both in terms of increased quantity and greater number, represents a key development in the advancement of medical science. However, the potential for detrimental side effects as a result of uncontrolled constitutive expression of foreign genes in transgenic animals is a well-recognised limitation of such systems. Previously, using a tetracycline-inducible expression system, we demonstrated the induction of expression of a transgene encoding green fluorescent protein (GFP) in transgenic chickens by feeding with doxycycline, a tetracycline derivative; expression of GFP reverted to pre-induction levels when the inducer was removed from the diet (Kwon et al. 2011 Biochem. Biophys. Res. Commun. 410, 890–894). As a proof of principle study, however, quantitative assessment of expression was not possible, as only 1 G0 and 1 G1 transgenic chicken was obtained. In the current study, with 7 G2 transgenic chickens obtained from 1 G1 hen, we confirmed stable genomic integration of a single copy number of the transgene by Southern blot analysis. As we have observed in G1 transgenic chicken previously, all of the G2 transgenic chickens emitted a green fluorescence upon doxycycline feeding (50 mg kg–1 of formula feed). Fluorescence became detectable 4 days after starting doxycycline feeding, and maximum GFP expression was detected after 2 weeks. Removal of doxycycline from the diet after 14 days of induction feeding resulted in the return of external fluorescence to pre-induction levels after 39 days. Quantitative analysis of gene induction was done using protein and mRNA extracted from primary cultured cells derived from 6-day transgenic chicken embryos. The eggs were obtained by mating a nontransgenic wild-type hen with 1 of G2 transgenic roosters. Protein levels of GFP were analysed by immunoblot and quantified using a densitometer. In the absence of doxycycline, the amount of GFP per 1 µg of total protein was 0.2 ng. However, when the cells were treated with doxycycline for 6 days, the amount of GFP increased to 3.1 ng per 1 µg of total protein, which was 16-fold higher than that of the cells pre-treated with doxycycline. Switching to doxycycline-free medium after doxycycline induction resulted in significant abrogation of GFP expression in 6 days; the amount of GFP reduced from 3.1 to 0.5 ng, a 6.2-fold reduction. Transcription of the GFP gene was also assessed by Northern blot. The amount of GFP mRNA measured by band density increased as much as 20-fold (3.9/0.2) with 6 days of doxycycline induction and declined to 1/8 (3.9/0.5) when doxycycline was removed from the cell culture media for 6 days. The use of an inducible expression system that can be regulated by dietary supplementation could help mitigate the physiological disruption that can occur in transgenic animals as a result of uncontrolled constitutive expression of a transgene.

Spatial-frequency requirements for reading revisited

Blur is one of many visual factors that can limit reading in both normal and low vision. Legge et al. [Legge, G. E., Pelli, D. G., Rubin, G. S., & Schleske, M. M. (1985). Psychophysics of reading. I. Normal vision. Vision Research, 25, 239-252.] measured reading speed for text that was low-pass filtered with a range of cutoff spatial frequencies. Above 2cycles per letter (CPL) reading speed was constant at its maximum level, but decreased rapidly for lower cutoff frequencies. It remains unknown why the critical cutoff for reading speed is near 2 CPL. The goal of the current study was to ask whether the spatial-frequency requirement for rapid reading is related to the effects of cutoff frequency on letter recognition and the size of the visual span. Visual span profiles were measured by asking subjects to recognize letters in trigrams (random strings of three letters) flashed for 150ms at varying letter positions left and right of the fixation point. Reading speed was measured with Rapid Serial Visual Presentation (RSVP). The size of the visual span and reading speed were measured for low-pass filtered stimuli with cutoff frequencies from 0.8 to 8 CPL. Low-pass letter recognition data, obtained under similar testing conditions, were available from our previous study (Kwon & Legge, 2011). We found that the spatial-frequency requirement for reading is very similar to the spatial-frequency requirements for the size of the visual span and single letter recognition. The critical cutoff frequencies for reading speed, the size of the visual span and a contrast-invariant measure of letter recognition were all near 1.4 CPL, which is lower than the previous estimate of 2 CPL for reading speed. Although correlational in nature, these results are consistent with the hypothesis that the size of the visual span is closely linked to reading speed.

Calibration of electron cyclotron emission radiometer for KSTAR

We developed and installed an electron cyclotron emission radiometer for taking measurements of Korea Superconducting Tokamak Advanced Research (KSTAR) plasma. In order to precisely measure the absolute value of electron temperatures, a calibration measurement of the whole radiometer system was performed, which confirmed that the radiometer has an acceptably linear output signal for changes in input temperature. It was also found that the output power level predicted by a theoretical calculation agrees with that obtained by the calibration measurement. We also showed that the system displays acceptable noise-temperature performance around 0.23 eV.

Electron cyclotron emission diagnostics on KSTAR tokamak

A new electron cyclotron emission (ECE) diagnostics system was installed for the Second Korea Superconducting Tokamak Advanced Research (KSTAR) campaign. The new ECE system consists of an ECE collecting optics system, an overmode circular corrugated waveguide system, and 48 channel heterodyne radiometer with the frequency range of 110-162 GHz. During the 2 T operation of the KSTAR tokamak, the electron temperatures as well as its radial profiles at the high field side were measured and sawtooth phenomena were also observed. We also discuss the effect of a window on in situ calibration.