Evidence for the aqueous absorption of gas from the eye following vitreoretinal surgery

A standard part of vitrectomy surgery is to inject a bubble of gas into the eye, and an important question for the surgeon and patient alike is to know the volume of the bubble and how long it is likely to last. A related question of considerable importance is the mechanism by which it is absorbed. In this paper, we show how to use patients' measurements of the daily variation of their far points to calculate the changing volume of the bubble and hence the rate of gas absorption throughout the post-operative period. The results show that the rate of absorption contains a term in time squared, indicative of absorption through the exposed surface area of the aqueous fluid rather than via the exposed retina.

HIV-infected liver and kidney transplant recipients: 1- and 3-year outcomes

Improvements in human immunodeficiency virus (HIV)-associated mortality make it difficult to deny transplantation based upon futility. Outcomes in the current management era are unknown. This is a prospective series of liver or kidney transplant recipients with stable HIV disease. Eleven liver and 18 kidney transplant recipients were followed for a median of 3.4 years (IQR [interquartile range] 2.9-4.9). One- and 3-year liver recipients' survival was 91% and 64%, respectively; kidney recipients' survival was 94%. One- and 3-year liver graft survival was 82% and 64%, respectively; kidney graft survival was 83%. Kidney patient and graft survival were similar to the general transplant population, while liver survival was similar to the older population, based on 1999-2004 transplants in the national database. CD4+ T-cell counts and HIV RNA levels were stable; and there were two opportunistic infections (OI). The 1- and 3-year cumulative incidence (95% confidence intervals [CI]) of rejection episodes for kidney recipients was 52% (28-75%) and 70% (48-92%), respectively. Two-thirds of hepatitis C virus (HCV)-infected patients, but no patient with hepatitis B virus (HBV) infection, recurred. Good transplant and HIV-related outcomes among kidney transplant recipients, and reasonable outcomes among liver recipients suggest that transplantation is an option for selected HIV-infected patients cared for at centers with adequate expertise.

Rural internships for final year students: clinical experience, education and workforce

INTRODUCTION

The James Cook University School of Medicine is the only complete medical school in northern Australia, and it has a mission to prepare graduates to meet the unique needs of the region with a particular emphasis on rural, remote, Indigenous and tropical health. Eight-week 'rural internships' have been undertaken by all sixth-year medical students at James Cook University since 2005. Each student had previously completed at least 12 weeks of structured rural placements in years 2 and 4, as well as other core teaching in rural health including the year 2 subject, 'Rural, Remote, Indigenous and Tropical Health'. Students worked in rural hospitals across northern Australia developing and practising clinical skills under the supervision of senior staff. Students undertook full-time inpatient and outpatient responsibilities under supervision, being rostered for after-hours work with appropriate support. Assessment involved a learning portfolio, including multi-source feedback from peers, supervisors and patients, and a population health project and a telephone referral exercise.

METHODS

This article describes the development, implementation and assessment of the first years of the program, from 2005 to 2007. Evaluation included student questionnaires, site visits and interviews, and follow-up teleconferences with preceptors.

RESULTS

The rural internship provides senior medical students with valuable experience by active participation in the healthcare team. Students reported a rich and varied clinical experience. Students accept limited supervised responsibility and further their ability and confidence to undertake the role of the intern. Importantly, they proved not to be a burden to the system. This rotation therefore appears to meet educational needs without compromising the local workforce (and indeed may add to it). Students felt welcomed by their communities and enjoyed the social and cultural aspects of their attachment, as well as the clinical aspects and the opportunity to further their understanding of rural communities, rural health care and the healthcare team. Preparation of the students, the preceptors and the communities emerged as a key element of success.

CONCLUSION

This model extends and enhances the traditional apprenticeship model by its rural focus and distributed nature, and involvement of the entire student cohort. In addition, the contribution to patient care by senior students and junior doctors enables a consultant-registrar-resident model, in which experienced rural doctors function as consultants providing advice, support and tuition rather than predominantly face-to-face patient care. This approach also provides a means to address an emerging paradox: rural preceptors and communities want to teach students, appreciating the long-term workforce implications, but are increasingly constrained by resources, particularly time. Similar innovative approaches should be explored in other settings.

Phase II trial of irinotecan (Ir) plus cisplatin (CDDP) in patients with recurrent or metastatic squamous carcinoma of the head and neck (SCCHN)

6041

Background: Prognosis for recurrent or metastatic SCCHN patients remains poor with median survivals of 6–9 months. Therapies targeting this group are needed. We conducted a single arm Phase II trial of Ir plus CDDP in patients with recurrent or metastatic SCCHN. The goal of this trial was to evaluate the efficacy and toxicity of this combination in advanced SCCHN. Methods: Eligible patients had incurable SCCHN, an ECOG PS of 0–2 and were chemonaive (no prior chemotherapy or chemotherapy for primary disease at least 6 months prior to study entry). A two-stage accrual design (Simon) was used. Irinotecan 65 mg/m2 and CDDP 30 mg/m2 were administered weekly for 4 weeks, followed by a 2 week rest for a 6 week cycle. Due to GI toxicity and neutropenia, the Ir was decreased to 50 mg/m2 with CDDP 30 mg/m2. Response assessment was made after every cycle using WHO criteria. The primary endpoint was response rate. Results: Forty patients were enrolled (male: 33, female:7). Median age was 58 (33–79). Forty and 32 patients were evaluable for toxicity and response, respectively. Reasons for unevaluable: 7 without at least 1 full cycle of therapy; 1 patient with incomplete records. Overall response rate was 34% (11/32 PR) with 18% SD (6/32). Median progression free survival was 2.6 months. The median overall survival was 8.2 months. Toxicity was substantial at Ir 65 mg/m2 with a rate of Grade (G) 3 or 4 toxicity of 82% compared to 56% at Ir 50 mg/m2. For both dose levels, G 3 or 4 nausea and vomiting (23%), diarrhea (15%) and neutropenia (35%) were the most common toxicities. Conclusions: The combination of irinotecan and cisplatin is active in a poor prognosis group of patients. Toxicity of irinotecan at 65 mg/m2 with CDDP 30 mg/m2 is substantial. Irinotecan 50 mg/m2 and CDDP 30 mg/m2 is tolerable and provides a 34% response rate.

No significant financial relationships to disclose.

Cetuximab-related hypersensitivity reactions associated with pre-existing cetuximab-specific IgE antibody

9097

Background: Cetuximab is a chimeric (mouse/human) IgG1 monoclonal antibody against the epidermal growth factor receptor and is approved for use in patients (pts) with colorectal cancer and head and neck squamous cell carcinoma. Hypersensitivity reactions caused by cetuximab (C-HSR) have been reported; however, the mechanism underlying these reactions is unknown. We hypothesize that C-HSR are mediated by pre-existing cetuximab-specific IgE antibodies (C-IgE). Methods: A total of 140 serum samples were obtained under IRB approved protocols and retrospectively analyzed across 2 cohorts: 1) 71 pretreatment sera from cetuximab-treated pts collected from multiple centers (47 pts with no HSR and 24 pts with any grade HSR; samples were biased for HSR pts), and 2) 69 sera from healthy volunteers in the Nashville TN area. The samples were analyzed for total-, cetuximab-specific and mouse-specific IgE levels using a modified ImmunoCAP assay (Phadia US Inc.). Severe HSR was defined as grade 3/4 reactions during the first infusion by NCI CTC version 3.0 Allergic reaction/hypersensitivity criteria by a reviewer blinded to the immunoCAP assay results. Results: Of the 71 cetuximab-treated pts from cohort 1, 21 experienced severe HSR by retrospective evaluation. All C-IgE(+) pts (15/15) experienced severe HSR and were immediately discontinued from therapy. Of the remaining 6 severe HSR pts with C-IgE(-), 4 pts were re-challenged and completed their cetuximab infusion without any further reaction, suggestive of a non-IgE mediated mechanism, while 2 pts were not re-challenged. Also, the C- IgE(+) pts tended to have higher levels of total IgE compared to the C-IgE(-) pts. All 47 non-HSR pts were C-IgE(-). Mouse-specific IgE was not detected in any sera from the pts. Analysis of sera from healthy volunteers from the cohort 2 revealed that 15/69 (21.7%) were C-IgE(+), suggestive of pre-existing C-IgE; however, the association with C-HSR could not be made. Conclusion: Our data suggest that C-IgE antibodies are present prior to treatment and appears highly predictive of severe HSR during the first infusion; however, IgE-mediated reactions may not account for all cases of HSR. Prospective validation of the association between C-IgE and cetuximab-induced HSR is warranted.

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The development of novel organically modified sol-gel media for use with ATR/FTIR sensing

The ability to prepare and develop novel pre-concentration media by the sol-gel process, and their integration with mid-infrared transparent waveguides has been demonstrated. This research approach resulted in a mid-infrared sensing methodology in which the properties (porosity, functionality, polarity, etc.) of the recognition layer could be tailored by variation of the sol-gel precursors and processing conditions. Cross-linker type and concentration notably influenced p-xylene absorption and diffusion rate. Unreacted silanol groups appeared to be the dominant factor in the hydrophobicity of sol-gel layers. Variation of sol-gel precursors and thermal treatment altered both film cross-link density and polarity, as demonstrated by variation in the rate of analyte diffusion and equilibrium analyte concentration. The use of a novel 1 : 1 PTMOS : DPDMS material as pre-concentration medium in this analytical sensing approach was validated through the determination of p-nitrochlorobenzene in an aqueous environment. The response demonstrated linearity between 0-30 mg L(-1) with a correlation coefficient of 0.989 and a limit of detection of 0.7 mg L(-1). Sensing times for p-nitrochlorobenzene were also reduced from several hours to 24 minutes, without loss of measurement accuracy or sensitivity, by a 10 degrees C increase in the sensing temperature and the use of a predictive Fickian model previously developed by this research group.

Aspergillus infection limited to renal allograft: case report and review of literature

We report a case of a 28-year-old recipient of a cadaveric renal transplant who developed Aspergillus infection in the allograft without having disseminated disease. We review the previously reported cases of isolated Aspergillus in kidney transplant recipients and discuss the possible route of transmission in our patient. We also discuss the alternate but successful treatment that our patient received.

The proteolysis-inducing factor: in search of its clinical relevance in patients with metastatic gastric/esophageal cancer

The proteolysis-inducing factor is a putative mediator of cancer-associated weight loss. The goal of this study was to examine for the first time: (i) its prevalence in patients with metastatic gastric/esophageal cancer; and (ii) whether it possibly correlated with weight loss and anorexia and whether it predicted tumor response and patient survival. This study recruited 41 patients as part of a phase II therapeutic, chemotherapy protocol for patients with metastatic gastric/esophageal cancer. Patient eligibility criteria were designed to select a group of patients who would tolerate treatment with the drugs capecitabine and oxaliplatin. Urine for assaying the proteolysis-inducing factor was obtained at registration and then 6 weeks later. Patients completed the FACT-E questionnaire every 6 weeks and had their weights checked at the same interval. Patients were followed prospectively for tumor response and patient survival. Twenty-three (56%) patients had the proteolysis-inducing factor in their urine at registration, and 18 (64%) had it at 6 weeks. There was no statistically significant correlation between the presence of the proteolysis-inducing factor and weight loss or between its presence and anorexia. Moreover, there was no evidence that the presence of the proteolysis-inducing factor in urine was able to predict tumor response or patient survival. The proteolysis-inducing factor in urine does not appear to be tied to weight loss, anorexia, tumor response, or patient survival in the clinical setting of metastatic gastric/esophageal cancer.

Longitudinal Oncology Registry of Head and Neck Carcinoma (LORHAN), a new national cancer registry

5583

Background: Registries can be invaluable for describing patterns of care for a population of patients (pts). Most cancer registries, however, do not possess sufficient breadth or depth to provide a complete and reliable picture of clinical practice. We report the launch of LORHAN, a new national registry of head and neck carcinoma (HNC) pts. LORHAN is designed to extend current cancer registries by providing detailed data on radiation and/or cancer drugs delivered to HNC pts in all practice settings. Methods: This is a prospective, multi-center, longitudinal, observational registry. Pts with newly diagnosed HNC, scheduled to receive radiotherapy or drug therapy, ≥18 years of age and providing written informed consent are being enrolled. Patients participating in clinical trials are eligible for LORHAN. The primary objective of the registry is to describe, in detail, patterns of care for HNC pts. The secondary objectives are to document outcome by treatment regimen, determine the incidence and severity of major toxicities and to identify supportive care received for managing treatment-related complications. Pts are entered in the registry from the time of initial diagnosis and are followed for at least 2 years and up to 10 years. Detailed information on initial treatment and re-treatment is collected. Data entry is electronic and incorporates encrypted point-to-point data transfer via secure HTTP protocols. Physician and patient confidentiality are strictly maintained. Participating practitioners can review and compare their data on a real-time basis to the database. Registry pts may be linked to the NDI to minimize lost to follow-up. Analyses of data are primarily descriptive. Results: LORHAN was launched in Oct. 2005, and as of Dec., 7 sites have received IRB approval and 3 pts have been enrolled. Of the 7 sites, 1 is an academic site and the remaining are community-based practices. An additional 21 sites (17 academic, 4 community) are at various stages of participation. More than 100 medical oncologists and radiation oncologists are anticipated to participate and approximately 26,000 pts will be eligible each year. Accrual status will be updated. Conclusions: LORHAN is a new national initiative that may further the understanding of the care of HNC pts across practice settings.

[Table: see text]

Locally advanced resectable larynx (L) or oropharynx (OP) cancer: Updated results of organ preservation trial ECOG 2399

5527

Background: Taxane-based concurrent chemoradiation (CCR) for head and neck cancers has proven feasible and has a favorable toxicity profile compared to concurrent cisplatin and radiation. This phase II multi-institutional trial evaluates taxane-based induction chemotherapy followed by CCR for organ preservation in resectable Stage III/IV L and OP patients. Methods: Eligibility: Resectable stage T2N+, or T3-T4N0–3M0 biopsy-proven squamous Ca, age ≥18, PS 0–2, good organ function, and no prior chemotherapy or radiation. Treatment: induction paclitaxel (P) 175 mg/m2 and carboplatin (C) AUC 6 for 2 cycles q21d followed by concurrent P 30 mg/m2 q7d with 70 Gy if no evidence of progression. Weekly epoetin alpha 40kU was used if Hgb ≤15 (male) or ≤14 (female). The primary endpoint is organ preservation (freedom from salvage surgery with preserved speech and swallowing). Results: 105/111 pts (69 OP, 36 larynx) were eligible. Median FU is 33 months. No grade 5 toxicities occurred. 94% received full dose RT and 91% received ≥5 cycles of concurrent paclitaxel. At one year post-treatment, 13 (12%) patients required salvage surgery at the primary site (7-L, 6-OP), and 6 pts (6%) progressed and died (3-L, 3-OP). 1 pt (1%) died without progression and 85 pts (81%) are alive without progression (25-L, 60-OP). 12 pts (10%) have developed distant mets (6-L, 6-OP). 1-yr and 2-yr PFS for all pts is 77% and 64%. 12/69 OP and 9/36 L pts have died of disease. 1-yr event-free survival (EFS = no salvage surgery, recurrence or death) is 72% (77%-OP, 64%-L), and 2-yr EFS is 57% (68%-OP, 34%-L) (p = 0.02). 1-yr OS is 93%, 2-yr OS is 74% (OP vs. L p = 0.11). Conclusions: This regimen is well tolerated and is feasible in a multi-institutional setting. EFS with this regimen is lower than expected in larynx patients. The benefit of induction chemotherapy in this setting remains unproven but does not preclude CCR delivery. Funded, in part, by Bristol-Myers Squibb.

[Table: see text]

Preliminary results of the validation of a patient (pt) self-administered questionnaire (Oral Mucositis Weekly Questionnaire-Head and Neck [OMWQ-HN]) to assess the impact of OM on pain and functioning in head and neck cancer (HNC)

5548

Background: Pt self-reported questionnaires measuring acute and specific effects of OM are needed to assess effects of interventions and guide patient care. We evaluated the feasibility, validity, and reliability of the OMWQ-HN on OM and its impact on pts’ abilities to perform alimentary and other routine functions. Methods: Validity and reliability of the OMWQ-HN was assessed in 75 pts from a prospective multicenter study receiving radiotherapy ± chemotherapy (RTCT). Assessments included test-retest reliability, internal consistency reliability, and cross-sectional validity. The OMWQ-HN’s sensitivity to detect change was demonstrated by using the changes in the Performance Status Scale for HNC (PSS-HN) and the Functional Assessment of Cancer Therapy (FACT-HN) to form 3 independent groups (better, no change, worse) for comparison. Effect sizes (ES) were calculated for group comparisons to measure the clinical significance of differences. Results: Compliance rates were >90% throughout the study. The OMWQ-HN demonstrated good test-retest reliability (r = 0.89). Cronbach’s alpha was >0.85 and mouth, throat, and pain-related items correlated highly with each other (r>0.7). Cross-sectional analyses to assess validity showed that OMWQ-HN scores were different across levels of pain, with those in the worst pain category reporting the most severe OMWQ-HN scores (ES >0.5 for all comparisons). The OMWQ-HN was sensitive to change in FACT-HN and PSS-HN (p < 0.001 and p = 0.013, respectively). Patients reported increases in mouth and throat soreness (MTS) that corresponded with a steady decline in oral function. Conclusions: These results indicate the OMWQ-HN is a feasible, valid, and reliable instrument for assessing the impact of mucositis on patients receiving RTCT in the HNC patient care setting.

[Table: see text]

Incidental neurodevelopmental episodes in the etiology of schizophrenia: an expanded model involving epigenetics and development

Epidemiological data favors genetic predisposition for schizophrenia, a common and complex mental disorder in most populations. Search for the genes involved using candidate genes, positional cloning, and chromosomal aberrations including triplet repeat expansions have established a number of susceptibility loci and genomic sites but no causal gene(s) with a proven mechanism of action. Recent genome-wide gene expression studies on brains from schizophrenia patients and their matched controls have identified a number of genes that show an alteration in expression in the diseased brains. Although it is not possible to offer a cause and effect association between altered gene expression and disease, such observations support a neurodevelopmental model in schizophrenia. Here, we offer a mechanism of this disease, which takes into account the role of developmental noise and diversions of the neural system. It suggests that the final outcome of a neural developmental process is not fixed and exact. Rather it develops with a variation around the mean. More important, the phenotypic consequence may cross the norm as a result of fortuitous and/or epigenetic events. As a result, a normal genotype may develop as abnormal with a disease phenotype. More important, susceptible genotypes may have reduced penetrance and develop as a normal phenocopy. The incidental episodes in neurodevelopment will explain the frequency of schizophrenia in most populations and high discordance of monozygotic twins.

Successful treatment of vancomycin-resistant Enterococcus faecium endocarditis with linezolid in a renal transplant recipient with human immunodeficiency virus infection

Infections with vancomycin-resistant Enterococci cause significant morbidity and mortality in hospitalized patients, including transplant recipients. We report the successful use of oral linezolid to treat a case of vancomycin-resistant Enterococcus faecium endocarditis in a renal transplant recipient with human immunodeficiency virus infection.

Analysis of the CTLA-4, CD28, and inducible costimulator (ICOS) genes in autoimmune thyroid disease

The cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) gene on 2q33 is associated with autoimmune thyroid diseases (AITDs). Our earlier study in 56 families showed linkage of 2q33 to the presence of thyroid antibodies (TAbs). The goals of this study were to confirm the linkage of the 2q33 region to TAbs, to fine map this region, and study the ICOS gene. We performed a linkage study in an expanded data set of 99 multiplex AITD-TAb families (529 individuals). The highest two-point LOD score of 2.9 was obtained for marker D2S325 on 2q33. To fine map this locus, we genotyped 238 Caucasian AITD patients and 137 controls for five additional markers in the linked locus, which contained the CTLA-4, CD28, and ICOS genes. The A/G single-nucleotide polymorphism at position 49 of CTLA-4 was associated with AITD (P=0.01, OR=1.5), while markers inside CD28 and ICOS were not. Functional studies have shown that the G allele was associated with reduced inhibition of T-cell proliferation by CTLA-4. We concluded that: (1) the AITD gene in the 2q33 locus is the CTLA-4 gene and not the CD28 or ICOS genes; and (2) the G allele is associated with decreased function of CTLA-4.

Involvement of gene-diet/drug interaction in DNA methylation and its contribution to complex diseases: from cancer to schizophrenia

Most biological processes, including diseases, involve genetic and non-genetic factors. Also, the realization of a genetic potential may depend on environmental factors by directly affecting the expression of gene(s). Exactly how different environmental factors affect gene expression is not well understood. One of the mechanisms may involve DNA methylation and thereby gene expression. Diet, chemicals, and metals are known to affect DNA methylation and other epigenetic processes but are just beginning to be elucidated. For example, methylation of cytosine(s) in the promoter region could prevent the binding of transcription factors or create binding sites for complexes that deacetylate neighboring histones that in turn compact the chromatin, encouraging a gene to become silent. This article will discuss DNA methylation as an epigenetic mechanism of gene regulation and examine how factors like diet, chemicals, and metals may affect DNA methylation. The effect of alterations in DNA methylation may include aberrant expression of genes or genomes and chromosomal instability, which in turn may contribute to the etiology of complex multifactorial diseases. A similar mechanism is now recognized in a number of cancers. There is also indirect evidence to suggest that methylation could apply to a number of complex diseases, including schizophrenia.

The validity and reliability of surface EMG to assess the neuromuscular response of the abdominal muscles to rapid limb movement

The transversus abdominus muscle (TrA) has been demonstrated to be active prior to rapid movements of the upper and lower limbs. This activity is termed feed forward motivation. The lack of feed-forward activation for TrA has been demonstrated in subjects with low back pain. The measures used for investigation of TrA function have been fine-wire needle EMG. This limits the practical application of TrA study due to the cost and level of specialisation required for this technique. The objective of the current study was to investigate the validity and reliability of using a surface EMG site to replicate the findings for the feed-forward activation of TrA prior to rapid limb movement. A population of healthy, young males (n = 20) were studied and it was found that four of the subjects did not meet feed-forward criteria. These results were shown to be highly reliable after a 2-week period for the TrA/IO site only. The validity of the signal was further investigated using several functional tasks to specifically target muscles of the abdominal region. Using a cross-correlation analysis to evaluate crosstalk from adjacent muscles, it was concluded that the signal representing TrA/IO accurately demonstrates the functional activity of the muscle. This study has demonstrated a viable surface EMG method to evaluate the feed-forward activation of TrA/IO prior to rapid limb movement. This may lead to opportunities for the clinical application of this method. It was also a finding of this study that four asymptomatic subjects did not pre-activate, therefore providing a rationale for future prospective investigations on whether the lack of TrA/IO feed-forward activation is a cause or an effect of low back pain.