Evolving applications of liquid biopsies in gastrointestinal cancers

Liquid biopsy is a test that allows for the diagnosis and analysis of cancer by sampling cancer cells or byproducts present in biological fluids such as blood or urine. It has the potential to create a new paradigm in oncologic care, being a less invasive approach than conventional tissue biopsy. Liquid biopsy has multifaceted applications for longitudinal disease monitoring in terms of surveillance, treatment response, and identification of emerging resistance mechanisms. Multiple assays currently exist or are in development for detecting circulating tumor cells, DNA, RNA, exosomes, proteins, fragmentomic markers, and metabolomes. Here, we review the applications of liquid biopsy in gastrointestinal cancers, emphasizing its use in both perioperative and advanced settings. We also examine its role in screening, diagnostics, and other cancer-related scenarios.

Prognostic utility of preoperative and postoperative KRAS-mutated circulating tumor DNA (ctDNA) in resected pancreatic ductal adenocarcinoma: A systematic review and meta-analysis

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a challenging disease, with surgery being the only possible cure. However, despite surgery, the majority of patients experience recurrence. Recent evidence suggests that perioperative KRAS-mutated circulating tumor DNA (ctDNA) may have prognostic value. Therefore, we conducted a systematic review and meta-analysis to explore the prognostic significance of preoperative and postoperative KRAS-mutated ctDNA testing in resected PDAC.

METHODS

We searched PubMed/MEDLINE, Embase, and Cochrane Central Register of Controlled Trials databases for studies that reported the effect of preoperative and postoperative KRAS-mutated ctDNA on overall survival (OS) and/or relapse-free survival (RFS) in resected PDAC. We used a random-effects model to determine the pooled OS and RFS hazard ratios (HR) and their corresponding 95 % confidence intervals (CI).

RESULTS

We identified 15 studies (868 patients) eligible for analysis. In the preoperative setting, positive ctDNA correlated with worse RFS in 8 studies (HR, 2.067; 95 % CI, 1.346-3.174, P < 0.001) and worse OS in 10 studies (HR, 2.170; 95 % CI, 1.451-3.245, P < 0.001) compared to negative ctDNA. In the postoperative setting, positive ctDNA correlated with worse RFS across 9 studies (HR, 3.32; 95 % CI, 2.19-5.03, P < 0.001) and worse OS in 6 studies (HR, 6.62; 95 % CI, 2.18-20.16, P < 0.001) compared to negative ctDNA.

CONCLUSION

Our meta-analysis supports the utility of preoperative and postoperative KRAS-mutated ctDNA testing as a prognostic marker for resected PDAC. Further controlled studies are warranted to confirm these results and to investigate the potential therapeutic implications of positive KRAS-mutated ctDNA.

Perioperative therapy landscape for locally advanced, resectable esophageal cancer: an updated literature review

Background and Objective

The poor oncologic outcomes associated with esophageal cancer (EC) are primarily due to its presentation at an advanced stage and patient comorbidities. While multimodal therapy improves overall outcomes, there is a lack of uniform practice in terms of perioperative management, partly because this is a rapidly evolving field in a heterogeneous patient population. With numerous recent studies incorporating precision medicine with radiographic, pathologic, and genomic biomarkers and with emerging trials using targeted therapies, it is necessary for providers who care for these patients to be familiar with the current and evolving treatment standards to optimize patient outcomes. The objective of this paper is to perform an updated review of the main historical and recently emerging studies that impact the perioperative management of patients with locally advanced, upfront-resectable EC.

Methods

We mined and reviewed PubMed and American Society of Clinical Oncology databases for pivotal works shaping the current perioperative treatment landscape in locally advanced EC.

Key Content and Findings

EC are a vastly heterogeneous disease, and treatment options vary based on tumor anatomic location, histology, and patient comorbidities. Perioperative chemotherapy (CTX), chemoradiation (CRT), and, recently, immunotherapy have improved survival in patients with locally advanced disease. However, optimizing sequencing, de-escalating therapy, and incorporating novel targeted therapies in the perioperative setting are promising strategies that are under ongoing investigation to improve patient outcomes further.

Conclusions

There is an ongoing need to identify predictive biomarkers and novel treatment strategies to personalize perioperative approaches and optimize outcomes of patients with EC.

Propagated Circulating Tumor Cells Uncover the Potential Role of NFκB, EMT, and TGFβ Signaling Pathways and COP1 in Metastasis

Circulating tumor cells (CTCs), a population of cancer cells that represent the seeds of metastatic nodules, are a promising model system for studying metastasis. However, the expansion of patient-derived CTCs ex vivo is challenging and dependent on the collection of high numbers of CTCs, which are ultra-rare. Here we report the development of a combined CTC and cultured CTC-derived xenograft (CDX) platform for expanding and studying patient-derived CTCs from metastatic colon, lung, and pancreatic cancers. The propagated CTCs yielded a highly aggressive population of cells that could be used to routinely and robustly establish primary tumors and metastatic lesions in CDXs. Differential gene analysis of the resultant CTC models emphasized a role for NF-κB, EMT, and TGFβ signaling as pan-cancer signaling pathways involved in metastasis. Furthermore, metastatic CTCs were identified through a prospective five-gene signature (BCAR1, COL1A1, IGSF3, RRAD, and TFPI2). Whole-exome sequencing of CDX models and metastases further identified mutations in constitutive photomorphogenesis protein 1 (COP1) as a potential driver of metastasis. These findings illustrate the utility of the combined patient-derived CTC model and provide a glimpse of the promise of CTCs in identifying drivers of cancer metastasis.

Success rates and clinicopathologic associations with experimental outcomes of a novel circulating tumor cell (CTC) technology in advanced colon cancer (CC) and pancreatic cancer (PC)

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Background: Studying CTC cultures (cx) ex-vivo can provide valuable insights into cancer metastases (mets). However, current immunoaffinity- and size-based-methods used to isolate and expand these cells have low success rates for culturing CTCs (6-20%). Here, we report our experience using a novel technology developed at Georgetown for culturing CTCs from patients (pts) with metastatic (m) CC, mPC, and locally advanced PC (LAPC). Methods: 44 peripheral blood samples were prospectively collected from 35 pts with adenocarcinoma across 3 cohorts (18 samples from 15 mCC pts, 21 samples from 15 mPC pts, and 5 samples from 5 LAPC pts). Pts were previously treated, treatment-naïve, or actively undergoing treatment. FiColl-Paque-based separation of red blood cells was performed, plasma and buffy coat cells were resuspended in cx medium, and successfully grown CTC cxs were processed and injected subcutaneously (subQ) in the flanks of mice. A single predetermined sample from each pt was used in assessing the clinicopathologic associations with experiment outcomes and survival analyses. Results: CTC cxs were successfully grown from 81.8% (36/44) of all samples. Cxs grew from 72.2% (13/18) of mCC, 85.7% (18/21) of mPC, and 100% (5/5) of LAPC samples. At the time of analysis, 25 injected mice were evaluable for subQ tumor growth. 4 mice failed to grow tumor, 10 were still under monitoring, and 11 grew tumor, 9 of which also developed mets. These were mostly macro-mets and partially mirrored the met pattern seen in the matched pt. Across all cohorts, samples were predominantly collected from pts during systemic treatment (79.5%), during 2nd- (36.4%) and 1st-line treatment (20.5%), at a median of 15 (0-111) and 5 (1-20) months after diagnosis in mPC/mCC and LAPC pts, respectively, after scans with new/progressing disease (72.7%), and with a median of 3 (1-9) sites of disease on scans done within 2 months of collection . In all pts, no clinicopathologic or genomic factor predicted for cx growth. In the mCC subgroup, female sex (p=0.044), longer time from diagnosis to CTC collection (p=0.033), and presence of lung mets (p=0.022) were associated with cx growth. With cohorts combined, the median pt progression-free survival was 174 days (95% CI 97-220) and median overall survival was not reached. There was no statistically significant relationship between cx growth and pt survival. Conclusions: This novel platform demonstrated historically high rates of successful CTC cx and xenograft tumor growth using samples from advanced CC and PC pts. Studies to elucidate reasons for mice failing to grow tumor and others with matched tumor-CTC molecular analyses are ongoing to validate this promising technology to ultimately use to identify biomarkers for metastases, uncover novel therapeutic targets, and inform clinical decisions.

Continuous maintenance (Maint) capecitabine (Cape) dosing for colorectal (CRC) and pancreatic cancers (PC): A single-institution, retrospective, real-world study

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Background: Cape is an oral fluoropyrimidine (FP) used as maint therapy in CRC and PC. While the standard FDA dosing is 1250 mg/m2 twice daily (BID) for 14 days followed by 7 days off in a 21-day cycle, there are variations across institutions as to the preferred schedule. To improve tolerability and convenience, our institution adopted a “continuous” dosing schedule where cape is taken BID Monday-Friday (M-F) with a treatment break on Saturday and Sunday. Here, we describe our institution’s experience with continuous maint dosing in advanced CRC and PC patients (pts) and explore real-world outcomes. Methods: Pts ≥ 18 years of age treated with continuous maint cape (+/- bevacizumab) after any line of therapy for stage 4 CRC/PC or locally advanced PC between 1/2016-12/2020 were identified in the COTA real-world database. The final study population included 35 PC and 85 CRC pts. Pt characteristics were analyzed descriptively and progression-free survival (PFS) was calculated using Kaplan Meier methods. Results: Among the 35 PC pts, the median age was 66 years (IQR: 61-73), 57.1% were females, and 65.7% were Caucasian. Among the 85 CRC pts, the median age was 54 years (IQR: 47-66), 47.1% were females, and 55.3% were Caucasian. Most PC (71.4%) and CRC (57.7%) pts were initially prescribed a total daily cape dose of 2 g (range 0.5-4 g). Dose adjustments, including dosage/schedule changes, occurred 11 times amongst PC and 36 times amongst CRC pts, and the leading cause was toxicity (72.7% in PC, 55.6% in CRC). Among PC pts, 14.3% had a dose reduction, 3% had a dose increase, and 11.4% switched to an alternative dosing schedule. Among CRC pts, these rates were 32.9%, 12.9%, and 9.4%, respectively. The leading cause of maint discontinuation was progression of disease (POD) (55.6% in PC, 59.3% in CRC). Additional outcomes are summarized in the table. Conclusions: Although maint FP is an established standard of care, it is often underutilized due to inherent inconveniences and toxicities associated with FDA cape dosing or intravenous FP therapy. The PFS reported here using a continuous cape dosing (predominantly starting at 2 g daily dosing) was in range with those previously reported in PC/CRC 1st-line maint studies using FDA cape dosing or intravenous FP. The rates of cape discontinuation attributed to toxicity we report may be confounded by not controlling for the treatment setting. We argue fixed cape dosing (1 g BID) M-F should be considered a standard maint regimen based on efficacy, convenience, tolerability, and feasibility of dose adjustments.[Table: see text]

Comparative analysis of the molecular profile and tumor immune microenvironment (TIME) of human epidermal growth factor receptor 2 (HER2) low (L)- versus high (H)-expressing gastroesophageal cancers (GEC)

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Background: Addition of immune checkpoint blockade to anti-HER2 therapy has improved outcomes in HER2-positive GEC. Anti-HER2 antibody-drug conjugates have shown activity in some HER2-L tumors in other tumor types. We aimed to compare the molecular profile and TIME of HER2-L and HER-H GEC. Methods: 8678 GEC (gastric, GE junction, and esophageal) adenocarcinoma and squamous cell carcinoma samples were analyzed by next-generation sequencing (NGS) of RNA (whole transcriptome, NovaSeq), DNA (592 genes, NextSeq, or whole exome sequencing, NovaSeq), and immunohistochemistry (IHC, Caris Life Sciences, Phoenix, AZ). Cohorts were stratified by IHC HER2 values of 0 (non-expressors), 1-2+ (HER2-L), or 3+ (HER2-H) and compared using X2 or Fisher-Exact. Statistical significance was determined as P-value adjusted for multiple comparisons (q < 0.05). Microenvironment cell population (MCP) counter was used to quantify immune cell infiltration. Results: Tumor were grouped into HER2 non-expressors (N = 5217), L (N = 2660), and H (N = 801). Mutations of TP53 (72% vs 92%) and amplification of MYC (4% vs 7%), CCNE1 (7% vs 12%), CCND3 (2% vs 4%), CDK6 (3% vs 6%), SMARCE1 (2% vs 25%) and RARA (3% vs 24%) were significantly lower in HER2-L compared to HER2-H (q < 0.05). ARID1A (14% vs 9%), PIK3CA (8% vs 3%), KRAS (9% vs 2%), GNAS (2% vs 0.3%), KMT2D (6% vs 1%), CDH1 (5% vs 1%), and ATM (4% vs 1%) mutations were significantly higher in HER2-L compared to HER2-H (q < 0.05). HER2-L was associated with more TMB-H (9.3% vs. 5%; q<0.05), MSI-H (4.7% vs. 0.6%; q<0.05), and a trend towards higher PD-L1 expression than in HER2-H (80.8% vs 76.1%, p < 0.05 but q > 0.05). Immuno-oncology (IO)-related gene expression inversely correlated with HER2 expression with lowest expression of PDCD1LG2, CD274, CTLA4, PDCD1, HAVCR2, CD80, IFNG, LAG3, and CD86 in HER2-H (q < 0.05). HER2-L had significantly higher median immune infiltration of B cells (fold change [FC]: 1.22), T cells (FC: 1.16), CD8+ T cells (FC: 1.56), NK cells (FC: 1.12), neutrophils (FC: 1.10), cytotoxic lymphocytes (FC: 1.36), and myeloid dendritic cells (FC: 1.34), compared to HER2-H (q < 0.05). HER2 non-expressors showed similar immune cell infiltrates compared to HER2-H. HER2-H was associated with lower T-cell inflamed scores and IFN gamma signature when compared to HER2-L and non-expressors (q < 0.05). Conclusions: To our knowledge, this study is the first and largest comparison of molecular profile and TIME in HER2-expressing GEC. We demonstrated distinct molecular and TIME profiles with higher immunogenic profiles in HER-L as compared to HER2-H. IO-related gene expression and TIME cell distribution differences in HER2-H GEC suggest that response to IO and HER2 therapy combinations is likely related to HER2-targeted treatment effect on TIME rather than baseline immunogenicity of the tumor.

Response Surface Methodology Analysis of Energy Harvesting System over Pathway Tiles

This paper presents an experimental analysis of the optimization of PZT-based tiles for energy harvesting. The hardware (actual experiment), PZT-based tiles, were developed using 6 × 6 piezoelectric (PZT-lead zirconate titanate) sensors of 40 mm in diameter on a hard cardboard sheet (300 × 300 mm²). Our experimental analysis of the designed tiles obtained an optimized power of 3.626 mW (85 kg or 0.83 kN using 36 sensors) for one footstep and 0.9 mW for 30 footsteps at high tapping frequency. Theoretical analysis was conducted with software (Design-Expert) using the response surface methodology (RSM) for optimized PZT tiles, obtaining a power of 6784.155 mW at 150 kg or 1.47 kN weight using 34 sensors. This software helped to formulate the mathematical equation for the most suitable PZT tile model for power optimization. It used the quadratic model to provide adjusted and predicted R2 values of 0.9916 and 0.9650, respectively. The values were less than 0.2 apart, which indicates a high correlation between the actual and predicted values. The outcome of the various experiments can help with the selection of input factors for optimized power during pavement design.

Establishing the feasibility of a patient-engagement tool to improve outpatient symptom management and dosing of patients on regorafenib

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Background: Regorafenib (rego), an oral multikinase inhibitor, improves overall survival in patients (pts) with metastatic colorectal cancer (mCRC). However, its toxicity profile including, but not limited to, hand-foot skin reactions, fatigue, and hypertension significantly limits its use and often requires dose interruptions (40% rate) or modifications (20-25% rate). Inadequate symptom management can lead to frequent clinic visits, reduced quality of life, therapy non-adherence, and poor clinical outcomes. We aimed to establish the feasibility and usability of a CarePrompter smartphone application (app), a digital pt engagement tool with a pt and provider interface, to monitor and triage pt symptoms when starting rego. Methods: mCRC pts starting rego for the first time and with access to an iOS or Android smartphone with a data plan were recruited at MGUH. Pts were enrolled for the duration of their rego treatment. Once consented, recruiters downloaded and registered pts on the mobile app. Pts were provided a blood pressure (BP) cuff and trained on how to record their BP and answer a customized set of up to 17 questions daily on the app. The questions included documenting the status of the daily dose taken, completion of weekly labs, BP, whether pts needed advice, and severity of various side-effects if present on a 1-10 scale. Oncologists and nurses trained to use a CarePrompter triage tool were alerted when pts indicated missed doses, missed labs, high blood-pressure, high side-effect scores (8-10), and request for advice. Results: A total of 11 pts enrolled in the study. The study duration ranged from 1 to 5 months per pt. Pts, on average, completed the app questionnaire 10 out of 30 days, with the lowest rate of completion being 2 out of 30 days and the highest rate being 20 out of 30 days. BP recordings were logged an average of 10 times per pt in a 30-day period. An average of 2 provider alerts were triggered per pt. The alerts were primarily from pts documenting not performing labs or omitting rego doses. All alerts were acknowledged and resolved by a provider through the CarePrompter-triage tool. Providers found the tool usable based on qualitative interviews. There was an average dose increase of 1.25 rego pills from pt’s start to end dose. While 62.5% of pts were treated with the highest dose (160 mg) at one point in their treatment, by the end of the study 25%, 50%, and 25% remained on 160 mg, 120 mg, and 80 mg doses, respectively. Conclusions: The CarePrompter mobile app was technically feasible and usable by cancer patients and providers in monitoring symptoms and addressing real-time ambulatory issues during rego dosing. Additional studies are warranted to determine if routine utilization of this app in clinic translates to enhanced patient experiences, toxicity management, daily dosing, therapeutic compliance, and survival.

The Role of Immunotherapy in Pancreatic Cancer

Pancreatic adenocarcinoma remains one of the most lethal cancers globally, with a significant need for improved therapeutic options. While the recent breakthroughs of immunotherapy through checkpoint inhibitors have dramatically changed treatment paradigms in other malignancies based on considerable survival benefits, this is not so for pancreatic cancer. Chemotherapies with modest benefits are still the cornerstone of advanced pancreatic cancer treatment. Pancreatic cancers are inherently immune-cold tumors and have been largely refractory to immunotherapies in clinical trials. Understanding and overcoming the current failures of immunotherapy through elucidating resistance mechanisms and developing novel therapeutic approaches are essential to harnessing the potential durable benefits of immune-modulating therapy in pancreatic cancer patients.

The current state of molecular profiling in gastrointestinal malignancies

This is a review of the current state of molecular profiling in gastrointestinal (GI) cancers and what to expect from this evolving field in the future. Individualized medicine is moving from broad panel testing of numerous genes or gene products in tumor biopsy samples, identifying biomarkers of prognosis and treatment response, to relatively noninvasive liquid biopsy assays, building on what we have learned in our tumor analysis and growing into its own evolving predictive and prognostic subspecialty. Hence, the field of GI precision oncology is exploding, and this review endeavors to summarize where we are now in preparation for the journey ahead.

Prognostic utility of preoperative and postoperative circulating tumor DNA (ctDNA) in resected pancreatic ductal adenocarcinoma: A systematic review and meta-analysis

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Background: Surgical resection offers the only chance of cure for localized pancreatic ductal adenocarcinoma (PDAC). Despite surgical resection, 80% of patients experience disease recurrence. There is growing evidence that support the prognostic role of perioperative KRAS-mutated circulating tumor DNA (ctDNA). We conducted a systematic review and meta-analysis to investigate the prognostic utility of preoperative and postoperative KRAS-mutated ctDNA testing in resected PDAC. Methods: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a comprehensive search of PubMed/MEDLINE, Embase, and Cochrane Central Register of Controlled Trials databases was performed in September 2021. We included studies that reported on the effects of preoperative and postoperative KRAS-mutated ctDNA on overall survival (OS) and/or relapse free survival (RFS) in resected PDAC. The random-effects model was used to calculate pooled OS and RFS hazard ratios (HRs) and 95% confidence intervals (CIs). Publication bias was assessed by visual inspection of a funnel plot of the included studies. Results: We identified 6,986 studies, and 13 studies were eligible for analysis. A total of 954 patients were included for the final evaluation. In the preoperative setting, positive ctDNA correlated with worse RFS in 8 studies (HR, 2.067; 95% CI, 1.346-3.174; P < 0.001) and worse OS in 10 studies (HR, 2.170; 95% CI, 1.451-3.245; P < 0.001) compared to negative ctDNA. In the postoperative setting, positive ctDNA correlated with worse RFS across 7 studies (HR, 2.986; 95% CI, 1.897-4.699; P <.001), and worse OS in 5 studies (HR, 5.812; 95% CI, 1.757-19.228; P = 0.004) compared to negative ctDNA. There was visible symmetry in the funnel plot of the studies included, suggesting no publication bias. Conclusions: In resected PDAC, preoperative and postoperative KRAS-mutated ctDNA positivity may be useful markers of poor prognosis in terms of RFS and OS. Clinically, KRAS-mutated ctDNA testing may also have implications when considering the aggressiveness and duration of adjuvant therapy in PDAC, although prospective trials are needed to assess this utility.

Lessons Learned in Managing Patients with Colorectal Cancer During the COVID-19 Pandemic

OPINION STATEMENT

The COVID-19 pandemic forced us to rapidly and dramatically shift our medical priorities and decision making. With little literature or experience to rely on, the initial priority was to minimize patient exposure to the hospital and to others. It remains unclear whether cancer patients are at higher risk of infection or serious complications, or if it is our traditional therapies that place them to be at higher risk. By far, the greatest negative impact was on screening. Routine colonoscopies were considered elective, and as a result, delays in diagnosis will be felt for years to come. The most positive changes were the incorporation of tele-visits, increased use of oral therapies, alterations in treatment schedules of both chemotherapy and radiation, and an increased emphasis on neoadjuvant therapy. These too will be felt for years to come. The colorectal cancer medical community has responded collaboratively and effectively to maintain treatment and to optimize outcomes for our patients during the COVID-19 pandemic.

The gut microbiome and potential implications for early-onset colorectal cancer

Recently, there has been an unexpected trend toward increased incidence of colorectal cancer in younger individuals, particularly distal colon and rectal cancer in those under age 50. There is evidence to suggest that the human gut microbiome may play a role in carcinogenesis. The microbiome is dynamic and varies with age, geography, ethnicity and diet. Certain bacteria such as Fusobacterium nucleatum have been implicated in the development of colorectal and other gastrointestinal cancers. Recent data suggest that bacteria can alter the inflammatory and immune environment, influencing carcinogenesis, lack of treatment response and prognosis. Studies to date focus on older patients. Because the microbiome varies with age, it could be a potential explanation for the rise in early-onset colorectal cancer.

Genomic Alterations and Their Implications on Survival in Nonmetastatic Colorectal Cancer: Status Quo and Future Perspectives

The selection of treatment according to genomic alterations is a standard approach in metastatic colorectal cancer but is only starting to have an impact in the earlier stages of the disease. The status if genes like KRAS, BRAF, and MMR has substantial survival implications, and concerted research efforts have revolutionized treatment towards precision oncology. In contrast, a genomic-based approach has not changed the adjuvant setting after curative tumor-resection in the daily routine so far. This review focuses on the current knowledge regarding prognostic and predictive genomic biomarkers in patients with locally advanced nonmetastasized colorectal cancer. Furthermore, we provide an outlook on future challenges for a personalized adjuvant treatment approach in patients with colorectal cancer.

The Relevance of Hereditary Cancer Risks to Precision Oncology: What Should Providers Consider When Conducting Tumor Genomic Profiling?

Through tumor genomic profiling (TGP), existing and novel treatments can be selected to better target the specific dysregulated molecular pathways that drive growth and spread of a patient's tumor. Although the primary purpose of TGP is to detect targetable somatic mutations for treatment, TGP may also uncover germline mutations with important implications for patients and family members. Oncology care providers should be aware of the hereditary cancer risks associated with genes commonly tested by TGP. Further, patients should be informed about the possible discovery of hereditary cancer risk information and the relevance of this information to their health and that of family members, and should have their preferences toward further evaluation of hereditary risk information that could be revealed by TGP documented in the medical record and followed.

Sleep-disordered breathing and hypertension among African Americans

This study investigated differences in sleep-disordered breathing (SDB) between hypertensives without a family history of hypertension and hypertensives with a family history. Furthermore, it examined whether these two groups differed in the severity of SDB. Patients were African Americans (n=162, mean age=51.19+/-13.77 years; mean body mass index (BMI)=37.85+/-9.51 kg/m2, male=57%), who were referred to the clinic because of a sleep complaint. Sleep was recorded in the laboratory using standard physiological parameters; all parameters were analysed by a trained scorer. Altogether, 91% of the patients received an SDB diagnosis. Of these patients, 25% were hypertensives without a family history, 20% were hypertensives with a family history, and 55% were normotensives. We found a significant difference between these patient groups regarding the severity of SDB (F14,158=1.823, P<0.05), but no significant group difference was observed in the rate of SDB. Increasing weight was accompanied by increasing severity of SDB. The finding that hypertensive patients with or without a positive family history showed worse oxygenation and respiratory characteristics than did normotensives is consistent with previous research. Of note, hypertensives reporting a family history were characterized by a greater number of oxygen desaturations and apnoea hypopnoea index than those typified only by a current diagnosis of hypertension. Hypertensives with a family history are likely to show a profile of greater blood pressure, higher BMI, and more severe SDB, which by all accounts are more common among African Americans.

Reduction in vancomycin-resistant Enterococcus and Clostridium difficile infections following change to tympanic thermometers

OBJECTIVE

To contain a nosocomial outbreak of vancomycin-resistant Enterococcus (VRE).

DESIGN

Intervention study, with comparison of incidence rates before and after intervention to assess whether changes in incidence followed the intervention and were greater than expected based on trends observed before the intervention.

SETTING

A 343-bed acute-care hospital serving a predominantly elderly population referred from nursing homes, as well as patients admitted from the community.

METHODS

Interventions strategies were tested on three high-risk nursing stations. These included enhanced environmental sanitation; intensive staff retraining in Universal Precautions, body substance isolation, and proper use of gloves; and the use of tympanic thermometers to avoid possible rectal or oral VRE transmission during temperature taking.

RESULTS

Nosocomial VRE infections were reduced by 48% 9 months after switching to tympanic thermometers; incidence of Clostridium difficile infections also was reduced. As a result, tympanic thermometers were introduced facilitywide; additional observation for 20 months showed a risk reduction of 60% for VRE and 40% for C difficile.

CONCLUSION

Cross-transmission of VRE and C difficile during temperature taking may result in bowel colonization, placing the patient at increased risk for infection. This risk may be reduced by the use of tympanic thermometers.

Genetics of epidermal ridges: a study in subjects with refractive errors

The dermatoglyphic characteristics of subjects with refractive errors when compared with control group revealed significant differences in both qualitative and quantitative parameters. The loops were increased in male myopics; the whorls were increased in male hypermetropics and astigmatics and the arches were decreased in all types of refractive errors in males. However, the whorls were decreased in female hypermetropics only. The mean total ridge count was significantly higher in male astigmatics only. As regards pattern intensity (fingers) no significant difference in the mean value was observed in either sex with any type of refractive errors when compared with those of controls.

Serum zinc in corneal ulcer--a preliminary report

In recent times zinc is emerging as a nutrient of clinical importance and had been found to be low in serum in various disease conditions. In the current study 11 control cases and 22 corneal ulcer cases were taken. Their serum zinc level was measured by atomic absorption spectrophotometer. Serum zinc level in recalcitrant corneal ulcer cases was found to be below normal.

Positive airway pressure in patients receiving intermittent mandatory ventilation at zero rate. The role in weaning in chronic obstructive pulmonary disease

Over a 20-month period, we treated 180 mechanically ventilated patients in our respiratory intensive care unit. Among these patients, we observed an interesting previously unreported phenomenon in 20 patients with severe chronic obstructive disease. During the weaning from mechanical ventilators of these 20 patients, there was a marked clinical deterioration when the mode of ventilation was changed from intermittent mandatory ventilation (IMV) at zero rate to that of a T-tube setup. To explain this previously unreported observation, we studied and compared nine different intubated patients for possible differences in airway pressure between IMV set up at zero rate and a T tube. We observed that peak airway pressures were greater on IMV at zero rate compared to the peak airway pressures on the T piece in all nine patients. At the end of expiration, seven out of the nine patients had higher airway pressures on IMV at zero rate compared to the T tube. These differences in the peak airway pressures and end-expiratory pressures were statistically significant in both groups. In spite of the obvious limitation of extrapolating the experimental results obtained in one group of patients to explain the clinical observations made in another group of patients, we believe that the higher airway pressures on the IMV system (even without any mechanical ventilation) prevent early collapse of the airways, and this may be of significant importance in successfully weaning patients with COPD.