False-positive reverse transcriptase polymerase chain reaction screening for SARS-CoV-2 in the setting of urgent head and neck surgery and otolaryngologic emergencies during the pandemic: Clinical implications.

BACKGROUND: No reports describe falsepositive reverse transcriptase polymerase chain reaction (RT-PCR) for novel coronavirus in preoperative screening. METHODS: Preoperative patients had one or two nasopharyngeal swabs, depending on low or high risk of viral transmission. Positive tests were repeated. RESULTS: Forty-three of 52 patients required two or more preoperative tests. Four (9.3%) had discrepant results (positive/negative). One of these left the coronavirus disease (COVID) unit against medical advice despite an orbital abscess, with unknown true disease status. The remaining 3 of 42 (7.1%) had negative repeat RT-PCR. Although ultimately considered falsepositives, one was sent to a COVID unit postoperatively and two had urgent surgery delayed. Assuming negative repeat RT-PCR, clear chest imaging, and lack of subsequent symptoms represent the "gold standard," RT-PCR specificity was 0.97. CONCLUSIONS: If false positives are suspected, we recommend computed tomography (CT) of the chest and repeat RT-PCR. Validated serum immunoglobulin testing may ultimately prove useful.

Mortality increases for octogenarians undergoing esophagogastrectomy for esophageal cancer.

BACKGROUND: As the general population ages, it becomes increasingly important to understand the potential contribution of chronologic age to mortality after esophagectomy. Because this risk is poorly defined, we sought to determine whether extreme age (>80 years) is an independent risk factor after esophagectomy. METHODS: We analyzed a prospectively maintained, single-institution database of 858 consecutive patients who underwent esophagectomy between January 1996 and May 2005. Data evaluated included patient demographics, medical comorbidity, types of resections performed, length of stay, postoperative adverse events, and overall survival. We used univariate, multivariate, and Kaplan-Meier analysis to determine the influence of age on postoperative morbidity, in-hospital survival, and overall survival. RESULTS: Of 858 patients, 31 (10 female, 21 male) were older than 80 years of age. Preliminary analysis indicated that patients younger than 50 years (n = 107) had significantly fewer comorbidities; these were excluded from the analysis. In the remaining 751 patients, the age older than 80 cohort was compared with patients aged 50 to 79. Patients aged 50 to 79 were grouped because of similar characteristics (length of stay, hospital death). There were no significant differences in comorbidities, types of resections, or postoperative complication type or severity between the two groups. Postoperative death, length of stay, and survival, however, were significantly worse in patients older than 80. In a logistic regression model controlling for comorbidity, age older than 80 was significantly associated with increased perioperative mortality (hazard-ratio, 3.9; p < 0.01). CONCLUSIONS: Patients older than 80 years have increased mortality risk after esophagectomy, independent of comorbidity. Octogenarian status should be a consideration in the management of these patients.

Telomere length assessment in tissue sections by quantitative FISH: image analysis algorithms.

BACKGROUND: Telomeres are tandem repeated DNA sequences at the ends of every chromosome, which cap, stabilize, and prevent chromosome fusions and instability. Telomere regulation is an important mechanism in cellular proliferation and senescence in normal diploid and neoplastic cells. Quantitative methods to assess telomere lengths are essential to understanding how telomere dynamics play a role in these processes. METHODS: Telomere lengths have been conventionally measured using terminal restriction fragment (TRF), quantitative fluorescence in situ hybridization (QFISH), and flow FISH. In this study, we have applied QFISH to measure average telomere lengths in cultured cells and human tissues of the GI tract. Importantly, this method can be used to analyze telomere lengths in sections using confocal microscopy. We describe and compare three image analysis algorithms: a simple pixel histogram calculation of background corrected fluorescence, a telomere spot-finding method, and a background curve subtraction algorithm. RESULTS: Using normal human diploid fibroblasts (NHDF) either dropped on slides or sectioned after agar embedding, similar telomere length shortening is evident with increasing population doubling levels (PDLs), using peptide nucleic acid (PNA) and an N3'-P5'-phosphoamidate (PA) oligonucleotide probe for all three methods. Validation of these in situ telomere quantification methods showed excellent agreement with the commonly used telomere repeat fragment-Southern blot method. Telomere length reductions can also be demonstrated in tissue sections from histologically normal mucosa from patients with chronic ulcerative colitis (with dysplasia or cancer elsewhere in the colon), in colon adenomas, and in mucosal biopsies from patients with Barrett's esophagus. Both on slides and in tissue sections, the telomere spot-finding method has the greatest variability, while intra- and inter-biopsy variability in telomere length assessment using the other methods is relatively low. CONCLUSIONS: Accurate and reproducible telomere length measurements can be made in tissue sections using QFISH and confocal microscopy. The simplest methods proved the most reliable and make these methods readily accessible to many laboratories. The use of these methods will enhance the ability to measure telomere lengths in tissue samples and aid in the understanding of the role of telomere length in aging and disease.

Chromosomal instability in pancreatic ductal cells from patients with chronic pancreatitis and pancreatic adenocarcinoma.

Pancreatic adenocarcinoma is a disease with high mortality for which chronic pancreatitis confers a markedly increased risk. We hypothesize that chromosome instability and genomic damage occur in pre-neoplastic pancreatic ductal epithelium, and that this damage may be related to oxidative stress. We used dual-color fluorescence in situ hybridization with centromere probes and locus-specific arm probes for chromosome arms 11q, 17p, and 18q to identify genomic instability in cultures of normal-appearing human pancreatic ductal epithelium from normal organ donor controls compared to patients with chronic pancreatitis or pancreatic adenocarcinoma. To examine early pancreatic tumorigenesis, we studied only normal-appearing pancreatic ductal cells adjacent to pancreatitis or carcinoma. We found that, compared to the finding in normal controls, chromosomal abnormalities are present in normal-appearing human pancreatic ductal epithelia obtained from patients with chronic pancreatitis or pancreatic adenocarcinoma. Furthermore, these chromosomal abnormalities could be induced in cultured pancreatic ductal epithelium from normal organ donors by chronic exposure to dilute hydrogen peroxide, suggesting that oxidative stress may contribute to the development of chromosomal instability in the pancreas. These results elucidate a potential mechanism linking chronic pancreatitis to pancreatic cancer and suggest that chromosomal instability may be an early event in the pathogenesis of pancreatic cancer.

Chromosomal instability in ulcerative colitis is related to telomere shortening.

Ulcerative colitis, a chronic inflammatory disease of the colon, is associated with a high risk of colorectal carcinoma that is thought to develop through genomic instability. We considered that the rapid cell turnover and oxidative injury observed in ulcerative colitis might accelerate telomere shortening, thereby increasing the potential of chromosomal ends to fuse, resulting in cycles of chromatin bridge breakage and fusion and chromosomal instability associated with tumor cell progression. Here we have used quantitative fluorescence in situ hybridization to compare chromosomal aberrations and telomere shortening in non-dysplastic mucosa taken from individuals affected by ulcerative colitis, either with (UC progressors) or without (UC non-progressors) dysplasia or cancer. Losses, but not gains, of chromosomal arms and centromeres are highly correlated with telomere shortening. Chromosomal losses are greater and telomeres are shorter in biopsy samples from UC progressors than in those from UC non-progressors or control individuals without ulcerative colitis. A mechanistic link between telomere shortening and chromosomal instability is supported by a higher frequency of anaphase bridges--an intermediate in the breakage and fusion of chromatin bridges--in UC progressors than in UC non-progressors or control individuals. Our study shows that telomere length is correlated with chromosomal instability in a precursor of human cancer.

Flow cytometric analysis of the cell cycle phase specificity of DNA damage induced by radiation, hydrogen peroxide and doxorubicin.

We have optimized a flow cytometric DNA alkaline unwinding assay to increase the sensitivity in detecting low levels of DNA damage (strand breaks and alkali-labile sites) and to permit the measurement of the extent of DNA damage within each cell cycle compartment. The lowest gamma radiation dose that induced detectable DNA damage in each cell cycle phase of HeLa and CEM cells was 10 cGy. The lowest H(2)O(2) concentration that induced detectable DNA damage in each cell cycle phase was 0.5 microM in HeLa cells, and 1-2.5 TmicroM in CEM cells. For both HeLa cells and CEM cells, DNA damage in each cell cycle compartment increased approximately linearly with increasing doses of gamma radiation and H(2)O(2). Although untreated HeLa and CEM cells in S phase consistently exhibited greater DNA unwinding than did G(1) or G(2) cells (presumably due to DNA strand breaks associated with replication forks), there was no difference between the susceptibility of G(0)/G(1), S and G(2)/M phase cells to DNA damage induced by gamma radiation or H(2)O(2), or in the rate of repair of this damage. In each cell cycle phase, the susceptibility to gamma radiation-induced DNA damage was greater in CEM cells than in HeLa cells. In contrast to the lack of cell cycle phase-specific DNA damage induced by exposure to gamma radiation or H(2)O(2), the cancer chemotherapeutic drug doxorubicin (adriamycin) predominantly induced DNA damage in G(2) phase cells.