Emergency Department Visits Due to Dyspnea: Association with Inhalation Therapy in COPD and Cases with Adverse Drug Reactions.

Purpose: Dyspnea is a leading symptom of COPD that causes presentations in emergency departments or negatively impacts on them. Guideline-based inhalation therapies are intended to reduce dyspnea in COPD patients. This study analyzed how common guideline recommended inhalation therapy regimens are occurring in clinical practice among COPD patients presenting to emergency departments due to adverse drug reactions in polytherapy using data of the German ADRED database. Patients and Methods: In total, 269 COPD cases were identified. In a further analysis, all cases were analyzed for documented GOLD stage and guideline-recommended inhalation therapy for COPD. Dyspnea and other symptoms identified during ED presentation were analyzed and compared between patients who did and did not receive the guideline's recommended inhalation therapy. Results: In this observation, 41% (n = 46) of all 112 cases with a documented COPD and GOLD stage received an underdosed therapy according to current guidelines. Dyspnea was the most common identified symptom (32%, n = 36) in this cohort and occurred more often in patients who received an underdosage of inhalation therapy (p < 0.01). Conclusion: Patients with COPD presenting to ED with ADRs show a high rate of non-guideline-recommended inhalation therapy and present more often with dyspnea compared to those COPD patients who received an adequate dosing of inhalation therapy.

In Vitro Effects of Paralytic Shellfish Toxins and Lytic Extracellular Compounds Produced by Alexandrium Strains on Hemocyte Integrity and Function in Mytilus edulis.

Harmful effects caused by the exposure to paralytic shellfish toxins (PSTs) and bioactive extracellular compounds (BECs) on bivalves are frequently difficult to attribute to one or the other compound group. We evaluate and compare the distinct effects of PSTs extracted from Alexandrium catenella (Alex5) cells and extracellular lytic compounds (LCs) produced by A. tamarense (NX-57-08) on Mytilus edulis hemocytes. We used a 4 h dose-response in vitro approach and analyzed how these effects correlate with those observed in a previous in vivo feeding assay. Both bioactive compounds caused moderated cell death (10-15%), being dose-dependent for PST-exposed hemocytes. PSTs stimulated phagocytic activity at low doses, with a moderate incidence in lysosomal damage (30-50%) at all tested doses. LCs caused a dose-dependent impairment of phagocytic activity (up to 80%) and damage to lysosomal membranes (up to 90%). PSTs and LCs suppressed cellular ROS production and scavenged H2O2 in in vitro assays. Neither PSTs nor LCs affected the mitochondrial membrane potential in hemocytes. In vitro effects of PST extracts on M. edulis hemocytes were consistent with our previous study on in vivo exposure to PST-producing algae, while for LCs, in vivo and in vitro results were not as consistent.

Broncho-alveolar lavage in patients with acute respiratory distress syndrome due to COVID-19.

As data about microbiological testing and the cellular composition of the broncho-alveolar lavage (BAL) fluid in patients ventilated due to coronavirus disease 2019 (COVID-19) are lacking, this was investigated in a retrospective analysis (n = 58). Co-infection with pathogens was detected in 31 patients, whereas the analysis of BAL cellularity showed an increased total cell count and an alveolitis dominated by neutrophils. None of the physicians performing bronchoscopies in COVID-19 patients had serological evidence of severe acute respiratory syndrome coronavirus 2 infection.

Six Months Follow-Up of Patients with Invasive Mechanical Ventilation due to COVID-19 Related ARDS.

Although patients who recovered from acute coronavirus disease 2019 (COVID-19) may have prolonged disabilities, follow-up data of those who have survived COVID-19 related acute respiratory distress syndrome (ARDS) is still very scarce. Therefore, COVID-19-ARDS survivors requiring invasive mechanical ventilation (IMV) were followed six months after discharge. Pulmonary function tests (PFTs), 6-min walk test (6MWT) and echocardiography were performed. Quality of life (QoL), depression and anxiety were assessed using validated questionnaires. Patients were compared based on respiratory mechanics and CT-phenotype during intensive care unit (ICU) stay. Eighteen patients were included (61 ± 7 years; ICU-stay: 34 ± 16 days; IMV: 30 ± 15 days). At follow-up (197 ± 15 days after discharge), PFTs did not reveal significant limitations (VC: 92 ± 16%; FEV1: 92 ± 20%; DLco/VA: 81 ± 16%). Cardiac systolic function was normal in all patients, but 50% of them had diastolic dysfunction. 6MWT was under the lower limit of normal in only two patients. Eight patients (44%) reported tiredness, six (33%) suffered from fatigue and one patient (6%) had depression and anxiety. Surprisingly, patients with worse respiratory mechanics during IMV reported fewer symptoms and less exertional dyspnea at follow-up. In conclusion, patients with COVID-19-ARDS have the possibility to fully recover regarding pulmonary function and exercise capacity, which seems to be independent of disease severity during ICU stay.

Follow up of patients with severe coronavirus disease 2019 (COVID-19): Pulmonary and extrapulmonary disease sequelae.

BACKGROUND: Since December 2019 the novel coronavirus disease 2019 (COVID-19) has been burdening all health systems worldwide. However, pulmonary and extrapulmonary sequelae of COVID-19 after recovery from the acute disease are unknown. MATERIAL AND METHODS: Hospitalized COVID-19 patients not requiring mechanical ventilation were included and followed 6 weeks after discharge. Body plethysmography, lung diffusion capacity (DLco), blood gas analysis (ABG), 6-min walk test (6MWT), echocardiography, and laboratory tests were performed. Quality of life (QoL), depression, and anxiety were assessed using validated questionnaires. RESULTS: 33 patients with severe disease were included. Patients were discharged without prophylactic anticoagulation. At follow-up there were no thromboembolic complications in any patient. 11 patients (33%) had dyspnea, 11 (33%) had cough, and 15 (45%) suffered from symptoms of fatigue. Pulmonary function tests including ABG did not reveal any limitations (TLC: median=94% of predicted {IQR:85-105}; VC: 93% {78-101}; FEV1: 95% {72-103}; FEV1/FVC 79% {76-85}; PaO2: 72 mmHg {67-79}; PaCO2: 38 mmHg {35-38}), except for slightly reduced DLco (77% {69-95}). There were no echocardiographic impairments. 6MWT distance was reduced in most patients without oxygen desaturation. According to standardized questionnaires, patients suffered from reduced QoL, mainly due to decreased mobility (SGRQ activity score: 54 {19-78}). There were no indicators for depression or anxiety (PHQ-9: 7 {4-11}, GAD-7: 4 {1-9}, respectively). CONCLUSIONS: Hospitalized patients with severe COVID-19, who did not require mechanical ventilation, are unlikely to develop pulmonary long-term impairments, thromboembolic complications or cardiac impairments after discharge but frequently suffer from symptoms of fatigue.

Variability of dinoflagellates and their associated toxins in relation with environmental drivers in Ambon Bay, eastern Indonesia.

The aim of the present work was to unravel which environmental drivers govern the dynamics of toxic dinoflagellate abundance as well as their associated paralytic shellfish toxins (PSTs), diarrhetic shellfish toxins (DSTs) and pectenotoxin-2 (PTX2) in Ambon Bay, Eastern Indonesia. Weather, biological and physicochemical parameters were investigated weekly over a 7-month period. Both PSTs and PTX2 were detected at low levels, yet they persisted throughout the research. Meanwhile, DSTs were absent. A strong correlation was found between total particulate PST and Gymnodinium catenatum cell abundance, implying that this species was the main producer of this toxin. PTX2 was positively correlated with Dinophysis miles cell abundance. Vertical mixing, tidal elevation and irradiance attenuation were the main environmental factors that regulated both toxins and cell abundances, while nutrients showed only weak correlations. The present study indicates that dinoflagellate toxins form a potential environmental, economic and health risk in this Eastern Indonesian bay.

Separate and combined effects of neurotoxic and lytic compounds of Alexandrium strains on Mytilus edulis feeding activity and hemocyte function.

Multiple toxic and bioactive compounds produced by Alexandrium spp. cause adverse effects on bivalves, but these effects are frequently difficult to attribute to a single compound class. To disentangle the effect of neurotoxic vs lytic secondary metabolites, we exposed blue mussels to either a paralytic shellfish toxin (PST) producing Alexandrium spp. strain, or to an exclusively lytic compound (LC) producing strain, or a strain containing both compound classes, to evaluate the time dependent effects after 3 and 7 days of feeding. Tested parameters comprised signs of paralysis, feeding activity, and immune cell integrity (hemocyte numbers and viability; lysosomal membrane destabilization) and function (ROS production). Both compound classes caused paralysis and immune impairment. The only effect attributable exclusively to PST was increased phagocytic activity after 3 days and impaired feeding activity after 7 days, which curtailed toxin accumulation in digestive glands. Lysosomal membrane destabilization were more closely, but not exclusively, matched with LC exposure. Effects on circulating hemocyte integrity and immune related functions were mostly transient or remained stable within 7 days; except for increased lysosomal labialization and decreased extracellular ROS production when mussels were exposed to the toxin combination. M. edulis displays adaptive fitness traits to survive and maintain immune capacity upon prolonged exposure to environmentally relevant concentrations of PST and/or LC producing Alexandrium strains.

Phenotypes of organ involvement in sarcoidosis.

Sarcoidosis is a highly variable, systemic granulomatous disease of hitherto unknown aetiology. The GenPhenReSa (Genotype-Phenotype Relationship in Sarcoidosis) project represents a European multicentre study to investigate the influence of genotype on disease phenotypes in sarcoidosis.The baseline phenotype module of GenPhenReSa comprised 2163 Caucasian patients with sarcoidosis who were phenotyped at 31 study centres according to a standardised protocol.From this module, we found that patients with acute onset were mainly female, young and of Scadding type I or II. Female patients showed a significantly higher frequency of eye and skin involvement, and complained more of fatigue. Based on multidimensional correspondence analysis and subsequent cluster analysis, patients could be clearly stratified into five distinct, yet undescribed, subgroups according to predominant organ involvement: 1) abdominal organ involvement, 2) ocular-cardiac-cutaneous-central nervous system disease involvement, 3) musculoskeletal-cutaneous involvement, 4) pulmonary and intrathoracic lymph node involvement, and 5) extrapulmonary involvement.These five new clinical phenotypes will be useful to recruit homogenous cohorts in future biomedical studies.

Optimizing inhalation technique using web-based videos in obstructive lung diseases.

BACKGROUND: Inhaled agents are widely used in the treatment of chronic airway diseases. Correct technique is required to ensure appropriate drug deposition, but poor technique is common. This study investigated whether inhalation technique could be improved by patient training using short videos from the German Airway League. METHODS: Outpatients from a university hospital respiratory clinic who had incorrect inhalation technique were asked to demonstrate this again immediately after viewing the training videos, and after 4-8 weeks' follow-up. Inhalation technique was rated by a study nurse using specific checklists. RESULTS: One hundred and twelve patients with obstructive lung disease treated with inhaled bronchodilators or corticosteroids were included. More than half (51.8%) had at least one mistake in inhalation technique at baseline. Of these, most (88%) understood the training videos, 76% demonstrated correct device use immediately after training, and 72% were still able to demonstrate correct inhalation technique at follow-up (p = 0.0008 for trend). In addition, the number of mistakes decreased significantly after video training (by 1.82 [95% confidence interval 1.39-2.25]; p < 0.0001 vs. baseline). CONCLUSIONS: German Airway League inhalation technique training videos were easy to understand and effectively improved inhalation technique in patients with airway diseases.

Nebulized versus Standard Local Application of Lidocaine during Flexible Bronchoscopy: A Randomized Controlled Trial.

BACKGROUND: Endobronchial administration of local anesthetics such as lidocaine is often used for cough suppression during bronchoscopy. To achieve a better distribution of lidocaine in the tracheobronchial tree, spray catheters have been developed, allowing nebulization of the local anesthetic solution. However, there are little data on the efficacy and safety of this approach, or on the consumption of sedative drugs and lidocaine during nebulized administration. OBJECTIVES: To investigate the tolerability of nebulized lidocaine compared to conventional lidocaine administration via syringe through the working channel of the bronchoscope in patients undergoing bronchoscopy. Consumption of sedative drugs and lidocaine was also compared between the two lidocaine administration approaches. METHODS: Patients requiring bronchoscopy with endobronchial or transbronchial biopsy were randomly assigned to receive topical lidocaine either via syringe or via nebulizer. Endpoints were consumption of lidocaine and sedative drugs, as well as patient tolerance and safety. RESULTS: Thirty patients were included, 15 in each group. Patients in the nebulizer group required lower doses of endobronchial lidocaine (184.7 ± 67.98 vs. 250.7 ± 21.65 mg, p = 0.0045) and intravenous fentanyl (0.033 ± 0.041 vs. 0.067 ± 0.045 mg, p = 0.0236) than those in the syringe group; midazolam or propofol dosages did not differ between the two groups. In addition, there were no between-group differences in patient tolerance or safety (all p > 0.05). CONCLUSION: Endobronchial administration of lidocaine during bronchoscopy via nebulizer was found to be well tolerated and safe and was associated with reduced lidocaine and fentanyl dosages compared to administration via syringe.

Optimal lymph node harvest in rectal cancer (UICC stages II and III) after preoperative 5-FU-based radiochemotherapy. Acetone compression is a new and highly efficient method.

INTRODUCTION: Preoperative 5-fluorouracil-based radiochemotherapy (RCT), followed by total mesorectal excision, is accepted as standard therapy in rectal cancers (UICC stages II and III). The accurate evaluation of ypN status after RCT with valuable lymph node (LN) harvest is essential for postoperative risk-adapted treatment decisions. Actual numbers of assessed LNs and validity of ypN status vary extensively depending on the methods used. MATERIAL AND METHODS: This prospective study validates the acetone compression (AC), whole mesorectal compartment embedding (WME), and fat clearance (FC) methods for LN retrieval in n=257 rectal cancer specimens obtained from 2 high-volume surgical centers. For optimal LN retrieval, the AC method (n=161 specimens: 52 cases with RCT, 109 cases without RCT) was compared with the WME (n=64 cases, with RCT) and FC methods (n=32 cases: 17 cases with RCT, 15 cases without RCT). The efficacy of LN retrieval, costs involved, and molecular diagnostics were measured. RESULTS: Using the AC method, 41 LNs (mean; range 14 to 86 LNs) were detectable in total mesorectal excision specimens after RCT and 44 LNs (mean; range 9 to 78 LNs) in cases without RCT. The LN yield after RCT obtained by using the AC method was equivalent to that of the WME method (mean 32 LNs/specimen; range 12 to 81 LNs) but demonstrated a better time and cost-efficacy. In addition, the AC method facilitated assessment of any tumor deposits, including perineural invasion, and did not hamper molecular analyses. The AC method increased LN retrieval 4- to-6-fold as compared with the literature and 2-fold compared with manual dissection after the FC method. DISCUSSION: The AC method is the method of choice for accurate LN staging in locally advanced rectal cancer, especially after preoperative RCT, and is well suited for routine gastrointestinal pathology workup.

Reduced mRNA expression in paraffin-embedded tissue identifies MLH1- and MSH2-deficient colorectal tumours and potential mutation carriers.

Based on the principle of nonsense-mediated mRNA decay, we sought to identify MLH1 or MSH2-deficient colorectal tumours through relative quantification of mRNA expression with real-time PCR (RT-PCR) analysis. MLH1 and MSH2 mRNAs were almost equally expressed as defined by MLH1 to MSH2 transcript ratio (mean 1.41) in microsatellite stable, mismatch repair (MMR) proficient tumours (n = 16). A close correlation between loss of protein expression and MMR-mRNA levels was found in highly microsatellite instable (MSI-H) tumours deficient of MLH1 or MSH2. MLH1/MSH2 ratio was low in 11 sporadic and nine hereditary MLH1-deficient carcinomas (mean 0.51), whereas the ratio was high in 17 MSH2-deficient hereditary non-polyposis colorectal cancer (HNPCC) associated carcinomas (mean 6.8). Notably, in the normal tissues of HNPCC patients with MSH2 mutations, the MLH1/MSH2 transcript ratios were significantly elevated (ratio > 2.0) as compared to the ratios of normal mucosa in patients with MMR-proficient tumours (27 of 32 ratio < 2.0; p = 0.00113). Analysis of B-lymphocytes of HNPCC patients with proven MMR gene mutation confirmed these findings. In conclusion, RT-PCR allows relative quantification of MMR gene mRNA expression in formalin-fixed and paraffin-embedded tissue. Furthermore, this approach enables quantification of haploinsufficiency due to nonsense-mediated mRNA decay in normal tissue and B-lymphocytes from patients carrying MSH2 germline mutations and may be useful for identification of asymptomatic carriers of pathogenic germline mutations.

Implantation of a colorectal stent as a therapeutic approach in the treatment of esophageal leakage.

BACKGROUND: While the mortality of esophageal surgery has decreased due to technological advancements, there is still a complication rate of about 30%. One of the main complications is the anastomotic leakage associated with a significant rate of morbidity and mortality. To close the leakage the efficacy of self-expanding stents (SES) has been shown in different studies. However, the high rate of stent migration limits the use of commercial available stents. In our case we were faced with the problem that the diameter of all available stents was too small to attach tightly to the mucosal wall of the esophagogastric anastomosis. CASE PRESENTATION: We used, for the first time to our knowledge, a metal stent designed for colorectal application in an extensive anastomotic leak after esophageal resection in a patient with an esophageal cancer. After primary surgery with subtotal esohagectomy the anastomotic leak was stented endoscopically with a Polyflex self-expanding covered plastic stent after no response to intensive conventional management. Even though the stent was placed correctly, the diameter of the Polyflex stent was too small to attach onto the wall of the esophagogastric anastomosis. Again surgery was performed with a thoracal resection of the esophageal remnant and a hand made anastomosis. Unfortunately, again an anastomotic leak was detected soon after. To close the leak we decided to use a covered colorectal stent (Hanarostent) with an inner diameter of 30 mm. Sixteen weeks later the stent was extracted and complete mucosal healing of the esophageal leak was observed. CONCLUSION: The stent implantation with a large wide diameter offers a good chance to close more extensive leaks and prevent stent migration.

Analysis of the base excision repair genes MTH1, OGG1 and MUTYH in patients with squamous oral carcinomas.

A number of environmental factors, such as tobacco and alcohol, have been implicated, through oxidative DNA damage, in the development of squamous cell carcinomas of the head and neck (SCCHN). Several pathways are involved in the repair of DNA lesions caused by oxidative stress, such as the base excision repair system (BER), which repairs mutation involving 8-oxoguanine and comprises the MUTYH, OGG1 and MTH1 genes. We analysed 29 patients, assessing germline polymorphisms or mutations in these genes by complete genomic sequencing of exons and adjacent intronic regions. Thirty healthy blood donors served as controls. No pathogenic germline mutations were identified. We found common and rare new variants in the coding and adjacent intronic regions. In summary, our data do not support a major role for MUTYH, OGG1 and MTH1 variants in the etiology of sporadic squamous oral/oropharyngeal carcinomas. This does not exclude the involvement of the three BER genes in the tumorigenesis of SCCHN through other mechanisms such as promotor hypermethylation, genomic rearrangements or mutations involving regulatory sequences.

The additive effect of p53 Arg72Pro and RNASEL Arg462Gln genotypes on age of disease onset in Lynch syndrome patients with pathogenic germline mutations in MSH2 or MLH1.

p53 and the prostate-cancer-susceptibility gene RNASEL are tumour suppressor genes involved in apoptosis. We have previously reported that the common, functionally different variants Arg72Pro in p53 and Arg462Gln in RNASEL are associated with the age of disease onset of colorectal cancer in Lynch syndrome patients. To assess the combined effect of both variants, we screened 246 unrelated Lynch syndrome patients with a pathogenic germline mutation either in MSH2 (n=138) or in MLH1 (n=108) and colorectal cancer as first tumour, and 245 healthy controls. The global log rank test revealed significant differences in the age of disease onset for the genotypes of each variant (p=0.0176 for p53 and p=0.0358 for RNASEL) and for the combined genotypes of both variants (p=0.0174). The highest difference in median age of disease onset was seen between homozygotes for the wild-types in both genes (42years [range 22-75]) and homozygotes for the variant alleles in both genes (30years [range 26-47]). A multivariate Cox regression model indicated that only the p53 and RNASEL genotypes had a significant influence on age of disease onset (p=0.016 for p53 and p=0.014 for RNASEL) in an additive mode of inheritance, and that the effects of both variants are purely additive, which supports the notion that the p53 and RNaseL pathways do not interact. These findings may be relevant for preventive strategies in Lynch syndrome.

Microsatellite stable colorectal cancers in clinically suspected hereditary nonpolyposis colorectal cancer patients without vertical transmission of disease are unlikely to be caused by biallelic germline mutations in MYH.

Microsatellite analysis and immunohistochemistry are commonly used initial screening tests for hereditary nonpolyposis colorectal cancer. However, tumors in roughly one-half of the patients fulfilling the Bethesda guidelines are microsatellite stable. In addition, normal mismatch repair protein expression in these tumors suggests that a defect in the mismatch repair system is unlikely. Because biallelic MYH mutations occur in patients with both high and low numbers of adenomas, we hypothesized that MYH is involved in the tumorigenesis of microsatellite stable colorectal cancers in patients without vertical transmission of disease and who fulfill the Bethesda guidelines. MYH was analyzed in 50 cancer patients and 116 healthy controls by complete genomic DNA sequencing. No biallelic germline mutations were identified. One patient was a heterozygous carrier for the p.G382D missense mutation, and another patient was a heterozygous carrier for the novel missense mutation p.Q484H. We identified six common variants, three in the coding region (p.V22M, p.Q324H, and p.S501F) and three in adjacent intronic regions (c.157+30A>G, c.462+35G>A, and c.1435-40G>C). In summary, biallelic germline mutations of MYH are unlikely to cause colorectal cancer in patients sharing clinical features with hereditary nonpolyposis colorectal cancer families without mismatch repair defect and therefore cannot fill the molecular diagnostic gap in this subgroup of Bethesda-positive patients.

Prevalence of the mismatch-repair-deficient phenotype in colonic adenomas arising in HNPCC patients: results of a 5-year follow-up study.

In hereditary nonpolyposis colorectal cancer (HNPCC) syndrome, more than 90% of the carcinomas show microsatellite instability (MSI) due to a loss of mismatch repair (MMR) function. Although adenomas are very common in HNPCC and demonstrate an accelerated adenoma-carcinoma sequence, data about the prevalence and development of MSI in these early neoplastic lesions are lacking. To determine whether MSI and loss of MMR-protein expression are already present in early stages of tumorigenesis and could therefore be used as a screening tool to identify HNPCC patients before they develop an invasive carcinoma, we analyzed 71 adenomas of 36 HNPCC patients during a 5-year follow-up study. These 36 patients were part of a cohort of 122 HNPCC patients who were investigated at the Institute of Pathology, Klinikum Kassel, as part of the multicentric German HNPCC Consortium, which currently serves more than 2,880 registered families. The diagnosis of HNPCC was based either on the detection of a pathogenic germline mutation in the MSH2, MLH1, or MSH6 genes or in cases where a pathogenic mutation was not found; diagnosis of HNPCC was made, because all patients fulfilled the Amsterdam or Bethesda criteria and revealed a high degree of MSI (MSI-H) as well as loss of one of the MMR proteins by IHC in the cancer tissue. We found that most adenomas (58/71) were MSI-H and had loss of MMR-protein expression. Of the 71 adenomas, 3 were MSI-H with expression of all MMR proteins, and 3 out of 71 displayed loss of a MMR protein with the microsatellites being classified as microsatellite stable (MSS). However, 7 of the 31 adenomas that were located more than 5 cm away from the carcinoma revealed an MSS status (n=6) or low in MSI (n=1) and expressed all MMR proteins. In summary, a significant percentage of HNPCC-associated adenomas (7/31, 22.6%) developing at a distance of more than 5 cm from the corresponding carcinoma did not show the MSI-H MMR-deficient phenotype and expressed all MMR genes. To our knowledge, this is the first study that shows that in most HNPCC patients, the mutator pathway is already detectable in adenomas, but MMR-proficient adenomas can also be found. Therefore, screening for MMR deficiency should not be applied routinely in adenomas with the goal to identify HNPCC patients.

A novel MSH2 germline mutation in homozygous state in two brothers with colorectal cancers diagnosed at the age of 11 and 12 years.

Hereditary non-polyposis colorectal cancer (HNPCC) syndrome is caused by heterozygous germline mutations in DNA mismatch repair genes (MMR), (MSH2, MLH1, MSH6, and PMS2) and it is inherited in an autosomal dominant pattern with high penetrance. Several patients have been reported carrying bi-allelic MMR gene mutations and whose phenotype resembled a syndrome with childhood malignancies including hematological malignancies, brain, and colorectal tumors. This phenotype is similar to the tumor spectrum of MMR knockout mice. Herein we describe two brothers of healthy consanguineous parents from Pakistan, who had developed two and three colorectal cancers at the ages of 11 and 12 years, respectively, and less than 30 polyps. Tumor specimens were microsatellite instable (MSI-H), and expression of MSH2 and MSH6 was lost. Mutation analyses of DNA samples from both patients revealed a novel homozygous c.2006-5T > A mutation in intron 12 of the MSH2 gene. This phenotype of the brothers is unusual as they neither develop hematological malignancies nor brain tumors at an older age of presentation than other patients with homozygous MSH2 mutations. The milder phenotype may be due to the expression of low amounts of MSH2 protein with reduced activity.

Microsatellite analysis of hereditary nonpolyposis colorectal cancer-associated colorectal adenomas by laser-assisted microdissection: correlation with mismatch repair protein expression provides new insights in early steps of tumorigenesis.

Although microsatellite instability (MSI) testing is a useful tool for molecular screening of hereditary nonpolyposis colorectal cancer (HNPCC) carcinomas, conflicting results have been obtained in colorectal adenomas. This might result from different techniques of tissue sampling and MSI analysis. Alternatively, some HNPCC-associated adenomas may follow a molecular route that differs from the MSI pathway. In the present study we examined the MSI status of 18 adenomas from 17 HNPCC patients by comparing manual adenoma dissection under gross visual control with laser microdissection of single adenoma crypts. After manual gross dissection, 50% (9 of 18) and 11.1% (2 of 18) of the adenomas displayed high-level (MSI-H) and low-level (MSI-L) MSI, respectively. The same set of adenomas split into 83.3% (15 of 18) MSI-H and 5.6% (1 of 18) MSI-L after laser microdissection. The expression pattern of mismatch repair (MMR) proteins showed a higher concordance rate with the MSI status in laser-dissected (94%) than gross-dissected (47%) adenomas. Whereas two adenomas remained microsatellite stable (MSS) and MMR proficient even after laser-assisted dissection, two MSI-H cases showed either rare instabilities at coding microsatellites or intratumoral heterogeneity of MSI with and without MSH2 expression. This suggests that in some adenomas development of MMR dysfunction occurs stepwise with MSI, arising before complete loss of MMR gene expression, whereas other HNPCC-associated adenomas might develop independently of MMR deficiency.

MSI-testing in hereditary non-polyposis colorectal carcinoma (HNPCC).

Genomic instability at simple repeated sequences, termed microsatellite instability (MSI), plays an important role in the analysis of sporadic and hereditary colon cancers. In hereditary non-polyposis colorectal cancer syndrome (HNPCC) more than 90% of cases show MSI, whereas only 10-15% of sporadic colorectal cancers do so. Thus, microsatellite analysis is commonly used as the first diagnostic screening test for HNPCC. In 1997, an international collaborative workshop sponsored by the National Cancer Institute (NCI) proposed a set of guidelines for MSI-testing to improve reliability and reproducibility of the analysis as well to allow comparisons between different studies and different laboratories. In this review we assess the value of current protocols for MSI-testing and discuss some diagnostic pitfalls. Our findings support continued use of the MSI marker panel recommended in 1997. Additionally, MSI-testing should be improved by use of microdissection, which helps to identify additional patients with MSI due to enrichment of tumor cells and therefore increased sensitivity. In our view, immunohistochemical staining for mismatch repair protein expression is not a substitute for MSI-analysis but complements MSI screening and helps direct further testing. In summary, MSI-analysis is a highly sensitive and reliable screening method for HNPCC, that requires a well-equipped laboratory as well as an experienced pathologist. Integration of family history and histo-pathological features is also critical.