Manfred Gross

Association of Laryngopharyngeal Symptoms With Gastroesophageal Reflux Disease

Objectives The prevalence of gastroesophageal reflux disease (GERD) in patients with laryngopharyngeal disorders is probably greater than realized.

DHPLC mutation analysis of the hereditary nonpolyposis colon cancer (HNPCC) genes hMLH1 and hMSH2.

Denaturing high-performance liquid chromatography (DHPLC) is an efficient method for detection of mutations involving a single or few numbers of nucleotides, and it has been successfully used for mutation detection in disease-related genes. Colorectal cancer is one of the most common cancers, and mutations in the genes for hereditary nonpolyposis colon cancer (HNPCC), hMLH1 and hMSH2, also involve mainly point mutations. Sequence analysis is supposed to be a screening method with high sensitivity; however, it is time-consuming and expensive. We therefore decided to test sensitivity and reproducibility of DHPLC for 71 sequence variants in hMLH1 and hMSH2 initially found by sequence analysis in DNA samples of German HNPCC patients. DHPLC conditions of the PCR products were based on the melting pattern of the wild-type sequence of the corresponding PCR fragments. All but one of the 71 mutations was detected using DHPLC (sensitivity of 97%). Running time per sample averaged only 7 min, and the system is highly automated. Thus DHPLC is a rapid and sensitive method for the detection of hMLH1 and hMSH2 sequence variants.

Hereditary non-polyposis colorectal cancer: clinical and molecular evidence for a new entity of hereditary colorectal cancer

Background: Hereditary non-polyposis colorectal cancer (HNPCC) is clinically defined by familial clustering of colorectal cancer and other associated tumours. Methods: By thorough molecular and clinical evaluation of 41 families, two different groups were characterised: group 1, 25 families with truncating mutations in MLH1 or MSH2 (12 novel mutations); and group 2, 16 Amsterdam positive families without mutations in these genes and without microsatellite instability in their corresponding tumours. Results: Significant clinical differences between these two groups were found. Firstly, earlier age of onset for all colorectal cancers (median 41 v 55 years; p<0.001) and all tumours (median 43 v 56 years; pu200a=u200a0.022) was observed, comparing groups 1 and 2. Secondly, 68% of the index colorectal cancers were localised proximally of the splenic flexure in group 1 compared with 14% in group 2 (p<0.010). Thirdly, more synchronous and metachronous colorectal (pu200a=u200a0.017) and extracolorectal tumours (p<0.001) were found in group 1. Fourthly, a higher colorectal adenoma/carcinoma ratio (pu200a=u200a0.030) and a tendency towards more synchronous or metachronous adenomas in group 2 (pu200a=u200a0.084) was observed, indicating a slower progression of adenomas to carcinomas. As three mutation negative tumours revealed chromosomal instability after comparative genomic hybridisation, these tumours may be caused by one or more highly penetrant disease alleles from the chromosomal instability pathway. Conclusion: These data show that HNPCC includes at least two entities with clinical and molecular differences. This will have implications for surveillance programmes and for cancer research.

Hyponatraemia as a complication of colonoscopy

A case of colonoscopy-induced hyponatraemic encephalopathy led us to study the risk of hyponatraemia after gastrointestinal endoscopy. We assessed 40 patients before and after colonoscopy. 20 gastroscopy patients served as controls. Our findings show a high incidence (7.5%) of hyponatraemia after colonoscopy, in association with raised serum concentrations of arginine vasopressin. Physicians should be aware of this complication, since it may contribute to psychological and neurological symptoms after colonoscopy.

Nutritional status and quality of life in patients with percutaneous endoscopic gastrostomy (PEG) in practice: prospective one-year follow-up.

Sixty patients (age 73 ± 14 years; 22 women, 38 men) with dysphagia (67% neurological diseases, 33% tumors) were followed up for 1 year after placement of a percutaneous endoscopic gastrostomy (PEG). Before PEG placement and at six appointments thereafter, the patients nutritional status was measured using bioelectric impedance analysis (BIA) and hematological nutritional parameters. A validated questionnaire was used to assess quality of life (the Gastrointestinal Quality of Life Index, GIQLI). The overall mortality rate was 65%, and mortality during the hospitalization period was 22%. Depending on the duration of the dysphagia, marked nutritional deficits were observed at the start of the study (deficiencies in albumin in 49% of the patients, calcium in 15%, magnesium in 18%, retinol in 78%, α-tocopherol in 16%, folic acid in 16%, vitamin B12 in 8%, vitamin D in 40%, and zinc in 46%). With the exception of vitamin E, all parameters returned to normal during the follow-up period. At the start of the study, BIA indicated nutritional deficiency in 90% of the patients, with no overall improvement being observed during the follow-up period. The GIQLI scores, on average, reached a figure of 61% of an unrestricted quality of life. In conclusion, long-term nutrition via the PEG tube maintained the patients quality of life. For BIA most patients were malnourished during the follow-up period, but nevertheless PEG feeding was enough to compensate for gross nutritional deficiencies. Not infrequently, the indication for PEG placement is established too late.

Extended microsatellite analysis in microsatellite stable, MSH2 and MLH1 mutation-negative HNPCC patients: genetic reclassification and correlation with clinical features.

Background: Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominant disorder predisposing to predominantly colorectal cancer (CRC) and endometrial cancer frequently due to germline mutations in DNA mismatch repair (MMR) genes, mainly MLH1, MSH2 and also MSH6 in families seen to demonstrate an excess of endometrial cancer. As a consequence, tumors in HNPCC reveal alterations in the length of simple repetitive genomic sequences like poly-A, poly-T, CA or GT repeats (microsatellites) in at least 90% of the cases. Aim of the Study: The study cohort consisted of 25 HNPCC index patients (19 Amsterdam positive, 6 Bethesda positive) who revealed a microsatellite stable (MSS) – or low instable (MSI-L) – tumor phenotype with negative mutation analysis for the MMR genes MLH1 and MSH2. An extended marker panel (BAT40, D10S197, D13S153, D18S58, MYCL1) was analyzed for the tumors of these patients with regard to three aspects. First, to reconfirm the MSI-L phenotype found by the standard panel; second, to find minor MSIs which might point towards an MSH6 mutation, and third, to reconfirm the MSS status of hereditary tumors. The reconfirmation of the MSS status of tumors not caused by mutations in the MMR genes should allow one to define another entity of hereditary CRC. Their clinical features were compared with those of 150 patients with sporadic CRCs. Results: In this way, 17 MSS and 8 MSI-L tumors were reclassified as 5 MSS, 18 MSI-L and even 2 MSI-H (high instability) tumors, the last being seen to demonstrate at least 4 instable markers out of 10. Among all family members, 87 malignancies were documented. The mean age of onset for CRCs was the lowest in the MSI-H-phenotyped patients with 40.5 ± 4.9 years (vs. 47.0 ± 14.6 and 49.8 ± 11.9 years in MSI-L- and MSS-phenotyped patients, respectively). The percentage of CRC was the highest in families with MSS-phenotyped tumors (88%), followed by MSI-L-phenotyped (78%) and then by MSI-H-phenotyped (67%) tumors. MSS tumors were preferentially localized in the distal colon supposing a similar biologic behavior like sporadic CRC. MSH6 mutation analysis for the MSI-L and MSI-H patients revealed one truncating mutation for a patient initially with an MSS tumor, which was reclassified as MSI-L by analyzing the extended marker panel. Conclusion: Extended microsatellite analysis serves to evaluate the sensitivity of the reference panel for HNPCC detection and permits phenotype confirmation or upgrading. Additionally, it confirms the MSS status of hereditary CRCs not caused by the common mutations in the MMR genes and provides hints to another entity of hereditary CRC.

Molecular biology of AMP deaminase deficiency

In man, there are at least four isoforms of adenosine monophosphate deaminase (AMPD): myoadenylate deaminase in skeletal muscle, the L isoform in liver, and the E1 and E2 isoforms in erythrocytes. Myoadenylafe deaminase is encoded by the AMPD1 gene located on chromosome 1 p13-p21, the L isoform by the AMPD2 gene, and both isoforms in erythrocytes by the AMPD3 gene. Myoadenylate deaminase deficiency is found in 2–3% of all muscle biopsies. The inborn type of myoadenylate deaminase deficiency is caused by a single mutant allele harbouring two mutations: C34→T (Gin→Stop) and C143→T (Pro-48→Leu). Population studies revealed a frequency of the mutant allele of 0.12 in Caucasian Americans and Germans. The C34→T mutation is located in exon 2, which is alternatively spliced in part of the AMPD1 transcript in human muscle. Since the second mutation does not affect enzyme function, alternatively spliced mRNA encodes a catalytically active enzyme. Only one patient with a disorder linked to liver AMPD has been described so far. In this patient the decreased inhibition of this enzyme by GTP resulted in uric acid overproduction and gout. A complete lack of erythrocyte AMPD activity is found in asymptomatic subjects. The molecular basis of both disorders is not yet known.

Clopidogrel and proton pump inhibitor (PPI) interaction: separate intake and a non-omeprazole PPI the solution?

BackgroundDual therapy with aspirin and clopidogrel increases the risk of gastrointestinal bleeding. Therefore, co-therapy with a proton pump inhibitor (PPI) is recommended by most guidelines. However, there are warnings against combining PPIs with clopidogrel because of their interactions with cytochrome P450 isoenzyme 2C19 (CYP2C19).MethodsThe effects of the combined or separate intake of 20 mg of omeprazole and 75 mg of clopidogrel on the clopidogrel-induced inhibition of platelet aggregation were measured in four healthy subjects whose CYP2C19 exon sequences were determined. The effects of co-therapy with 10 mg of rabeprazole were also examined.ResultsTwo subjects showed the wild-type CYP2C19 sequence. The concurrent intake of omeprazole had no effect on clopidogrel-induced platelet inhibition in these subjects. Two subjects were heterozygous for the *2 allele, with predicted reduced CYP2C19 activity. One of them was a clopidogrel non-responder. In the second heterozygous subject, omeprazole co-therapy reduced the clopidogrel anti-platelet effect when taken simultaneously or separately. However, the simultaneous intake of rabeprazole did not reduce the clopidogrel effect.ConclusionThe clopidogrel-PPI interaction does not seem to be a PPI class effect. Rabeprazole did not affect the clopidogrel effect in a subject with a clear omeprazole-clopidogrel interaction. The separate intake of PPI and clopidogrel may not be sufficient to prevent their interaction.

Benzbromarone and Fenofibrate are Lipid Lowering and Uricosuric: A Possible Key to Metabolic Syndrome?

Patients with hyperlipidemia often suffer from hyperuricemia and conversely. This is proven in many studies, e. g. our laboratory studied the levels of uric acid, cholesterol and triglycerides in German blood donors (Gresser et al., 1990; Gathof et al., 1991). 68 % of the men and 57 % of the women showed cholesterol levels of 200 mg/dl and more. Levels above 250 mg/dl were found in 25 % of the men and 15 % of the women. Hyperuricemia occured in 28.6 % of men and 2.6 % of women. There was a statistically significant correlation (p<0.001) between the level of uric acid and cholesterol respectively triglycerides. After elimination of the factor age the correlation coefficients dropped, especially in women, but still remained significant.

Myoadenylate deaminase deficiency, hypertrophic cardiomyopathy and gigantism syndrome

We report a 20-year-old man with gigantism syndrome, hypertrophic cardiomyopathy, muscle weakness, exercise intolerance, and severe psychomotor retardation since childhood. Histochemical and biochemical analysis of skeletal muscle biopsy revealed myoadenylate deaminase deficiency; molecular genetic analysis confirmed the diagnosis of primary (inherited) myoadenylate deaminase deficiency. Plasma, urine, and muscle carnitine concentrations were reduced. L-Carnitine treatment led to gradual improvement in exercise tolerance and cognitive performance; plasma and tissue carnitine levels returned to normal, and echocardiographic evidence of left ventricular hypertrophy disappeared. The combination of inherited myoadenylate deaminase deficiency, gigantism syndrome and carnitine deficiency has not previously been described.