Biomedical subjects
Publications and source records attributed to K M Keller.
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Sitaxsentan (3, TBC11251) (Wu et al. J. Med. Chem. 1997, 40, 1690) is an orally active ET(A) selective endothelin antagonist that attenuates pulmonary vascular hypertension and cardiac hypertrophy in rats (Tilton et al. Pulm. Pharmacol. Ther. 2000, 13, 87). It has demonstrated efficacy in a phase II clinical trial for congestive heart failure (Givertz et al. Circulation 2000, 101, 2922). During the discovery of 3, we observed several structure-oral bioavailability relationships. To investigate whether there is any generality in these trends, we synthesized some similar pairs of compounds in the latest series (Wu et al. J. Med. Chem. 1999, 42, 4485) and evaluated their oral properties. In both series, an acyl group at the 2-position of the anilide of these thiophene sulfonamides improved oral bioavailability. As a result of this exercise, TBC3214 (17) was identified as a sitaxsentan follow-on candidate. It is very potent (IC(50) for ET(A) = 40 pM) and highly selective for ET(A) vs ET(B) receptors (400 000-fold), with a half-life of >4 h and oral bioavailability of 25% in rats, 42% in cats, and 70% in dogs.
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BACKGROUND: Hirschsprung disease (HSCR) is a frequent congenital disorder with an incidence of 1 in 5000 live births, characterised by the absence of parasympathetic intramural ganglion cells in the hindgut resulting in intestinal obstruction in neonates and severe constipation in infants and adults. Intestinal neuronal dysplasia (IND) shares clinical features with HSCR but the submucosal parasympathetic plexus is affected. IND has been proposed as one of the most frequent causes of chronic constipation and is often associated with HSCR. METHODS: We examined 29 patients diagnosed with sporadic HSCR, 20 patients with IND, and 12 patients with mixed HSCR/IND for mutations in the coding regions of the RET, GDNF, EDNRB, and EDN3 genes. The entire coding regions were analysed by single strand conformational polymorphism and DNA sequencing. RESULTS: Only three RET mutations were detected in patients with HSCR. In patients with IND or a mixed HSCR/IND phenotype, no mutations in these genes were observed. While HSCR and HSCR/IND showed over representation of a specific RET polymorphism in exon 2, IND exhibited a significantly lower frequency comparable with that of controls. CONCLUSIONS: The mutation frequency found in our sporadic HSCR patients (10%) and the allelic distribution of RET polymorphisms are comparable with earlier published data. A significantly different allelic distribution in an established HSCR associated polymorphism argues against common genetic pathways for HSCR and IND.
The diagnosis of Peutz-Jeghers syndrome is based on the occurrence of hamartomatous gastrointestinal polyps and perioral pigment spots. In view of the development of hamartomatous polyps in several syndromes and the variability of pigment spots in Peutz-Jeghers patients, identification of affected individuals is difficult. Recently, germline mutations in the STK11 gene have been reported as a molecular cause of Peutz-Jeghers syndrome. We present four novel inactivating mutations identified by direct sequencing of all 9 exons of the STK11 gene in 4 patients suggestive of Peutz-Jeghers syndrome: three frameshift mutations (125-137del; 474-480del; 516-517insT) and one nonsense mutation (Q220X). Our data obtained in these patients and in those reported previously emphasize the diagnostic value of histological discrimination between different types of hamartomatous polyps and of molecular analysis, particularly in cases with no family history of the disease.
BACKGROUND: Magnetic resonance cholangiography (MRC) is a relatively new, non-invasive imaging technique of the biliary tree that has shown good correlation with endoscopic retrograde cholangiopancreatography. The liver manifestation of autosomal recessive polycystic kidney disease (ARPKD) is congenital hepatic fibrosis (CHF). CHF may be accompanied by Caroli's disease, which is characterised by a non-obstructive dilation of the intrahepatic bile ducts. OBJECTIVE: A prospective study was conducted to determine the presence and extent of Caroli's disease in children with ARPKD. MATERIALS AND METHODS: Seven children with ARPKD aged from 3.0 to 10. 1 years were examined. CHF was confirmed in all biopsied cases (5 of 7). All children had been followed by repeated abdominal US examinations for many years. The MR examination included a morphological imaging study using a T2-weighted turbo spin-echo sequence and a heavily T2-weighted inversion-recovery turbo spin-echo sequence with three-dimensional maximum intensity projection (MIP) reconstructions for MRC. RESULTS: The diagnosis of Caroli's disease could be made in one case by US; in two other children Caroli's disease was suspected, but the differentiation from hepatic cysts was not possible. By MRC, Caroli's disease could be diagnosed in three of seven children. Furthermore, MRC with MIP reconstructions demonstrated the extent of the disease by showing the entire biliary tree from different angles. CONCLUSIONS: MRC is a valuable method to establish the diagnosis and demonstrate the extent of Caroli's disease.
PURPOSE: Evaluation of 3D-TSE MR-cholangiography with respiratory triggering in the work up of hepatopathies in infants and young children. PATIENTS AND METHOD: 16 infants (4-16 years) with increased transaminases, two with recurrent pancreatitis, were examined at 1.5 T (ACS-NT II, Philips Medical Systems) using a 3D-TSE MRCP with respiratory triggering in addition to a regular MRI of the liver. The MRCP was compared to ERCP. Two radiologists and one gastroenterologist evaluated the technical quality, visualization of the pancreaticobiliary system, and the diagnostic value of the examinations. RESULTS: Technically feasible were 14/16 MRCPs and 13/16 ERCPs. Two MRCP were not of diagnostic value due to motion artifacts and in three ERCP cannulation of the papilla was not possible. 14/16 ERCP required general anaesthesia, while MRCP needed i.v. sedation in two patients only. Extrahepatic ducts/cystic duct/pancreatic duct were visualized in 14/12/8 patients using MRCP, and in 13/10/3 patients using ERCP, both without adverse effects or complications. Intrahepatic ducts were better delineated with MRCP. In 10 patients with histologically proven periportal fibrosis (n = 7) and liver fibrosis (n = 1) or antineutrophil cytoplasmatic antibodies and associated inflammatory bowel disease, MRCP and ERCP revealed pathological results. CONCLUSION: MRCP using a 3D-TSE sequence with respiratory triggering is a good non-invasive technique for delineation of the biliary tract in infants and young children for the work up to hepatopathies.
AIM: To determine the frequency of GB virus C (GBV-C)/hepatitis G virus (HGV) infection before and after switch to the use of virus inactivated concentrates in haemophiliac patients infected with human immunodeficiency virus (HIV). PATIENTS AND METHODS: Initial and follow up sera from 49 children with haemophilia were analysed for the presence of GBV-C/HGV RNA and antibodies to HGV (anti-HGV). All patients had been infected with HIV while receiving concentrates without virus inactivation before 1984 and were subsequently treated with virus inactivated concentrates. RESULTS: In the first available serum sample (1987 or later), two of 49 patients were GBV-C/HGV RNA positive and two further patients were anti-HGV positive. During follow up (mean, 6 years), 14 patients developed markers of GBV-C/HGV infection. Eleven of these had received no blood products except clotting factor concentrates that had been prepared with virus inactivation. CONCLUSIONS: Despite being treated with virus inactivated clotting factor concentrates, HIV positive patients with haemophilia are at an increased risk of manifesting GBV-C/HGV infection. We hypothesise that GBV-C/HGV is transmitted by these clotting factor concentrates. However, we cannot rule out the emergence of markers of GBV-C/HGV infection as a result of the progression of immune impairment in the course of HIV infection.
OBJECTIVE: To compare dual therapy (omeprazole and amoxicillin) with triple therapy (omeprazole, amoxicillin, and clarithromycin) in the treatment of Helicobacter pylori infection. The efficacy of 1 mg/kg/day omeprazole was randomly compared with 2 mg/kg/day. STUDY DESIGN: 252 patients (median age, 11.0 years; range, 3-18) presenting with chronic abdominal pain underwent endoscopy and a 13C-urea breath test. Gastric biopsy specimens were taken for histological examination and for the rapid urease test. Patients were treated for two weeks: group A (n = 63) received amoxicillin (50 mg/kg; maximum, 2 g/day), group B (n = 73) received amoxicillin and clarithromycin (20 mg/kg; maximum, 1 g/day). Both groups were randomly treated with either 1 or 2 mg/kg omeprazole (maximum, 80 mg/day). Diagnostic procedures were repeated four weeks after the end of treatment. RESULTS: 11 patients were excluded; 136 patients were H pylori positive (56%), 105 of whom were re-examined after treatment. Helicobacter pylori was eradicated in 52% of group A and 83% of group B. The dose of omeprazole had no influence on the eradication rate. Specificity and sensitivity of the rapid urease test were 94% and 93%, respectively. Specificity and sensitivity of the 13C-urea breath test were 93% and 95%, respectively. CONCLUSIONS: Dual therapy can no longer be recommended. Triple therapy is more effective than dual therapy in the eradication of H pylori infection. The lower dose of 1 mg/kg omeprazole was as effective as 2 mg/kg.
BACKGROUND: Intestinal neuronal dysplasia (IND) of the colonic submucous plexus is considered to be a congenital malformation of the enteric nervous system causing symptoms resembling those of Hirschsprung's disease. In contrast with the established diagnosis of aganglionosis using enzyme histochemistry, controversy exists over the diagnostic criteria of IND on rectal biopsies previously defined by a consensus report and the causal relation between morphological findings and clinical symptoms. AIMS: The interobserver variability was prospectively investigated with respect to final diagnoses and several histological features in rectal biopsy specimens from children suspected of having colonic motility disturbances. METHODS: 377 biopsy specimens from 108 children aged 4 days to 15 years were independently coded without knowledge of clinical symptoms by three experienced pathologists for 20 histological features, and a final diagnosis was given for every case. Interobserver variation for the different items and the final diagnosis were analysed using Cohen's kappa statistic. Clinical data at biopsy and outcome after 12 months were related to morphological findings. RESULTS: The three pathologists agreed completely with respect to the diagnosis Hirschsprung's disease (kappa = 1), but in only 14% of the children without aganglionosis. In 15 (17%) of the 87 children without aganglionosis, at least one pathologist judged the case as normal, while another diagnosed IND. kappa values were close to the zero value expected by chance for the diagnoses normal and IND. Young age was related to the presence of several morphological features-for example, acetylcholine esterase staining and presence of giant ganglia. Children with chronic constipation diagnosed as having IND, given no other specific diagnosis by any of the pathologists, were significantly younger (median 8.8 months) and had a higher cure rate after one year (60%) than constipated patients considered by all observers to have no histological abnormalities (median 6.1 years, cure rate 23%). CONCLUSIONS: In contrast with Hirschsprung's disease, there is a high interobserver variation with regard to the different morphological features and final diagnosis of IND, based on the criteria and conditions of the previous consensus report. The high frequency of histological "abnormalities" in young infants suggests that some of the features may represent a normal variant of postnatal development rather than a pathological process. Investigations using more refined and morphometric methods in rectal specimens from infants and children without bowel disease are needed to define the normal range of morphological appearance at different ages. These preliminary data indicate that, with current knowledge, rectal biopsy for diagnostic purposes should only be performed in constipated children for diagnosis of Hirschsprung's disease.
Familial juvenile polyposis (FJP) is a hamartomatous polyposis syndrome characterized by the appearance of juvenile polyps in the gastrointestinal tract. Patients with this syndrome are at an increased risk for cancer of the colon, stomach, and pancreas. Recently, germline mutations in the SMAD4/DPC4 gene (official symbol MADH4) have been found in the majority of patients suffering from FJP. We have examined 11 unrelated patients with FJP for MADH4 germline mutations by direct sequencing of genomic DNA encompassing all 11 exons of the gene. Besides a novel mutation (959-960delAC at codon 277, exon 6) in one patient, we observed a 4-bp deletion (1372-1375delACAG) in exon 9 in two unrelated patients. Examination with microsatellite markers flanking MADH4 supports an independent origin of the mutation in these two families. The same 4-bp deletion in exon 9 has previously been described in three out of nine patients examined for MADH4 mutations. Our results combined with these previous data demonstrate that a unique 4-bp deletion in exon 9 of MADH4 accounts for about 25% of all FJP cases and that other MADH4 mutations occur in an additional 15% of patients. Genes Chromosomes Cancer 25:403-406, 1999.
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A 4-year-old German girl was diagnosed as having glycogen storage disease type la and showed no other marked symptoms except hepatomegaly. The glucose-6-phosphatase activity in the liver was approximately 1.5% to 5.0% of normal values, and molecular analysis revealed compound heterozygosity for R83C and the novel mutation N264K. This result indicates that there is a wide clinical variation of glucose-6-phosphatase deficiency. DNA analysis is helpful for confirmation of the diagnosis, as well as establishment of the genotype and phenotype correlation in glycogen storage disease type 1a.
Complete avulsion of the external ear, much less common than other minor ear trauma, presents a complex and difficult problem. The authors present a 35-year-old male cigarette smoker who suffered traumatic avulsion of the right ear, and describe the replantation procedure and the patient's postoperative course. Aesthetic positioning of the replanted ear, treating the external auditory meatus, protecting the ear against exposure to the sun, and counseling the patient about issues related to sensation are important factors in the care of patients who have undergone such a procedure.
BACKGROUND: Recently two Flaviviridae-like viruses have been discovered and named GB virus C and hepatitis G virus. Molecular characterization showed them to be different subtypes of the same virus. An association with posttransfusion hepatitis and with sporadic and fulminant hepatitis was reported, but most infected people remain asymptomatic. Data concerning hepatitis G virus infection in infants and children have not been reported to date. The prevalence of hepatitis G virus infection in children after transfusion of blood products in the neonatal period was studied. METHODS: Serum samples from 251 children, who had received blood products in the first 4 weeks of life and who had been reexamined as part of another study at a mean interval of 37 months (range, 10-70) after last transfusion, were analyzed for hepatitis G virus infection. Follow-up examinations were performed in 14 of 19 hepatitis G virus-positive children 12 to 17 years after the last transfusion. Presence of hepatitis G virus RNA in serum was determined by a reverse transcription polymerase chain reaction assay with nested primers from the helicase region of the hepatitis G virus. To prove specificity of the hepatitis G virus, reverse transcription polymerase chain reaction assay and compare follow-ups with initial sequences, direct sequencing of the NS3 and NS5 regions of the hepatitis G virus was performed. RESULTS: Hepatitis G virus RNA was detected in 19 of 251 patients (7.6%); sequence analysis showed the isolates to be of hepatitis G virus type. None of the patients with hepatitis G virus infection had evidence of liver disease, although 3 patients were coinfected with hepatitis C virus. Four of 14 patients who were reinvestigated after a mean of 15 years showed persistent hepatitis G virus infection. Each of the 4 children was healthy. In none were clinical signs of liver disease observed; liver function test results were within the normal range. CONCLUSIONS: Children receiving blood transfusions in the neonatal period are at increased risk of hepatitis G virus infection with a high rate of chronic infection. However, as in the findings in several studies of adult transfusion recipients, in the current results, no association between hepatitis G virus infection and clinical or biochemical signs of hepatitis or extrahepatic disease could be seen.
BACKGROUND: Cystic fibrosis is the most common inherited disease with a fatal outcome in industrialised nations. With the improvement in life expectancy, supporting patients and their families in adapting to life with this chronic progressive disease has become increasingly important. The aim of the present study was to investigate the relationship between health related quality of life (HRQOL) in this population, severity of disease, and cognitive/behavioural factors such as subjective health perception and ways of coping. METHODS: A sample of 89 adolescent and adult patients with cystic fibrosis and 125 parents of younger patients with cystic fibrosis completed questionnaires on health related quality of life and on ways of coping with the illness. Parents were asked to fill out the questionnaires regarding their own quality of life and coping. Multiple regression analyses were performed to examine the relationship between different predictor variables and quality of life. RESULTS: After accounting for the impact of disease severity and hours of treatment per day, the subjective health perception of patients significantly explained variance in their quality of life. Ways of coping were also significantly correlated with HRQOL. In parents the most important factor in explaining variance of HRQOL seems to be the coping style, whereas disease severity of the child and subjective health perception did not show any influence. CONCLUSIONS: The findings support the important role of cognitive and behavioural factors in specific subjective health perception and ways of coping in the adaptation to this severe chronic disease, both in patients themselves and in parents. The results call for a careful assessment of issues of coping and professional support for families of patients with cystic fibrosis in the early course of disease.
13C-labeled glycosyl ureides were recently proposed as a new marker of the orocecal transit time: after passing the small bowel the sugar-urea bond is split by bacterial allantoicase. Further degradation results in 13CO2 which can be measured in the exhaled breath. The aim of this study was to detect an eventual allantoicase-like activity in the human gut and to elucidate the metabolism of glycosyl ureides by human intestinal brush border enzymes. Biopsies of 15 duodenal specimen and 6 colon specimen were homogenised and incubated with several disaccharides and their corresponding disaccharide ureides under various experimental conditions. Hydrolysis of the sugar-urea bond could not be observed neither in the small bowel nor in the colon. However, the conjugation between the two sugars was split. In a modified Dahlqvist assay lactase showed the same kinetics with lactose and lactose ureide as substrates whereas maltose showed a significantly 2.6-fold higher affinity to maltase than maltose ureide (P < 0.001). No major difference between these two substrates could be detected when total maltase activity was inhibited by acarbose. In summary, the human gut tissue possesses no allantoicase-like activity. Therefore, glycosyl ureides seem to be appropriate substances to test the orocecal transit time.
Previously we reported the discovery of amidothiophenesulfonamides as endothelin receptor-A antagonists with high potency and selectivity. Replacement of an amide group in this class of compounds with an acetyl group maintained the in vitro binding affinity and in vivo activity while providing a compound with oral bioavailability and longer duration of action. The optimal compound discovered during these studies, 15q (TBC11251), binds competitively to human ETA receptors with a Ki of 0.43 +/- 0.03 nM and an IC50 of 1.4 nM (IC50 for ETB = 9800 nM). This compound inhibits ET-1-induced stimulation of phosphoinositide turnover with a Ki of 0.686 nM and a pA2 of 8.0. The compound has a serum half-life in the rat and the dog of 6-7 h and 60-100% oral bioavailability. This compound is one of the most selective ETA antagonists reported and therefore is suitable for additional pharmacological and clinical investigation of the role of ETA receptors in diseases.