Clinical pictures of 75 patients with neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD).

We clarified the clinical features of NICCD (neonatal intrahepatic cholestasis caused by citrin deficiency) by retrospective review of symptoms, management and long-term outcome of 75 patients. The data were generated from questionnaires to paediatricians in charge of the patients. Thirty of the patients were referred to hospitals before 1 month of age because of positive results in newborn screening (hypergalactosaemia, hypermethioninaemia, and hyperphenylalaninaemia). The other 45, the screen-negative patients, were referred to hospitals with suspected neonatal hepatitis or biliary atresia because of jaundice or discoloured stool. Most of the screen-negative patients presented before 4 months of age, and 11 had failure to thrive. Laboratory data showed elevated serum bile acid concentrations, hypoproteinaemia, low levels of vitamin K-dependent coagulation factors and hypergalactosaemia. Hypoglycaemia was detected in 18 patients. Serum amino acid analyses showed significant elevation of citrulline and methionine concentrations. Most of the patients were given a lactose-free and/or medium-chain triglyceride-enriched formula and fat-soluble vitamins. Symptoms resolved in all but two of the patients by 12 months of age. The two patients with unresolved symptoms suffered from progressive liver failure and underwent liver transplantation before their first birthday. Another patient developed citrullinaemia type II (CTLN2) at age 16 years. It is important to recognize that NICCD is not always a benign condition.

Renal transplantation in a 14-year-old girl with vitamin B12-responsive cblA-type methylmalonic acidaemia.

Renal tubular dysfunction and chronic renal failure are well recognised complications of methylmalonic acidaemia (MMA) and can occur even in the context of optimal medical metabolic management. Organ transplantation, such as renal and combined liver and renal transplants, have been utilised in the past for children whose disease cannot be managed by conservative medical practices and those with end stage renal disease. Our patient was diagnosed with B(12)-responsive MMA (subsequently proven to be cblA-type MMA) in the postoperative period following renal transplantation for idiopathic chronic renal failure. She remains well, with excellent graft function and metabolic control 4 years after transplantation. This patient highlights the importance of testing for the inborn errors of metabolism in patients presenting with recurrent acidosis and progressive renal impairment.

A comparison of the end-tidal CO2 measured by portable capnometer and the arterial PCO2 in spontaneously breathing patients.

An end-tidal CO2 (ETCO2) monitor (capnometer) is used most often as a noninvasive substitute for PaCO2 in anesthesia, anesthetic recovery and intensive care. However, the utility and accuracy of the portable capnometer in spontaneously breathing patients with or without chronic pulmonary diseases has received little recognition. To determine the utility of the portable capnometer in general wards and in in-home care, we examined the correlation between ETCO2 measured by a portable capnometer and simultaneous PaCO2 measured in 41 spontaneously breathing patients. TV-ETCO2 (ETCO2 measured by tidal volume maneuver) was lower than PaCO2 by an average of 9.0 mmHg and VC-ETCO2 (ETCO2 measured by vital capacity maneuver) was lower than PaCO2 by an average of 0.5 mmHg. The mean difference between PaCO2 and VC-ETCO2 was not statistically significant. Regression analysis showed a close correlation between VC-ETCO2 and PaCO2 (r = 0.91, P < 0.0001). Thus,VC-ETCO2 was highly correlated with PaCO2. Furthermore, a close correlation between VC-ETCO2 and PaCO2 was also observed in patients with compromised pulmonary function (r = 0.88, P < 0.0001 in patients with below 70% of FEV(1.0)%; r = 0.89, P < 0.0001 in patients with below 80% of %VC). Our studies show that VC-ETCO2 measured by the portable capnometer gives a reliable pointestimate of PaCO2, and can be useful to evaluate the respiratory condition of spontaneously breathing patients in general wards and in in-home care.

Prognostic factors of nosocomial pneumonia in general wards: a prospective multivariate analysis in Japan.

To determine prognostic factors of nosocomial pneumonia in general wards, we performed prospective clinical study using multivariate statistical analysis. Eighty patients with nosocomial pneumonia in our units were enrolled in the study between December, 1996 and January 1998. Clinical setting and severity of pneumonia were evaluated, and laboratory data were collected at the occurrence of nosocomial pneumonia. Death due to nosocomial pneumonia occurred in 29 of 80 patients (mortality rate 36%). Univariate analysis showed the following factors associated with mortality: the presence of an ultimately or rapidly fatal underlying condition, prior antibiotics use, use of antacids, presence of 'high-risk' micro-organisms, sepsis, respiratory failure, multiple organ failure, bilateral chest X-ray infiltrates, a Simplified Acute Physiology Score (SAPS) index > or = 11, albumin < 3.0 g dl(-1), and lactate dehydrogenase (LDH) > or = 796 IUI(-1). Furthermore, multivariate analysis identified three factors significantly associated with mortality: the presence of an ultimately or rapidly fatal underlying condition [odds ratio (OR)=7.0; 95% confidence interval (CI)=1.2-41.1; P=0.03]; SAPS index > or = 11 (OR=7.6; 95% CI=1.1-51.9, P=0.04); LDH > or = 796 IUI(-1) (OR=28.2; 95% CI=2.0-406, P=0.01). Our study indicates that host factors and disease severity factors are important prognostic factors of nosocomial pneumonia in general wards.

Structure of human holocarboxylase synthetase gene and mutation spectrum of holocarboxylase synthetase deficiency.

Holocarboxylase synthetase (HLCS) is an enzyme that catalyzes the incorporation of biotin into apo-carboxylases, and its deficiency causes biotin-responsive multiple carboxylase deficiency. The reported sequences of cDNA for human HLCS from liver, lymphocyte, and KG-1 myeloid cell lines differ at their 5' regions. To elucidate variations of the human HLCS mRNA and longer 5' cDNA ends, we performed screening of the human liver cDNA library and rapid amplification of the cDNA ends (RACE). Our results suggest the existence of three types of HLCS mRNA that start at different exons. The first type starts at exon 1, and the second type starts at exon 3, and both are found in various human tissues. The third type, corresponding to the cDNA from the KG-1 cell, starts at exon 2 of the HLCS gene. Various splicing patterns from exons 3-6 were also observed. None of the variations of cDNA found created a new initiation codon. Mutation screening from exons 6-14, therefore, was sufficient to detect amino acid changes in HLCS in patients. Our direct sequencing strategy for screening mutations in the HLCS gene revealed mutations in five Japanese patients and seven non-Japanese patients. Our analyses involving 12 Japanese and 13 non-Japanese patients and studies by others indicate that (1) there is no panethnically prevalent mutation; (2) the Arg508Trp, Gly581Ser, and Val550Met mutations are found in both Japanese and non-Japanese populations; (3) the IVS10+5G-->A mutation is predominant and probably a founder mutation in European patients; (4) the 655-656insA, Leu237Pro, and 780delG mutations are unique in Japanese patients; (5) the spectrum of the mutations in the HLCS gene may vary substantially among different ethnic groups.

A novel intronic mutation of the TAZ ( G4.5) gene in a patient with Barth syndrome: creation of a 5' splice donor site with variant GC consensus and elongation of the upstream exon.

Mutation analysis of the TAZ ( G4.5) gene was performed on a patient with Barth syndrome. The reverse transcription/polymerase chain reaction procedure showed aberrant splicing and elongation of exon 3 because of the insertion of 106 bases (IVS3+1 to +106) between exons 3 and 4. The genomic DNA revealed an intronic mutation four bases downstream from the new cleavage site (IVS3+110G-->A). The IVS3+110G-->A mutation created a novel 5' splice site that showed GC but not GT, and the additional splice site was used preferentially over the upstream authentic slice site. This is a new type of splicing mutation responsible for a human genetic disease.

Expression of discoidin domain receptor 1 tyrosine kinase on the human bronchial epithelium.

Discoidin domain receptor 1 (DDR1) tyrosine kinases constitute a novel family of receptors characterized by a unique structure in the ectodomain (discoidin-I domain). The DDR1 ligand is the extracellular matrix protein collagen. To identify receptor tyrosine kinases (RTKs) involved in control of growth and differentiation of human bronchial epithelial (HBE) cells, a polymerase chain reaction-based search for RTKs in HBE cells was performed. DDR1 was the most abundant clone identified. Northern analysis detected a 3.6 kb DDR1 messenger ribonucleic acid (mRNA) expressed in HBE cells and transformed HBE lines, BET-1A and BEAS-2B. In addition, fluorescence-activated cell sorter (FACS) analyses using an anti-DDR1 antibody showed that DDR1 was expressed on HBE cells and two HBE lines. Immunohistochemical staining using human bronchial tissue demonstrated that DDR1 was mainly expressed at the basolateral cell surface of the bronchial epithelium. Furthermore, immunostaining of type IV collagen, a major component of the basement membrane, clearly showed that the basement membrane was closely attached to the basal surface of the bronchial epithelium. Since collagen binds to and activates discoidin domain receptor 1 tyrosine kinase, colocalization of discoidin domain receptor 1 and its ligand type IV collagen demonstrates a potential interaction of discoidin domain receptor 1 on the bronchial epithelium with type IV collagen. Further study of this interaction may define the functional significance of the collagen-discoidin domain receptor 1 signalling pathway in health and in disease.

Immunohistochemical analysis of distribution of RON receptor tyrosine kinase in human digestive organs.

The immunohistochemical distribution of RON receptor tyrosine kinase in digestive organs of both human fetus and adult, including the esophagus, stomach, duodenum, small intestine, colon, rectum, liver, gallbladder, pancreas, and spleen, was investigated semiquantitively using an affinity-purified rabbit polyclonal antibody. RON was observed to be widely distributed throughout various digestive organs and cell types in humans. The immunoreactivity for RON was observed in the epithelium of the esophagus, small intestine, colon, hepatocytes, Kupffer cells, and splenic macrophages both in the adult and the fetus, suggesting that the MSP/RON signaling pathway possesses the proper biological properties to possibly be involved in morphogenesis or differentiation of cells in these organs and cell types. Several organs differed in immunoreactivity between adult and fetus. No immunoreactive cells were found in the pancreas of adults; however, immunoreactivity was observed in acinar cells and in some of the duct or ductular cells and endocrine cells of the islet of the fetus. Similarly, immunoreactivity was not observed in gastric mucosa except in the intestinal metaplastic cells in adults; however, immunoreactivity was found in the foveolar epithelium of the stomach of the fetus. Although the biological significance of RON in malignancy is unclear, the presence of RON immunoreactivity in the fetus and it lack in the adult may indicate that RON is a oncofetal substance in human pancreas and stomach.

Neonatal presentation of adult-onset type II citrullinemia.

Adult-onset type II citrullinemia (CTLN2) is characterized by a liver-specific argininosuccinate synthetase deficiency caused by a deficiency of the citrin protein encoded by the SLC25A13 gene. Until now, however, no SLC25A13 mutations have been reported in children with liver diseases. We described three infants who presented as neonates with intrahepatic cholestasis associated with hypermethioninemia or hypergalactosemia detected by neonatal mass screening. DNA analyses of SLC25A13 revealed that one patient was a compound heterozygote for the 851de14 and IVS11+IG-->A mutations and two patients (siblings) were homozygotes for the IVS11+lG-->A mutation. These results suggested that there may be a variety of liver diseases related to CTLN2 in children.

Mutation analysis of the GLUT2 gene in patients with Fanconi-Bickel syndrome.

Fanconi-Bickel syndrome (FBS) is an autosomal recessive disorder manifesting hepatorenal glycogen accumulation, Fanconi nephropathy, and impaired utilization of glucose and galactose. Several mutations in a gene encoding a glucose transporter, GLUT2, have recently been reported in patients with FBS. We performed molecular analysis on three Japanese patients and found four novel mutations: a splice-site mutation (IVS2-2A>G), a nonsense mutation (Q287X), and two missense mutations (L389P and V423E). Heterozygotes of L389P or V423E mutation from the patients' families showed renal glucosuria. These data suggested that GLUT2 gene defects may be a cause of renal glucosuria.

Elevated levels of macrophage-stimulating protein in induced sputum of patients with bronchiectasis.

We recently showed that macrophage-stimulating protein (MSP), a serum protein homologous to hepatocyte growth factor, promotes ciliary motility by activating its receptor, RON, on the airway ciliated epithelium. To investigate the functional involvement of MSP and RON in bronchiectasis, in which mucociliary clearance (MCC) is impaired, first we examined RON expression on the bronchial ciliated epithelium of patients with bronchiectasis. We confirmed RON expression at the apical surface of bronchial ciliated epithelium of patients with bronchiectasis as well as those of normal human bronchus. Next, we examined whether MSP is present in sputum of patients with bronchiectasis and normal control subjects. By Western blotting, we found that half of the MSP in sputum is present as a biologically active alpha/beta chain heterodimer (mature MSP). In addition, we found that the MSP concentrations in sputum were significantly elevated in patients with bronchiectasis (n=8; 16.8+/-3.0 ng ml(-1)) compared with normal controls (n=9; 8.4+/-2.4 ng ml(-1); P<0.05). In contrast, the difference in concentrations of serum MSP (pro-MSP) was not significant between the two groups. These results indicate that (i) MSP is supplied to the airways and converted to a biologically active form, (ii) MSP is increased in patients with bronchiectasis compared with normal controls. Taken together, our findings suggest that increased MSP may be involved in compensation for impaired MCC in bronchiectasis.

Heterogeneous mutations in the glucose-6-phosphatase gene in Japanese patients with glycogen storage disease type Ia.

Glycogen storage disease type Ia (GSD-Ia) is an autosomal recessive disorder of glycogen metabolism caused by glucose-6-phosphatase (G6Pase) deficiency. It is characterized by short stature, hepatomegaly, hypoglycemia, hyperuricemia, and lactic acidemia. Various mutations have been reported in the G6Pase gene (G6PC). However, in Japanese patients, a g727t substitution was found to be the major cause of GSD-Ia, accounting for 20 of 22 mutant alleles [Kajihara et al., 1995], and no other mutations have been found in this population. We analyzed four Japanese GSD-Ia patients and identified three other mutations in addition to the g727t. They included two missense mutations (R83H and P257L) and one nonsense mutation (R170X). Each of the three mutations exhibited markedly decreased G6Pase activity when expressed in COS7 cells. A patient homozygous for R170X showed multiple episodes of profound hypoglycemia associated with convulsions, while P257L was associated with a mild clinical phenotype. The presence of R170X in three unrelated families may implicate that it is another important mutation in the etiology of GSD-Ia in Japanese patients. Thus, the detection of non-g727t mutations is also important in establishing the DNA-based diagnosis of GSD-Ia in this population.

Diagnosis and molecular analysis of an atypical case of holocarboxylase synthetase deficiency.

Holocarboxylase synthetase (HCS) deficiency is a disorder of biotin metabolism characterised by metabolic ketoacidosis and skin lesions due to reduced activities of multiple biotin-dependent carboxylases. The onset of this disease is usually between the neonatal and infantile period. Here we report the molecular analysis of an atypical case of HCS deficiency, where the patient developed his first episode of acidosis at age 8 years and had an exceptionally slow response to biotin therapy. A homozygous mutation was identified at the + 5 position of the splice donor site in intron 10 of the HCS gene (IVs10 + 5(g-->a)), resulting in abnormal splicing of HCS mRNA. A moderate decrease in the amount of normal HCS mRNA may account for the atypical, late-onset phenotype of this patient. Conclusion Molecular analysis is a useful tool for understanding the phenotypic variations in holocarboxylase synthetase deficiency.

Haplotype analysis suggests that the two predominant mutations in Japanese patients with holocarboxylase synthetase deficiency are founder mutations.

Holocarboxylase synthetase (HCS) deficiency is a rare autosomal recessive disorder of biotin metabolism. Including three new Japanese patients we diagnosed in this study, ten Japanese families have, so far, been accumulated. In these families, the mutations 237Leu > Pro (seven alleles) and 1067delG (five alleles) were predominant; 508Arg > Trp and 55(Val > Met mutations were identified in three families in the heterozygous form and in one patient in the homozygous form, respectively. To determine the origin of these mutations, we identified new polymorphic microsatellite markers in the HCS gene and analyzed the haplotypes of the patients. All the 237Leu > Pro and the 1067delG alleles were associated with haplotype 2-2. This finding is consistent with the notion that these mutations are founder mutations in the Japanese population. Three Japanese 508Arg > Trp alleles were associated with several haplotypes, including 2-3 and 1-4. The haplotype of a Taiwanese patient homozygous for the 508Arg > Trp mutation was 2-3/2-3. The haplotype of one Japanese patient homozygous for the 550Val > Met mutation was 1-4/1-4, whereas that of a Jewish patient with the same homozygous mutation was 2-3/2-3. Both mutations were associated with at least two haplotypes and were found in several ethnic groups. The changes 508Arg > Trp and 550Val > Met occurred at CpG dinucleotide. The data suggest that these two mutations represent a mutational hot-spot.

Relationship between kinetic properties of mutant enzyme and biochemical and clinical responsiveness to biotin in holocarboxylase synthetase deficiency.

Holocarboxylase synthetase (HCS) deficiency is a metabolic disorder that causes a biotin-responsive multiple carboxylase deficiency. We analyzed the kinetic properties of seven mutant HCS proteins. Two of these enzymes harbored mutations within the putative biotin-binding region of HCS and showed elevated Km values for biotin compared with that of the wild-type form (Km mutant; Gly581Ser: 45 times, delThr610: 3 times). The remaining five mutations (Arg183Pro, Leu216Arg, Leu237Pro, Val333Glu, and Val363Asp) were located outside the biotin-binding region. The enzymes containing these mutations showed normal or low Km values for biotin (non-Km mutant). Symptoms of patients who have the non-Km, mutants, as well as those of patients who have the Km, mutants, responded to biotin therapy. This is probably because the Km value for biotin of normal HCS is higher than the physiologic concentration of biotin in human cells. The Vmax values of all mutant HCS proteins were considerably decreased, but to a variable degree. The responsiveness to biotin supplementation of propionyl-CoA carboxylase activity in cultured cells bearing the mutations correlated well with the degree of reduction in the Vmax of HCS. Patients who have mutant HCS proteins with lower Vmax showed poorer clinical and biochemical responses to biotin therapy. These observations suggest that the reduction of Vmax is an essential factor for pathophysiology and prognosis of HCS deficiency under treatment with large amounts of biotin. The determination of HCS genotype can be valuable for characterizing the clinical phenotype in HCS deficient patients.