Characterization of a bifunctional cellulase and its structural gene. The cell gene of Bacillus sp. D04 has exo- and endoglucanase activity

Bacillus sp. D04 secreted a bifunctional cellulase that had a molecular weight of 35,000. This cellulase degraded Cm-cellulose, cellotetraose, cellopentaose, p-nitrophenyl-beta-D-cellobioside, and avicel PH101. Based on the high performance liquid chromatography analysis of the degradation products, this cellulase randomly cleaved internal beta-1, 4-glycosidic bonds in cellotetraose and cellopentaose as an endoglucanase. It also hydrolyzed the aglycosidic bond in p-nitrophenyl-beta-D-cellobioside and cleaved avicel to cellobiose as an exoglucanase. Cellobiose competitively inhibited the p-nitrophenyl-beta-D-cellobioside degrading activity but not Cm-cellulose degrading activity. Ten mM p-chloromercuribenzoate inhibited p-nitrophenyl-beta-D-cellobioside degrading activity completely, but Cm-cellulose degrading activity incompletely. Cm-cellulose increased p-nitrophenyl-beta-D-cellobioside degrading activity, and vice versa, whereas methylumbelliferyl-beta-D-cellobiose strongly inhibited p-nitrophenyl-beta-D-cellobioside degrading activity. The cellulase gene (cel gene), 1461 base pairs, of Bacillus sp. D04 was cloned. The nucleotide sequence of the cel gene was highly homologous to those of Bacillus subtilis DLG and B. subtilis BSE616. The cel gene was overexpressed in Escherichia coli, and its product was purified. The substrate specificity and substrate competition pattern of the purified recombinant cellulase were the same as those of the purified cellulase from Bacillus sp. D04. These results suggest that a single polypeptide cellulase had both endo- and exoglucanase activities and each activity exists in a separate site.

Long-term follow-up of gracilis muscle transposition in children

Sixteen children of uncontrollable fecal incontinence have been treated with Pickrell's gracilis muscle transposition since 1983: 12 had an imperforate anuses with multiple corrective operative procedures and 4 had traumatic destructions of anal sphincters. We report a series of 11 cases whom we followed-up over a period of 0.8 to 10.5 years (mean; 5.6 years). Seven patients were evaluated by anorectal manometry. All patients except one who had left hemipelvectomy and permanent colostomy showed nearly normal continence during the follow-up period. There was no evidence of fibrosis in the transposed muscles and the tensions of the transposed muscles were well maintained. The voluntary contractions of the transposed muscles were well maintained and efficient in all cases. The general manometric parameters did not correlate well with the functional results; however, there was a strong correlation in the S/R ratio (maximum squeeze pressure/resting pressure) with the functional results. We believe that the good functional outcome of this procedure need not only the meticulous surgical technique but also the personal motivation and the compliance with physiotherapy. In conclusion, although the gracilis muscle transposition never results in normal continence, acceptable continence can be achieved in the selected patients.

Ultrasonographic evaluation of multicystic dysplastic kidney

Eleven cases of multicystic dysplastic kidney (MCDK) in children were diagnosed over an 11 year period. All underwent postnatal ultrasound (US) studies. Four different patterns of MCDK were recognized: (1) Six cases presented with the classic sonogram of multicystic components. (2) Three cases had hydronephrotic form; correct diagnosis between hydronephrotic form of MCDK and hydronephrosis was difficult as there was a medially-located, large, lobulated cyst and there was connection between the large cyst and neighboring small cysts. (3) One case initially presented with normal renal sonogram but a small cyst appeared on follow up sonogram and there was also decreased renal size and increased echogenecity. (4) One case had only two moderate-sized cysts but no identifiable renal parenchyma. Two cases had follow-up US examination and one dysplastic kidney decreased in renal size on follow-up sonogram. Intravenous urography and radionuclide study revealed both these dysplastic kidneys to be nonfunctioning. Nine children had surgical resection of the diseased kidneys. Contralateral renal anomalies were detected in five children, which included ureteropelvic junction stenosis, ureterovesical junction stenosis, distal ureteral stenosis and polycystic kidney disease. Two of three hydronephrotic forms of MCDK had contralateral ureteral stenosis. Two of six classic forms of MCDK had contralateral ureteral stenosis. The proportion of contralateral ureteral stenosis was higher in the group of hydronephrotic forms of MCDK. Ultrasonography is beneficial for conclusive diagnosis of MCDK; however, a differential diagnosis of simple hydronephrosis needs to be considered.

Transhiatal gastric transposition of a long gap esophageal atresia

Transhiatal gastric transposition was performed in a long gap esophageal atresia without tracheoesophageal fistula. The patient was a 12 months old female infant with previous stamm-type gastrostomy. The stomach was mobilized preserving the right gastric artery, the right gastroepiploic artery and spleen. The proximal and distal blind pouches of esophagus were excised by transcervical and transhiatal route, respectively. The mobilized stomach was pulled up into the neck through esophageal hiatus and posterior mediastinal route. The esophagogastrostomy, the only one anastomosis of this procedure, was safely performed in the neck. There were neither anastomotic leak nor early anastomotic stricture. The oral feeding was quickly established. There was no clinical evidence of regurgitation, difficulty of gastric emptying, hoarseness or respiratory problem. The low morbidity combined with satisfactory functional result indicates that the transhiatal gastric transposition is a safe and easy alternative surgical procedure for esophageal replacement in long gap esophageal atresia.

Conformation and sweet tastes of L-aspartyl dipeptide methyl esters

In order to investigate the conformational preferences to elicit tastes, conformational free energy calculations using an empirical potential (ECEPP/2) and the hydration shell model were carried out on the L-aspartyl dipeptide methyl esters, L-(+)HAsp(-)-L-Xaa-OMe, in the hydrated state, where Xaa includes sweet (Phe, Tyr, Met, and Gly), bitter (Ala, Trp, Val, Leu, and Ile), and tasteless (Ser, Thr, and Abu) residues. The refined preferred conformation of the Phe dipeptide (aspartame) with side chain chi 1/2 conformation g- is g-Fg- in the hydrated state, which is consistent with the structure deduced from 1H-nmr experiments. Irrespective of the Xaa and taste, all the dipeptides have the same conformation for the Asp residue, which is attributable to the hydrogen bond between protonated amino hydrogen and carboxylate oxygen and the favored hydration of the carboxylate group. This implies that the L-aspartyl residue is a necessary factor for the dipeptides to be sweet not a sufficient factor. The computed conformational preferences for sweet, bitter, and tasteless dipeptides in the hydrated state indicate to us that the conformation about the N--C alpha bond of the Xaa residue, i.e., the orientation of the hydrophobic moiety with respect to the AH/B functionalities in the aspartyl moiety, seems to be crucial to elicit the tastes. In addition, the hydrophobicity and the size of the Xaa residue are found to play a major role in determining the tastes. These well accord with the related works reported previously.

Conformational study on trans- and cis-N-acetyl-N'-methylamides of Pro-Xaa dipeptides

Conformational free energy calculations using an empirical potential (ECEPP/2) and the hydration shell model were carried out on the N-acetyl-N'-methylamides of Pro-Xaa dipeptides (Xaa = Ala, Leu, Val, Gly, Cys, Met, Phe, Tyr, Asn, Asp, and Ser) with trans and cis peptide bonds preceding proline residue in the unhydrated and hydrated states. As compared with the results obtained by using the earlier version of ECEPP, the values of beta-bend probabilities are doubled. The average calculated population of cis-dipeptide is about 4%, which is close to the abundance obtained from the analysis of X-ray crystal structures of proteins. The beta-bends are the most dominant structures of cis-dipeptides. Type I, usually having intramolecular hydrogen bonds, contributes greatly to the beta-bend conformations of trans- and cis-dipeptides. However, type I beta-bends of cis-dipeptides do not have any hydrogen bonds. By including the hydration, the beta-bend probabilities for trans- and cis-dipeptides decreased, indicating that the interactions of water molecules with a backbone or side-chain may force the dipeptides to be more distorted or extended. In particular, type II is found to be a dominant beta-bend conformation of trans- and cis-Pro-Gly dipeptides in both the unhydrated and hydrated states. In general, the calculated propensities for Pro-Xaa dipeptides to adopt beta-bend conformations are reasonably consistent with available experimental data. From comparing conformations of Pro and Xaa residues in the dipeptides and single residues, we found that inter-residue interactions and hydration are of importance in determining the conformational properties of the Pro-Xaa dipeptide.

Non-saturable transport of [3H]oestradiol across the blood-brain barrier in female rats is reduced by neonatal serum

Adult ovariectomized rats were decapitated 5 sec after intracarotid injection of a 200-microliter bolus containing [3H]oestradiol plus [14C]butanol, which served as a freely diffusible reference for transport across the blood-brain barrier. When buffered Ringer's solution (with 20% ethanol added to dissolve the oestradiol) was used as the injection vehicle, 83 +/- 6% (mean +/- s.e.m.) of the injected [3H]oestradiol (0.17 microM) reaching the brain microvasculature was extracted in one circulatory passage. Addition of unlabelled oestradiol (34 or 68 microM) to the injection bolus did not reduce this percentage of extraction. When 0.1% bovine serum albumin rather than ethanol was added to buffered Ringer's solution to ensure solubilization of [3H]oestradiol (0.043 microM), the percentage brain extraction was 82 +/- 6%, and again, addition of unlabelled oestradiol (300 microM) did not reduce this value significantly. This finding suggests that oestradiol diffuses into the rat brain passively and is not transported via saturable carrier molecules. When serum from and adult, ovariectomized, female rat was used as the injection medium, the brain extracted 56 +/- 4% of the injected [3H]oestradiol (0.17 microM), whereas only 13 +/- 1% was extracted from a pool of serum obtained from 9-day-old young rats of both sexes. Brain extraction of [3H]oestradiol (0.043 microM) was significantly lower when the injection vehicle used was serum collected from female rats killed on Days 0, 5 or 20 after birth than on Days 30 or 120. These in-vivo results suggest that neonatal rat serum contains a factor (presumably alpha-fetoprotein) that restricts oestradiol influx into the developing brain.