Endoscopic transesophageal vs. thoracoscopic removal of mediastinal lymph nodes: a prospective randomized trial in a long term animal survival model

BACKGROUND AND STUDY AIMS

In cases where biopsies remain inconclusive, removal of mediastinal lymph nodes for further analysis requires surgical means. Natural orifice transluminal endoscopic surgery (NOTES) procedures allow incision/closure of the gut wall, which might enable endoscopic excision of pre-marked nodes. The aims of the current study were to investigate the feasibility, safety, and reproducibility of lymph node generation in an animal model to enable endoscopic ultrasound-guided (EUS) lymph node removal (ELR) using transesophageal NOTES access/closure and to compare this procedure with thoracoscopic lymph node removal (TLR) in a randomized long term survival animal study.

PATIENTS AND METHODS

Lymph node creation using graphite injection was performed in 12 pigs. After randomization into ELR and TLR groups, lymph nodes were marked with newly developed anchors under EUS guidance and removed using either ELR or TLR. ELR included incision of the esophageal wall and closure after lymph node removal. The main outcome measures were success in lymph node generation, technical success of lymph node removal, complications, and comparability of ELR and TLR.

RESULTS

Generation of lymph nodes proved successful in all animals in 46/48 sites injected (96 %). Anchors were placed through the selected nodes in a mean of 9.4 minutes. TLR and ELR were successful in all cases. One bleeding occurred during esophageal incision in ELR, which was stopped endoscopically. After lymph node removal, endoscopic suturing of the incision took a mean of 18 minutes. Procedure time was longer for ELR than TLR (mean 48 vs. 42 minutes). All animals survived the procedures. Autopsy after 4 weeks showed two thoracic wall abscesses in the TLR group and none in the ELR group.  Microscopic analysis revealed well healed esophageal scars.

CONCLUSION

ELR proved to be feasible in this limited sample size and complications were not observed more frequently in this group than in the TLR group.

The feasibility of wireless capsule endoscopy in detecting small intestinal pathology in children under the age of 8 years: a multicentre European study

OBJECTIVE

To systematically evaluate the feasibility and methodology to carry out wireless capsule endoscopy (WCE) in children <8 years to define small intestinal pathology.

DESIGN

Prospective European multicentre study with negative prior investigation.

PATIENTS AND INTERVENTIONS

83 children aged 1.5-7.9 years were recruited. Initially, all were offered "swallowing" (Group 1) for capsule introduction. If this failed endoscopic placement (Group 2) was used and the Roth net, Advance or custom-made introducers were compared.

OUTCOME MEASURES

Primary endpoint: to determine pathology; secondary endpoint: comparison of capsule introduction methods.

RESULTS

Capsule introduction: 20 (24%) children aged 4.0-7.9 years (mean, 6.9 years; 14 male) comprising Group 1 were older (p<0.025) than 63 (76%) aged 1.5-7.9 years (mean, 5.25 years; 30 male) forming Group 2.

COMPLICATIONS

Roth net mucosal trauma in 50%; no others occurred. The available recording apparatus was inappropriate for those <3 years.

INDICATIONS

gastrointestinal bleeding: n = 30 (16 positive findings: four ulcerative jejunitis, four polyps, two angiodysplasia, two blue rubber blebs, two Meckel's diverticula, one anastomotic ulcer, one reduplication); suspected Crohn's disease: n = 20 (11 had Crohn's disease); abdominal pain: n = 12 (six positive findings: three Crohn's disease, two lymphonodular hyperplasia, one blue rubber bleb); protein loss: n = 9 (four lymphangectasia); malabsorption: n = 12 (seven positive findings: six enteropathy, one ascaris). No abnormalities overall: 45%.

CONCLUSION

WCE is feasible and safe down to the age of 1.5 years. 20 children >4 years swallowed the capsule. The Advance introducer proved superior for endoscopic placement. The pathologies encountered showed age specificity and, unlike in adolescents, obscure gastrointestinal bleeding was the commonest indication.

Pharmacokinetic evaluation of gemcitabine and 2',2'-difluorodeoxycytidine-5'-triphosphate after prolonged infusion in patients affected by different solid tumors

BACKGROUND

The study determined pharmacokinetic parameters, toxicity profile and preliminary clinical activity of gemcitabine administered i.v. at different infusion rates in patients with a range of solid tumors.

PATIENTS AND METHODS

Twenty patients were enrolled for both pharmacokinetic and clinical studies. Gemcitabine 300 mg/m(2) was administered during 1 h, 2 h or 3 h, and as a conventional dose of 1000 mg/m(2) during 30 min infusion. Administration was on days 1, 8 and 15 every 4 weeks.

RESULTS

Patients were randomly assigned to one of the four arms. After 30 min infusion of 1000 mg/m(2) gemcitabine the plasma concentration remained above the saturation level of 10-20 microM, whereas after 1, 2 or 3 h infusion 300 mg/m(2) gemcitabine it remained below the saturation level for most of the time (being in the range 2.5-10 microM). Gemcitabine triphosphate was determined in the four arms in white blood cells; for infusion times from 0.5 to 3 h there was a progressive enhancement of gemcitabine triphosphate levels. In all evaluable patients the toxicity was mild, myelosuppression being the main toxicity. No grade 3 or 4 toxicities occurred. Clinical response was similar in patients receiving 300 mg/m(2) gemcitabine in 2 and 3 h and in the 1000 mg/m(2) arm.

CONCLUSIONS

300 mg/m(2) gemcitabine during 3 h infusion produced the highest accumulation of gemcitabine triphosphate. Thus, to achieve the highest possible gemcitabine triphosphate level, prolonged infusion time would appear to be more important than a high dose administered as a short infusion. However, there was no substantial difference in toxicity or antitumoral activity in the all different patient groups.

Which parameters might predict complications after natural orifice endoluminal surgery (NOTES)? Results from a randomized comparison with open surgical access in pigs

BACKGROUND AND STUDY AIMS

Natural orifice transluminal endoscopic surgery (NOTES) is currently developed and assessed mainly in pig experiments. The vast majority of studies show a good outcome in short-term follow-up. The current study aims at comparing various parameters of postinterventional assessment and surveillance in relation to clinical behavior and autopsy results to find suitable control parameters and also to assess the pig as suitable model for NOTES compared with open surgery.

METHODS

Within the framework of a randomized prospective study of 20 pigs with iatrogenic colonic perforation comparing endoscopic with open surgical closure, clinical examination, including observation of behavior, food intake, and body temperature, was carried out daily. Laboratory parameters (white blood cells [WBC], granulocytes) were measured in 14 animals. Weight was measured preoperatively and on days 2 and 7 postoperatively. Results were matched with complications found during/after 2 weeks' survival. Pre-autopsy sterile cultures were taken from the peritoneal cavities to determine possible bacterial contamination.

RESULTS

Three animals from the surgical group were sacrificed on days 4, 8, and 12 because they became severely ill, with autopsy revealing intussusception from adhesions, peritoneal abscess, and peritonitis, in one pig each; another animal had culture positive for ESCHERICHIA COLI. Three minor complications (2 cough, 1 continuing fever with adhesions to the bladder found on autopsy) occurred in the endoscopic group without compromised recovery. WBC were measured in 14 animals, and found to be elevated (8 - 36 x 10 (9)/l) in six on day 2 including the two animals with severe complications. Between pre- and post-procedure, WBC increased about twofold in the uneventful cases but fourfold in the two animals with severe complications. Cultures from the abdominal cavity before autopsy were negative in all but one animal.

CONCLUSION

Animal behavior was a reliable indicator of severe complications. Fever, body weight, and the results of in vitro cultures of the peritoneal fluid did not indicate complications. WBC proved not to be specific but showed a larger increase in pigs with severe complications.

The effect of five different administration intervals on the pharmacokinetics (pk) of paclitaxel (PTX) and pegylated liposomal doxorubicin (PLD) association regimen

13012

Background: The PTX-PLD association is a promising schedule for recurrent head/neck cancer. Their pk behavior could be dependent not only on PTX excipient (polyethoxylated castor oil) interference, but even on different i.v. administration intervals between the two drugs. This study evaluated any possible administration interval-dependent pk interaction, when PLD infusion started 0, 1, 3, 12 or 24 h after PTX infusion end. Methods: 25 patients, affected by recurrent cisplatin pre-treated squamous cell head/neck cancer, were randomized to receive PTX 80 mg/m2 q1w and PLD 12.5 mg/m2 q2w at administration intervals of 0, 1, 3, 12 or 24 h. Pk parameters were evaluated during the first course by non-compartmental analysis, while statistical analysis was performed by non-parametric Kruskal Wallis test. Results: Median PK parameters are reported in the table . PTX pk profile is strongly affected by PLD administration. PTX total exposure is highly reduced, with a consequent increase in Cltot; this alteration is totally due to Kel modifications. On the other side, no statistically significant interactions affected PLD pk parameters. Some in vitro experiments indicate that PLD is able to partially absorb PTX, driving to PTX plasmatic concentration reduction, when PLD is administered at 0–1 h intervals. Conclusions: PLD liposomal components seem to be able to entrap PTX, therefore reducing PTX plasmatic concentrations; so, it is very important to choose the ideal administration interval. In order to avoid pk interaction, the i.v. administration interval between PTX and PLD had to be 3 h at least. For shorter intervals, patients could be underexposed to PTX, with lesser clinical efficacy.

[Table: see text]

No significant financial relationships to disclose.

Effects of reduced glutathione (GSH) on oxaliplatin pharmacokinetics (OXA pk) and on Pt-DNA adducts formation in advanced colorectal cancer patients treated by FOLFOX4 regimen

2559

Background: Neurotoxicity is a common OXA toxicity in FOLFOX4 regimen for patients with advanced colorectal cancer. Recently, Cascinu et al. (JCO 2002; 20: 3478–3483) provided evidence that GSH reduces the OXA-induced neurotoxicity, but GSH influence on the formation of Pt-DNA adducts still remains unknown. This study evaluated the effect of GSH addition on OXA pk and on Pt-DNA adducts formation Table of Contents Methods: 28 patients were given twelve FOLFOX4 courses and randomized to receive either GSH 1,500 mg/m2 or normal saline solution (placebo) before OXA iv infusion. OXA pk and Pt-DNA adducts formation were evaluated at courses 5, 9 and 12. Total and ultrafiltered platinum were analyzed by atomic adsorption, Pt-DNA adducts in leukocytes (as model for tumour tissue) by adsorptive stripping voltammetry. Pk analysis were done by non-compartmental analysis, statistical analysis by non-parametric Mann-Whitney test. Results: Median total and ultrafiltered platinum median Cmax and AUCtot values were comparable to previously reported ones, being higher in the placebo arm, due to a moderate reduction of platinum clearance. The formation of Pt-DNA adducts was more pronounced in GSH arm (median value 20.3 Pt atoms/106 nucleotides vs. 5.7 Pt atoms/106 nucleotides), even not statistically significant. Conclusions: The addition of GSH to FOLFOX4 regimen is able to reduce the OXA-induced neurotoxicity, without affecting either the OXA pk behaviour or the formation of Pt-DNA adducts, without modifying FOLFOX4 clinical efficacy.

[Table: see text]

No significant financial relationships to disclose.

Successful resection of a congenital superior mesenteric arteriovenous malformation

A 15-month-old male presented with severe gastrointestinal bleeding and heart failure. Imaging revealed a superior mesenteric artery arteriovenous malformation, associated with a congenital portosystemic shunt. The heart failure was cured by resection of the arteriovenous malformation.

Paclitaxel and pegylated liposomal doxorubicin in recurrent head/neck cancer: An unexpected administration interval-dependent pharmacokinetic interaction

2042

Background: Combination of paclitaxel (PTX) with pegylated liposomal doxorubicin (PLD) is an interesting opportunity for recurrent head/neck cancer treatment. Their pharmacokinetic (PK) behavior could be dependent not only on PTX excipient (polyethoxylated castor oil) interference, but also on different iv administration interval between the two drugs. The study endpoint was to evaluate any possible administration interval-dependent PK interaction, when PLD infusion start is delayed from 0 to 24 h after PTX infusion end. Methods: 24 patients affected by recurrent cisplatin pre-treated squamous cellhead/neck cancer were enrolled, receiving PTX 80 mg/m2 q 1w and PLD 12.5 mg/m2 q 2w for 6w/2w rest. Administration interval was 0 h at d1 (PTX-PLD 0) and 24 h at d15 (PTX-PLD 24). Blood sampling was performed at d1–15, PTX and PLD blood levels were analyzed by high performance liquid chromatography techniques, while PK parameters by non-compartmental analysis. Results: PTX PK parameters had large statistically significant differences (median/IQR, PTX-PLD 0 vs. PTX-PLD 24, Mann-Whitney test): Cmax 261/219–531 vs. 407/250–1473 ng/ml p=0.142, AUC 869/688–1331 vs. 3361/969–7853 ng*h/ml p=0.013, Kel 0.39/0.26–0.57 vs. 0.11/0.02–0.26 h⁁−1 p=0.001, Cl 153/89–198 vs. 41/17–138 l/h p=0.013. Similarly, PLD Cmax and AUC were higher in PTX-PLD 24 (Cmax 5.1/3.3–8.1 vs. 6.8/5.3–7.8 mg/l p=0.043, AUC 341/104–1472 vs. 603/106–1006 mg*h/l p=1.000). The overall response rate was 37.5%, including 1 CR (4%); median response duration was 5.5 months (range, 2–16), median overall survival 10 months (range, 2–25+). Conclusions: This exploratory study, having a favourable palliative role in heavily pre-treated patients, showed that PTX PK profile is unexpectedly affected by a different administration interval. In PTX-PLD 0, PTX AUC is fourfold reduced, with a similar increase in Cl, totally due to Kel alteration: therefore, patients could be underexposed to PTX. PLD PK behavior confirmed previous studies results, in which PTX modified PLD disposition, prolonging the duration of its elimination phase and increasing total body exposure to PLD.

No significant financial relationships to disclose.

CathCam guide wire-directed colonoscopy: first pilot study in patients with a previous incomplete colonoscopy

BACKGROUND AND STUDY AIMS

Conventional colonoscopy as the gold standard for large-bowel diagnostics and therapy may fail in 5 %-20 % of cases, depending on the experience of the examiner. Colonoscopy is regarded as difficult and painful by many patients. In an attempt to overcome the limitations of conventional colonoscopes, a guide wire-directed, thin, flexible diagnostic colonoscope, the CathCam was developed. In this prospective pilot study, we report its use in patients in whom conventional colonoscopy had failed.

PATIENTS AND METHODS

49 patients with a previous or current failure of complete colonoscopy were invited to participate in a trial using the new CathCam system, and 14 (nine men; mean age 59 years) accepted. The CathCam is an 11-mm diameter disposable, multilumen catheter, with visualization by a 3-mm camera with six light-emitting diodes. In the first five patients, the CathCam was inserted over a newly developed 0.024-inch, hinged, lumen-seeking guide wire. Subsequently, a modified combined approach was used: a conventional colonoscope was introduced into the sigmoid or left colon, then the guide wire was advanced as far as possible, followed by CathCam insertion over it. Caecal intubation rate, insertion times and patient discomfort were recorded; patients received low-dose midazolam sedation (2-5 mg).

RESULTS

One patient was excluded during colonoscopy. The caecum could be eventually reached in 12 of 13 patients; in the remaining patient a significant sigmoid stricture could be passed, but further advancement appeared too risky. The mean caecal intubation time was 24 minutes (range 3-105 min). Only two patients experienced pain and discomfort during the procedure (one immediate assessment and one case reported at later telephone interview). No complications occurred, and previously undiagnosed important findings were obtained in 9 cases.

CONCLUSIONS

A combined approach, consisting of guide wire insertion via a partially introduced colonoscope followed by CathCam or colonoscope insertion into the caecum was successful in over 90 % of patients with previous failure of complete colonoscopy. Further improvements may make this system suitable for use as a standard diagnostic colonoscope, either as a single unit (CathCam plus guide wire) or using the guide wire alone with a standard colonoscope in difficult cases.

In yeast sterol biosynthesis the 3-keto reductase protein (Erg27p) is required for oxidosqualene cyclase (Erg7p) activity

In Saccharomyces cerevisiae, the 3-keto reductase (Erg27p) encoded by ERG27 gene is one of the key enzymes involved in the C-4 demethylation of the sterol intermediate, 4,4-dimethylzymosterol. The oxidosqualene cyclase (Erg7p) encoded by the ERG7 gene converts oxidosqualene to lanosterol, the first cyclic component of sterol biosynthesis. In a previous study, we found that erg27 strains grown on cholesterol- or ergosterol-supplemented media did not accumulate lanosterol or 3-ketosterols but rather squalene, oxidosqualene, and dioxidosqualene intermediates normally observed in ERG7 (oxidosqualene cyclase) mutants. These results suggested a possible interaction between these two enzymes. In this study, we present evidence that Erg27p interacts with Erg7p, facilitating the association of Erg7p with lipid particles (LPs) and preventing digestion of Erg7p both in the endoplasmic reticulum (ER) and LPs. We demonstrate that Erg27p is required for oxidosqualene cyclase (Erg7p) activity in LPs, and that Erg27p co-immunoprecipitates with Erg7p in LPs but not in microsomal fractions. While Erg27p is essentially a component of the ER, it can also be detected in LPs. In erg27 strains, a truncated Erg7p mislocalizes to microsomes. Restoration of Erg7p enzyme activity and LPs localization was achieved in an erg27 strain transformed with a plasmid containing a wild-type ERG27 allele. We suggest that the physical interaction of Erg27p with Erg7p is an essential regulatory tool in yeast sterol biosynthesis.

Subcellular localization of oxidosqualene cyclases from Arabidopsis thaliana, Trypanosoma cruzi, and Pneumocystis carinii expressed in yeast

Cycloartenol synthase from Arabidopsis thaliana and lanosterol synthase from Trypanosoma cruzi and Pneumocystis carinii were expressed in yeast, and their subcellular distribution in the expressing cells was compared. Determination of enzymatic (oxidosqualene cyclase, OSC) activity and SDS-PAGE analysis of subcellular fractions proved that enzymes from T. cruzi and A. thaliana have high affinity for lipid particles, a subcellular compartment rich in triacylglycerols, and steryl esters, harboring several enzymes of lipid metabolism. In lipid particles of strains expressing the P. carinii enzyme, neither OSC activity nor the electrophoretic band at the appropriate M.W. were detected. Microsomes from the three expressing strains retained some OSC activity. Affinity of enzymes from A. thaliana and T. cruzi for lipid particles is similar to that of OSC of Saccharomyces cerevisiae, which is mainly located in this compartment. A different distribution of OSC in yeast cells suggests that they differ in some structural features critical for the interaction with the surface of lipid particles. Computer analysis supports the hypothesis of the structural difference since OSC from S. cerevisiae, A. thaliana, and T. cruzi lack or contain only one transmembrane spanning domain (a structural feature that makes a protein poorly inclined to associate with lipid particles), whereas OSC from P. carinii possesses six transmembrane domains. In the strain expressing cycloartenol synthase from A. thaliana, the accumulation of lipid particles largely exceeded that of the other strains.

Vinyl sulfide derivatives of truncated oxidosqualene as selective inhibitors of oxidosqualene and squalene-hopene cyclases

Various vinyl sulfide and ketene dithioacetal derivatives of truncated 2,3-oxidosqualene were developed. These compounds, having the reactive functions at positions C-2, C-15 and C-19 of the squalene skeleton, were studied as inhibitors of pig liver and Saccharomyces cerevisiae oxidosqualene cyclases (OSC) (EC 5.4.99.7) and of Alicyclobacillus acidocaldarius squalene hopene cyclase (SHC) (EC 5.4.99.-). They contain one or two sulfur atoms in alpha-skeletal position to carbons considered to be cationic during enzymatic cyclization of the substrate and should strongly interact with enzyme nucleophiles of the active site. Most of the new compounds are inhibitors of the OSC and of SHC, with various degrees of selectivity. The methylthiovinyl derivative, having the reactive group at position 19, was the most potent and selective inhibitor of the series toward S. cerevisiae OSC, with a concentration inhibiting 500% of the activity of 50 nM, while toward the animal enzyme it was 20 times less potent. These results could offer new insight for the design of antifungal drugs.

Radial aplasia, poikiloderma and auto-immune enterocolitis--new syndrome or severe form of Rothmund-Thomson syndrome?

A syndrome is described in three isolated patients in whom the main features are bilateral radial aplasia, short stature, an inflammatory based 'elastic' pyloric stenosis, a pan-enteric inflammatory gut disorder that appears to be due to an autoimmune process, and poikiloderma. Other features in individual cases include cleft palate, micrognathia, anal atresia, patellar aplasia/hypoplasia and sensorineural deafness. This combination may represent a severe form of Rothmund-Thomson syndrome or possibly a previously unrecognized condition.

Rationally designed inhibitors as tools for comparing the mechanism of squalene-hopene cyclase with oxidosqualene cyclase

The inhibition of squalene-hopene cyclase (SHC) (E.C. 5.4.99.-), an enzyme of bacterial membranes catalyzing the formation of pentacyclic sterol-like triterpenes, was studied by using different classes of compounds originally developed as inhibitors of oxidosqualene cyclase (OSC) (E.C. 5.4.99.7), the enzyme of eukaryotes responsible for the formation of tetracyclic precursors of sterols. The mechanism of cyclization of squalene by SHC, beginning with a protonation of the 2,3 double bond by an acidic residue of the enzyme, followed by a series of electrophilic additions of the carbocationic intermediates to the double bonds, is similar to the mechanism of cyclization of 2,3-oxidosqualene by OSC. The inhibitors studied included: (i) analogs of the carbocationic intermediates formed during cyclization, such as aza-analogs of squalene and 2,3-oxidosqualene; (ii) affinity-labeling inhibitors bearing a methylidene reactive group; and (iii) vinyldioxidosqualenes and vinylsulfide derivatives of the substrates. Comparison of the results obtained with the two enzymes, SHC and OSC, showed that many of the most effective inhibitors of OSC were also able to inhibit SHC, while some derivatives acted as specific inhibitors. Differences could be easily explained on the basis of the different substrate specificity of the two enzymes.

Stereospecific syntheses of trans-vinyldioxidosqualene and 3-hydroxysulfide derivatives, as potent and time-dependent 2,3-oxidosqualene cyclase inhibitors

trans-Vinyldioxidosqualene and beta-hydroxysulfide derivatives were synthesized stereospecifically and evaluated as inhibitors of animal and yeast oxidosqualene cyclases. Only trans-vinyldioxidosqualene and 2,3-epoxy-vinyl-beta-hydroxysulfides, having the reactive function at crucial positions 14,15 and 18,19, were active as inhibitors of animal and yeast cyclases. (14-trans)-28-Methylidene-2,3: 14,15-dioxidoundecanorsqualene 27 was the most potent inhibitor of the series of pig liver cyclase, with an IC50 of 0.4 microM, and it behaved also as the most active time-dependent inhibitor of the animal enzyme.

Colon involvement in Langerhans' cell histiocytosis

BACKGROUND

Langerhans' cell histiocytosis (LCH), a granulomatous disorder of unknown cause, most often affects the bony skeleton and skin. Obvious gut involvement is uncommon, and colon involvement has been cited in only a small number of case reports, probably because most patients who have LCH with diarrhoea and/or failure to thrive are not investigated by colonoscopy and biopsy. The current study was conducted to determine the incidence of symptomatic colon involvement among patients with multisystem LCH treated at a single institution.

METHOD

A retrospective review of cases in hospital records and the literature.

RESULTS

Of the 275 children with LCH in the database, 5 were identified as having biopsy-confirmed colonic involvement. Another 14 cases were identified by a literature review.

CONCLUSION

Colonic involvement in patients with multisystem LCH is probably more common than currently recognised. In addition to the other investigations recommended by the Writing Group of the Histiocyte Society, it is recommended that patients with any symptoms suggestive of gut involvement undergo colonoscopy and biopsy of the colonic mucosa.

19-Azasqualene-2,3-epoxide and its N-oxide: metabolic fate and inhibitory effect on sterol biosynthesis in Saccharomyces cerevisiae

19-Azasqualene-2,3-epoxide was more inhibitory than the corresponding N-oxide against 2,3-oxidosqualene cyclase (OSC) solubilized from Saccharomyces cerevisiae (IC50 7+/-2 and 25+/-5 microM, respectively). Both compounds showed a reversible, noncompetitive-type inhibition on solubilized OSC. Different inhibitory properties between the compounds were especially evident when measuring [14C]acetate incorporation into nonsaponifiable lipids extracted from treated cells. In cells treated with 19-azasqualene-2,3-epoxide at 30 microM, the radioactivity associated with the oxidosqualene fraction, which was negligible in the controls, rose to over 40% of the nonsaponifiable lipids, whereas it remained at a slightly appreciable level in cells treated with the N-oxide derivative under the same conditions. 19-Azasqualene-2,3-epoxide was also more effective than the N-oxide as a cell growth inhibitor (minimal concentration of compound needed to inhibit yeast growth: 45 and >100 microM, respectively). The two inhibitors underwent different metabolic fates in the yeast: while 19-azasqualene-2,3-epoxide did not undergo any transformation, its N-oxide was actively reduced to the corresponding amine in whole and in "ultrasonically stimulated" cells. The N-oxide reductases responsible for this transformation appear to be largely confined within the microsomal fractions and require NADPH for their activity. A possible relationship between the inhibitory properties of the two compounds and their metabolic fates is discussed.

Systematic analysis of yeast strains with possible defects in lipid metabolism

Lipids are essential components of all living cells because they are obligate components of biological membranes, and serve as energy reserves and second messengers. Many but not all genes encoding enzymes involved in fatty acid, phospholipid, sterol or sphingolipid biosynthesis of the yeast Saccharomyces cerevisiae have been cloned and gene products have been functionally characterized. Less information is available about genes and gene products governing the transport of lipids between organelles and within membranes or the turnover and degradation of complex lipids. To obtain more insight into lipid metabolism, regulation of lipid biosynthesis and the role of lipids in organellar membranes, a group of five European laboratories established methods suitable to screen for novel genes of the yeast Saccharomyces cerevisiae involved in these processes. These investigations were performed within EUROFAN (European Function Analysis Network), a European initiative to identify the functions of unassigned open reading frames that had been detected during the Yeast Genome Sequencing Project. First, the methods required for the complete lipid analysis of yeast cells based on chromatographic techniques were established and standardized. The reliability of these methods was demonstrated using tester strains with established defects in lipid metabolism. During these investigations it was demonstrated that different wild-type strains, among them FY1679, CEN.PK2-1C and W303, exhibit marked differences in lipid content and lipid composition. Second, several candidate genes which were assumed to encode proteins involved in lipid metabolism were selected, based on their homology to genes of known function. Finally, lipid composition of mutant strains deleted of the respective open reading frames was determined. For some genes we found evidence suggesting a possible role in lipid metabolism.

The role of cisapride in the treatment of pediatric gastroesophageal reflux. The European Society of Paediatric Gastroenterology, Hepatology and Nutrition

BACKGROUND

Cisapride is a gastrointestinal prokinetic agent that is used worldwide in the treatment of gastrointestinal motility-related disorders in premature infants, full-term infants, and children. Efficacy data suggest that it is the most effective commercially available prokinetic drug.

METHODS

Because of recent concerns about safety, a critical and in-depth analysis of all reported adverse events was performed and resulted in the conclusions and recommendations that follow.

RESULTS

Cisapride should only be administered to patients in whom the use of prokinetics is justified according to current medical knowledge. If cisapride is given to pediatric patients who can be considered healthy except for their gastrointestinal motility disorder, and the maximum dose does not exceed 0.8 mg/kg per day in 3 to 4 administrations of 0.2 mg/kg (not exceeding 40 mg/d), no special safety procedures regarding potential cardiac adverse events are recommended. However, if cisapride is prescribed for patients who are known to be or are suspected of being at increased risk for drug-associated increases in QTc interval, certain precautions are advisable. Such patients include those:(1) with a previous history of cardiac dysrhythmias, (2) receiving drugs known to inhibit the metabolism of cisapride and/or adversely affect ventricular repolarisation, (3) with immaturity and/or disease causing reduced cytochrome P450 3A4 activity, or (4) with electrolyte disturbances. In such patients, ECG monitoring to quantitate the QTc interval should be used before initiation of therapy and after 3 days of treatment to ascertain whether a cisapride-induced cardiac adverse effect is present.

CONCLUSIONS

With rare exceptions, the total daily dose of cisapride should not exceed 0.8 mg/kg divided into 3 or 4 approximately equally spaced doses. If higher doses than this are given, the precautions above are advisable. In any patient in whom a prolonged QTc interval is found, the dose of cisapride should be reduced or the drug discontinued until the ECG normalizes. If the QTc interval returns to normal after withdrawal of cisapride, and the administration of cisapride is considered to be justified because of its efficacy and absence of alternative treatment options, cisapride can be restarted at half dose with control of the QTc interval. Unfortunately, at present, normal ranges of QTc interval in children are unknown. However, a critical analysis of the literature suggests that a duration of less than 450 milliseconds can be considered to be within the normal range and greater than 470 milliseconds as outside it.

Synthesis of novel 4,5-diphenylthiazole derivatives as potential acyl-CoA:cholesterol O-acyltransferase inhibitors

Several novel N-(4,5-diphenylthiazol-2-yl)-N'-aryl or alkyl (thio)ureas and N-(4,5-diphenylthiazol-2-yl)alkanamides were prepared as potential acyl-CoA: cholesterol O-acyltransferase (ACAT) inhibitors. Synthesis was accomplished by reaction of 2-amino-4,5-diphenylthiazole with the suitable isocyanate, isothiocyanate or acyl chloride. Some analogues without the 5-phenyl substituent or both the phenyl groups in 4 and 5 position of the thiazole ring were also prepared. Moreover, some bioisosters of the title compounds in which the thiazole ring was replaced by an imidazole were synthesized starting from the 2-amino-4,5-diphenyl-1H-imidazole. The ability of synthesized compounds to inhibit ACAT was evaluated in vitro by measuring the formation of cholesteryl[14C]oleate from cholesterol and [1-14C]oleoyl-CoA in rat liver microsomes. Among the tested compounds, only some thiazole ureas were able to inhibit ACAT in a reasonable degree. N-(4,5-diphenylthiazol-2-yl)- N'-[2,6-bis(2-methylethyl)phenyl] urea (11) and N-(4,5-diphenylthiazol-2-yl)-N'-n-butyl urea (16) were the most active compounds in the series showing IC50 values in the low micromolar range.

Long-term outcome of brain manganese deposition in patients on home parenteral nutrition

Manganese intoxication has been described in children on long term parenteral nutrition presenting with liver and nervous system disorders. Cases are reported of a brother and sister on long term parenteral nutrition with hypermanganesaemia and basal ganglia manganese deposition, detected by magnetic resonance imaging (MRI), without overt neurological signs. Following reduction of manganese intake, basal ganglia manganese was monitored by repeated MRI, and neurological and developmental examinations. An MRI intensity index of the globus pallidus declined over a three year period from 0.318 and 0.385 to 0.205 and 0.134 with concomitant falls in whole blood manganese from 323 and 516 to 226 and 209 nmol/l (normal range, 73-210 nmol/l). Unlike adult experience these children developed normally without neurological signs. In conclusion, deposited manganese is removed from neural tissue over time and the prognosis is good when neurological manifestations and liver disease are absent.

A survey of phenotypic features in juvenile polyposis

Solitary juvenile polyps are quite frequent in children, but juvenile polyposis (JP) is a rare autosomal dominant trait characterised by the occurrence of numerous polyps in the gastrointestinal tract. Extracolonic phenotypic abnormalities are well documented in patients with familial adenomatous polyposis and Peutz-Jeghers syndrome and can allow a clinical diagnosis to be made before the bowel pathology becomes available. Though described, characteristic extracolonic abnormalities have not been clearly defined in juvenile polyposis. We sought to determine whether there are consistent extracolonic phenotypic abnormalities in JP patients and how frequently this would allow diagnosis of one of the genetic syndromes known to be associated with juvenile polyposis. Twenty-two JP patients underwent clinical examination and data from one patient were obtained from case notes. Those consenting to further investigations had x rays of the skull, chest, and hands and an echocardiogram if clinically indicated. Significant extracolonic phenotypic abnormalities were present in 18 patients (14 male and four female), and included dermatological (13), skeletal (16), neurological (5), cardiopulmonary (4), gastrointestinal (3), genitourinary (4), and ocular (1) features. In five patients the diagnosis of a genetic syndrome was possible: two had Bannayan-Riley-Ruvalcaba syndrome, two had Gorlin syndrome, and one had hereditary haemorrhagic telangiectasia (HHT, also known as Osler-Rendu-Weber syndrome). Other patients had some features of these conditions and of Cowden and Simpson-Golabi-Behmel syndromes, but these were not sufficient to allow a definitive diagnosis.

29-Methylidene-2,3-oxidosqualene derivatives as stereospecific mechanism-based inhibitors of liver and yeast oxidosqualene cyclase

Two pairs of isomers (18Z)- (8), (18E)-29-methylidene-2,3-oxidohexanorsqualene (21), and (18Z)- (31), (18E)-29-methylidene-2,3-oxidosqualene (34), have been obtained in a fully stereospecific manner, as inhibitors of rat and yeast oxidosqualene cyclase. A new method for the synthesis of C22 squalene aldehyde 2,3-epoxide is reported, as well as that of other 19-modified 2,3-oxidosqualene analogues. We found that the activity is the opposite in the two series: the (E)-hexanormethylidene 21 and the (Z)-methylidene 31 are potent and irreversible inhibitors of oxidosqualene cyclase, while (Z)-hexanormethylidene 8 and (E)-methylidene 34 are almost completely inactive. Reduction of the 18,19-double bond, such as in 39, eliminates the activity, while removal of both of the 19-linked groups such as in heptanor derivative 40 greatly reduces inhibition of the enzyme. (E)-Hexanormethylidene 21 results the first irreversible inhibitor of the series toward the yeast enzyme.

Human alpha-thrombin inhibition by the highly selective compounds N-ethoxycarbonyl-D-Phe-Pro-alpha-azaLys p-nitrophenyl ester and N-carbobenzoxy-Pro-alpha-azaLys p-nitrophenyl ester: a kinetic, thermodynamic and X-ray crystallographic study

Kinetics, thermodynamics and structural aspects of human alpha-thrombin (thrombin) inhibition by newly synthesized low molecular weight derivatives of alpha-azalysine have been investigated. The thrombin catalyzed hydrolysis of N-ethoxycarbonyl-D-Phe-Pro-alpha-azaLys p-nitrophenyl ester (Eoc-D-Phe-Pro-azaLys-ONp) and N-carbobenzoxy-Pro-alpha-azaLys p-nitrophenyl ester (Cbz-Pro-azaLys-ONp) was investigated at pH 6.2 and 21.0 degrees C, and analyzed in parallel with that of N-alpha-(N,N-dimethylcarbamoyl)-alpha-azalysine p-nitrophenyl ester (Dmc-azaLys-ONp). Decarboxylation following the enzymatic hydrolysis of these p-nitrophenyl esters gave the corresponding 1-peptidyl-2(4-aminobutyl) hydrazines (peptidyl-Abh) showing properties of thrombin competitive inhibitors. Therefore, thermodynamics for the reversible binding of D-Phe-Pro-Abh, Cbz-Pro-Abh and Dmc-Abh to thrombin was examined. These results are consistent with the minimum four-step catalytic mechanism for product inhibition of serine proteinases. Eoc-D-Phe-Pro-azaLys-ONp and Eoc-D-Phe-Pro-Abh display a sub-micromolar affinity for thrombin together with a high selectivity versus homologous plasmatic and pancreatic serine proteinases acting on cationic substrates. The three-dimensional structures of the reversible non-covalent thrombin:Eoc-D-Phe-Pro-Abh and thrombin:Cbz-Pro-Abh complexes have been determined by X-ray crystallography at 2.0 A resolution (R-factor = 0.169 and 0.179, respectively), and analyzed in parallel with that of the thrombin:Dmc-azaLys acyl-enzyme adduct. Both Eoc-D-Phe-Pro-Abh and Cbz-Pro-Abh competitive inhibitors are accommodated in the thrombin active center, spanning the region between the aryl binding site and the S1 primary specificity subsite.

Surface electrogastrography in children with esophageal atresia

Surface electrogastrography was performed in 18 patients with esophageal atresia (EA) and 10 normal controls to investigate the possible role of a congenital enteric nerve defect as a cause of gastroesophageal reflux (GER), which is common after repair of EA. The means of the dominant frequencies and ranges of the frequency distribution were compared. The dominant frequencies (0.047+/-0.007 Hz) in the EA group did not differ significantly from those of the controls (0.050+/-0.007 Hz, P >0.1), although 2 patients had bradygastria and 2 had tachygastria in the EA group. The range of the frequency distribution was significantly wider in the EA group compared with normal children (P = 0.002). The wide frequency distribution in children with EA suggests disturbed electrical activity of the stomach, which could be associated with poor electromechanical coupling and, hence abnormal gastric contraction.

N-ethoxycarbonyl-D-phenylalanyl-L-prolyl-alpha-azalysine p-nitrophenyl ester: a novel, high selective and optimal chromogenic active site titrant for human and bovine alpha-, beta- and gamma-thrombin

The serine proteinase catalyzed hydrolysis of N-ethoxycarbonyl-D-phenylalanyl-L-prolyl-alpha-azalysine p- nitrophenyl ester (Eoc-D-Phe-Pro-azaLys-ONp) was investigated at pH 6.2 and 21.0 degrees C. The results are consistent with the minimum three-step catalytic mechanism. The acylation step is rate limiting for human (Lys 77 species) and porcine plasmin, and for bovine beta-trypsin, the deacylation rate being limiting, on the other hand, for human and bovine alpha-, beta- and gamma-thrombin. Moreover the M(r) 33,000 species of human urokinase and the neuraminidase-treated porcine pancreatic beta-kallikrein-B do not catalyze the hydrolysis of the tripeptide. According to the specificity properties of the serine proteinases considered. Eoc-D-Phe- Pro-azaLys-ONp shows the characteristics of a novel, high selective and optimal chromogenic active site titrant for human and bovine alpha-, beta- and gamma-thrombin.

Haematological abnormalities in Shwachman-Diamond syndrome

We have analysed the haematological parameters in 21 patients with Shwachman-Diamond syndrome (SDS) seen over a 25-year period at our institution. Neutropenia, although present in all patients, was intermittent in two-thirds, constant in the rest and was associated with impaired chemotaxis in all of those patients tested. Fetal haemoglobin (HbF) was elevated in 80% of the patients at some stage, and anaemia and thrombocytopenia was documented in 66% and 24% respectively. Bone marrow samples were taken in over half of the patients. Myelodysplastic syndrome (MDS) developed in seven (33%) patients, five of whom had acquired clonal structural chromosome abnormalities in their bone marrows. In five of the patients with MDS (24%) transformation to acute myeloid leukaemia occurred. Like other constitutional bone marrow failure syndromes. SDS has a predilection to leukaemic transformation hitherto assumed to be in the region of 5-10%. The data presented here suggest that this figure probably represents an underestimate. Shwachman-Diamond syndrome is an interesting model of leukaemia development and greater understanding of the clinical spectrum of this rare disorder should produce further insights into its pathobiology.

Human alpha-thrombin inhibition by the active site titrant N alpha-(N,N-dimethylcarbamoyl)-alpha-azalysine p-nitrophenyl ester: a comparative kinetic and X-ray crystallographic study

Kinetics for the hydrolysis of the chromogenic active site titrant N alpha-(N,N-dimethylcarbamoyl)-alpha-azalysine p-nitrophenyl ester (Dmc-azaLys-ONp) catalyzed by bovine beta-trypsin, bovine alpha-thrombin, human alpha-thrombin, human Lys77-plasmin, human urinary kallikrein, the M(r) 33,000 and M(r) 54,000 species of human urokinase, as well as by porcine pancreatic beta-kallikrein-A and B have been obtained between pH 6.0 and 8.0, at 21.0 degrees C. Moreover, the three dimensional structure of the human alpha-thrombin-(hirugen).Dmc-azaLys acyl.enzyme complex has been analyzed and refined by X-ray crystallography at 2.0 A resolution (R-factor = 0.168). As observed for bovine beta-trypsin, the acylating inhibitor molecule is covalently bound to the Ser195 catalytic residue, filling the human alpha-thrombin S1 primary specificity subsite with its lysyl side-group. However, the carbonyl group of the scissile human alpha-thrombin.Dmc-azaLys acyl bond does not occupy properly the oxyanion binding hole. At variance from the bovine beta-trypsin.Dmc-azaLys acyl.enzyme structure, a second, not covalently bound, inhibitor molecule, partly shielded by the 60-insertion loop of human alpha-thrombin, is contacting the enzyme "aryl-binding site".

Inhibition of bovine beta-trypsin by the active site titrant N alpha-(N,N-dimethylcarbamoyl)-alpha-azaornithine p-nitrophenyl ester: a kinetic and X-ray crystallographic study

Kinetics of the bovine beta-trypsin (trypsin) reaction with the active site titrant N alpha-(N,N-dimethylcarbamoyl)- alpha-aza-ornithine p-nitrophenyl ester (Dmc-azaOrn-ONp) was obtained at pH 6.2 and 21.0 degrees C. The results are consistent with the minimum three-step catalytic mechanism of serine proteinases involving a stable acyl.enzyme adduct. Dmc-azaOrn-ONp binds stoichiometrically to trypsin and allows the reliable determination of the active enzyme concentration between 1.0 x 10(-6) M and 3.0 x 10(-4) M. The three-dimensional structure of the trypsin.Dmc-azaOrn acyl.enzyme adduct has been solved by X-ray crystallography at 1.8 A resolution (R = 0.153). The Dmc-azaOrn moiety of the active site titrant is accommodated in the serine proteinase active center, occupying the S1 specificity subsite, and is covalently linked to the OG atom of the Ser195 catalytic residue.

Effects of vitamin E deficiency on vasomotor activity and ultrastructural organisation of rat thoracic aorta

1. The effects of vitamin E deficiency were evaluated in aortic rings isolated from rats maintained on a diet deficient in vitamin E. 2. Endothelium-dependent vasodilator responses to acetylcholine (ACh) and calcium ionophore, A23187, were reduced in preparations from treated animals, compared to the age-matched controls. The maximal vasodilation to ACh was 66.4 +/- 9 (n = 4) and 38.8 +/- 7 (n = 4) % in control and 10 month-treated preparations, respectively. 3. The endothelium-independent vasodilator responses to sodium nitroprusside as well as the concentration-dependent contractile responses to noradrenaline, did not differ between treated and control preparations. 4. Electron microscopic examination of vascular segments and revealed that, following vitamin E deficiency, normal tissue organisation was disrupted, the endothelial monolayer either not being in contact with the underlying tissue or being absent in most of the areas analysed. 5. It is concluded that during vitamin E deficiency both morphological disruption and functional impairment of endothelium occur without observable modification of muscle cell function and morphology.

Inhibition of bovine beta-trypsin, human alpha-thrombin and porcine pancreatic beta-kallikrein-B by 4',6-diamidino-2-phenylindole, 6-amidinoindole and benzamidine: a comparative thermodynamic and X-ray structural study

The inhibitory effect of 4',6-diamidino-2-phenylindole (DAPI) and 6-amidinoindole on the catalytic properties of bovine beta-trypsin (trypsin), human alpha-thrombin (thrombin) and porcine pancreatic beta-kallikrein-B (kallikrein) was investigated (between pH 3.0 and 7.0, I = 0.1 M; T = 30.0 +/- 0.5 degrees C), and analyzed in parallel with that of benzamidine, commonly taken as a molecular inhibitor model of serine proteinases. Next, the X-ray crystal structure of the trypsin:DAPI complex was solved at 1.9 A resolution (R = 0.161). Over the whole pH range explored, values of the association inhibition constant (Ki) for DAPI and 6-amidinoindole binding to trypsin, thrombin and kallikrein are higher than those found for benzamidine association, suggesting a binding mode of DAPI to the enzyme primary specificity pocket-based on the indole moiety of the inhibitor. On lowering the pH from 5.5 to 3.0, the decrease in affinity for DAPI, 6-amidinoindole and benzamidine binding to trypsin, thrombin and kallikrein reflects the acidic pK shift of the Asp189 invariant residue, present at the bottom of the primary specificity subsite of the serine proteinases considered, from 4.5, in the free enzyme, to 3.7, in the proteinase:inhibitor complexes. Inspection of the refined crystal structure of the trypsin:DAPI complex, however, does not allow a unique interpretation of the inhibitor binding mode. The present data were analysed in parallel with those reported for related serine (pro)enzyme/inhibitor systems.

Hypogammaglobulinaemia secondary to reflux oesophagitis

A 7 year old girl referred for investigation of hypogammaglobulinaemia had hypoalbuminaemia and severe necrotising oesophagitis on oesophagogastroduodenoscopy. Nissen fundoplication resolved all clinical and laboratory abnormalities, but she remains under surveillance because of histological findings of Barrett's oesophagus. Erosive reflux oesophagitis can present with minimal localising symptoms, and hypogammaglobulinaemia and hypoalbuminaemia, presumably from protein loss.

Active site titration of bovine beta-trypsin by N alpha-(N,N-dimethylcarbamoyl)-alpha-aza-lysine p-nitrophenyl ester: kinetic and crystallographic analysis

Kinetics of bovine beta-trypsin (trypsin) with the N alpha-(N,N-dimethylcarbamoyl)-alpha-aza-lysine p-nitrophenyl ester (Dmc-azaLys-ONp) was obtained at pH 6.2 and 21.0 degrees C. Dmc-azaLys-ONp shows the characteristics of an optimal active site titrant in that it (i) gives titrations in a short time, (ii) is a stable and soluble compound with a stoichiometric reaction that is easily and directly detectable, and (iii) allows titrations over a wide range of enzyme concentration. Moreover, the three-dimensional structure of the trypsin.N alpha-(N,N-dimet hylcarbamoyl)-alpha-aza-lysine acyl.enzyme adduct has been solved by X-ray crystallography at 2.0 A resolution (R = 0.145). The Dmc-azaLys moiety of the active site titrant is sited in the serine proteinase reaction center, and is covalently linked to the OG atom of the Ser195 catalytic residue.

Solubilization and identification of essential functional groups of Candida albicans oxidosqualene cyclase

The enzyme properties and location of essential functional groups of solubilized oxidosqualene cyclase of Candida albicans have been studied. We show that the C. albicans enzyme is much more heat-labile compared with Saccharomyces cerevisiae and rat liver cyclases, requires a histidyl residue for enzyme activity, contains an essential thiol residue either close to or in the active site and exhibits a carbocationic mechanism for catalysis, as the enzyme-bound substrate protects the enzyme from inactivation by a site-directed inactivator.

Inhibition of sterol biosynthesis in Saccharomyces cerevisiae and Candida albicans by 22,23-epoxy-2-aza-2,3-dihydrosqualene and the corresponding N-oxide

The abilities of 22,23-epoxy-2-aza-2,3-dihydrosqualene and the corresponding N-oxide, 22,23-epoxy-2-aza-2,3-dihydrosqualene-N-oxide, to inhibit sterol biosynthesis were studied in microsomes and cells of Saccharomyces cerevisiae and Candida albicans. 22,23-Epoxy-2-aza-2,3-dihydrosqualene, which differs from the other inhibitor only in lacking oxygen at position 2, exhibited higher inhibitory properties in all preparations tested. The different levels of effectiveness of the two azasqualene derivatives were evident mostly in microsomes from S. cerevisiae (the 50 inhibitory concentrations of the 2-aza derivative and the corresponding N-oxide on oxidosqualene cyclase were 30 and 120 microM respectively) and in cell cultures of the same strain (1 order of magnitude separated the inhibitory activities of the two compounds on sterol biosynthesis). A possible explanation for the differences between 22,23-epoxy-2-aza-2,3-dihydrosqualene and the corresponding N-oxide arose from the study of their metabolic fates in vivo and in vitro. While the 2-aza derivative did not undergo any transformation, the N-oxide compound was actively reduced to the corresponding amine in microsomes and in cells of both yeast strains. 22,23-Epoxy-2-aza-2,3-dihydrosqualene-N-oxide seems to behave as a proinhibitor of sterol biosynthesis, becoming active only after transformation into the active form 22,23-epoxy-2-aza-2,3-dihydrosqualene.

Electrolyte disturbance with omeprazole therapy

Omeprazole is an antagonist to the H+K+ ATPase of the gastric parietal cell. We report a case of severe electrolyte disturbance in a 5-year-old child treated with omeprazole associated with excessive urinary sodium loss, that responded completely to omeprazole withdrawal.

3-Carboxy-4-nitrophenyl-dithio-1,1',2-trisnorsqualene: a site-directed inactivator of yeast oxidosqualene cyclase

The role and location of essential thiol groups in 2,3-oxidosqualene cyclase from Saccharomyces cerevisiae was examined (i) by comparing inactivation properties of two known thiol reagents, 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) and 2-nitro-5-thiocyanobenzoic acid (NTCB), with 3-carboxy-4-nitrophenyl-dithio-1,1',2-trisnorsqualene (CNDT-squalene), a new thiol reagent designed as a site-directed inactivator of oxidosqualene cyclase and (ii) by testing the ability of the substrate to protect the enzyme against inactivation by the reagents. All reagents gave a time-dependent inactivation following pseudo-first order kinetics. DTNB and CNDT-squalene showed comparable inactivation ability (Ki = 0.67 and 1.21 mM), whereas NTCB was less effective (Ki = 15.6 mM). Strong differences between the two most active inhibitors, DTNB and CNDT-squalene, were observed when the enzyme was saturated with substrate prior to incubation with the thiol reagent. While substrate did not protect the enzyme against the inactivation caused by DTNB, a reduction in the inactivation ability of CNDT-squalene was observed under protection conditions. The data suggest that the squalene-like inactivator modifies a thiol group located at the active site of the enzyme.

Bovine colostrum immunoglobulin concentrate for cryptosporidiosis in AIDS

Lactobin-R is a commercial hyperimmune bovine colostrum with potent anticryptosporidial activity. It was administered to a 4 year old child with AIDS and severe diarrhoea associated with cryptosporidiosis. There was significant clinical improvement in the diarrhoea and permanent elimination of the parasite from the gut as assessed through serial jejunal biopsy and stool specimens.

Differential inhibition of fungal oxidosqualene cyclase by 6E and 6Z isomers of 2,3-epoxy-10-aza-10,11-dihydrosqualene

Inhibitory properties of 6E (compound 1) and 6Z (compound 2) isomers of 2,3-epoxy-10-aza-10,11-dihydrosqualene against oxidosqualene-lanosterol cyclase were assayed on microsomes and whole cells of Saccharomyces cerevisiae and Candida albicans. Only the 6E isomer (compound 1), bearing a correct substrate-like configuration, strongly inhibited the enzyme both in microsomes and cell cultures. The difference between compounds 1 and 2 (which had an unfavorable geometry) was especially evident when measuring [14C]acetate incorporation into non-saponifiable lipids extracted from treated cells. While isomer Z was totally ineffective at up to 30 microM, in cells treated with 5 microM isomer E, labelled oxidosqualene, the level of which was negligible in the control, rose to over 60% of the non-saponifiable lipids.

Psychological characteristics of children with Shwachman syndrome

Twelve children and young adults with Shwachman syndrome were compared with their unaffected siblings and with controls suffering from cystic fibrosis in terms of intellectual ability, motor skills, and behaviour. There were highly significant differences in intelligence quotient between those with Shwachman syndrome and the other two groups. Four of the index subjects but none of the control subjects were below the normal range. The differences between groups on other tests of cognitive and motor skills were not significant, though those with Shwachman syndrome tended to have the lowest scores. There was no evidence that those with Shwachman syndrome had more behavioural difficulties than the control subjects. We suggest that the intellectual difficulties of patients with Shwachman syndrome may be of neurological rather than social origin and that they may originate before birth.

Sucrase-isomaltase deficiency in humans. Different mutations disrupt intracellular transport, processing, and function of an intestinal brush border enzyme

Eight cases of congenital sucrase-isomaltase deficiency were studied at the subcellular and protein level with monoclonal antibodies against sucrase-isomaltase. At least three phenotypes were revealed: one in which sucrase-isomaltase protein accumulated intracellularly probably in the endoplasmic reticulum, as a membrane-associated high-mannose precursor, one in which the intracellular transport of the enzyme was apparently blocked in the Golgi apparatus, and one in which catalytically altered enzyme was transported to the cell surface. All patients expressed electrophoretically normal or near normal high-mannose sucrase-isomaltase. The results suggest that different, probably small, mutations in the sucrase-isomaltase gene lead to the synthesis of transport-incompetent or functionally altered enzyme which results in congenital sucrose intolerance.