Short term outcomes of neonatal opioid withdrawal syndrome: a comparison of two approaches

OBJECTIVE

To evaluate outcomes in opioid exposed neonates (OENs) assessed by the Eat, Sleep, Console (ESC) tool compared to the Finnegan Neonatal Abstinence Scoring System (FNASS).

METHODS

Retrospective analysis of a statewide database of OENs from 2017 to 2020 with birthing hospitals classified based on the assessment tool used. Four main outcomes were examined using multivariable and Poisson logistic regression models.

RESULTS

Of 2375 OENs, 42.1% received pharmacotherapy (PT) with a consistent decrease in PT, length of treatment (LOT), and length of stay (LOS) over the study period. There was no change in use of mother's own milk (MoM). While outcomes were significantly associated with several specific variables, there were no differences in outcomes between assessment methods.

CONCLUSION

While there was a significant decrease over time in PT, LOT, and LOS, improvements were independent of the assessment tool used and likely related to the increased use of non-pharmacologic care.

Progression of Enteral Feeding Volumes in Extremely Low Birth Weight Infants in the "Connection Trial"

OBJECTIVE

 Investigate daily feeding volumes and their association with clinical variables in the early postnatal care of premature infants of the "Connection Trial."

STUDY DESIGN

 A total of 641 infants of 510 to 1,000-g birth weight (BW, mean: 847 g) and mean 27 weeks' gestational age at birth (GA) were analyzed for total daily enteral (TDE) feeding volumes of 10, 20, 40, 80, and 120 mL/kg/d and their association with 24 clinical variables. Uni- and multivariable Cox regression models were used to calculate hazard ratios (HR) with 95% confidence intervals as a measure of the chance of reaching each of the TDE volumes.

RESULTS

 Daily feeding volumes were highly variable and the median advancement from 10 to 120 mL/kg/d was 11 mL/kg/d. Univariable analyses showed the lowest chance (HR, 0.22-0.81) of reaching the TDE volumes for gastrointestinal (GI) serious adverse events (SAEs), GI perforation, GI obstruction, and necrotizing enterocolitis, as well as respiratory SAEs, persistent ductus arteriosus, and hypotension. Each GA week, 100-g BW, and point in 5-minute Apgar score at birth associated with 8 to 20% increased chance of reaching the TDE volumes. Multivariable analyses showed independent effects for BW, GA, Apgar score, GI SAEs, abdominal symptoms/signs, respiratory SAEs, days on antibiotics, and hypotension.

CONCLUSION

 This observational analysis demonstrates the variable and cautious progression of enteral feedings in contemporary extremely low BW infants and the extent to which clinical variables associate with this progression.

KEY POINTS

· Total feedings of 10 and 120 mL/kg/d were reached at median 4 and 14 day of age, respectively, and at a daily increase of 11 mL/kg.. · Each incremental GA week, 100-g BW, and point in 5-minute Apgar score associated with 8 to 20% increased chance of reaching enteral feedings of 10 to 120 mL/kg/d.. · Progression of enteral feeding associated with several clinical events and was slower than advocated in common feeding protocols..

Neonatal Opioid Withdrawal Syndrome: A Comparison of As-Needed Pharmacotherapy

BACKGROUND AND OBJECTIVE

Methadone and morphine are commonly administered medications for neonatal opioid withdrawal syndrome (NOWS). Infants are increasingly treated with as-needed or "pro re nata" (PRN) medication. The optimal pharmacologic agent for PRN treatment of NOWS has not been examined. This study's objective is to compare NOWS hospital outcomes between infants treated with PRN methadone versus morphine.

METHODS

We performed a retrospective cohort study of infants pharmacologically treated for NOWS across 4 Massachusetts hospitals between January 2018 and February 2021. Infants born ≥36 weeks gestation with prenatal opioid exposure treated with PRN methadone or morphine were included. Mixed effects logistic and linear regression models were employed to evaluate differences in transition rates to scheduled dosing, length of stay, and number of PRN doses administered depending on PRN treatment agent.

RESULTS

There were 86 infants in the methadone group and 52 in the morphine group. There were no significant differences in NOWS hospital outcomes between groups in adjusted models: transition to scheduled dosing (methadone 31.6% vs morphine 28.6%, adjusted odds ratio 1.21, 95% confidence interval [CI] 0.87-1.19), mean length of stay (methadone 15.5 vs morphine 14.3 days, adjusted risk ratio 1.06, 95% CI 0.80-1.41), and the mean number of PRN doses (methadone 2.3 vs morphine 3.4, adjusted risk ratio 0.65, 95% CI 0.41-1.02). There was an association with nonpharmacologic care practices and improved NOWS hospital outcomes.

CONCLUSIONS

There were no significant differences in NOWS hospitalization outcomes based on pharmacologic agent type; nonpharmacologic care practices were most strongly associated with improved NOWS hospitalization outcomes.

Volumetric laser endomicroscopy and its application to Barrett's esophagus: results from a 1,000 patient registry

Volumetric laser endomicroscopy (VLE) uses optical coherence tomography (OCT) for real-time, microscopic cross-sectional imaging. A US-based multi-center registry was constructed to prospectively collect data on patients undergoing upper endoscopy during which a VLE scan was performed. The objective of this registry was to determine usage patterns of VLE in clinical practice and to estimate quantitative and qualitative performance metrics as they are applied to Barrett's esophagus (BE) management. All procedures utilized the NvisionVLE Imaging System (NinePoint Medical, Bedford, MA) which was used by investigators to identify the tissue types present, along with focal areas of concern. Following the VLE procedure, investigators were asked to answer six key questions regarding how VLE impacted each case. Statistical analyses including neoplasia diagnostic yield improvement using VLE was performed. One thousand patients were enrolled across 18 US trial sites from August 2014 through April 2016. In patients with previously diagnosed or suspected BE (894/1000), investigators used VLE and identified areas of concern not seen on white light endoscopy (WLE) in 59% of the procedures. VLE imaging also guided tissue acquisition and treatment in 71% and 54% of procedures, respectively. VLE as an adjunct modality improved the neoplasia diagnostic yield by 55% beyond the standard of care practice. In patients with no prior history of therapy, and without visual findings from other technologies, VLE-guided tissue acquisition increased neoplasia detection over random biopsies by 700%. Registry investigators reported that VLE improved the BE management process when used as an adjunct tissue acquisition and treatment guidance tool. The ability of VLE to image large segments of the esophagus with microscopic cross-sectional detail may provide additional benefits including higher yield biopsies and more efficient tissue acquisition. Clinicaltrials.gov NCT02215291.

The Consensus from the Mycobacterium avium ssp. paratuberculosis (MAP) Conference 2017

On March 24 and 25, 2017 researchers and clinicians from around the world met at Temple University in Philadelphia to discuss the current knowledge of Mycobacterium avium ssp. paratuberculosis (MAP) and its relationship to human disease. The conference was held because of shared concern that MAP is a zoonotic bacterium that poses a threat not only to animal health but also human health. In order to further study this problem, the conferees discussed ways to improve MAP diagnostic tests and discussed potential future anti-MAP clinical trials. The conference proceedings may be viewed on the www.Humanpara.org website. A summary of the salient work in this field is followed by recommendations from a majority of the conferees.

Abstract P4-07-05: MEDI3379, an antibody against HER3, is active in HER2-driven human breast tumor models

HER3 (ERBB3) is a member of the EGFR/HER family of receptor tyrosine kinases (RTK), consisting of EGFR, HER2, HER3 and HER4. Unlike the other HER family members, HER3 lacks intrinsic tyrosine kinase activity and therefore needs to form heterodimers with EGFR, HER2 or other kinase-proficient RTKs to be functionally active. Dimerization is induced by overexpression of EGFR or HER2 in a ligand-independent (LI) manner. In this process HER3 acts as a driver in divergent cancer types including HER2-positive breast cancer (BC) via induction of the PI3K-AKT pathway. Alternatively, heregulin (NRG1/HRG), the major HER3 ligand, induces a conformational shift in HER3 which leads to dimer formation with a partner RTK in a ligand-dependent (LD) manner.

We have developed an antagonistic human monoclonal antibody against HER3, termed MEDI3379, and tested it in multiple breast cancer cell lines. We observed effective suppression of constitutive pHER3 and pAKT with MEDI3379, leading to anti-proliferation effects in cell culture models. Preclinical evaluation of MEDI3379 demonstrated antitumor activity in several orthotopic BC xenografts in nude mice which did not express HRG. For example, the BC xenograft model BT474 with amplified HER2 responded to MEDI3379 (65% dTGI). In conclusion, our findings with targeting of HER3 in mouse models support continued development of MEDI3379 for cancer.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-07-05.

Endoscopic sutured closure of a gastric natural orifice transluminal endoscopic surgery access gastrotomy compared with open surgical closure in a porcine model. A randomized, multicenter controlled trial

BACKGROUND AND STUDY AIMS

In natural orifice transluminal endoscopic surgery (NOTES) procedures it is essential to be able to perform secure closure of the access perforation. The aim of this study was to compare endoscopically sutured closure of a gastric access gastrotomy using the tissue apposition system (TAS), with closure via laparotomy in a randomized multicenter study.

METHODS

A total of 32 pigs (18 - 42 kg) were used in this study. The gastric NOTES access was created using a needle knife and a 20-mm balloon. Following transgastric pelvic peritoneoscopy, the endoscope was withdrawn into the stomach. The animals were then randomized to endoscopic closure or laparotomy with surgical closure. Procedure time, recovery time, and weight gain were measured. At necropsy, adhesions, abscesses or peritonitis were recorded.

RESULTS

Of the 32 pigs, 29 survived 14 days without complications. All endoscopic and all open surgical closures were secure at postmortem. On average two suture pairs were used for endoscopic closure. Surgical closure was quicker (12.5 vs. 20.1 minutes). Recovery time and postoperative weight gain were similar for both groups. Two pigs in the endoscopic group died: one of gastric dilatation, without leakage from the gastrotomy; another was euthanized due to rectal prolapse. In the laparotomy group one pig was euthanized after 7 days due to abdominal wound dehiscence. At necropsy there were significantly more intra-abdominal adhesions in the laparotomized group.

CONCLUSION

This randomized controlled study of endoscopic and surgical closure of a gastrotomy made for transperitoneal access for NOTES procedures suggests that both techniques are comparable in technical closure rates, postoperative recovery, and prevention of peritonitis. There were fewer adhesions in the endoscopic group.

Modeling stem cell asymmetry in yeast

For adult stem cells to both self-renew and give rise to differentiating progenitors, they must undergo an inherently asymmetric division. This defining model of asymmetric cell division requires either that stem cells preferentially distribute internal factors, thereby maintaining a stem cell phenotype in one lineage, or that extrinsic signals determine the fate of daughter cells, allowing the maintenance of one stem cell lineage. Although microbial systems are often used to model asymmetry, lineage-specific asymmetry has not been characterized in these organisms. Recently, we identified a stem-cell-like lineage-specific pattern of kinetochore asymmetry in postmeiotic yeast spores. Because the function of the kinetochore is to segregate chromosomes, this asymmetry has the potential to segregate sister chromatids nonrandomly. This may be relevant to stem cells because more than 30 years ago, it was proposed that stem cells selectively segregate one strand of their chromosomes into the self-renewing stem cell lineage (Cairns 1975). Although advanced labeling methods have provided evidence to both support and refute this hypothesis, it remains unclear how nonrandom sister-chromatid segregation might be achieved in a stem cell lineage. We have identified a kinetochore-specific mechanism in yeast that could support lineage-specific nonrandom sister-chromatid segregation and we discuss the implications of this observation.

Endoscopic full-thickness plication for the treatment of GERD: long-term multicenter results

BACKGROUND

The purpose of the present study was to assess the long-term safety and durability of effect for endoscopic full-thickness plication for the treatment of symptomatic gastroesophageal reflux disease (GERD). The Plicator (NDO Surgical, Inc., Mansfield, MA) used delivers a transmural suture through the gastric cardia to restructure the antireflux barrier. Published reports have shown the Plicator procedure to be effective in reducing GERD symptoms and medication use at 1 year post-plication.

METHODS

Twenty-nine patients with chronic heartburn requiring maintenance daily anti-secretory therapy were treated at five sites. Patients received a single full-thickness plication in the gastric cardia 1cm below the gastroesophageal junction (GE) junction. Re-treatments were not permitted. Patients were evaluated at baseline for GERD symptoms and medication use. Intermediate (12 month) and long-term subject follow-up (median follow-up: 36.4 months; range, 31.2-43.9 months) were completed to evaluate procedure safety and durability of effect.

RESULTS

Twenty-nine patients completed the 12-month and 36-month follow-up. All procedure-related adverse events occurred acutely, and no new events were observed during extended follow-up. At 36-months post-procedure, 57% (16/28) of baseline proton pump inhibitor (PPI)-dependent patients remained off daily PPI therapy. Treatment effect remained stable from 12- to 36-months, with 21/29 patients off daily PPI at 12 months compared to 17/29 patients at 36-months. Median GERD- Health Related Quality of Life (HRQL) scores remained significantly improved at 36 months versus baseline off-meds scores (8 versus 19, p < 0.001). In addition, the proportion of patients achieving > or = 50% improvement in GERD-HRQL score was consistent from 12 months (59%) to 36 months (55%).

CONCLUSIONS

Endoscopic full-thickness plication can reduce GERD symptoms and medication use for at least 3-years post-procedure. Treatment effect is stable from 1 to 3 years, and there are no long-term procedural adverse effects.

Histamine receptor antagonists and incident colorectal adenomas

BACKGROUND

Prior studies suggest that histamines may modulate the development of colorectal neoplasia.

AIM

To assess whether histamine receptor antagonist use was associated with adenoma formation.

METHODS

Patients (n = 2366) were drawn from three adenoma chemoprevention trials. All underwent baseline colonoscopy with removal of adenoma(s) and were deemed free of remaining lesions; they were followed with surveillance colonoscopy. Medication use was assessed by questionnaire. Adjusted risk ratios for adenoma formation related to histamine receptor antagonist use (histamine H1 and H2 receptor, H1RA and H2RA) were determined using log linear models.

RESULTS

In pooled analyses, H1RA exposure was not associated with subsequent adenoma risk (RR = 1.10; 95% CI 0.97-1.25) or multiple adenoma formation (RR = 0.85; 95% CI 0.67-1.07). H2RA use also was not associated with adenoma (RR = 0.90; 95% CI 0.77-1.06), or multiple adenoma (RR = 0.77; 95% CI 0.57-1.04) in the pooled analyses, but H2RA users in the first trial had a decreased risk of adenoma (RR = 0.70; 95% CI 0.48-1.03) and multiple adenoma (RR = 0.31; 95% CI 0.12-0.79).

CONCLUSION

H2RA use was associated with reduced risk for adenoma in one trial, but not in the pooled analyses. Further study would be warranted before undertaking randomized trials of H2RAs for adenoma chemoprevention.

Rad52 forms DNA repair and recombination centers during S phase

Maintenance of genomic integrity and stable transmission of genetic information depend on a number of DNA repair processes. Failure to faithfully perform these processes can result in genetic alterations and subsequent development of cancer and other genetic diseases. In the eukaryote Saccharomyces cerevisiae, homologous recombination is the major pathway for repairing DNA double-strand breaks. The key role played by Rad52 in this pathway has been attributed to its ability to seek out and mediate annealing of homologous DNA strands. In this study, we find that S. cerevisiae Rad52 fused to green fluorescent protein (GFP) is fully functional in DNA repair and recombination. After induction of DNA double-strand breaks by gamma-irradiation, meiosis, or the HO endonuclease, Rad52-GFP relocalizes from a diffuse nuclear distribution to distinct foci. Interestingly, Rad52 foci are formed almost exclusively during the S phase of mitotic cells, consistent with coordination between recombinational repair and DNA replication. This notion is further strengthened by the dramatic increase in the frequency of Rad52 focus formation observed in a pol12-100 replication mutant and a mec1 DNA damage checkpoint mutant. Furthermore, our data indicate that each Rad52 focus represents a center of recombinational repair capable of processing multiple DNA lesions.

Mutational and structural analyses of the ribonucleotide reductase inhibitor Sml1 define its Rnr1 interaction domain whose inactivation allows suppression of mec1 and rad53 lethality

In budding yeast, MEC1 and RAD53 are essential for cell growth. Previously we reported that mec1 or rad53 lethality is suppressed by removal of Sml1, a protein that binds to the large subunit of ribonucleotide reductase (Rnr1) and inhibits RNR activity. To understand further the relationship between this suppression and the Sml1-Rnr1 interaction, we randomly mutagenized the SML1 open reading frame. Seven mutations were identified that did not affect protein expression levels but relieved mec1 and rad53 inviability. Interestingly, all seven mutations abolish the Sml1 interaction with Rnr1, suggesting that this interaction causes the lethality observed in mec1 and rad53 strains. The mutant residues all cluster within the 33 C-terminal amino acids of the 104-amino-acid-long Sml1 protein. Four of these residues reside within an alpha-helical structure that was revealed by nuclear magnetic resonance studies. Moreover, deletions encompassing the N-terminal half of Sml1 do not interfere with its RNR inhibitory activity. Finally, the seven sml1 mutations also disrupt the interaction with yeast Rnr3 and human R1, suggesting a conserved binding mechanism between Sml1 and the large subunit of RNR from different species.

Evolutionary implications of the frequent horizontal transfer of mismatch repair genes

Mutation and subsequent recombination events create genetic diversity, which is subjected to natural selection. Bacterial mismatch repair (MMR) deficient mutants, exhibiting high mutation and homologous recombination rates, are frequently found in natural populations. Therefore, we have explored the possibility that MMR deficiency emerging in nature has left some "imprint" in the sequence of bacterial genomes. Comparative molecular phylogeny of MMR genes from natural Escherichia coli isolates shows that, compared to housekeeping genes, individual functional MMR genes exhibit high sequence mosaicism derived from diverse phylogenetic lineages. This apparent horizontal gene transfer correlates with hyperrecombination phenotype of MMR-deficient mutators. The sequence mosaicism of MMR genes may be a hallmark of a mechanism of adaptive evolution that involves modulation of mutation and recombination rates by recurrent losses and reacquisitions of MMR gene functions.

Intragenic inversion of mtDNA: a new type of pathogenic mutation in a patient with mitochondrial myopathy

We report an unusual molecular defect in the mitochondrially encoded ND1 subunit of NADH ubiquinone oxidoreductase (complex I) in a patient with mitochondrial myopathy and isolated complex I deficiency. The mutation is an inversion of seven nucleotides within the ND1 gene, which maintains the reading frame. The inversion, which alters three highly conserved amino acids in the polypeptide, was heteroplasmic in the patient's muscle but was not detectable in blood. This is the first report of a pathogenic inversion mutation in human mtDNA.

Calcium supplements and colorectal adenomas. Polyp Prevention Study Group

Experimental and observational findings suggest that calcium intake may protect against colorectal neoplasia. To investigate this hypothesis, we conducted a randomized, double-blind trial of colorectal adenoma recurrence. Nine hundred thirty patients with a recent history of colorectal adenomas were randomly given calcium carbonate (3 gm daily; 1200 mg elemental calcium) or placebo, with follow-up colonoscopies one and four years after the qualifying examination. The main analysis focused on new adenomas found after the first follow-up endoscopy, up to (and including) the second follow-up examination. Risk ratios of at least one recurrent adenoma and ratios of the average numbers of adenomas were calculated as measures of calcium effect. There was a lower risk of recurrent adenomas in subjects assigned calcium. Eight hundred thirty-two patients had two follow-up examinations and were included in the main analysis; the adjusted risk ratio of one or more adenomas was 0.81 (95% CI 0.67 to 0.99); the adjusted ratio of the average numbers of adenomas was 0.76 (95% CI 0.60 to 0.96). Among subjects who had at least one follow-up colonoscopy, the adjusted risk ratio of one or more recurrent adenomas was 0.85 (95% CI 0.74 to 0.98). The effect of calcium seemed independent of initial dietary fat and calcium intake. No toxicity was associated with supplementation. These findings indicate that calcium supplementation has a modest protective effect against colorectal adenomas, precursors of most colorectal cancers.

YAC transgene-mediated olfactory receptor gene choice

In the mouse, individual olfactory neurons express one of a thousand distinct olfactory receptor genes. Furthermore, only one allele of the expressed gene is transcribed. This phenomenon, random allelic inactivation, along with the observation that the olfactory receptor genes reside in large chromosomal arrays, suggests a role for long-range gene regulation in olfactory receptor gene choice. We have constructed a 300-kb yeast artificial chromosome (YAC) transgene in which a single receptor gene is marked while maintaining its coding region. This 300-kb piece of DNA functions as an independent olfactory receptor gene locus in directing olfactory receptor gene choice in both the olfactory system and the accessory olfactory system (vomeronasal organ, VNO). Furthermore, the transgene, like endogenous olfactory receptor loci, is subject to allelic inactivation.

Rsp5, a ubiquitin-protein ligase, is involved in degradation of the single-stranded-DNA binding protein rfa1 in Saccharomyces cerevisiae

In Saccharomyces cerevisiae, RAD1 and RAD52 are required for alternate pathways of mitotic recombination. Double-mutant strains exhibit a synergistic interaction that decreases direct repeat recombination rates dramatically. A mutation in RFA1, the largest subunit of a single-stranded DNA-binding protein complex (RP-A), suppresses the recombination deficiency of rad1 rad52 strains (J. Smith and R. Rothstein, Mol. Cell. Biol. 15:1632-1641, 1995). Previously, we hypothesized that this mutation, rfa1-D228Y, causes an increase in recombinogenic lesions as well as the activation of a RAD52-independent recombination pathway. To identify gene(s) acting in this pathway, temperature-sensitive (ts) mutations were screened for those that decrease recombination levels in a rad1 rad52 rfa1-D228Y strain. Three mutants were isolated. Each segregates as a single recessive gene. Two are allelic to RSP5, which encodes an essential ubiquitin-protein ligase. One allele, rsp5-25, contains two mutations within its open reading frame. The first mutation does not alter the amino acid sequence of Rsp5, but it decreases the amount of full-length protein in vivo. The second mutation results in the substitution of a tryptophan with a leucine residue in the ubiquitination domain. In rsp5-25 mutants, the UV sensitivity of rfa1-D228Y is suppressed to the same level as in strains overexpressing Rfa1-D228Y. Measurement of the relative rate of protein turnover demonstrated that the half-life of Rfa1-D228Y in rsp5-25 mutants was extended to 65 min compared to a 35-min half-life in wild-type strains. We propose that Rsp5 is involved in the degradation of Rfa1 linking ubiquitination with the replication-recombination machinery.

Characterization of genetic interactions with RFA1: the role of RPA in DNA replication and telomere maintenance

Replication protein A (RPA) is a heterotrimeric single-stranded DNA binding protein whose role in DNA replication, recombination and repair has been mainly elucidated through in vitro biochemical studies utilizing the mammalian complex. However, the identification of homologs of all three subunits in Saccharomyces cerevisiae offers the opportunity of examining the in vivo role of RPA. In our laboratory, we have previously isolated a missense allele of the RFA1 gene, encoding the p70 subunit of the RPA complex. Strains containing this mutant allele, rfa1-D228Y, display increased levels of direct-repeat recombination, decreased levels of heteroallelic recombination, UV sensitivity and a S-phase delay. In this study, we have characterized further the role of RPA by screening other replication and repair mutants for a synthetic lethal phenotype in combination with the rfa1-D228Y allele. Among the replication mutants examined, only one displayed a synthetic lethal phenotype, pol12-100, a conditional allele of the B subunit of pol alpha-primase. In addition, a delayed senescence phenotype was observed in raf1-D228Y strains containing a null mutation of HDF1, the S. cerevisiae homolog of the 70 kDa subunit of Ku. Interestingly, a synergistic reduction in telomere length observed in the double mutants suggests that the shortening of telomeres may be the cause of the decreased viability in these strains. Furthermore, this result represents the first evidence of a role for RPA in telomere maintenance.

A double-blind multicenter comparison of domperidone and metoclopramide in the treatment of diabetic patients with symptoms of gastroparesis

OBJECTIVE

A double-blind, multicenter, randomized trial was conducted to compare the side effects and efficacy of domperidone and metoclopramide in symptomatic diabetic gastroparesis.

METHODS

Ninety-three insulin-dependent diabetes patients with a > or = 3-month history of gastroparesis symptoms were recruited; 48 received domperidone 2 x 10-mg tablets 4 times daily, and 45 received metoclopramide 1 x 10-mg tablet + 1 placebo tablet 4 times daily. Nausea, vomiting, bloating/distension, and early satiety were evaluated for severity after 2 and 4 wk. Adverse central nervous system (CNS) effects of somnolence, akathisia, asthenia, anxiety, depression, and reduced mental acuity were elicited and graded for severity at 2 and 4 wk.

RESULTS

Domperidone and metoclopramide were equally effective in alleviating symptoms of diabetic gastroparesis. Elicited adverse CNS effects were more severe and more common with metoclopramide. Somnolence was acknowledged by 49% of patients (mean severity score, 1.03) after 4 wk of metoclopramide compared with 29% of patients (mean severity score, 0.49) after 4 wk of domperidone (incidence, p = 0.02; severity; p = 0.03). A reduction in mental acuity was acknowledged by 33% of patients (mean severity score, 0.62) after 4 wk of metoclopramide, compared with 20% of patients (mean severity score, 0.27) after 4 wk of domperidone (incidence, p = 0.04; severity, p = 0.04). Akathisia, asthenia, anxiety, and depression were also acknowledged less often, and at a lower severity, after 4 wk of domperidone, although these differences were not statistically significant.

CONCLUSIONS

Domperidone and metoclopramide effectively reduce the symptoms of diabetic gastroparesis; CNS side effects are more pronounced with metoclopramide.

A double-blind multicenter comparison of domperidone and metoclopramide in the treatment of diabetic patients with symptoms of gastroparesis

OBJECTIVE

A double-blind, multicenter, randomized trial was conducted to compare the side effects and efficacy of domperidone and metoclopramide in symptomatic diabetic gastroparesis.

METHODS

Ninety-three insulin-dependent diabetes patients with a > or = 3-month history of gastroparesis symptoms were recruited; 48 received domperidone 2 x 10-mg tablets 4 times daily, and 45 received metoclopramide 1 x 10-mg tablet + 1 placebo tablet 4 times daily. Nausea, vomiting, bloating/distension, and early satiety were evaluated for severity after 2 and 4 wk. Adverse central nervous system (CNS) effects of somnolence, akathisia, asthenia, anxiety, depression, and reduced mental acuity were elicited and graded for severity at 2 and 4 wk.

RESULTS

Domperidone and metoclopramide were equally effective in alleviating symptoms of diabetic gastroparesis. Elicited adverse CNS effects were more severe and more common with metoclopramide. Somnolence was acknowledged by 49% of patients (mean severity score, 1.03) after 4 wk of metoclopramide compared with 29% of patients (mean severity score, 0.49) after 4 wk of domperidone (incidence, p = 0.02; severity; p = 0.03). A reduction in mental acuity was acknowledged by 33% of patients (mean severity score, 0.62) after 4 wk of metoclopramide, compared with 20% of patients (mean severity score, 0.27) after 4 wk of domperidone (incidence, p = 0.04; severity, p = 0.04). Akathisia, asthenia, anxiety, and depression were also acknowledged less often, and at a lower severity, after 4 wk of domperidone, although these differences were not statistically significant.

CONCLUSIONS

Domperidone and metoclopramide effectively reduce the symptoms of diabetic gastroparesis; CNS side effects are more pronounced with metoclopramide.

Three-dimensional microscopy of the Rad51 recombination protein during meiotic prophase

An open question in meiosis is whether the Rad51 recombination protein functions solely in meiotic recombination or whether it is also involved in the chromosome homology search. To address this question, we have performed three-dimensional high-resolution immunofluorescence microscopy to visualize native Rad51 structures in maize male meiocytes. Maize has two closely related RAD51 genes that are expressed at low levels in differentiated tissues and at higher levels in mitotic and meiotic tissues. Cells and nuclei were specially fixed and embedded in polyacrylamide to maintain both native chromosome structure and the three dimensionality of the specimens. Analysis of Rad51 in maize meiocytes revealed that when chromosomes condense during leptotene, Rad51 is diffuse within the nucleus. Rad51 foci form on the chromosomes at the beginning of zygotene and rise to approximately 500 per nucleus by mid-zygotene when chromosomes are pairing and synapsing. During chromosome pairing, we consistently found two contiguous Rad51 foci on paired chromosomes. These paired foci may identify the sites where DNA sequence homology is being compared. During pachytene, the number of Rad51 foci drops to seven to 22 per nucleus. This higher number corresponds approximately to the number of chiasmata in maize meiosis. These observations are consistent with a role for Rad51 in the homology search phase of chromosome pairing in addition to its known role in meiotic recombination.

The essential role of yeast topoisomerase III in meiosis depends on recombination

Yeast cells mutant for TOP3, the gene encoding the evolutionary conserved type I-5' topoisomerase, display a wide range of phenotypes including altered cell cycle, hyper-recombination, abnormal gene expression, poor mating, chromosome instability and absence of sporulation. In this report, an analysis of the role of TOP3 in the meiotic process indicates that top3Delta mutants enter meiosis and complete the initial steps of recombination. However, reductional division does not occur. Deletion of the SPO11 gene, which prevents recombination between homologous chromosomes in meiosis I division, allows top3Delta mutants to form viable spores, indicating that Top3 is required to complete recombination successfully. A topoisomerase activity is involved in this process, since expression of bacterial TopA in yeast top3Delta mutants permits sporulation. The meiotic block is also partially suppressed by a deletion of SGS1, a gene encoding a helicase that interacts with Top3. We propose an essential role for Top3 in the processing of molecules generated during meiotic recombination.

An allele of RFA1 suppresses RAD52-dependent double-strand break repair in Saccharomyces cerevisiae

An allele of RFA1, the largest subunit of the single-stranded DNA-binding complex RP-A, was identified as a suppressor of decreased direct-repeat recombination in rad1 rad52 double mutants. In this study, we used two LEU2 direct-repeat assays to investigate the mechanism by which the rfa1-D228Y allele increases recombination. We found that both intrachromatid and sister chromatid recombination are stimulated in rfa1-D228Y strains. In a rad1 rad52 background, however, the majority of the increased recombination is caused by stimulation of deletion events by an intrachromatid recombination mechanism that is likely to be single-strand annealing. Studies in which an HO endonuclease cut was introduced between the two leu2 copies indicate that the rfa1-D228Y mutation partially suppresses the rad52 defect in recovering recombination products. Furthermore, molecular analysis of processing and product formation kinetics reveals that, in a rad52 background, the rfa1-D228Y mutation results in increased levels of recombinant products and the disappearance of large single-stranded intermediates characteristic of rad52 strains. On the basis of these results, we propose that in the absence of wild-type Rad52, the interaction of RP-A with single-stranded DNA inhibits strand annealing, and that this inhibition is overcome by the rfa1-D228Y mutation.

Calcium supplements for the prevention of colorectal adenomas. Calcium Polyp Prevention Study Group

BACKGROUND AND METHODS

Laboratory, clinical, and epidemiologic evidence suggests that calcium may help prevent colorectal adenomas. We conducted a randomized, double-blind trial of the effect of supplementation with calcium carbonate on the recurrence of colorectal adenomas. We randomly assigned 930 subjects (mean age, 61 years; 72 percent men) with a recent history of colorectal adenomas to receive either calcium carbonate (3 g [1200 mg of elemental calcium] daily) or placebo, with follow-up colonoscopies one and four years after the qualifying examination. The primary end point was the proportion of subjects in whom at least one adenoma was detected after the first follow-up endoscopy but up to (and including) the second follow-up examination. Risk ratios for the recurrence of adenomas were adjusted for age, sex, lifetime number of adenomas before the study, clinical center, and length of the surveillance period.

RESULTS

The subjects in the calcium group had a lower risk of recurrent adenomas. Among the 913 subjects who underwent at least one study colonoscopy, the adjusted risk ratio for any recurrence of adenoma with calcium as compared with placebo was 0.85 (95 percent confidence interval, 0.74 to 0.98; P=0.03). The main analysis was based on the 832 subjects (409 in the calcium group and 423 in the placebo group) who completed both follow-up examinations. At least one adenoma was diagnosed between the first and second follow-up endoscopies in 127 subjects in the calcium group (31 percent) and 159 subjects in the placebo group (38 percent); the adjusted risk ratio was 0.81 (95 percent confidence interval, 0.67 to 0.99; P=0.04). The adjusted ratio of the average number of adenomas in the calcium group to that in the placebo group was 0.76 (95 percent confidence interval, 0.60 to 0.96; P=0.02). The effect of calcium was independent of initial dietary fat and calcium intake.

CONCLUSIONS

Calcium supplementation is associated with a significant - though moderate - reduction in the risk of recurrent colorectal adenomas.

The colonoscopic miss rate and true one-year recurrence of colorectal neoplastic polyps. Polyp Prevention Study Group

OBJECTIVE

Studies of tandem colonoscopies have reported that 15-25% of neoplastic polyps <1 cm in size and 0-6% of larger polyps are overlooked at the time of colonoscopy. We determined the miss rate and "true" 1-yr recurrence of neoplastic polyps in a population of patients reflecting a broad spectrum of different gastroenterology practice settings.

METHODS

Patient data from several sources were examined for repeat colonoscopies performed on the same patient within 120 days of each other. Examination pairs were included for analysis if both colonoscopies had good preps and reached the cecum. The miss rate was calculated by two methods: 1) a pooled rate, the total number of polyps on all second examinations divided by the total number on both examinations, and 2) a within-person rate, the average of the individual miss-rates. We estimated a "true" 1-yr recurrence rate by subtracting the proportion of patients with a missed neoplastic polyp from the proportion of patients with a neoplastic polyp found at 1 yr.

RESULTS

A total of 76 colonoscopy pairs a mean 47 days apart (range, 1-119 days) were identified from a total of approximately 15,000 examinations and used to calculate the overall miss rates. For the category "all polyps" (neoplastic and nonneoplastic polyps), 17% by the pooled method and 11% by the within-person method were missed. The corresponding rates for neoplastic polyps were 12% by the pooled method and 8% by the within-person method. A total of 17% of patients had one or more neoplastic polyps missed on the initial examination. The observed 1-yr recurrence rate was determined from 1,314 colonoscopy pairs performed a mean of 379 days apart and found to be 28% for neoplastic polyps. By comparing this to the proportion of patients with one or more missed neoplastic polyps, we found the true 1-yr recurrence of neoplastic polyps to be 11%.

CONCLUSION

There is a significant colonoscopic miss rate for neoplastic polyps and "all polyps" in clinical practice that is comparable to that previously stated in special research settings. The within-person rate more accurately reflects the true colorectal polyp miss rate for any given colonoscopic exam than does the pooled rate. The difference between the observed 1-yr recurrence rate and the proportion of patients with a missed polyp represents the true 1-yr recurrence of neoplastic polyps.

Safety profiles of leading nonsteroidal anti-inflammatory drugs

Recently introduced nonsteroidal anti-inflammatory drugs (NSAIDs) have capitalized on new formulations or unique physical and pharmacologic properties in an attempt to provide a greater margin of gastrointestinal (GI) safety. The use of enteric coatings and nonoral or pro-drug formulations have not necessarily provided the expected safety, but other properties have been identified that appear to be more promising. However, as demonstrated by oxaprozin, considered to be one of the least safe NSAIDs but one of the leading drugs on the US market, success may not be dependent on safety. In contrast, the improved tolerability of 2 other new NSAIDs, nabumetone and etodolac, has been established in clinical trials and limited postmarketing surveillance. This improved tolerability is probably associated with several pharmacologic properties that have been suggested to contribute to GI safety: (1) nonacidic pro-drug formulation; (2) lack of enterohepatic recirculation; (3) a short plasma half-life; and (4) preferential inhibition of cyclo-oxygenase-2 (COX-2). Although these factors may not improve efficacy, their incorporation into the design of drugs suggests that safer NSAIDs may be a clinical reality. However, the safety and clinical value of any new drug for the general population will be validated only through extensive postmarketing surveillance.

A suppressor of two essential checkpoint genes identifies a novel protein that negatively affects dNTP pools

In Saccharomyces cerevisiae, MEC1 and RAD53 are essential for cell growth and checkpoint function. Their essential role in growth can be bypassed by deletion of a novel gene, SML1, which functions after several genes whose overexpression also suppresses mec1 inviability. In addition, sml1 affects various cellular processes analogous to overproducing the large subunit of ribonucleotide reductase, RNR1. These include effects on mitochondrial biogenesis, on the DNA damage response, and on cell growth. Consistent with these observations, the levels of dNTP pools in sml1 delta strains are increased compared to wild-type. This effect is not due to an increase in RNR transcription. Finally, both in vivo and in vitro experiments show that Sml1 binds to Rnr1. We propose that Sml1 inhibits dNTP synthesis posttranslationally by binding directly to Rnr1 and that Mec1 and Rad53 are required to relieve this inhibition.

Effect of leuprolide acetate in treatment of abdominal pain and nausea in premenopausal women with functional bowel disease: a double-blind, placebo-controlled, randomized study

We have previously reported impressive results in using a gonadotropin-releasing hormone analog, leuprolide acetate (Lupron), in the treatment of moderate to severe symptoms (especially abdominal pain and nausea) in patients with functional bowel disease (FBD). Pain is the hallmark of patients with FBD, and there is no consistent therapy for the treatment of these patients. The purpose of the present study was to expand the investigation to study similar patients (menstruating females) in a multicenter, double-blind, placebo-controlled, randomized study using Lupron Depot (which delivers a continuous dose of drug for one month), 3.75 mg (N = 32) or 7.5 mg (N = 33), or placebo (N = 35) given intramuscularly every four weeks for 16 weeks. Symptoms were assessed using daily diary cards to record abdominal pain, nausea, vomiting, early satiety, anorexia, bloating, and altered bowel habits. Additional assessment tools were quality of life questionnaires, psychological profile, oral-to-cecal transit using the hydrogen breath test, antroduodenal manometry, reproductive hormone levels, and global evaluations by both patient and investigator. Patients in both Lupron Depot-treated groups showed consistent improvement in symptoms; however, only the Lupron Depot 7.5 mg group showed a significant improvement for abdominal pain and nausea compared to placebo (P < 0.001). Patient quality of life assessments and global evaluations completed by both patient and investigators were highly significant compared to placebo (P < 0.001). All reproductive hormone levels significantly decreased for both Lupron Depot-treated groups by week 4 and were significantly different compared to placebo at week 16 (P < 0.001). This study shows that leuprolide acetate is effective in controlling the debilitating symptoms of abdominal pain and nausea in patients with FBD.

The development of dysplasia and adenocarcinoma during endoscopic surveillance of Barrett's esophagus

OBJECTIVE

Periodic endoscopic surveillance is generally recommended for patients with Barrett's esophagus. The optimal follow-up strategy for uncomplicated Barrett's esophagus is controversial, in part because of limited data on the rate of neoplastic progression (through the sequence of metaplasia-dysplasia-carcinoma) during endoscopic surveillance. This study aims to quantify the development of dysplasia in patients with uncomplicated Barrett's esophagus and to explore clinical risk factors associated with the development of dysplastic lesions.

METHODS

We identified 102 patients with endoscopic evidence of Barrett's esophagus and the presence of specialized columnar epithelium who had received endoscopic surveillance for adenocarcinoma at our medical center between 1970 and 1994. We abstracted endoscopic and histologic data from the medical record. All specimens that showed any degree of atypia (per report) were reexamined in blinded fashion by a team of study pathologists who indicated the grade of dysplasia. Time to first diagnosis of dysplasia was plotted using Kaplan-Meier survival curves, and risk factors for development of dysplasia were assessed using Cox regression.

RESULTS

During 563 patient-yr of endoscopic follow-up, three patients developed adenocarcinoma at least 4 yr after initial diagnosis (one developed adenocarcinoma of the cardia, which was incidentally detected during surveillance for Barrett's esophagus). At some point during follow-up, 19 patients developed new onset, low grade dysplasia and four developed high grade dysplasia. None of the patients who had received antireflux surgery developed dysplasia.

CONCLUSION

If confirmed by larger follow-up studies, our results suggest that surveillance endoscopy can be safely deferred for at least 2 yr following an initial biopsy that is negative or indeterminate for dysplasia. Adoption of this approach would substantially reduce the cost of surveillance for adenocarcinoma. Future trials should explore the role of antireflux surgery in protecting against neoplastic transformation of Barrett's esophagus.

High-resolution YAC-cosmid-STS map of human chromosome 13

We have assembled a high-resolution physical map of human chromosome 13 DNA (approximately 114 Mb) from hybridization, PCR, and FISH mapping data using a specifically designed set of computer programs. Although the mapping of 13p is limited, 13q (approximately 98 Mb) is covered by an almost continuous contig of 736 YACs aligned to 597 contigs of cosmids. Of a total of 10,789 cosmids initially selected from a chromosome 13-specific cosmid library (16,896 colonies) using inter-Alu PCR probes from the YACs and probes for markers mapped to chromosome 13, 511 were assembled in contigs that were established from cross-hybridization relationships between the cosmids. The 13q YAC-cosmid map was annotated with 655 sequence tagged sites (STSs) with an average spacing of 1 STS per 150 kb. This set of STSs, each identified by a D number and cytogenetic location, includes database markers (198), expressed sequence tags (93), and STSs generated by sequencing of the ends of cosmid inserts (364). Additional annotation has been provided by positioning 197 cosmids mapped by FISH on 13q. The final (comprehensive) map, a list of STS primers, and raw data used in map assembly are available at our Web site (genome1.ccc.columbia.edu/ approximately genome/) and can serve as a resource to facilitate accurate localization of additional markers, provide substrates for sequencing, and assist in the discovery of chromosome 13 genes associated with hereditary diseases.

The complete set of predicted genes from Saccharomyces cerevisiae in a readily usable form

Nearly all of the open reading frames (ORFs) of the yeast Saccharomyces cerevisiae have been synthesized by PCR using a set of approximately 6000 primer pairs. Each of the forward primers has a common 22-base sequence at its 5' end, and each of the back primers has a common 20-base sequence at its 5' end. These common termini allow reamplification of the entire set of original PCR products using a single pair of longer primers-in our case, 70 bases. The resulting 70-base elements that flank each ORF can be used for rapid and efficient cloning into a linearized yeast vector that contains these same elements at its termini. This cloning by genetic recombination obviates the need for ligations or bacterial manipulations and should permit convenient global approaches to gene function that require the assay of each putative yeast gene.

Cloning-free PCR-based allele replacement methods

Efficient homologous recombination permits the directed introduction of specific mutations into the yeast genome. Here we describe a cloning-free, PCR-based allele replacement method that simplifies allele transfer between yeast strains. The desired allele from one strain is amplified by PCR, along with a selectable/counterselectable marker. After transformation, the resident allele in the target strain is replaced by creating a duplication of the new allele. Selection for direct repeat recombinants results in a single copy of the new allele in the target strain. Specifically, the desired allele is amplified by PCR with a pair of adaptamers, which are chimeric oligonucleotides that are used to amplify the allele and differentially tag its 5' and 3' ends. These tags allow the directed fusion to two different, but overlapping, regions of an appropriately tagged selectable/counterselectable marker after a second round of PCR amplification. Following cotransformation of the two fusion fragments into yeast, homologous recombination efficiently generates a duplication of the amplified allele flanking the intact selectable marker in the genome. After counterselection, only the desired allele is retained as a result of direct repeat recombination. A simple modification of this method allows the creation of de novo mutations in the genome.

Holliday junctions accumulate in replication mutants via a RecA homolog-independent mechanism

The Holliday junction recombination intermediate, an X-shaped DNA molecule (xDNA), was analyzed at rDNA in mitotically growing yeast. In wild-type cells, xDNA is only detected at S phase, suggesting that recombination is stimulated to repair replication-related lesions. A search for mutations that increase the level of xDNA uncovered a gene encoding a subunit of DNA polymerase alpha. Systematic examination of replication mutants revealed that defects in polymerase alpha and delta but not the epsilon complex stimulate the level of xDNA. These xDNAs are Holliday junctions and not replication intermediates. The level of Holliday junctions is greatly reduced in rad52 mutants, but surprisingly, not in mutants defective in the three known mitotically expressed yeast RecA homologs.

Direct association between the yeast Rad51 and Rad54 recombination proteins

The RAD54 and RAD51 genes are involved in genetic recombination and double-strand break repair in the yeast Saccharomyces cerevisiae. The Rad51 protein is thought to be a yeast analogue of the Eschericia coli recA gene product and catalyzes strand exchange between homologous single- and double-stranded DNAs in vitro. RAD54 exhibits homologies to several known ATPases and is a member of the SWI2/MOT1 family. We show here that the Rad54 protein interacts with the Rad51 protein in vivo and in vitro and that the NH2-terminal 115 residues of the Rad54 protein are necessary for this interaction. Combined with previously reported results, these data imply that the Rad54 protein is part of a multiprotein yeast recombination complex.

DNA strand annealing is promoted by the yeast Rad52 protein

The Saccharomyces cerevisiae RAD52 gene plays a pivotal role in genetic recombination. Here we demonstrate that yeast Rad52 is a DNA binding protein. To show that the interaction between Rad52 and DNA is direct and not mediated by other yeast proteins and to facilitate protein purification, a recombinant expression system was developed. The recombinant protein can bind both single- and double-stranded DNA and the addition of either Mg2+ or ATP does not enhance the binding of single-stranded DNA. Furthermore, a DNA binding domain was found in the evolutionary conserved N terminus of the protein. More importantly, we show that the protein stimulates DNA annealing even in the presence of a large excess of nonhomologous DNA. Rad52-promoted annealing follows second-order kinetics and the rate is 3500-fold faster than that of the spontaneous reaction. How this annealing activity relates to the genetic phenotype associated with rad52 mutant cells is discussed.

Reliability of whole crypt mitotic count as a measure of cellular proliferation in rectal biopsies

We conducted a reliability study of whole crypt mitotic count, a measure of cellular proliferation with potential use as an intermediate marker in studies of colorectal cancer risk and prevention. The study involved biopsies taken from two distinct locations at 8-10 cm from the anal verge for 20 subjects scheduled to undergo routine endoscopy. In addition to the overall count of mitoses per crypt (mitotic count), we investigated two novel measures based on the percentages of heights of mitotic cells within crypts: the mean height, and the maximum minus minimum (max - min) height of mitoses. The max - min height was positively correlated with mitotic count (r = 0.64); however, there was little correlation between mitotic count and the mean height of mitotic cells (r = 0.12). Components of variance were estimated for the three measures; for mitotic count and max - min height, the variability between persons was substantially greater than that between locations within an individual. For mean height, the between-person and between-location variabilities were roughly equal. These results suggest that whole crypt mitotic count has promise as a reliable measure of rectal cellular proliferation, but further studies will be necessary to assess the utility of this assay.

Sterol esterification in yeast: a two-gene process

Unesterified sterol modulates the function of eukaryotic membranes. In human cells, sterol is esterified to a storage form by acyl-coenzyme A (CoA): cholesterol acyl transferase (ACAT). Here, two genes are identified, ARE1 and ARE2, that encode ACAT-related enzymes in yeast. The yeast enzymes are 49 percent identical to each other and exhibit 23 percent identity to human ACAT. Deletion of ARE2 reduced sterol ester levels to approximately 25 percent of normal levels, whereas disruption of ARE1 did not affect sterol ester biosynthesis. Deletion of both genes resulted in a viable cell with undetectable esterified sterol. Measurements of [14C]acetate incorporation into saponified lipids indicated down-regulation of sterol biosynthesis in the are1 are2 mutant cells. With the use of a consensus sequence to the yeast and human genes, an additional number of the ACAT gene family was identified in humans.

Gene conversion plays the major role in controlling the stability of large tandem repeats in yeast

The genomic stability of the rDNA tandem array in yeast is tightly controlled to allow sequence homogenization and at the same time prevent deleterious rearrangements. In our study, we show that gene conversion, and not unequal sister chromatid exchange, is the predominant recombination mechanism regulating the expansion and contraction of the rDNA array. Furthermore, we found that RAD52, which is essential for gene conversion, is required for marker duplication stimulated in the absence of the two yeast type I topoisomerases. Our results have implications for the mechanisms regulating genomic stability of repetitive sequence families found in all eukaryotes.

A high-resolution annotated physical map of the human chromosome 13q12-13 region containing the breast cancer susceptibility locus BRCA2

Various types of physical mapping data were assembled by developing a set of computer programs (Integrated Mapping Package) to derive a detailed, annotated map of a 4-Mb region of human chromosome 13 that includes the BRCA2 locus. The final assembly consists of a yeast artificial chromosome (YAC) contig with 42 members spanning the 13q12-13 region and aligned contigs of 399 cosmids established by cross-hybridization between the cosmids, which were selected from a chromosome 13-specific cosmid library using inter-Alu PCR probes from the YACs. The end sequences of 60 cosmids spaced nearly evenly across the map were used to generate sequence-tagged sites (STSs), which were mapped to the YACs by PCR. A contig framework was generated by STS content mapping, and the map was assembled on this scaffold. Additional annotation was provided by 72 expressed sequences and 10 genetic markers that were positioned on the map by hybridization to cosmids.

Transfer of yeast artificial chromosomes into mammalian cells and comparative study of their integrity

Yeast artificial chromosomes (YACs) from the CEPH MegaYAC library (Paris, France) ranging in size from 350 to 1600 kb and mapping to the q22.1 and q22.2 regions of human chromosome 21 were transferred into mammalian cells by spheroplast fusion. The integrity of the YACs from two adjacent parts of the region was compared after retrofitting and stable transfer into mammalian cells. We found that large YACs could easily be manipulated to allow transfer of the YAC material into mammalian cells and that the size of the YAC did not appear to be limiting for fusion. However, we show that there was great variability in the integrity of the YACs from the two regions, which was not related to the size of the YACs. Four YACs in region I from sequence-tagged site (STS) G51E05 up to STS LL103 showed, in general, no loss of material and correct gene transfer into mammalian cells. In contrast, the three YACs in the more centromeric region II (from STS G51B09 up to G51E05) frequently showed a loss of human material during handling, retrofitting and transfer. As a YAC from another library covering region II was also found to be unstable, we propose that the integrity of the YACs is highly dependent on the incorporated human chromosomal DNA.