Implantable venous access devices in children with hemophilia: a report of low infection rates

OBJECTIVE

The objective of this study was to define the efficacy and complications of implantable venous access devices (IVADs) in children with hemophilia.

STUDY DESIGN

Records were reviewed on all patients with congenital blood coagulation disorders monitored at two children's hospitals in whom one or more central venous catheters had been placed.

RESULTS

Since 1989 external and implantable central venous catheters have been inserted to enhance venous access for regular factor concentrate infusion in 45 patients with hemophilia ranging in age from 8 months to 19.5 years (median 7.4 years); 37 patients had factor VIII deficiency and 8 factor IX deficiency. Hemorrhagic complications of catheter placement were infrequent and minor. In the 41 patients having one or more IVADs in place for a median of 31 months, only six episodes of bacteremia occurred in 5 patients during 44,070 days of follow-up. The overall rate of bacteremia complicating IVADs in these patients was 0.14 episodes per 1000 catheter days. Other catheter-related complications were uncommon. Catheters are still in place in 33 patients for a median of 32 months.

CONCLUSION

The low risk of infection and other complications associated with the use of IVADs makes the use of these devices attractive in the treatment of patients with hemophilia who require frequent venous access for factor concentrate infusions.

Similar incidence of K-ras mutations in lung carcinomas of FVB/N mice and FVB/N mice carrying a mutant p53 transgene

Mutated p53 genes are capable of complementing activated ras genes in the transformation of primary rat embryo fibroblasts in vitro. Mutations in both genes have also been found in several human cancers, including lung carcinomas. We generated transgenic mice containing a p53 construct with a missense mutation in exon 5 (ala135val) to study the role of p53 mutations in lung tumorigenesis, and to facilitate identification of other genetic events that might complement p53 mutations in mouse lung carcinogenesis. The p53 transgenic lines exhibited a higher frequency of lethal lung tumors than the parental FVB/N strain. We examined the spontaneously-arising lung carcinomas from mice expressing the mutated p53 transgene for K-ras mutations using single-stranded conformation polymorphism (SSCP) and/or direct sequencing approaches. Fifteen of 29 (52%) carcinomas contained mutations in the K-ras oncogene. Six of 15 of the K-ras mutations were in codon 61 and 9/15 were in codon 12. Subsequent analysis of spontaneous lung carcinomas from mice of the FVB/N parental strain showed that 9/12 (75%) carcinomas examined contained K-ras mutations. Two of these were in codon 12, one in codon 13, and 6 were in codon 61. These results demonstrate that the frequency of ras mutations does not differ between the p53 FVB/N transgenic mice and their parental FVB/N strain but suggest that a high frequency of mutations K-ras can be correlated with lung tumorigenesis in both groups of mice.

Genetic alterations of p53 and ras genes in 1,3-butadiene- and 2',3'-dideoxycytidine-induced lymphomas

Mutations of p53 and ras genes were analyzed in 40 and 31 1,3-butadiene (BD)-induced lymphomas of B6C3F1 mice (BLFs), respectively, and in 63 2',3'-dideoxycytidine-induced lymphomas, which were collected from B6C3F1 (n = 16) or NIH Swiss mice (DLSs; n = 47). The frequencies of K- and N-ras mutations in BLFs (32 and 13%, respectively) were higher than those in DLSs (13 and 2%, respectively). Seven of 10 K-ras-mutated BLFs contained codon 13 CGC mutations, whereas no mutation in K-ras codon 13 was detected in DLSs, suggesting that the codon 13 CGC mutation is specific for BD exposure. Interestingly, 8 of 13 BLFs with ras mutations were from low-dose (< or = 200 ppm) or stop-exposure (26 weeks) groups. These results suggest that ras mutations play an important role in the development of BD-induced lymphoma and may represent an early event. Analysis of genetic alterations in exons 5-8 of the p53 gene revealed mutations in seven of the BLFs and three of the DLSs. All seven BLFs carrying p53 mutations were collected from the high-dose (625 ppm) continuous exposure group, which might indicate that p53 is involved in the progression of BD-induced lymphoma and in late stage of lymphomagenesis. Mutations in ras and p53 genes are relatively infrequent in 2',3'-dideoxycytidine-induced lymphomas, suggesting that other genes must be involved.

Allelotype analysis of 2',3'-dideoxycytidine- and 1,3-butadiene-induced lymphomas in B6C3F1 mice

To identify potential tumor suppressor genes involved in lymphoma development, we generated allelotypes of 16 2',3'-dideoxycytidine (ddC and 31 1,3-butadiene (BD)-induced lymphomas from C57BL/6 x C3H/He F1 (hereafter called B6C3F1) mice. Two or more anonymous simple sequence length polymorphisms per autosome were examined for loss of heterozygosity (LOH). Allelic losses throughout the genome were generally infrequent, except for markers on chromosome 2, 4, 11 and 12. The highest frequency of allelic losses was observed on chromosome 12, with 38 and 39% in ddC and BD-induced lymphomas, respectively. The most prevalent LOH was localized to the distal region bounded by markers D12Mit263 and D12Nds2. No known tumor suppressor genes have been mapped to this region, and no obvious candidates could be identified, suggesting the presence of novel suppressor gene(s). LOH on chromosome 2 was observed in 31% of ddC-induced lymphomas but in only 3% (1/31) of BD-induced lymphomas, suggesting a ddC-specific genetic effect. Detailed analysis localized a potential tumor suppressor gene residing on the distal region of chromosome 2, between markers D2Mit147 and D2Mit148. Twenty-five % of ddC-induced and 23% of BD-induced lymphomas showed LOH on chromosome 4, and two discrete regions were identified. One of the regions includes the IFN gene cluster and is syntenic to human chromosome 9p2l-22. Candidate tumor suppressor genes, Mts1 (multiple tumor suppressor 1) and Mts2 have been mapped to this region. The second region is located on the distal part of chromosome 4, which is homologous to human chromosome 1p35-36, a region that is frequently deleted in various types of human tumors. Finally, 19% of ddC-induced and 29% of BD-induced lymphomas revealed LOH on chromosome 11 at the Acrb locus, which lies within 1 cM of p53, suggesting that the p53 tumor suppressor gene also plays a role in lymphomagenesis. These results suggest that multiple potential suppressor loci contribute to lymphoma development in B6C3F1 mice.

BRCA2 mutations in primary breast and ovarian cancers

The second hereditary breast cancer gene, BRCA2, was recently isolated. Germline mutations of this gene predispose carriers to breast cancer, and, to a lesser extent, ovarian cancer. Loss of heterozygosity (LOH) at the BRCA2 locus has been observed in 30-40% of sporadic breast and ovarian tumours, implying that BRCA2 may act as a tumour suppressor gene in a proportion of sporadic cases. To define the role of BRCA2 in sporadic breast and ovarian cancer, we screened the entire gene for mutations using a combination of techniques in 70 primary breast carcinomas and in 55 primary epithelial ovarian carcinomas. Our analysis revealed alterations in 2/70 breast tumours and none of the ovarian carcinomas. One alteration found in the breast cancers was a 2-basepair (bp) deletion (4710delAG) which was subsequently shown to be a germline mutation, the other was a somatic missense mutation (Asp3095Glu) of unknown significance. Our results suggest that BRCA2 is a very infrequent target for somatic inactivation in breast and ovarian carcinomas, similar to the results obtained for BRCA1.

Mutation analysis of the BRCA2 gene in 49 site-specific breast cancer families

The hereditary breast cancer gene BRCA2 was recently cloned and is believed to account for almost half of site-specific breast cancer families and the majority of male breast cancer families. We screened 49 site-specific breast cancer families for mutations in the BRCA2 gene using single strand conformation analysis (SSCA) followed by direct sequencing. We found mutations in eight families, including all four families with male breast cancer. The eight mutations were small deletions with the exception of a single nonsense mutation, an all were predicted to interrupt the BRCA2 coding sequence and to lead to a truncated protein product. Other factors which predicted the presence of a BRCA2 mutation included a case of breast cancer diagnosed at age 35 or below (P = 0.01) and a family history of pancreatic cancer (P = 0.03). Two mutations were seen twice, including a 8535delAG, which was detected in two French Canadian families. Our results suggest the possibility that the proportion of site-specific breast cancer families attributable to BRCA2 may be overestimated.

Isolation of the mouse homologue of BRCA1 and genetic mapping to mouse chromosome 11

The BRCA1 gene is in large part responsible for hereditary human breast and ovarian cancer. Here we report the isolation of the murine Brca1 homologue cDNA clones. In addition, we identified genomic P1 clones that contain most, if not all, of the mouse Brca1 locus. DNA sequence analysis revealed that the mouse and human coding regions are 75% identical at the nucleotide level while the predicted amino acid identity is only 58%. A DNA sequence variant in the Brca1 locus was identified and used to map this gene on a (Mus m. musculus Czech II x C57BL/KsJ)F1 x C57BL/KsJ intersubspecific backcross to distal mouse chromosome 11. The mapping of this gene to a region highly syntenic with human chromosome 17, coupled with Southern and Northern analyses, confirms that we isolated the murine Brca1 homologue rather than a related RING finger gene. The isolation of the mouse Brca1 homologue will facilitate the creation of mouse models for germline BRCA1 defects.

BRCA1 mutations in primary breast and ovarian carcinomas

Loss of heterozygosity data from familial tumors suggest that BRCA1, a gene that confers susceptibility to ovarian and early-onset breast cancer, encodes a tumor suppressor. The BRCA1 region is also subject to allelic loss in sporadic breast and ovarian cancers, an indication that BRCA1 mutations may occur somatically in these tumors. The BRCA1 coding region was examined for mutations in primary breast and ovarian tumors that show allele loss at the BRCA1 locus. Mutations were detected in 3 of 32 breast and 1 of 12 ovarian carcinomas; all four mutations were germline alterations and occurred in early-onset cancers. These results suggest that mutation of BRCA1 may not be critical in the development of the majority of breast and ovarian cancers that arise in the absence of a mutant germline allele.

A strong candidate for the breast and ovarian cancer susceptibility gene BRCA1

A strong candidate for the 17q-linked BRCA1 gene, which influences susceptibility to breast and ovarian cancer, has been identified by positional cloning methods. Probable predisposing mutations have been detected in five of eight kindreds presumed to segregate BRCA1 susceptibility alleles. The mutations include an 11-base pair deletion, a 1-base pair insertion, a stop codon, a missense substitution, and an inferred regulatory mutation. The BRCA1 gene is expressed in numerous tissues, including breast and ovary, and encodes a predicted protein of 1863 amino acids. This protein contains a zinc finger domain in its amino-terminal region, but is otherwise unrelated to previously described proteins. Identification of BRCA1 should facilitate early diagnosis of breast and ovarian cancer susceptibility in some individuals as well as a better understanding of breast cancer biology.

Localization of the VHR phosphatase gene and its analysis as a candidate for BRCA1

The VH1-related human protein (VHR) gene was localized to human chromosome 17q21 in a region thought to contain the BRCA1 locus, a locus that confers susceptibility to breast and ovarian cancer. VHR encodes a phosphatase with dual specificity for tyrosine and serine residues. Thus it is a plausible candidate for a tumor suppressor gene such as BRCA1. To test this possibility, the VHR coding sequence was screened in individuals with familial breast cancer and in sporadic breast tumor and breast cancer cell lines. No mutations were detected, suggesting that the VHR gene is not BRCA1.

Isolation of a diverged homeobox gene, MOX1, from the BRCA1 region on 17q21 by solution hybrid capture

Using the technique of solution hybridization coupled with magnetic bead capture, we have isolated a novel homeobox-containing gene from the BRCA1 region of 17q21. This gene is the human homologue of the mouse Mox1 gene previously localized to a syntenic region of mouse chromosome 11. Multiple overlapping cDNAs of human MOX1 were identified using both a cosmid and a P1 genomic clone containing the microsatellite markers D17S750 and D17S858 which map within the BRCA1 region defined by D17S776 and D17S78. MOX1 expression was observed in a variety of normal tissues examined, including breast and ovary. Given that the gene contains a homeobox domain and has the potential to regulate growth and differentiation, MOX1 represents an attractive candidate for the BRCA1 gene. This possibility was investigated in a series of BRCA1 kindreds and primary sporadic breast tumors. No evidence for mutation was found in the coding sequence, making it unlikely that MOX1 is the BRCA1 gene. However, the widespread expression of MOX1 in non-embryonal tissues suggests a role in normal cell biology which warrants further study.

Non-insulin-mediated glucose disappearance in subjects with IDDM. Discordance between experimental results and minimal model analysis

Both insulin and glucose contribute to the regulation of glucose metabolism in vivo. We directly measured the ability of glucose per se to promote glucose disposal in subjects with insulin-dependent diabetes mellitus (IDDM). We compared our results with predictions of the minimal model of glucose metabolism. To identify minimal model parameters, a frequently sampled intravenous glucose tolerance test (FSIVGTT) was administered to each subject while they were connected to a Biostator (a device that monitors blood glucose and gives insulin to mimic normal insulin secretion). Data from this test reflected normal glucose tolerance and were in excellent agreement with minimal model predictions. The FSIVGTT was then repeated without the Biostator in the same diabetic subjects in order to directly measure the effect of glucose per se to promote glucose disposal in the absence of an incremental insulin effect (a basal insulin drip was maintained). To compare these results with minimal model predictions, the equations describing glucose disappearance in the absence of an incremental insulin effect were solved using parameters identified from the Biostator experiment. The glucose disappearance measured in the absence of an incremental insulin response was much slower than the minimal model predictions. Thus, the minimal model appears to overestimate the effect of glucose per se on glucose uptake and underestimate the contribution of incremental insulin.

Allelotyping of butadiene-induced lung and mammary adenocarcinomas of B6C3F1 mice: frequent losses of heterozygosity in regions homologous to human tumor-suppressor genes

To identify the potential involvement of tumor-suppressor gene inactivation during neoplastic development in B6C3F1 mice, genetic losses were determined from allelotypes of butadiene-induced lung and mammary adenocarcinomas. By using length polymorphisms in restriction fragments and simple sequence repeats, or "microsatellites," markers on each autosome were analyzed for allele losses in tumor DNAs. Losses of heterozygosity on chromosome 11 were observed at several loci surrounding the p53 tumor-suppressor gene (Trp53) in 12 of 17 mammary tumors and 2 of 8 lung tumors. Although most of these alterations appeared to result from nondisjunction, at least two examples of somatic recombination or deletion were also observed. Southern analysis revealed a homozygous deletion of the remaining Trp53 allele of one of these mammary tumors. Losses of heterozygosity were also detected at the Rb-1 tumor-suppressor gene in 7 of 17 mammary tumors and 1 lung tumor. Finally, frequent allele losses were observed on chromosome 4 in lung tumors. Analysis of nine chromosome 4 loci defined an interstitial deletion containing the Ifa gene cluster in one of the lung tumors. A tumor-suppressor gene was previously mapped to this region of chromosome 4 in studies with somatic cell hybrids. In addition, homozygous deletions have been reported in a homologous region of human chromosome 9p for acute lymphocytic leukemias, glioblastomas, melanomas, and lung carcinomas. These findings suggest that the inactivation of tumor-suppressor genes including Trp53, Rb-1, and an unidentified gene on chromosome 4 plays a significant role during carcinogenesis in mice.

Mutation analysis of the THRA1 gene in breast cancer: deletion/fusion of the gene to a novel sequence on 17q in the BT474 cell line

We have previously described a common region of deletion and allele loss on chromosome 17q in sporadic breast cancers that is likely to contain a tumor suppressor gene. The region, mapped to 17q12-q21, was bordered by D17S250 and D17S579 on the centromeric and telomeric sides, respectively. This deletion region overlaps the BRCA1 locus, which predisposes to familial breast and ovarian cancer. The most frequent loss of heterozygosity was observed at the thyroid hormone receptor alpha (THRA1) locus. Southern analysis revealed a rearrangement of THRA1 in the BT474 breast cancer cell line. This rearrangement represented a deletion of exons 8-10 of one THRA1 allele that was also coamplified with ERBB2. Northern blots showed two mutant transcripts in BT474 cells. Analysis of the mutant transcripts revealed fusion of the THRA1 exon 7 by splicing to a novel sequence designated BTR for "BT474 transcribed rearrangement." BTR was found to be highly conserved and mapped to 17q. The deletion in BT474 cells spans the entire BRCA1 region. To search for additional mutations in the THRA1 gene, all nine protein-encoding exons of THRA1 were examined for point mutations via single strand conformation analysis in a series of primary breast tumors, breast cancer cell lines, and lymphoblastoid cell lines derived from the youngest affected members of several German breast cancer families. No point mutations were detected, including the unrearranged THRA1 allele in BT474. We have thus excluded THRA1 as a commonly mutated sporadic breast cancer tumor suppressor gene and as the BRCA1 gene.

Infrequent p53 mutations in 7,12-dimethylbenz[a]anthracene-induced mammary tumors in BALB/c and p53 hemizygous mice

We conducted experiments to determine if p53 alterations, which are frequent in human breast cancers, were also common in murine mammary tumors. In 13 mammary tumors from 7,12-dimethylbenz[a]anthracene (DMBA)-treated BALB/c mice were immunohistochemically analyzed for overexpression of p53; p53 protein was not detectable. Three of the tumors were established as cell lines in vitro. p53 protein was rarely detected at passage 4 in these lines but was overexpressed by passage 8 in two of them. The p53 nucleotide sequence was shown to be wild type in one primary mammary tumor and in the two p53-overexpressing cell lines. One cell line that overexpressed p53 in vitro was implanted into BALB/c mice. The resulting tumors retained the wild-type p53 nucleotide sequence but no longer expressed detectable levels of p53 protein, suggesting that the overexpression of wild-type p53 was related to in vitro culture conditions. The effect of DMBA on mammary-tumor development was also tested in mice rendered hemizygous for p53. These mice and wild-type littermate controls had no differences in susceptibility to induction of mammary tumors by oral administration of DMBA. Furthermore, Southern blot hybridization detected no gross alterations in the wild-type p53 allele in mammary tumors from the p53-deficient mice. Point mutation of the wild-type p53 allele was also infrequent in the DMBA-induced mammary tumors from hemizygous p53 mice; it occurred in only one of seven tumors. Thus, the p53 gene is apparently not a primary target for genetic alterations in DMBA-induced mammary tumors. Next, we examined mammary tumors derived from D1 and D2 transplantable hyperplastic alveolar nodule (HAN) outgrowths, which rapidly form tumors containing Ha-ras mutations after DMBA treatment. As ras and p53 mutants can cooperate in transformation, we examined whether D1 and D2 HAN outgrowths have p53 mutations. Unlike in the DMBA-induced primary mammary tumors, nuclear p53 accumulation was observed frequently (10 of 14) in tumors that arose from D1 and D2 HAN outgrowths. Direct sequencing of the entire coding region of the p53 cDNA from six D1 and D2 tumors confirmed that the sequence was wild type. Although wild-type p53 was retained in both DMBA-induced mammary tumors and mammary tumors derived from D1 and D2 preneoplastic outgrowths, wild-type p53 overexpression was detected only in D1 and D2 tumors. Therefore, D1 and D2 tumors appear to arise by a pathway in which p53 expression is altered, whereas DMBA induction affects a different pathway that does not require such alteration.

Detection of frequent allelic loss on proximal chromosome 17q in sporadic breast carcinoma using microsatellite length polymorphisms

Analyses of losses of heterozygosity and linkage studies have implicated a gene(s) on chromosome 17q in the genesis of sporadic and early-onset familial breast carcinomas, respectively. To define the critical region of 17q, we examined DNAs from a series of 20 sporadic breast carcinomas and corresponding blood samples for allelic losses of chromosome 17q using microsatellite length polymorphisms. With these highly informative markers (average heterozygosity, 0.73), we observed frequent deletions of 17q at several loci. We found that D17S250 was deleted in 50% (7 of 14), THRA1 in 79% (11 of 14), D17S579 in 59% (11 of 19), NME1 in 29% (5 of 17), MPO in 36% (4 of 11), and GH in 25% (4 of 16) in the tumor set examined. A common region of deletion was found that was flanked by D17S250 to D15S579. These markers have recently been localized to a 6-cM interval of proximal chromosome 17q in bands 17q11.2-q21 and map within the region of the early-onset familial breast cancer locus, implying that the same gene or genes may be involved in both sporadic and familial breast tumors. Thyroid hormone receptor alpha and retinoic acid receptor alpha are two potential candidate genes in this region.

Lack of effect of vitamin B-6 supplementation on the lipoprotein profile of post-menopausal chronic hemodialysis patients

This study was designed to analyze the effect of vitamin B-6 supplementation on the lipoprotein profile of chronic hemodialysis patients. Individuals on chronic hemodialysis experience an acceleration of atherosclerosis, which is often accompanied by abnormal lipid metabolism. Although total plasma cholesterol is usually normal, high-density-lipoprotein (HDL) cholesterol is often low. Recently, it has been suggested that the development of atherosclerotic lesions in chronic hemodialysis patients may be the result of a decreased plasma concentration of pyridoxal 5'-phosphate (PLP) and concomitant alterations in plasma amino acid and/or lipoprotein profiles. All subjects in this study were supplemented with 0.97 mmol (200 mg) pyridoxine hydrochloride per day for 28 days; then, concentrations of PLP, total cholesterol, and lipoprotein cholesterol fractions were determined in the plasma. No significant difference was noted in PLP concentration between Group 1 (five post-menopausal women with a history of atherosclerosis who were undergoing maintenance hemodialysis therapy) and Group 2 (six subjects who were non-symptomatic). However, both groups had significant increases in PLP concentrations between the pre- and post-supplementation periods (p less than .01). In contrast, there was a statistically significant difference in total plasma cholesterol and very-low-density- and low-density-lipoprotein (VLDL and LDL) cholesterol concentrations between groups, but no significant changes in total cholesterol or VLDL and LDL cholesterol content were found during vitamin B-6 supplementation. No statistically significant differences in HDL, HDL2, and HDL3 cholesterol concentrations were observed between Group 1 and Group 2 subjects or within either group during vitamin B-6 supplementation.

Randomized study of continuous infusion fluorouracil versus fluorouracil plus cisplatin in patients with metastatic colorectal cancer

One hundred twenty-two chemotherapy-naive patients with histologically confirmed colorectal adenocarcinoma were entered into a randomized trial comparing infusional fluorouracil (FU) versus cisplatin (CDDP) and FU. In both groups, patients received continuous infusion FU 1,000 mg/m2/d for 5 consecutive days every 4 weeks. Patients randomized to CDDP/FU also received CDDP 20 mg/m2 intravenous (IV) bolus on days 1 to 5 of each cycle. Patients were comparable in terms of age, performance status, baseline laboratory values, dominant sites of measurable disease, and percent of liver involvement. The partial response rate was significantly greater in patients who received CDDP/FU versus FU alone (25% v 3%, P = .001). Patients who received CDDP/FU experienced significantly greater toxicity compared with FU alone: grades 3 and 4 hematologic toxicity occurred in 22% and 0% of patients, respectively (P = .0001); grades 2 to 4 nausea and vomiting occurred in 80% and 15% of patients, respectively (P = .0001). There were no significant differences in either the duration of response (median, 6 and 4.7 months for CDDP/FU and FU groups, respectively) or survival (median 10, and 12 months, respectively). Compared with infusional FU alone, CDDP/FU provided a significantly greater partial response rate with increased toxicity, but it did not improve overall survival in patients with advanced colorectal carcinoma. Therefore, the use of CDDP/FU as routine therapy for the treatment of colorectal carcinoma cannot be recommended.

Effect of aspartame on plasma amino acid profiles of diabetic patients with chronic renal failure

A randomized, double-blind study was conducted to determine the possible effects of aspartame on the plasma amino acid profiles of 23 diabetic patients with renal failure who were undergoing maintenance hemodialysis. Subjects were given a single dose of 10 mg aspartame/kg (approximately equivalent to 25 packets of Equal [NutraSweet Consumer Products, Inc, Chicago, IL] or the amount of phenylalanine in a 300-mL glass of milk) or a placebo in a crossover study design. Three postdialysis blood samples were drawn just before and 1 and 2 h after aspartame or placebo consumption. After aspartame consumption statistically significant increases in only two amino acids, phenylalanine and tyrosine, were noted at 1 and 2 h when compared with placebo values. The increases in phenylalanine were within the normal postprandial range for healthy subjects; no other increases in essential or nonessential amino acids, except for tyrosine, were detected. This study supports the view that aspartame is safe for diabetic subjects with chronic renal failure.

Reactive perineurial fibroblastic proliferation of the median nerve: MR characteristics

We report a case of fibroblastic proliferation of the median nerve presenting as a focal mass. This report discusses the pathological and magnetic resonance correlations and reviews the differential diagnosis for median nerve masses.