Clinical safety and performance of VIVIA: a novel home hemodialysis system

Background

The VIVIA Hemodialysis System (Baxter Healthcare Corporation, Deerfield, IL, USA) was designed for patient use at home to reduce the burden of treatment and improve patient safety. It has unique features including extended use of the dialyzer and blood set through in situ hot-water disinfection between treatments; generation of on-line infusible-quality dialysate for automated priming, rinseback and hemodynamic support during hypotension and a fully integrated access disconnect sensor.

Methods

The safety and performance of VIVIA were assessed in two clinical studies. A first-in-man study was a prospective, single-arm study that involved 22 prevalent hemodialysis (HD) patients who were treated for ∼4 h, four times a week, for 10 weeks. A second clinical study was a prospective, single-arm study (6-8 h of dialysis treatment at night three times a week) that involved 17 prevalent patients treated for 6 weeks.

Results

There were 1114 treatments from the two studies (first-in-man study, 816; extended duration study, 298). Adverse events (AEs) were similar in the two studies to those expected for prevalent HD patients. No deaths and no device-related serious AEs occurred. Adequacy of dialysis ( Kt / V ) urea in both clinical trials was well above the clinical guidelines. VIVIA performed ultrafiltration accurately as prescribed in the two studies. The majority of patients achieved 10 or more uses of the dialyzer. Endotoxin levels and bacterial dialysate sampling met infusible-quality dialysate standards.

Conclusion

These results confirm the safety and expected performance of VIVIA.

A multicenter investigation with D-FISH BCR/ABL1 probes

Twenty-eight laboratories evaluated a new fluorescence in situ hybridization (FISH) strategy for chronic myeloid leukemia. In a three-part study, bcr/abl1 D-FISH probes were used to study bone marrow specimens. First, laboratories familiarized themselves with the strategy by applying it to known normal and abnormal specimens. Then, collectively the laboratories studied 20 normal and 20 abnormal specimens blindly and measured workload. Finally, each laboratory and two experts studied six serial dilutions with 98-0% abnormal nuclei. Using the reported normal cutoff of < 1% abnormal nuclei, participants reported no false-negative cases and 15 false-positive cases (1-6.6% abnormal nuclei). Results provided by participants for serial dilutions approximated the expected percentages of abnormal nuclei, but those from the experts exhibited greater precision. The clinical sensitivity, precision, nomenclature, workload, recommendations for training, and quality assurance in methods using D-FISH in clinical practice are discussed.

A multicenter investigation with interphase fluorescence in situ hybridization using X- and Y-chromosome probes

Twenty-six laboratories used X and Y chromosome probes and the same procedures to process and examine 15,600 metaphases and 49,400 interphases from Phaseolus vulgaris-leucoagglutinin (PHA)-stimulated lymphocytes. In Part I, each laboratory scored 50 metaphases and 200 interphases from a normal male and a normal female from its own practice. In Part II, each laboratory scored 50 metaphases and 200 interphases on slides prepared by a central laboratory from a normal male and a normal female and three mixtures of cells from the male and female. In Part III, each laboratory scored 50 metaphases (in samples of 5, 10, 15, and 20) and 100 interphases (in samples of 5, 10, 15, 20, and 50) on new, coded slides of the same specimens used in Part II. Metaphases from male specimens were scored as 98-99% XY with no XX cells, and 97-98% of interphases were scored as XY with 0.04% XX cells. Metaphases from female specimens were scored as 96-97% XX with 0.03% XY cells, and 94-96% of interphases were scored as XX with 0.05% XY cells. Considering the data as a model for any probe used with fluorescence in situ hybridization (FISH), a statistical approach assessing the impact of analytical sensitivity on the numbers of observations required to assay for potential mosaicisms and chimerisms is discussed. The workload associated with processing slides and scoring 50 metaphases and 200 interphases using FISH averaged 27.1 and 28.6 minutes, respectively. This study indicates that multiple laboratories can test/develop guidelines for the rapid, efficacious, and cost-effective integration of FISH into clinical service.

Characterization of neo-centromeres in marker chromosomes lacking detectable alpha-satellite DNA

Recent studies have implicated alpha-satellite DNA as an integral part of the centromere, important for the normal segregation of human chromosomes. To explore the relationship between the normal functioning centromere and alpha-satellite DNA, we have studied eight accessory marker chromosomes in which fluorescence in-situ hybridization could detect neither pancentromeric nor chromosome-specific alpha-satellite DNA. These accessory marker chromosomes were present in the majority of or all cells analyzed and appeared mitotically stable, thereby indicating the presence of a functional centromere. FISH analysis with both chromosome-specific libraries and single-copy YACs, together with microsatellite DNA studies, allowed unequivocal identification of both the origin and structure of these chromosomes. All but one of the marker chromosomes were linear mirror image duplications, and they were present along with either two additional normal chromosomes or with one normal and one deleted chromosome. Indirect immunofluorescence analysis revealed that the centromere protein CENP-B was not present on these markers; however, both CENP-C and CENP-E were present at a position defining a 'neo-centromere'. These studies provide insight into a newly defined class of marker chromosomes that lack detectable alpha-satellite DNA. At least for such marker chromosomes, alpha-satellite DNA at levels detectable by FISH appears unnecessary for chromosome segregation or for the association of CENP-C and CENP-E at a functional centromere.

Sex chromosome markers: characterization using fluorescence in situ hybridization and review of the literature

Fluorescence in situ hybridization (FISH) using biotin labeled X- and Y-chromosome DNA probes was utilized in the analysis of 23 sex chromosome-derived markers. Specimens were obtained through prenatal diagnosis, because of a presumptive diagnosis of Ullrich-Turner syndrome, mental retardation, and minor anomalies or ambiguous genitalia; three were spontaneous abortuses. Twelve markers were derived from the X chromosome and eleven from the Y chromosome; this demonstrates successfully the value and necessity of FISH utilizing DNA probes in the identification of sex chromosome markers. Both fresh and older slides, some of which had been previously G-banded, were used in these determinations. We have also reviewed the literature on sex chromosome markers identified using FISH.

Toward quality assurance for metaphase FISH: a multicenter experience

Although fluorescent in situ hybridization (FISH) is rapidly becoming a part of clinical cytogenetics, no organization sponsors multicenter determinations of the efficacy of probes. We report on 23 laboratories that volunteered to provide slides and to use a probe for small nuclear ribonucleoprotein polypeptide N (SNRPN) and a control locus. Experiences with FISH for these laboratories during 1994 ranged from 0 to 645 utilizations (median = 84) involving blood, amniotic fluid, and bone marrow. In an initial study of hybridization efficiency, the median percentage of metaphases from normal individuals showing two SNRPN and two control signals for slides prepared at each site was 97.0 (range = 74-100); for slides prepared by a central laboratory, it was 97.8 (range = 81.6-100). In a subsequent blind study, each laboratory attempted to score 5 metaphases from each of 23 specimens [8 with del(15)(q11.2-->q12) and 15 with normal #15 chromosomes]. Of 529 challenges, the correct SNRPN pattern was found in 5 of 5 metaphases in 457 (86%) and in 4 of 5 in 33 (6%). Ambiguous, incomplete, or no results were reported for 32 (6%) challenges. Seven (1%) diagnostic errors were made, including 6 false positives and 1 false negative: 1 laboratory made 3 errors, 1 made 2, and 2 made 1 each. Most errors and inconsistencies seemed due to inexperience with FISH. The working time to process and analyze slides singly averaged 49.5 min; slides processed in batches of 4 and analyzed singly required 36.9 min. We conclude that proficiency testing for FISH by using an extensive array of challenges is possible and that multiple centers can collaborate to test probes and to evaluate costs.

Toward quality assurance for metaphase FISH: a multi-center experience

Although fluorescent in situ hybridization (FISH) is rapidly becoming a part of clinical cytogenetics, no organization sponsors multi-center determinations of the efficacy of probes. We report on 23 laboratories that volunteered to provide slides and to use a probe for SNRPN and a control locus. Experiences with FISH for these laboratories during 1994 ranged from 0 to 645 utilizations (median = 84) involving blood, amniotic fluid and bone marrow. In an initial study of hybridization efficiency, the median percentage of metaphases from normal individuals showing two SNRPN and 2 control signals for slides prepared at each site was 97.0 (range = 74-100); for slides prepared by a central laboratory, it was 97.8 (range = 81.6-100). In a subsequent blind study, each laboratory attempted to score 5 metaphases from each of 23 specimens [8 with del(15) (q11.2-->q12) and 15 with normal 15 chromosomes]. Of 529 challenges, the correct SNRPN pattern was found in 5 of 5 metaphases in 457 (86%) and in 4 of 5 in 33 (6%). Ambiguous, incomplete or no results were reported for 32 (6%) challenges. Seven (1%) diagnostic errors were made including 6 false positives and 1 false negative: 1 laboratory made 3 errors, 1 made 2, and 2 made 1 each. Most errors and inconsistencies seemed due to inexperience with FISH. The working time to process and analyze slides singly averaged 49.5 minutes; slides processed in batches of 4 and analyzed singly required 36.9 minutes. We conclude that proficiency testing for FISH using an extensive array of challenges is possible and that multiple centers can collaborate to test probes and to evaluate costs.

Uniparental isodisomy 13 in a normal female due to transmission of a maternal t(13q13q)

Chromosomes from a normal 23-year-old, primigravid woman were examined at 10 weeks of gestation because of her mother's history: 8 miscarriages and two liveborn infants (the proposita and a brother who died at 3 days with multiple anomalies). Karyotypes of the proposita and her normal mother were 45,XX,t(13q13q). No evidence of mosaicism was encountered. When the proposita inherited the t(13q13q), she received two copies of 13q from her mother. Moreover, she and her mother shared the same homozygous pattern of alleles from 7 highly polymorphic microsatellite repeats localized along 13q. No evidence of paternal markers from 13 was detected, although biparental inheritance was demonstrated with DNA markers from chromosomes 2 and 17. Cytogenetic and molecular findings indicated that the proposita's chromosomal complement included mUPD 13q. The proposita's normal phenotype suggested that no maternally imprinted genes map to 13q.

Partial X chromosome trisomy with functional disomy of Xp due to failure of X inactivation

A 5-month-old girl with mild phenotypic abnormalities, developmental delay, and seizures was found to have the de novo karyotype 46,XX,-13,+der(13)t(X;13)(p21.2;p11.1). The partial trisomy of Xp21.2-->pter was confirmed with fluorescence in situ hybridization, using an X chromosome painting probe and several cosmid and YAC probes for Xp sequences. Replication banding showed that one of the structurally normal X chromosomes was late-replicating, but that the Xp segment of the der(13) was early-replicating in all cells examined. Since segments of the X chromosome separated from the X inactivation center in Xq13.2 cannot undergo X inactivation, the result is functional disomy of distal Xp. As the loss of short arm material from chromosome 13 is not considered to be clinically significant, the genomic imbalance of Xp expressed in this patient most likely accounts for her abnormal phenotype.

Two anonymous DNA segments distinguish the Wilms' tumor and aniridia loci

The association of Wilms' tumor with aniridia (the WAGR complex) in children with 11p13 chromosomal abnormalities has been established, but the paucity of molecular probes in 11p13 has hampered identification of the responsible genes. Two new anonymous DNA segments have been identified that map to the WAGR region of 11p13. Both DNA probes identify a cytologically undetectable deletion associated with a balanced chromosome translocation inherited by a patient with familial aniridia, but not Wilms' tumor. The same two DNA segments are also included in the distal p13-p14.1 deletion of another patient, who has aniridia, Wilms' tumor, and hypogonadism, but they are not included in the p12-p13 deletion of a third patient, who does not have aniridia but has had a Wilms' tumor. The discovery of this aniridia deletion and these two DNA segments that physically separate the Wilms' tumor and aniridia loci should facilitate identification of the genes in the WAGR locus, beginning with the aniridia gene.

Dissociation of a t(12;21) resulting in a normal cell line in two trisomic 21 sons of a nonmosaic t(12;21) father?

A normal cell line arising from a translocation, t(12;21), possibly by dissociation, was observed in two brothers in early life. Each was conceived as trisomic 21 by their 45,XY,-12,-21,+t(12;21) father, who was phenotypically normal. Each brother showed morphologic manifestations of trisomy 21 syndrome, and each was mildly mentally retarded. Dermatoglyphic indices were not diagnostic of trisomy 21 syndrome. At 4 months the younger brother had a 50:50 proportion of trisomic:normal blood cells which became 25:75 of trisomic 21:normal at 36 months. The older brother had a 25:75 proportion of trisomic 21:normal when first studied at 41/2 years. A similar t(12;21) has not previously been reported. The occurrence of an apparently normal cell line arising spontaneously is unique.

Lymphocyte proliferation in a 31-week premature neonate with 69, XXX chromosomal constitution

The clinical syndrome of triploidy has only recently been described with its phenotypic characteristics emerging from a series of descriptive case reports. This paper describes the mitogen induced lymphocyte proliferative responses of a 31-week gestation neonate. Similar data, collected simultaneously, from 27 healthy 30-32-week gestation neonates is also reported for comparison. Since the capability of lymphocytes to become activated is dependent on and indicative of the host's ability to develop a cellular immune reaction, these data indicate no diminution in cell mediated immunity by this polyploid individual.

New deletion syndrome: 1q43

A male infant showed dysmorphology of the head and face, neck, extremities, and genitalia, as well as growth and mental retardation. His G-banded karyotype was 46,XY,--1+der(1),t(1;16)(q43;q24)mat. Combined with five previously reported cases involving similar terminal deletions beginning at 1q42 or 43, we show that the homology of phenotypic characteristics permits identification of a new deletion syndrome, the first involving chromosome 1.

Partial monosomy 7q syndrome due to distal interstitial deletion

A female infant was ascertained at 10 weeks because of failure to thrive and a peculiar cry and was found to have few morphologic variants. Her karyotype was 46,XX,del(7)(q3105::q3405). The parental karyotypes were normal. At one year she manifested physical retardation and development delay and required surgery for gastroesophageal incompetence. The phenotypic characteristics of this patient and those of six previously reported cases of 7q medial or distal interstitial deletion include many anomalies. Morphologic abnormalities of the head, ears, eyes, mouth, chest, hands, feet, and nerves combined with characteristics of birth weight, growth, and development define a detectable syndrome. An unusual cry may help in the recognition of this new syndrome.

Clinicopathological conference: a newborn monozygotic twin with abnormal facial appearance and respiratory insufficiency

The second of twins males expired of respiratory insufficiency shortly after birth. Unusual facial appearance included prominent forehead, flat nasal bridge, widely separated inner canthi, downward slanting eyes with narrow palpebral fissures, epicanthic folds, small mouth and micrognathia, and apparently low-set ears; there was also cryptorchidism bilaterally and a simian crease bilaterally. The pregnancy of the 19-year-old black woman was not unusual, but polyhydramnios accompanied the delivery of this twin. The twin placentae were diamniotic and monochorionic, one being slightly immature with a two-vessel cord. We interpreted the karyotype as 46,XY,del(10) (p11-15): The brother and parents were normal. The dysmorphic features of this and three previously reported cases of 10p- do not permit definition of a syndrome. These are apparently the first monozygous twins presenting discordance of chromosomal structure; previously reported chromosomal discordance in monozygous twins involved numerical abnormality. Considering that the mechanism monozygous twinning is not understood, we note that the occurrence of both twinning and a structural aberration in one of the twins suggests the possibility of a common cause.

Leukocyte chromosomes from parents of cytogenetically abnormal offspring: preliminary observations

The frequency of sporadic, hypermodal chromosomal spreads in cultures of leukocytes taken from the parents of aneuploids significantly exceeds that in comparison populations. Elimination of other possibilities suggests mitotic nondisjunction as the ultimate determinant for such spreads. This possibility requires that more attention be paid to the occurrence of hypermodal spreads, especially relative to the etiology of aneuploid concepti.