Mitigation of therapeutic anti-CD38 antibody interference with fab fragments: How well does it perform?

BACKGROUND

Administration of anti-CD38 antibodies is a state-of-the-art therapy for patients diagnosed with multiple myeloma (MM). However, this treatment frequently leads to pan-agglutination of red blood cells (RBCs) in patients' serological testing making accurate blood typing and timely transfusion of compatible blood a challenging effort. The antigen masking indirect antiglobulin test (AMIAT) is an approach to address this diagnostic challenge.

STUDY DESIGN AND METHODS

A new reagent, called DaraEx plus, uses anti-CD38 Fab fragments to mitigate the anti-CD38 antibody interference in serological assays by masking CD38 on the cell surface. Its performance is extensively examined with commercial sera as well as with patient samples, and compared to the current standard method using dithiothreitol (DTT), which denatures the CD38 antigens on test panel erythrocytes.

RESULTS

In the Bio-Rad ID System, DaraEx plus effectively mitigated the interference caused by anti-CD38 antibodies in 86% of patient samples tested while DTT was successful in only 68%. Moreover, there was no negative influence on DTT-sensitive blood group systems such as KEL upon DaraEx plus treatment. The agglutination reactions of all tested anti-CD38 antibodies (Daratumumab, Felzartamab, and Isatuximab) were inhibited by DaraEx plus. The treatment was successful only if DaraEx plus was added to the test cells before the sample. Some of the other gel card systems tested showed background reactions with DaraEx plus-treated cells.

CONCLUSION

DaraEx plus treatment is straightforward and quick to perform. In the Bio-Rad ID System, it is superior to DTT treatment in the prevention of anti-CD38 antibody interference.

Fragile sites induced by 5-azacytidine and 5-azadeoxycytidine in the murine genome

The cytosine analogues 5-azacytidine and 5-azadeoxycytidine were used to induce fragile sites on mouse chromosomes. Sites of relative frequent fragility were ascertained and compared with fragile sites induced by the antimetabolites methotrexate, fluorodeoxyuridine and aphidicolin as reported previously. Considerable overlap of fragile sites induced by the very different agents is evident. Fragile sites are common to all chromosomes and most of them are susceptible to different modes of induction.

Supernumerary der(1) marker chromosome derived from a ring chromosome 1 which has retained the original centromere and euchromatin from 1q21.1 --> q21.3 with substantial loss of 1q12 heterochromatin in a female with dysmorphic features and psychomotoric developmental delay

We report on a 5.5-year-old girl with dysmorphic features and psychomotoric developmental delay with a mitotically stable supernumerary marker chromosome. The origin of the marker was identified by microdissection and reverse painting of marker DNA as the pericentromeric region of chromosome 1. Fine mapping by FISH with selected YAC or BAC clones identified no p-arm material on the marker. The marker has retained its original centromere and euchromatin from 1q21.1-q21.3 but only small remnants of the 1q12 heterochromatin. Furthermore, some FISH clones presented single signals on the marker and others presented double signals indicating a partial duplication within the marker. These observations suggest a multi-step origin of the marker most probably with ring formation as the first step.

Zoogeography of the chromosome 1 HSR in natural populations of the house mouse (Mus musculus)

A polymorphism of the central part of chromosome 1 has been described from natural populations of the house mouse (Mus musculus). The region shows up as a C band-positive homogeneously staining region (HSR) under the light microscope. M. m. domesticus mice carry single band HSRs, whereas M. m. musculus animals have double band HSRs. HSR size variations have been described in both subspecies. The frequency of the HSR chromosome 1 in populations varies from 4% to 81%, but none of the large samples examined consisted only of homozygotes. In the subspecies M. m. domesticus, HSRs were found in North Africa and Western Europe, mainly in the hilly regions of Southern Germany and Switzerland. Localities with double HSRs are distributed all over the area of M. m. musculus. Based on the population data presented and DNA similarity of different HSRs, the origin and distribution of HSR chromosomes in the house mouse are discussed.

The Southwestern Ontario Joint Replacement Pilot Project: electronic point-of-care data collection. Southwestern Ontario Study Group

OBJECTIVE

To pilot a provincial joint replacement registry using electronic point-of-care data collection.

DESIGN

Data collection study.

SETTING

Southwestern Ontario, which has a population base of 3.5 million people.

PARTICIPANTS

Eighteen orthopedic surgeons.

METHOD

Information on total hip and knee replacements was obtained by the orthopedic surgeons over a 6-month period. Information was obtained in paper form and electronically on hand-held computers.

MAIN OUTCOME MEASURES

Patient demographics, waiting times from referral to operation, patient satisfaction and relevance and value of electronic records compared with paper records.

MAIN RESULTS

Data were collected on 815 total hip and knee arthroplasties. A slightly greater number of hips required revision than knees. The majority of patients were in the 60 to 90-year age range. With respect to the waiting time from referral to operation 10% of patients waited less than 5 weeks, 50% waited less than 30 weeks, and 90% waited less than 59 weeks. There was a high level of patient satisfaction with the operation and with hospital care received. Most surgeons found that the gathering and use of data electronically was relevant and easy. The electronic data were more timely, accurate and complete than paper records.

CONCLUSION

Electronic point-of-care data collection is appropriate, particularly in high-volume, high-cost surgical interventions such as total joint replacements.

Evaluation of children in six blind schools of Andhra Pradesh

PURPOSE

1. To determine the anatomical site and underlying causes of severe visual impairment and blindness in children in special education in Andhra Pradesh, India. 2. To compare the causes of blindness in two different regions in the state. 3. To evaluate improvement with correction of refractive error and low-vision devices (LVDs).

METHODS

Children in 6 schools for the blind and in 3 integrated education programmes were examined by one ophthalmologist, and were refracted and assessed for LVDs by an optometrist. The major anatomical site and underlying aetiology of severe visual impairment and blindness (SVI/BL; < 6/60 in the better eye) were recorded using the standardised WHO reporting form.

RESULTS

Two hundred and ninety one students under 16 years were examined, and after refraction, 267 (91.7%) were classified as being severely visually impaired or blind. The most common anatomical sites of SVI/BL were retina in 31.1% children; cornea in 24.3%; and whole globe in 20.2%. The aetiology was unknown in 38.2%, hereditary in 34.8% and childhood causes in 24%. 114 children (39.2%) had functional low vision (i.e. visual acuity < 6/18 to light perception with navigational vision). In this group, 36 children improved with spectacles and 16 benefited by LVDs. 41 children (15.4%) were able to read N10 point though they were studying Braille.

CONCLUSION

Overall 37.4% of children had "avoidable" causes of blindness. The major avoidable causes were vitamin-A deficiency and cataract. Vitamin-A deficiency and congenital anomalies were more common in the dry plateau areas of the state. One in seven children could read normal print with optical support.

Requirements for optical services in children with microphthalmos, coloboma and microcornea in southern India

PURPOSE

The aim of the study was (1) to determine the need for spectacles in children in Southern India with coloboma, microphthalmos and microcornea, (2) to describe their refractive errors and (3) to assess their needs for low vision aids (LVAs).

METHODS

Children with congenital eye anomalies were recruited from special education for the blind, schools for the mentally handicapped, community-based rehabilitation programmes and hospital records in Andhra Pradesh, India. All those with at least light perception vision (PL) in one eye and who had navigational vision were refracted. Those whose distance vision in their better eye improved with refraction were prescribed spectacles. Those unable to read N10 were assessed for LVAs for near. Those with distance visual acuity of < 6/18 in the better eye were assessed for telescopes to aid distance vision.

RESULTS

Ninety-nine children with coloboma, microcornea or microphthalmos had functional vision. Eight unilateral cases were excluded. Ninety-one bilateral cases were refracted and assessed for LVAs. The vision in 52 children (57%) improved in the better-seeing eye by 1 or more lines of Snellen acuity with spectacles. Spectacles were prescribed most frequently for myopia associated with choroidal coloboma. After refraction, all 19 children with a visual acuity of 6/18 or better could read N10, and 43 of the 72 children (60%) with a visual acuity of < 6/18 to PL with functional vision could read N10 unaided, or with distance correction. A further 6 (8%) reached this level with magnifiers. Thirteen children (18%) were given telescopes.

CONCLUSION

Children with congenital anomalies of the eye and functional vision benefit from refraction and low vision services.

Visual acuity in children with coloboma: clinical features and a new phenotypic classification system

OBJECTIVE

The aims of this study were to describe the clinical features and biometric findings in the eyes of children with coloboma and to develop a classification of coloboma that correlates with visual function.

DESIGN

Retrospective observational case series.

PARTICIPANTS

One hundred thirteen children and young adults (48 female, 65 male) aged 0 to 20 years with 196 eyes having coloboma.

METHODS

Children with coloboma were recruited from schools for the blind, integrated education programs, schools for the mentally handicapped, community-based rehabilitation services, and hospital clinics in Andhra Pradesh, India, between January 1998 and January 1999. Visual function was assessed, including distance and near visual acuity (VA), and navigational vision. The corneal diameter and axial length of eyes were measured wherever possible.

MAIN OUTCOME MEASURES

Anatomic site of coloboma, association with microcornea and/or microphthalmos, VA, presence of navigational vision and reading vision.

RESULTS

Of 196 eyes with colobomatous malformations, 11 had microphthalmos with cyst, and 185 eyes had coloboma (associated with microcornea in 155 eyes and with a normal corneal diameter in 30). Microphthalmos was present in 72 of the 185 eyes with coloboma, of which 71 of 72 also had microcornea. The prognosis for vision depended on the phenotype of the better eye. Microphthalmos with cyst had the worst prognosis (VA < 3/60, 100%; reading and navigational vision, 0%). Microcornea with microphthalmos had a worse prognosis than microcornea without microphthalmos (VA < 3/60: 66.7% vs. 23.3%; unable to read N10: 66.7% vs. 34.1 %; no navigational vision: 30.6% vs. 6.73%). Simple coloboma (no microcornea or microphthalmos) had the best prognosis (VA < 3/60: 6.7%; able to read N10: 93.3%; navigational vision: 100%). A corneal diameter <6 mm had a poor visual prognosis, whereas a corneal diameter >10 mm had a good prognosis.

CONCLUSIONS

A phenotypic classification of coloboma is proposed, which in this study showed a good correlation with visual acuity, reading, and navigational vision. Microphthalmos with cyst had the worst prognosis, coloboma with microcornea and microphthalmos a poor prognosis, coloboma with only microcornea had an intermediate prognosis, and simple coloboma had the best prognosis.

Demography and prognostic factors of ocular injuries in South India

PURPOSE

To evaluate the extent of visual recovery after multi-disciplinary approach of treatment in serious ocular injuries; to determine the prognostic factors associated with poor final visual outcome and suggest adequate precautionary measures.

METHODS

A retrospective analysis of 325 consecutive patients with direct ocular trauma who were examined and treated at a tertiary eye care centre in South India over a 3-year period was undertaken.

RESULTS

Males (86.8%) outnumbered the females (13.2%) and children (< 16 years) constituted 46.8% of the total affected population. Anterior segment was involved in 51.1%, the posterior segment in 8.9% and both anterior and posterior segments were involved in 31.4% of patients. Prompt and meticulous surgical treatment restored useful vision (better than or equal to 6/18) in 60.5% of patients. Post-treatment, a reduction in blindness and visual impairment rates in the affected eye with respect to WHO classification was 66.7 and 54.1% respectively (P < 0.0001). Two eyes needed prompt enucleation. The factors associated with visual impairment (visual acuity less than 6/18) were poor initial visual acuity, full chamber hyphema, endophthalmitis, retinal detachment, and vitreous haemorrhage.

CONCLUSIONS

Direct ocular trauma remains an important potentially preventable cause of ocular morbidity, but the advent of modern surgical techniques can often restore useful vision in such situations. Mandatory use of protective eye wear at work, public health education including awareness on the part of parents to the potential dangers of some childrens' toys can to an extent help reduce ocular morbidity due to direct ocular trauma.

Endoscopic adenoidectomy in a case of Scheie syndrome (MPS I S)

The mucopolysaccharidoses (MPS) are a heterogeneous group of relatively rare, progressive, inherited lysosomal storage disorders, characterized by a deficiency of lysosomal enzymes which are responsible for the stepwise degradation of glycosaminoglycans. Their deficiency leads to the accumulation of glycosaminoglycans in various organs causing progressive disruption of cellular functions and multiple systemic effects including otolaryngological problems, upper airway obstructive disease being the most common. Scheie syndrome (MPS I S) is due to the deficient activity of alpha-L-iduronidase leading to the intralysosomal accumulation of dermatan sulfate and heparan sulfate. We present our experience in one such case occuring in a 6-year-old girl with ENT manifestations and who underwent a successful endoscopic adenoidectomy for symptomatic adenoid hypertrophy. This procedure was preferred over a conventional adenoidectomy in order to avoid complications associated with abnormal cervical vertebrae.

Establishment of permanent wild-mouse cell lines with readily identifiable marker chromosomes

Physical gene mapping by in situ hybridization is a difficult task in an all-acrocentric mouse karyotype, because all of the chromosomes are morphologically very similar. These difficulties can be overcome by using the many different metacentric Robertsonian translocation (Rb) chromosomes derived from wild mice. Here we describe the establishment of two Moloney murine leukemia virus-transformed suspension cell lines, WMP-1 and WMP-2, derived from wild mice of the strain WMP/WMP. These mice carry nine pairs of metacentric Rb chromosomes containing chromosomes 1 to 18. Chromosome 19 and the sex chromosomes are the only acrocentric chromosomes. Furthermore, a heterozygous reciprocal translocation between chromosomes 13 and 17 involved in two Rb chromosomes is present in this stock and provides additional marker chromosomes. The chromosome designation of these mice is Rb(10.17)9Mpl Rb(13.15)10Mpl T(13.17)1Lub.

Inducible acceleration of G1 progression through tetracycline-regulated expression of human cyclin E

Cyclin E is a cell cycle-regulated protein that activates the cdc2-related protein kinases cdk2 shortly before S-phase entry. In order to analyse the biological role of cyclin E, we have generated HeLa cells that allow the conditional expression of ectopic human cyclin E. In these cells, a cyclin E cDNA is under the control of a bacterial tetracycline repressor-VP16 activator hybrid protein. In the absence of tetracycline, the endogenous gene becomes activated and leads to the synthesis of elevated levels of cyclin E. Concomitant with this increase in cyclin E expression we show by a combined time-lapse video recording/5-bromo-deoxyuridine labelling procedure a significant acceleration of G1 transition by approximately 1.5 hours. This observation is consistent with the idea that cyclin E is a rate-limiting factor with respect to the control of G1-->S transition. The experimental system described here should also prove useful to address the function of cyclin E in further detail.

Different fate of sibling cells upon inhibition of transcription in G1

In normally cycling populations of NIH3T3 cells, both sibling cells generated by a mitotic division require similar periods of time for completion of the cell cycle, with variations (intersibling times) of < or = 3 h for > 90% of the population. In this study, we analyzed by time-lapse video recording the effect of the RNA polymerase II inhibitor alpha-amanitin on the intersibling times of cells exposed to the drug at defined postmitotic ages. Our results led to the identification of three subpopulations of NIH3T3 cells. In the first one, both sibling cells were highly sensitive to alpha-amanitin. These cells were exposed to the inhibitor at a postmitotic age of < or = 2 h. The second subpopulation was composed of cells where one sibling showed normal kinetics of cell cycle progression, while the other sibling had an increased cell cycle length (intersibling times of up to 12 h) or did not divide at all during the period of observation. These cells were 2-8 h old at the time of treatment. In the third subpopulation, representing cells at later stages in the cell cycle, no significant increase in intersibling times was observed. These data indicate that alpha-amanitin increases the intersibling times of cells exposed to the drug during G1. In addition, our results suggest that the variable-length period of G1, thought to be located in late G1, is dependent on RNA polymerase II transcription.

Chromosomal localization and sequences of the murine Brn-3 family of developmental control genes

The POU proteins BRN-3a, -3b and -3c are transcription factors encoded by separate genes that are differentially expressed during neural development. Comparison of genomic and cDNA sequences revealed similar exon/intron structures for Brn-3a and -3c genes, whereas the Brn-3b gene appeared to contain an intronless coding region. Fluorescence in situ hybridization experiments with mouse chromosomes showed that Brn-3a maps to mouse chromosome 14E1-3, Brn-3b to XF1-5 and Brn-3c to 18B3-E1.

Inhibition of transcription blocks cell cycle progression of NIH3T3 fibroblasts specifically in G1

We have analysed the role of RNA polymerase II-dependent transcription in cell cycle progression. Time-lapse video recording and cytogenetic analysis were used to determine the sensitivity of NIH3T3 cells to the RNA polymerase II inhibitor alpha-amanitin at different stages of the cell cycle. Our results show that alpha-amanitin blocks cells specifically in G1, irrespective of the concentration within the range of 3 to 30 micrograms/ml. This indicates that transcription in G1 is required to overcome a restriction point located in this phase of the cell cycle. In agreement with this conclusion is the requirement for an uninhibited protein synthesis during G1 progression. In addition, the insensitivity of S-phase cells to RNA polymerase II inhibition suggests that the transcription of genes thought to be normally induced during S/G2 is not required for the completion of an ongoing cell cycle. S/G2 progression was however clearly dependent on protein synthesis. This suggests that cells exposed to alpha-amanitin are able to complete their cell cycle because sufficiently high levels of mRNA are present in S/G2 due to basal level transcription, or are left from preceding cell cycles. It is therefore unlikely that transcriptional regulation in S or G2 plays a crucial role in the control of cell cycle progression in NIH3T3 cells.

Gene order and genetic distance of 13 loci spanning murine chromosome 15

Thirteen genetic loci spanning murine chromosome 15 from 15A2 (Mlvi-2) to 15F2-3 (Gdc-1) have been mapped. The genetic distance extends to 55.4 cM. Among 151 animals, only 1 animal with a double cross-over was found. The linear order is unambiguous, with the exception of the distal end on 15F1-3. Our analysis favors the order cen-Ela-1/Hox-3-Wnt-1-Gdc-1-ter. This ordering makes necessary the introduction of three tightly spaced double recombination events around and within the Hox-3 locus. Alternatively, Hox-3 may be most distal, and several double recombinations at the telomere lead to map expansion. Despite the unequal distribution along chromosome 15 of G-versus R-bands, a comparison of distances determined by physical and genetic mapping does not indicate an overt difference in distance between both mapping techniques.

Molecular analysis of the aberrant replication banding pattern on chromosome 15 in murine T-cell lymphomas

Cytogenetic techniques revealed an altered early replication banding pattern on the distal part of chromosome 15 in some murine T-cell lymphomas. This pattern reverted back to normal replication in somatic cell hybrids that had become non-tumorigenic after fusion of leukemic cells with normal fibroblasts. The altered banding pattern was correlated with malignancy. To investigate the molecular basis of the aberrant pattern in more detail, centrifugal elutriation of cells containing bromodeoxyuridine labeled DNA was used to prepare newly replicated DNA from selected intervals of the S-phase from tumor cells, as well as from hybrid cells with the revertant phenotype. These different DNA fractions were probed for DNA sequences distributed over the distal half of chromosome 15. Only two out of ten chromosome 15 specific genes tested showed a clear change in replication timing between the two different cell lines tested. These two genes were the lymphocyte antigen-6, Ly-6, and the neighboring thyroglobulin gene, Tgn, which replicated at the beginning of S in the tumor cells and later in S in the non-tumorigenic hybrid cells.

Nonradioactive in situ nick translation combined with counterstaining: characterization of C-band and silver positive regions in mouse testicular cells

The DNase I sensitivity of three different chromatin regions in mouse testicular cells was analysed by in situ nick translation with biotin-dUTP combined with various counterstaining techniques. The regions were: (i) the constitutive centromeric heterochromatin, (ii) an interstitial C-band positive insertion on chromosome 1, Is(HSR1;C5)1Lub, and (iii) the chromatin containing rDNA (designated nucleolar chromatin herein). Incorporated biotin was detected either by the horseradish peroxidase reaction with diaminobenzidine (DAB) or the alkaline phosphatase reaction with fast red. The latter resulted in a water insoluble red precipitate, which was easily removable by any organic solution thus allowing the application of various counterstaining protocols. DNase I sensitivity of the three chromatin regions was screened in different cell types of the mouse testis. The interstitial Is(HSR) region was highly DNase I sensitive when it was recognizable by strong mithramycin fluorescence. The centromeric heterochromatin was DNase I resistant when it was compacted into microscopically visible chromosomal structures (mitosis, pachytene, metaphase I and II). In interphase nuclei from Sertoli cells and spermatogonia it became highly DNase I sensitive. In round spermatids it displayed medium DNase I sensitivity. Nucleolar chromatin was not labelled by in situ nick translation when silver staining demonstrated strong protein production. Sperm cells were highly DNase I sensitive from stages 11 to 15, but resistant as mature spermatozoa.

Amplification and rearrangement of c-myc in radiation-induced murine osteosarcomas

Fifty-one radiation-induced murine osteosarcomas were investigated for alterations in c-myc gene structure and c-myc expression. Amplification of c-myc was found in 30% of BALB/c tumors and 13% of NMRI tumors. A region of common proviral integration, Mlvi-1, localized on the same region on chromosome 15, was amplified concomitantly. Multiple copies of both loci were localized on double minutes. Three of the tumors with c-myc amplification also showed rearrangements of the c-myc gene region. One of these rearrangements included the 5' and 3'-flanking sequences and the noncoding part of the third exon. Repetitive sequences were found in the 5' region of the c-myc gene, and the 3' flanking region was substituted by sequences normally present in a more distant part of chromosome 15. Increased levels of c-myc transcripts of apparently normal size were found in tumors carrying amplified c-myc sequences. Abnormally high expression of c-myc in some tumors was correlated with an early stage of osteogenic differentiation, suggesting the involvement of the c-myc gene in the control of the osteogenic differentiation of transformed cells.

Evidence that replication initiates at only some of the potential origins in each oligomeric form of bovine papillomavirus type 1 DNA

In a subclone of ID13 mouse fibroblasts latently infected with bovine papillomavirus type 1 (BPV-1) DNA, the viral genome occurred as a mixture of extrachromosomal circular monomers and oligomers. Multiple copies were also associated with the host cell genome, predominantly at a single site in a head-to-tail tandem array. We examined the replicative intermediates of extrachromosomal forms of BPV-1 DNA by using two-dimensional gel electrophoresis. The results obtained indicate that initiation of DNA replication occurred near the center of the EcoRI-BamHI 5.6-kilobase fragment. In some molecules, however, this fragment was replicated from one end to the other by means of a single fork initiated elsewhere. Termination also occurred within this fragment. The EcoRI-BamHI 2.3-kilobase fragment replicated as a DNA molecule containing a termination site for DNA replication and also by means of a single fork traversing the fragment from one end to the other. Thus, replication forks proceeded through these fragments in different manners, apparently depending on whether they were part of a monomer, a dimer, a trimer, or higher oligomers. These observations lead to the conclusion that initiation of DNA replication in BPV-1 DNA takes place at or close to plasmid maintenance sequence 1. From this point, replication proceeds bidirectionally and termination occurs approximately 180 degrees opposite the origin. The results obtained are consistent with one or more replication origins being quiescent in BPV-1 DNA oligomers.

Improvement of peroral absorption of cyclosporine A by microemulsions

The rat was found to be a suitable model for pharmacokinetic and bioavailability studies of cyclosporine A (CsA). All pharmacokinetic parameters studied were in the same order of magnitude as those found in man. Two peroral formulations in the form of microemulsions were compared with a commercially available P.O. solution (to be diluted for administration) and a solution for intravenous administration. Of the two microemulsions, one resulted in an extent of absolute and relative bioavailability significantly higher than that of the available P.O. solution. Biliary recycling was observed upon all routes of administration. If uncorrected for biliary recycling, both absolute and relative bioavailability are overestimated.

Ion-trapping of meperidine: influence of antacid treatments on serum and gastric fluid concentrations

The ascorbic acid pretreated beagle dog was used to demonstrate the phenomenon of ion-trapping and the influence of three different antacid treatments on the serum and gastric fluid concentration of meperidine: pretreatment with magnesium-aluminum hydroxide (MA), pretreatment with cimetidine (C), and periodic total aspiration of gastric fluid (ASP). A significant correlation between pH and the meperidine concentration in gastric fluid was found; the lower the pH the higher is the secretion of meperidine into gastric fluid. The gastric fluid meperidine concentrations were 8-30 times as high as the respective serum concentrations. No significant differences between the meperidine concentration in the gastric fluid were found among the three treatments, MA, C, or ASP, versus control. Meperidine serum concentrations differed significantly versus control on two times for MA and on one time for ASP. The elimination half-life [h] and the mean residence time [h] differed significantly in the MA treatment (1.15 +/- 0.02 h and 1.23 +/- 0.24 h) versus control (1.90 +/- 0.19 h and 2.00 +/- 0.15 h).(ABSTRACT TRUNCATED AT 250 WORDS)

In situ nick translation of human metaphase chromosomes with the restriction enzymes MspI and HpaII reveals an R-band pattern

Several restriction enzymes (HindIII, HaeIII, MspI, HpaII, EcoRI, KpnI, and NotI) were evaluated for their ability to induce bands in human metaphase chromosomes during in situ nick translation. MspI and HpaII were able to induce a completely developed R-band pattern. Preferential cleavage of R-band chromatin is due to the presence of unmethylated CpG-residues present in CpG-rich islands, which are apparently unevenly distributed and mainly concentrated in R-bands.

The 5' flanking region and chromosomal localization of the gene encoding human platelet membrane glycoprotein Ib alpha

The human blood platelet membrane glycoprotein Ib (GPIb) functions as a receptor for von Willebrand factor and thrombin. The gene (gpIb alpha) encoding the GPIb alpha-chain was cloned from a genomic cosmid library. The promoter region of this gene was characterized by sequencing two BamHI fragments including 2.8 kb of the 5' flanking region where several Alu repeated elements and purine-rich sequences were found. Possible cis-regulatory elements were identified by comparing the gpIb alpha gene with established consensus sequences known to function as binding sites for transcription factors. To obtain further information on possible megakaryocyte-specific promoter or enhancer sequences, the gpIb alpha promoter region was compared with other genes expressed in platelets that are known so far. The gpIb alpha gene was found to be located on chromosome 17 in region 17p12-ter, by in situ hybridization.

Localization of the active type I DNA topoisomerase gene on human chromosome 20q11.2-13.1, and two pseudogenes on chromosomes 1q23-24 and 22q11.2-13.1

Different subfragments of a cDNA coding for DNA topoisomerase I were used as probes to determine the chromosomal localization of topoisomerase I sequences in human cells. Southern blotting of restricted DNA from a panel of rodent-human somatic cell hybrids revealed the localization of the complete gene on chromosome 20 and the presence of two truncated topoisomerase I pseudogene sequences on chromosomes 1 and 22. In situ chromosome hybridization experiments confirmed these results showing the location of the complete gene on band q11.2-13.1 of chromosome 20, and the location of the pseudogene sequences on band q23-24 of chromosome 1 and q11.2-13.1 of chromosome 22.

t(2;8) variant translocation in Burkitt's lymphoma: mapping of chromosomal breakpoints by in situ hybridization

In 6 different Burkitt lymphoma cell lines with t(2;8) variant translocations (J1, LY66, LY91, BL21, BL64, JBL2) the breakpoints on chromosome 8q+ were mapped in relation to each other and to c-myc by in situ hybridization. The probes used were derived from chromosome 8q24 and comprised a c-myc probe, a probe located 48 kb downstream of c-myc, 3 probes adjacent to the chromosomal breakpoints of BL64, LY91 and JBL2, respectively, and 2 probes located in the 5' and 3' part of the thyroglobulin gene. The breakpoints of LY91 and JBL2 lie less than 200 kb and greater than 200 kb downstream of c-myc, whereas the distance to c-myc of the BL64 breakpoint and of the thyroglobulin probes is unknown. By recording the hybridization signals specific for these probes on chromosomes 2p- and 8q+ of each cell line it was possible to establish the order of breakpoints on band 8q24 relative to the c-myc and thyroglobulin genes as follows: centromere--c-myc--J1--BL64--BL21--LY91--JBL2--+ ++LY66--thyroglobulin--telomere. This information is essential for further mapping of this important chromosomal region.

Fine localization of genes on distal murine chromosome 15

The following genes were localized by in situ hybridization on distal chromosome 15 of the mouse: thyroglobulin (Tgn) to 15D3/E, parvalbumin (Pva) to 15E, and the NADH-dependent cytosolic form of glycerol-3-phosphate dehydrogenase (Gdc-1) to 15F1-3. These genes belong to three different conserved chromosomal linkage groups on human chromosomes 8, 22, and 12, respectively.

The VK genes on human chromosome 22 are located at 22q11

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Chromosomal mapping of the structural gene coding for the mouse cell adhesion molecule uvomorulin

The gene coding for the mouse cell adhesion molecule uvomorulin has been mapped to chromosome 8. Uvomorulin cDNA clone F5H3 identified restriction fragment length polymorphisms in Southern blots of genomic DNA from mouse species Mus musculus domesticus and Mus spretus. By analyzing the segregation pattern of the gene in 75 offspring from an interspecific backcross a single genetic locus, Um, was defined on chromosome 8. Recombination frequency between Um and the co-segregating loci serum esterase 1 (Es-1) and tyrosine aminotransferase (Tat) places Um about 14 centimorgan (cM) distal to Es-1, and 5 cM proximal to Tat. In situ hybridization of uvomorulin [3H]cDNA to mouse metaphase chromosomes located the Um locus close to the distal end of chromosome 8 (bands C3-E1). Since uvomorulin is evolutionarily highly conserved, its chromosomal assignment adds an important marker to the mouse genetic map.

Suppression of tumorigenicity in T-cell lymphoma hybrids is correlated with changes in myc expression and DNA replication of the myc chromosomal domain

Intraspecific somatic cell hybrids between T-lymphoma cells and lymphocytes are highly tumorigenic whereas fusion of T-lymphoma cells with normal fibroblasts leads to reduced or even completely suppressed tumorigenicity of the hybrid cells. A particular cytogenetic phenomenon defines these two classes of hybrids. DNA replication analysis via bromodeoxyuridine pulse labelling reveals an aberrant banding pattern in the c-myc chromosomal domain in tumour cells and highly tumorigenic hybrids. In hybrids with suppressed tumorigenicity the tumor parent derived chromosomes have reverted to normal DNA replication banding. Aberrant DNA replication in tumour cells and highly tumorigenic hybrids coincides with enhanced c-myc expression. In hybrids with suppressed tumorigenicity and with normal DNA replication banding c-myc expression is also reduced. Thus, a correlation between aberrant DNA replication and enhanced expression of a gene located in the same chromosomal domain is observed. Reversion of aberrant DNA replication and reduction of c-myc expression to normal in hybrid cells may be due to a site-specific trans effect which overrides the control brought about in cis by retroviral insertion near the c-myc gene.

Localization of proviral integration sites (Mlvi-1, Mlvi-2, and Pvt-1) and the alpha-globin pseudogene, Hba-3ps, on murine chromosome 15

In situ hybridization was applied to map different proviral integration sites on murine chromosome 15. The Moloney murine leukemia virus integration site 1, Mlvi-1, was assigned to 15D2, Mlvi-2 to 15A2-B1, and the plasmacytoma variant translocation site 1, Pvt-1, to 15D2-3. The alpha-globin pseudogene, Hba-3ps, was mapped in close proximity to Mlvi-1 in 15D2.

In situ nick translation distinguishes between C-band positive regions on mouse chromosomes

In situ nick translation of mouse metaphase chromosomes by non-radioactive detection means and DNase I digestion followed by Giemsa staining were used to analyse the DNase I resistance of two different C-band positive regions. These were the centromeric heterochromatin of acro- and metacentric chromosomes and an interstitial C-band on chromosome 1 of wild mice, IS(HSR;1C5D)1Lub. Whereas the centromeric heterochromatin was clearly resistant to DNase I, the interstitial C-band showed very high DNase I sensitivity. Among centromeric C-bands, the heterochromatin in Robertsonian fusion biarmed chromosomes was more resistant to DNase I action than was the centromeric heterochromatin of the acrocentric chromosomes.

Metaphase association of mammalian chromosomes

The association behavior of chromosomes bearing nucleolar organizer region (NOR) and (or) C-heterochromatin in metaphase plates was analyzed. Different species with an informative chromosomal localization of NOR and C-heterochromatin were evaluated. Several examples indicate that the well-known metaphase association is not due to NORs or NOR activity per se. Other mechanisms such as ectopic pairing are responsible for the association. These types of pairing seem to be enhanced by the chromatin-decondensing effect of nearby NOR activity.

A comparative mapping study of fragile sites in the human and murine genomes

Fragile sites on murine chromosomes were induced by the antimetabolites methotrexate (MTX), fluorodeoxyuridine (FdU), and aphidicolin (APD). To facilitate chromosome identification the analysis was performed on chromosomes of a CD/CD mouse that possesses nine pairs of Robertsonian translocation chromosomes of known arm composition. The pattern of induced fragile sites was rather similar for the different antimetabolites used. Many of them, e.g., 2B, 3B, 5B and 9D, are included in Giemsa-negative bands. On the X chromosome a fragile site was mapped to the region XC/D. Comparative mapping data with human fragile sites have been informative in most instances. Conservation of synteny within known linkage groups seems very likely.

Evolution of tumor cytogenetic aberrations and N-myc oncogene amplification in a case of disseminated neuroblastoma

Chromosome analyses including in situ hybridization with the protooncogene N-myc were carried out at diagnosis and several times at relapse in the bone marrow cells of a girl with disseminated neuroblastoma (stage IV) at ages 9, 23, 24, and 26 months, respectively. The tumor karyotype was pseudodiploid exhibiting partial monosomy for the short arm of chromosome #1, an aberration of the short arm of chromosome #2, and double minutes at diagnosis. Further structural aberrations of chromosomes #4, #6, and #17, and homogeneously staining regions could be demonstrated at relapse. In particular, the following structural aberrations were encountered: t(1;?)(p22;?),t(2;?)(p24;?), t(4;6)(q31;q25), and a der(17q). All tumor metaphases without homogeneously staining regions contained double minutes. N-myc, normally positioned within bands 2p23-24, was found to be amplified in a homogeneously staining region on the short arm of chromosome #15 by in situ hybridization. It is speculated that the translocation t(2;?)(p24;?) might be related to N-myc oncogene activation and subsequent amplification.

Deletion of c-fms sequences in the 5q- syndrome

Southern blot analyses demonstrated hemizygosity of c-fms sequences in three cases of the 5q- syndrome, cytogenetically characterized by del(5)(q13;q35) or del(5)(q31;q35). In situ hybridization studies revealed a deletion of this oncogene from the 5q- chromosome in two cases; moreover, we localized c-fms to region 5q31-33.

Mapping of the oncogenes Myc, Sis, and int-1 to the distal part of mouse chromosome 15

Two proto-oncogenes, Myc and Sis, as well as a putative mouse oncogene, int-1, were localized by in situ hybridization to the distal third of mouse chromosome 15. The respective loci of these genes map to different cytogenetic sites with Myc in 15D2-D3, Sis in 15E, and int-1 in 15F1-F3. These data may be of considerable impact as to the correlation of mouse neoplasias with chromosomal aberrations involving chromosome 15.

Measurement of the effect of cardiovascular drugs by impedance cardiography in healthy subjects

Impedance cardiography is a non-invasive electrical method designed to measure cardiac function on a beat-to-beat basis. Impedance changes within a constant high frequency AC-current field are detected by two thoracic electrodes. The potential changes within these two inner electrodes reflect impedance changes due to underlying pulsatile volume displacements. The relevance of the method was shown in investigations with a beta 1,beta 2-mimetic drug, a beta-blocker, an alpha-agonist, an alpha-blocker and a diuretic drug.

In situ hybridization studies on variant t(2;8) translocations in Burkitt lymphoma lines

In situ hybridization studies were performed on two Burkitt lymphoma cell lines with variant t(2;8) translocation. In both cell lines the Ck-gene is found in juxtaposition to the c-myc gene on the 8q+ chromosome. The location of the c-myc gene 5' of an immunoglobulin constant gene appears to be a general feature of all Burkitt lymphomas. On the 2p chromosome the site of the breakpoint of the translocation is variable. In the cell line BL 64 the break is in the fragment carrying Jk sequences and in cell line JI it is between Jk and Vk. In the cell line BL 64 different marker chromosomes were observed which result from breakage near or within the JGK-gene cluster on chromosome 2p.

Oncogenes and the mammalian X chromosome

None of the up to now localized and expressed oncogenes maps to the mammalian X chromosome. This fact is discussed in the light of a trans-acting regulation mechanism for oncogenes. Such a specific regulation mechanism is demonstrated here for a qualitative change--i.e., varying timing of DNA-replication--at the putative c-myc gene locus in band 15E of murine T-cell leukemia. In intraspecific hybrids between tumor and non-tumor cells this qualitative change spreads over to all chromosomes 15 of the same cell, irrespective of their origin. This effect is thought to reflect a binary trans-acting regulation mechanism between homologous chromosomal loci. In the past specific chromosomal aberrations have been described in various tumors but none of these aberrations involve the X chromosome. For the mammalian X chromosome where there is usually only one gene copy per cell active the described kind of binary trans-acting regulation between homologous gene loci is rendered impossible.

In situ nick translation of metaphase chromosomes with biotin-labeled d-UTP

Limited nick translation experiments on fixed chromosomes were performed. Sites of preferential DNase-I nicking were made visible by the incorporation of biotin-labeled dUTP and subsequent binding of the streptavidin-peroxidase complex. This procedure leads to a banding pattern on the chromosomes which is strongly DNase-I concentration dependent. Along the chromosome arms, regions of enhanced DNase-I sensitivity alternate with regions of lower DNase-I sensitivity. No complete G- or R-type banding pattern was observed. The easily identifiable human Y chromosome was studied more intensively. Compiled data show the heterochromatin of the Y chromosome stained as heavily as the euchromatin. The boundary between the eu- and heterochromatin on the long arm appears to be a site of preferential DNase-I sensitivity.

Early replication banding reveals a strongly conserved functional pattern in mammalian chromosomes

One of the best documented autosomal linkage associations in man is on chromosome 1p and in the mouse on chromosome 4. On mitotic chromosomes this genetic homology is shown more clearly by early replication banding (RBG; induced by incorporation of 5'bromodeoxyuridine (BrdU) in the second half of the S phase) than by structural banding (induced on prefixed chromosomes by denaturation, RFA, or trypsin, GTG). To analyse this phenomenon in more detail, 11 chromosomal regions in man and the domestic cat with known genetic homology were compared. In four chromosome pairs RBG and GTG banding show the same degree of homology. In seven chromosome pairs the homology is more pronounced by RBG than by GTG banding. RFA banding does not reveal the same extent of homology as does RBG banding. These results clearly show a difference between the structural banding pattern, RFA and GTG, and the replication banding pattern, RBG. The following conclusions can be drawn: in chromosomal regions with homologous functions the DNA replicates in the same temporal order. Early replication banding (RBG) reveals a functional pattern in these regions which has been more strongly preserved during evolution than the underlying chromosomal DNA. Differences in chromosomal banding are most prominent in the GTG banding pattern, whereas similarities are most apparent in the RBG banding pattern.

c-myc and immunoglobulin kappa light chain constant genes are on the 8q+ chromosome of three Burkitt lymphoma lines with t(2;8) translocations

We have determined the localization of c-myc and the immunoglobulin kappa light chain genes on the 8q+/2p- chromosomes of the three Burkitt lymphoma lines BL21, LY66 and LY91 with t(2;8) translocation by in situ hybridization. BL21 is characterized by a complex translocation in which a piece of chromosome 9 appears to be located between the fragments of chromosome 8 and 2 on the 8q+ chromosome. Our data indicate that in all three cell lines the c-myc gene is located on the 8q+ chromosome proximal to the breakpoint in band 8q24. In all cell lines examined the cluster of kappa variable genes has remained on the 2p- chromosome. In LY91 cells the major part of the joining region remained on 2p-, while the joining region has moved to 8q+ in the cell lines BL21 and LY66. In all three cell lines the constant kappa light chain gene was found on the 8q+ chromosome. The fact that an essentially identical pattern was found in the cell line BL21, with the complex translocation, suggests that the insertion of the piece of chromosome 9 into the 8q+ chromosome might be a secondary event. Our present data fit into the concept that in all Burkitt lymphoma lines investigated so far, including cases with t(8;14) and the variant translocations t(2;8) and t(8;22), the c-myc gene becomes situated at the 5' side of an immunoglobulin constant gene. This may have implications for the generation of somatic mutations in the coding and non-coding part of the c-myc gene.

An extra segment in chromosome 1 of wild Mus musculus: a C-band positive homogeneously staining region

An extra segment in chromosome 1 between bands C5 and D has been found in wild mouse populations. Its size varies between 6.1% and 30.1% of the length of a standard chromosome 1. It differs among individuals and populations but is constant in a genetically homogeneous line. According to its staining properties and variation in length it is a homogeneously staining region (HSR), a kind of segment otherwise found only in cell lines under strong selection and in tumor cells. G-banding gives a homogeneous staining of medium intensity. With C-banding, staining is positive, though lighter than that of centromeric heterochromatin. Fluorescence is dull with Hoechst 33258 and bright with mithramycin. The extra segment does not contain mouse satellite DNA sequences in any quantity detectable by in situ hybridization. Such an extra segment was found in several European populations of mice from Spain to Russia. It is carried through the germ line. It has been introduced into a laboratory mouse strain, and, by recombination, inserted into a Robertsonian metacentric chromosome for easier handling and identification.