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Biomedical subjects

R Berger

Publications and source records attributed to R Berger.

At least 505 records · Page 28Linked to original sources
PubMed1991

Mutations in the p53 gene in myelodysplastic syndromes.

We have examined p53 alleles in 151 DNAs from patients with myelodysplastic syndrome using single-strand conformation polymorphism analysis of polymerase chain reaction products. We focused our study on the four highly conserved regions of the p53 gene and detected five patients with aberrantly migrating fragments. We confirmed the putative mutation in each case by direct sequencing analysis. Of these five patients, three had chromosome 17 monosomy associated with p53 mutation, one patient showed one mutated p53 allele and one wild-type allele, and the last patient demonstrated only the mutant allele, suggesting a homozygous state. Unlike many other types of human cancers, point mutations in the p53 tumor-suppressor gene appear to be a rare event in myelodysplastic syndromes.

Alleles↗
PubMed1991

Molecular cytogenetics of acute lymphoblastic leukemia.

From a fundamental research point of view, malignancies may be viewed as opportunities that deregulate cell growth and differentiation, thus providing the possibility to find new genes and understand how these genes act. Acute lymphoblastic leukemia (ALL) is one of the best examples of malignant proliferation that has benefited by considerable advances of molecular cytogenetics for the ten past years. Three types of chromosome abnormalities may be considered in ALL. Clonal anomalies may be more or less specific for a cellular type of leukemia, such as the t(8;14)(q24;q32) and t(9;22)(q34;q11) translocations related with Burkitt type of leukemia and Philadelphia-positive ALL (Ph1+ ALL) respectively, and for this reason are often designated as recurrent abnormalities. They are mainly structural chromosomal abnormalities, often translocations. A second type of clonal abnormalities consists of nonrandom alterations which are not apparently related with the differentiation type. They are the solely detected chromosomal changes (trisomy for instance) or may be associated with other anomalies and have been often considered as "secondary" abnormalities. Finally, nonclonal cytogenetic anomalies are the third type of anomalies. They may be present even prior any treatment and characterize a minority of ALL. This aspect of chromosomal instability of unknown mechanism will not be discussed here.

Chromosome Aberrations↗
PubMed1991

Two trials of an acellular DTP vaccine in comparison with a whole-cell DTP vaccine in infants: evaluation of two PT doses and two vaccination schedules.

The present trials being carried out in Switzerland and Turkey, the reactogenicity and immunogenicity of acellular DTP vaccines containing either 25 micrograms or 8 micrograms of PT and 25 micrograms of FHA were compared with those of a conventional whole-cell DTP vaccine during a primary vaccination course following either a 0-1-2 schedule starting at three months of age (Switzerland) or a 0-2-4 schedule starting at two months of age (Turkey). The whole-cell vaccine was associated with significantly more local reactions than the acellular vaccines; general reactions were also more frequent among whole-cell recipients. The 25 micrograms PT dose vaccine was no more reactogenic than the 8 micrograms PT dose vaccine. There was no evidence of increases in frequencies of local or general reactions from one acellular vaccine dose to the next. The 25 micrograms PT dose acellular DTP vaccine resulted in immune responses to all four antigens (PT, FHA, diphtheria and tetanus toxoids) at least equivalent to those observed with whole-cell vaccination. Significantly lower anti-PT antibody levels were seen with the 8 micrograms PT dose vaccine.

Antibodies, Bacterial↗
PubMed1991

Effects of acute asphyxia on brain energy metabolism in fetal guinea pigs near term.

In a previous study we suggested that--unlike other forms of asphyxia--acute asphyxia caused by arrest of uterine blood flow is accompanied by a fall in oxygen delivery to the fetal brain (Jensen et al., 1987). This may change cerebral energy metabolism by causing an increase in the glycolytic rate. To test this hypothesis we studied the time course of the changes in the levels of high-energy phosphates and glycolytic intermediates in the cerebral cortex of unanaesthetized fetal guinea pigs near term before and after 2 and 4 min of acute asphyxia. During asphyxia there was a progressive fall of adenosine triphosphate, creatine-phosphate, glucose and fructose-1,6-diphosphate concentrations, whereas adenosine diphosphate, adenosine monophosphate and lactate concentrations increased. Pyruvate concentrations did not change. We conclude that fetal cerebral energy metabolism becomes increasingly anaerobic during acute asphyxia caused by arrest of uterine blood flow, because oxygen delivery to the fetal brain falls.

Animals↗
PubMed1991

Lack of mutations in the TP53 tumor suppressor gene exons 5 to 8 in Fanconi's anemia.

The TP53 gene is considered to be a negative regulator of cell growth whose inactivation is an important step in the development or progression of malignancies. Recently, germ line TP53 mutations have been detected in a familial cancer syndrome, the dominantly inherited Li-Fraumeni syndrome. Using single strand conformation polymorphism analysis of PCR products, we looked for TP53 mutations in DNA of patients with Fanconi anemia, an autosomal recessive disease characterized by increased predisposition to neoplasia. We did not find any TP53 mutation in 13 patients, suggesting that this tumor suppressor gene is not directly involved in the cancer susceptibility observed in Fanconi's anemia.

Aged↗
PubMed1991

Fetal circulatory responses to oxygen lack.

The knowledge on fetal and neonatal circulatory physiology accumulated by basic scientists and clinicians over the years has contributed considerably to the recent decline of perinatal morbidity and mortality. This review will summarize the peculiarities of the fetal circulation, the distribution of organ blood flow during normoxemia, and that during oxygen lack caused by various experimental perturbations. Furthermore, the relation between oxygen delivery and tissue metabolism during oxygen lack as well as evidence to support a new concept will be presented along with the principal cardiovascular mechanisms involved. Finally, blood flow and oxygen delivery to the principal fetal organs will be examined and discussed in relation to organ function. The fetal circulatory response to hypoxemia and asphyxia is a centralization of blood flow in favour of the brain, heart, and adrenals and at the expense of almost all peripheral organs, particularly of the lungs, carcass, skin and scalp. This response is qualitatively similar but quantitatively different under various experimental conditions. However, at the nadir of severe acute asphyxia the circulatory centralization cannot be maintained. Then there is circulatory decentralization, and the fetus will experience severe brain damage if not expire unless immediate resuscitation occurs. Future work in this field will have to concentrate on the important questions, what factors determine this collapse of circulatory compensating mechanisms in the fetus, how does it relate to neuronal damage, and how can the fetal brain be pharmacologically protected against the adverse effects of asphyxia.

Animals↗
PubMed1991

Rearrangement of the E2A gene in the t (1;19) acute lymphoblastic leukemia.

Recent studies have demonstrated that the E2A gene encoding helix-loop-helix proteins E12/E47 is fused to a novel homeobox gene PBX1, as a result of the t (1;19) translocation observed in pre-B cell acute lymphoblastic leukemias. Molecular diagnostic techniques, including PCR, of the t (1;19) are now possible and provide an useful tool in conjunction with cytogenetics to identify involvement of E2A and PBX1 genes in acute lymphoblastic leukemia.

Chromosomes, Human, Pair 1↗
PubMed1991

Cerebral energy metabolism in guinea pig fetuses during development.

During development fetal arterial oxygen tension falls, whereas cerebral oxygen consumption rises due to an increase in cerebral metabolism. To compensate for this increase in oxygen consumption, blood flow and therefore oxygen delivery to the cerebrum rises. To determine whether during development oxygen delivery to the cerebrum meets cerebral oxygen consumption, we measured the concentrations of high-energy phosphates and glycolytic intermediates in the cerebral cortex of fetal guinea pigs at different gestational ages. During development there was no change in the concentrations of adenosine triphosphate, creatine phosphate, adenosine monophosphate, and lactate. However, cerebral concentrations of adenosine diphosphate increased and those of glucose decreased. Our results suggest that the increase in fetal cerebral oxygen delivery during development meets cerebral oxygen consumption with increasing gestational age. We speculate that the measured rise in the concentrations of adenosine diphosphate may accelerate glycolysis during development and therefore may cause a rise in both cerebral blood flow to maintain oxygen delivery.

Adenosine Diphosphate↗
PubMed1991

Two site-specific deletions and t(1;14) translocation restricted to human T-cell acute leukemias disrupt the 5' part of the tal-1 gene.

Analysis of several cases of t(1:14)(p32;q11) translocation present in 3% of T-cell acute leukemias (T-ALL) has revealed the tal-1 gene. This gene encodes a helix-loop-helix protein. It has been found to be expressed in normal bone marrow and in leukemic T-cell and erythroleukemia cell lines, but not in normal T cells. Recently, a site-specific deletion, tald, renamed tald1 in this paper, has been detected in a high proportion of pediatric T-ALL, which arose by a site-specific DNA recombination between tal-1 and a new locus termed SIL. In this study we searched for structural rearrangements within tal-1 in a panel of 134 non-selected leukemic patients (including 66 with T-ALL). Only 6% of patients with T-ALL harbored the tald1 deletion. A second specific deletion termed tald2 was observed in another 6% of T-ALL patients; it involves another site within tal-1 plus the same site as tald1 in the SIL locus. Similarly to tald1 deletion, tald2 junctions harbor structural characteristics that are reminiscent of aberrant recombinase activity. Moreover, we report a detailed analysis of the tal-1 gene structure. Transcription analysis and in vitro translation data are consistent with the differential expression of several TAL-1 protein species containing the HLH motif but differing in their amino terminus. Taken together, our data indicate that t(1;14) translocations and both tald deletions disrupt the 5' part of the tal-1 gene, placing its entire coding sequences under the control of the regulatory elements of the TCR-delta gene or the SIL gene, both of which are normally expressed in T-cell lineage.

Amino Acid Sequence↗
PubMed1991

Infrequent mutations in the P53 gene in primary human T-cell acute lymphoblastic leukemia.

Alterations of the P53 tumor suppressor gene are present in various human malignancies. P53 mutations have recently been detected in 60% of human T-cell leukemia permanent cell lines. To determine the frequency of P53 mutations in primary T-cell acute lymphoblastic leukemia (T-ALL), a powerful method for the detection of structural alterations of DNA was used, namely, single-strand conformation polymorphism analysis of DNA fragments amplified by the polymerase chain reaction. No point mutation in the P53 gene was shown in any of the 30 T-ALL patients tested. Unlike T-cell leukemia permanent cell lines, P53 mutations are uncommon in T-ALL.

Base Sequence↗
PubMed1991

A simple diagnostic test for Fanconi anemia by flow cytometry.

A simple diagnostic test for Fanconi anemia (FA) by flow cytometry is proposed. It is based on the cell cycle disturbances of FA cells and their sensitisation by alkylating agents. Following PHA-stimulation of whole blood cell cultures in the presence or absence of nitrogen mustard, the accumulation of cells in G2/M phase was measured. A sharp increase of cells in G2/M was observed in cultures from FA patients when nitrogen mustard was added. This increase allows one to distinguish FA patients from patients with anemias of other origin, healthy controls, and FA heterozygotes, as effectively as chromosome breakage studies. The rapidity of the test and its reliability as demonstrated on the ten FA patients studied, will make the diagnosis of FA easier in centers without cytogenetic laboratory facilities.

Cell Cycle↗
PubMed1991

Loss of genetic material from the short arm of chromosome 12 is a frequent secondary abnormality in non-Hodgkin's lymphoma.

Abnormalities of the short arm of chromosome 12 have been detected in a wide variety of hematopoietic disorders. Seven cases of non-Hodgkin's lymphoma (NHL) are reported with various rearrangements involving bands 12p13 or 12p11, associated with other chromosome changes. A review of the literature confirms that rearrangements of 12p, mainly at band 12p13, are nonrandom chromosomal abnormalities in all subtypes of NHL, as in other malignant blood disorders. No common translocation could, however, be detected, and 12p abnormalities may be considered as secondary chromosomal events. Most of the 12p rearrangements involving translocation of genetic material of unknown origin, suggest that they result in loss of 12p segment.

Chromosome Deletion↗
PubMed1991

Chromosomal abnormalities in T-cell malignant lymphoma.

Chromosomal abnormalities of T-cell malignant lymphoma are nonrandom and often complex. Some are common with those of other lymphomas, others are more characteristic for T-cell proliferations. The most frequent chromosomal breakpoints involve chromosomes 6, 1, 2, 9p, 17, and the bands where the TcR genes are localized. The frequent rearrangement of band 14q32 suggests that an oncogene is located within. The main results of molecular studies performed in T-cell malignant lymphomas are summarized.

Chromosome Aberrations↗
PubMed1990

Intrapleural tetracycline for the prevention of recurrent spontaneous pneumothorax. Results of a Department of Veterans Affairs cooperative study.

This prospective, multicenter, randomized, "unblinded," controlled clinical trial was designed to determine if the intrapleural instillation of 1500 mg of tetracycline hydrochloride would be effective in diminishing the ipsilateral rate of recurrence for spontaneous pneumothorax. During the 4-year enrollment period, 113 patients were assigned to the tetracycline group; 116 patients were assigned to the control group. During the 5-year study period, the recurrence rate in the tetracycline group (25%) was significantly less than that in the control group (41%). Use of tetracycline seemed to reduce the recurrence rates for patients with either primary or secondary spontaneous pneumothorax and for patients with either an initial or a recurrent pneumothorax. We conclude that the intrapleural administration of tetracycline in patients with spontaneous pneumothorax significantly reduces the rate of ipsilateral recurrence but is associated with intense chest pain. Intrapleural tetracycline therapy is indicated for patients with a spontaneous pneumothorax who are hospitalized and are treated with tube thoracostomy.

Adult↗
PubMed1990

Deletion of (7p13p14) in non-Hodgkin's lymphoma.

Deletion of the short arm of chromosome 7 at 7(p13p14) has been occasionally reported in non-Hodgkin's malignant lymphoma (NHL). The inclusion of this abnormality within the list of nonrandom changes awaited further data. We report three partial deletions of 7p with breakpoint at 7p13, found in various subtypes of NHL, and one deletion covering these bands (7p11 to 7p15). The association of 7p- with other chromosomal changes in the same NHL suggests that partial 7p deletion is a nonrandom secondary abnormality.

Adult↗