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D Cohen

Publications and source records attributed to D Cohen.

At least 343 records · Page 19Linked to original sources
PubMed1994

Six mutations in the glucokinase gene identified in MODY by using a nonradioactive sensitive screening technique.

We have reported that 56% of French families with maturity-onset diabetes of the young (MODY) carry a mutation in the glucokinase gene (GCK). Therefore, we have established a quick and sensitive nonradioactive technique (with the PhastSystem based on single-strand conformation polymorphism [SSCP] analysis) to routinely screen the 12 exons of GCK for mutations. We have studied GCK in 12 young hyperglycemic patients with a strong family history of type II diabetes. SSCP variants were observed in 6 of those 12 patients (50%), which cosegregated with diabetes in five families where DNA from additional members was available. Direct sequencing identified a 10-bp (base pair) deletion in exon 3; a 33-bp deletion at the exon 5/intron 5 junction, including the two consensus bases (GT) of the donor splice site; a nonsense mutation in exon 5 (Arg186-->Stop) in a Black-African family, which has been identified previously in a Caucasian family; and three missense mutations: Thr209-->Met209 in exon 6, Gly261-->Glu261 in exon 7, and Arg36-->Trp36 in exon 2. The missense mutation in exon 2 was found only in the second and third generation of the tested family but not in the first. To our knowledge, this is the first time that a de novo mutation of GCK is reported within a family. All six families carrying a mutation in GCK were typical MODY and most of their affected members had a mild form of diabetes. This nonradioactive SSCP technique may be useful to routinely diagnose glucokinase deficiency, which is an important cause of hyperglycemia among young type II diabetic patients.

Adult↗
PubMed1994

Maternally inherited diabetes and deafness is a distinct subtype of diabetes and associates with a single point mutation in the mitochondrial tRNA(Leu(UUR)) gene.

We have recently reported an A to G transition at nucleotide position 3243 in the mitochondrial DNA (mtDNA) tRNA(Leu(UUR)) gene in a large family with non-insulin-dependent diabetes mellitus (NIDDM). Characteristic was its maternal transmission and an associated sensorineural hearing loss. In a screening of a Dutch and French NIDDM population for the presence of the tRNA(Leu(UUR)) mutation we identified two new pedigrees in which NIDDM is present in combination with deafness. The mode of inheritance agrees with a maternal one. This result shows that patients with a phenotype of NIDDM and deafness can be identified within groups of NIDDM patients based on the tRNA(Leu(UUR)) mutation. The same mutation has also been linked to the syndrome of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS). How the same mutation can give rise to different clinical phenotypes is not clear. We obtained the complete mtDNA sequence from our initial pedigree and identified a number of additional mutations that could confer the phenotype of the tRNA(Leu(UUR)) mutation to diabetes. We examined the presence of these additional, potentially pathogenic mutations in the mtDNA from the two new pedigrees and from a previously described British pedigree. The absence of these mutations in all three pedigrees shows that the tRNA(Leu(UUR)) mutation alone associates with the phenotype of NIDDM and deafness. We conclude that maternally inherited diabetes and deafness is a distinct subtype of diabetes that is associated with a single mitochondrial tRNA(Leu(UUR)) mutation. We propose the abbreviation MIDD for this particular subtype.

Base Sequence↗
PubMed1994

Contribution of Molecular Biology to Pediatric and Adolescent Gynecology.

The authors address a few of the contributions that molecular biology has offered over the past five years to the fields of reproductive medicine and pediatric and adolescent gynecology. They cover a gamut of issues, from subtyping of human papillomavirus infection to the analysis of abnormal sexual differentiation.

Journal Article↗
PubMed1994

Hyalinization and cellular changes in uterine leiomyomata after gonadotropin releasing hormone agonist therapy.

This study evaluated the microscopic changes in leiomyomata following the use of a gonadotropin releasing hormone (GnRH) agonist. Seventeen women with symptomatic leiomyomata were included. Nine were treated with a GnRH agonist for three to six months prior to surgery, and the remaining eight served as controls. Following myomectomy, paraffin sections were prepared from the tumors. These sections were examined microscopically by two gynecologic pathologists, who were blind to the patient groups. The results showed increased cellularity and hyalinization in leiomyomata following GnRH agonist treatment.

Adult↗
PubMed1994

VQLM: a Visual Query Language for Macromolecular structural databases.

Databases of macromolecular structures allow researchers to identify general principles of molecular behavior. They do this by providing a variety of data obtained under a number of different experimental conditions. Many new tools have been developed recently to aid in exploratory analysis of structural data. However, some queries of interest still require considerable manual filtering of data. In particular, studies attempting to make generalizations about complex arrangements of atoms or building blocks in macromolecular structures cannot be approached directly with existing tools. Such studies are frequently carried out on only a few structures or else require a labor-intensive process. To address this problem, we have developed a visual language, VQLM (Visual Query Language for Macromolecules). A query is formulated in this language by drawing an abstract picture of substructures to be searched for in the database and specifying constraints on the objects in them. To illustrate the usefulness of our language, we show how to encode a number of queries that were found scientifically interesting in the published literature in molecular biology. VQLM relies on VQL, a new database language, as its underlying engine for database retrieval and computation. We believe that VQLM will make macromolecular structural data more accessible to scientists, enabling faster and deeper data analysis.

Animals↗
PubMed1994

Psychiatric symptoms in dementia associated with stroke: a case-control analysis among predominantly African-American patients.

As part of a case-control study, the psychiatric symptoms and behavioral problems of 61 multi-infarct dementia (MID) cases and 86 multi-infarct controls without dementia were compared to determine the prevalence of psychiatric symptoms and to clarify psychiatric predictors of dementia associated with cerebral infarcts. Ninety-two percent of the cases and 85% of the controls were African American. Cases were generally older, less well educated, and had a greater number of strokes and more neurologic deficits than controls. The most frequent psychiatric symptoms as reported by caregivers of patients with MID were irritability (57.3%), apathy (44.4%), insomnia (43.6%), agitation (40.7%), impatience (37%), and emotional lability (28.3%). In multivariate analysis, apathy and irritability were independent predictors of dementia associated with cerebral infarcts unless tests of cognitive function were added to the model. Our findings suggest that psychiatric symptoms are common in African-American vascular dementia patients, and cognitive impairment may be associated with psychiatric symptoms, behavioral problems, and personality changes. As there is a paucity of information about the prevalence of psychiatric symptoms in African Americans with vascular dementia, additional studies are needed to validate these findings. A better understanding of psychiatric symptoms in vascular dementia could lead to improved diagnosis and treatment of this disorder.

Black or African American↗
PubMed1994

Measles immunity in Israeli young adults: effects of second immunization at 18 years of age.

Measles morbidity and mortality in Israel have declined since the introduction of routine vaccination, even though measles continues to occur in epidemic cycles. In this study we examined the antibody response to measles revaccination, and the effect of prior administration of immune serum globulin (ISG) on the antibody response to measles vaccine. A study group of 312 young adults in army service received the Schwartz strain measles vaccine. Serum antibody levels were studied prior to vaccination and 2 and 4 weeks after vaccination. The finding of this study show that: a) booster response occurs in those vaccinees shown to have low or undetectable prerevaccination titers of measles antibodies; b) there is no effect of administration of ISG, prior to vaccination, on the antibody response to measles vaccine; and c) at the present level of immunity to measles in the Israeli adolescent population, we still may witness periodic epidemics in populations at risk.

Adolescent↗
PubMed1994

The immune response to booster vaccination against diphtheria toxin at age 18-21 years.

The purpose of this study was to evaluate the immunity of Israeli adults against the diphtheria toxin and to assess the immune response to a 2 Lf booster vaccination of diphtheria. The antibody levels against the toxin were measured in 200 volunteers aged 18-21. Later, a booster vaccination at a dosage of 2 Lf (flocculation units) was given and the immune response measured. We found that prior to the booster vaccination 174 (87%) of the study group had an antibody level > or = 0.1 IU/ml, 16 (8%) had an antibody level of > or = 0.06 IU/ml and < or = 0.09 IU/ml, and 10 (5%) had an antibody level of < or = 0.05 IU/ml. At the 10th day after the booster vaccination 185 (99%) acquired antibody level > or = 0.1 IU/ml, and at the 28th day all the vaccinees had antibody level above 0.1 IU/ml. When comparing the anamnestic and the delayed reaction to the booster vaccination, no significant difference was found between the group that prior to the vaccination had antibody level < or = 0.05 IU/ml and the group with antibody level > or = 0.06 IU/ml and < or = 0.09 IU/ml. Side effects were mainly local: 76 (38%) of the vaccinees had moderate local pain at the site of the injection and 40 (20%) had severe local pain. Abduction limitation of the injected arm was reported by 17 (8%) of the subjects. Weakness was reported by 67 (33%), headache by 18 (9%) and fever by 2 (1%) subjects. We conclude that antibody levels > or = 0.1 IU/ml are protective and booster vaccination at a dosage of 2 Lf raises the antibody levels to protective levels in all the vaccines.

Adolescent↗
PubMed1994

Nonradioactive screening of glucokinase mutations in maturity onset diabetes of the young.

DNA mutations were previously identified in the glucokinase gene in 56% of French families affected with maturity onset diabetes of the young (MODY), an early onset autosomal dominant form of non-insulin-dependent diabetes mellitus (NIDDM). Mutations were found on almost all exons using the common radioactive single-strand conformation polymorphism (SSCP) technique. In this paper, we describe a non-isotopic SSCP method using the Pharmacia Biotech PhastSystem for the routine screening of new mutations in diabetic patients or in offsprings of diabetic patients. The use of the PhastSystem allowed us to easily and reproducibly optimize the electrophoretic conditions for each exon. We demonstrate the efficiency of this technique by identifying 8 mutations, 7 of which have never previously been detected, in patients referred to us for diagnostic purposes. It appears to be a sensible, easy and reliable method to improve the routine diagnosis of MODY in diabetic subjects or relatives and should be applicable to other genetic diseases.

DNA Mutational Analysis↗
PubMed1994

Use of genetic and physical mapping to locate the spinal muscular atrophy locus between two new highly polymorphic DNA markers.

The gene for autosomal recessive forms of spinal muscular atrophy (SMA) has recently been mapped to chromosome 5q13, within a 4-cM region between the blocks D5S465/D5S125 and MAP-1B/D5S112. We identified two new highly polymorphic microsatellite DNA markers--namely, AFM265wf5 (D5S629) and AFM281yh9 (D5S637)--which are the closest markers to the SMA locus. Multilocus analysis by the location-score method was used to establish the best estimate of the SMA gene location. Our data suggest that the most likely location for SMA is between locus D5S629 and the block D5S637/D5S351/MAP-1B/D5S112/D5S357. Genetic analysis of inbred SMA families, based on homozygosity by descent and physical mapping using mega-YACs, gave additional information for the loci order as follows: cen-D5S6-D5S125/D5S465-D5S435-D5S629-SMA-+ ++D5S637-D5S351-MAP-1B/D5S112-D5S357- D5S39-tel. These data give the direction for bidirectional walking in order to clone this interval and isolate the SMA gene.

Child↗
PubMed1994

Dementia, depression, and nutritional status.

Dementia, depression, and Parkinson's disease are in themselves challenging problems in old age. Recognition and diagnosis are often suboptimal. In dementia, many contributing factors must be considered, including nutrition, but in all these conditions the effects of the cognitive, attitudinal, and motor changes can produce permanent and severe nutritional compromise. Yet many simple steps can be taken to prevent poor nutrition in these diseases, and the primary care practitioner is central to this process of recognition and intervention.

Aged↗
PubMed1993

A first-generation physical map of the human genome.

Sets of ordered overlapping cloned genomic DNA fragments that span each of the human chromosomes are urgently needed for identification of human disease genes. Such a physical map also provides unique material to study the structure and function of the genome. We have therefore exhaustively analysed the CEPH yeast artificial chromosome (YAC) library, which contains 33,000 clones, whose insert size was individually determined. These YACs have an average length of 0.9 megabases and cover the equivalent of 10 haploid genomes. Several mapping techniques were combined to provide multiple sources of structural information for most of these clones. Finally, the library was screened with more than 2,000 genetic markers quasiuniformly distributed over 90% of the genome. These results should allow the scientific community to construct detailed maps of all human chromosomes. Moreover, we propose a data analysis strategy that produces a first-generation integrated map covering most of the human genome.

Chromosome Mapping↗
PubMed1993

Structure/function studies of human beta-cell glucokinase. Enzymatic properties of a sequence polymorphism, mutations associated with diabetes, and other site-directed mutants.

Glucokinase plays a key role in the regulation of glucose metabolism in insulin-secreting pancreatic beta-cells and in the liver. Recent studies have shown that mutations in this enzyme can lead to the development of a form of non-insulin-dependent diabetes mellitus that is characterized by an autosomal dominant mode of inheritance and onset during childhood. Here, we report the catalytic properties of five additional missense mutations associated with diabetes (Glu70-->Lys, Ser131-->Pro, Ala188-->Thr, Trp257-->Arg and Lys414-->Glu), one polymorphism present in both normal and diabetic subjects (Asp4-->Asn), and three site-directed mutations (Glu177-->Lys, Glu256-->Ala, and Lys414-->Ala). The Trp257-->Arg mutation generated an enzyme that had an activity that was less than 0.5% of that for native human beta-cell glucokinase. By contrast, the Glu70-->Lys, Ser131-->Pro, Ala188-->Thr, and Lys414-->Glu mutations had a Vmax that was 20-100% of normal but a Km for glucose that was 8-14-fold greater than the native enzyme. There was no effect of the Asp4-->Asn polymorphism or the Glu177-->Lys substitution on glucokinase activity. The Lys414-->Ala substitution had no effect on Vmax but increased the Km for glucose 2-fold and the Glu256-->Ala substitution caused a approximately 200-fold decrease in Vmax. These studies have led to the identification of additional residues involved in glucokinase catalysis and substrate binding.

Amino Acid Sequence↗
PubMed1993

Progesterone regulates the murine multidrug resistance mdr1b gene.

P-glycoprotein, the product of the multidrug resistance (mdr) gene family, is a major determinant in the development of resistance to a large number of cancer chemotherapeutic agents and is also expressed normally in a variety of mammalian tissues. In rodents during pregnancy, there is a dramatic overproduction of the mdr1b form of P-glycoprotein at the lumenal surface of the secretory epithelium of the gravid uterus. An expression vector, mdr1b-CAT, was constructed by fusion of this promoter region to a reporter gene, the bacterial chloramphenicol acetyltransferase (CAT) gene. R5020, a progesterone agonist, increased approximately 3-fold the expression of mdr1b-CAT when transfected into T47D cells, a cell line that constitutively expresses the progesterone receptor. A far greater response to R5020 was observed when the cells were co-transfected with an expression vector for the A form of the progesterone receptor, but not the B form. A series of 5'-deleted clones of the mdr1b-CAT construct indicated that the region of responsiveness was located in the first untranslated exon of the gene. Furthermore, sequences from the first exon were able to confer responsiveness to the non-responsive thymidine kinase-CAT vector. This study demonstrates that progesterone specifically regulates the activity of the mdr1b promoter and that this response is directed solely by the A form of the progesterone receptor.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1993

Three distinct nuclear protein binding sites in the promoter of the murine multidrug resistance mdr1b gene.

Multidrug resistance in mammalian cells is often associated with the overproduction of a membrane glycoprotein, P-glycoprotein, that is encoded by mdr genes. Multidrug resistance cell lines selected with either vinblastine, colchicine, or taxol from the drug-sensitive murine macrophage-like cell line J774.2 overexpress the mdr1a and/or mdr1b genes, and overproduce P-glycoprotein. To elucidate the mechanisms of mdr1b gene expression, the mdr1b 5'-flanking sequences have been isolated from a normal mouse liver genomic library and analyzed by gel shift and DNase I footprinting assays. These analyses have demonstrated three nuclear protein binding sites, from -82 to -59 (site 1), from -123 to -101 (site 2), and from -272 to -249 (site 3), which interact with proteins present in nuclear extracts from both sensitive and resistant cells. Although site 1 contains a partially conserved AP-2 consensus sequence, our results indicate that the nuclear protein binding to site 1 is not AP-2 protein. The sequence of site 2 is conserved in the murine mdr1a, human mdr1, and hamster pgp1 promoters. Such conservation suggests that this sequence may have an important role in mdr gene expression. The use of a transient chloramphenicol acetyltransferase expression vector containing the basal promoter for herpes simplex virus thymidine kinase (tkCAT) and either site 1 or site 2 or both revealed that the sequences of sites 1 and 2 enhanced tkCAT activity. DNase I footprinting analyses demonstrated that site 3 is recognized by human AP-1 protein, indicating that the nuclear protein binding to this site is an AP-1-like protein. These observations suggest that mdr1b gene expression is mediated by preexisting transcription factors present in sensitive and resistant cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1993

Glucokinase mutations associated with non-insulin-dependent (type 2) diabetes mellitus have decreased enzymatic activity: implications for structure/function relationships.

The glycolytic enzyme glucokinase plays an important role in the regulation of insulin secretion and recent studies have shown that mutations in the human glucokinase gene are a common cause of an autosomal dominant form of non-insulin-dependent (type 2) diabetes mellitus (NIDDM) that has an onset often during childhood. The majority of the mutations that have been identified are missense mutations that result in the synthesis of a glucokinase molecule with an altered amino acid sequence. To characterize the effect of these mutations on the catalytic properties of human beta-cell glucokinase, we have expressed native and mutant forms of this protein in Escherichia coli. All of the missense mutations show changes in enzyme activity including a decrease in Vmax and/or increase in Km for glucose. Using a model for the three-dimensional structure of human glucokinase based on the crystal structure of the related enzyme yeast hexokinase B, the mutations map primarily to two regions of the protein. One group of mutations is located in the active site cleft separating the two domains of the enzyme as well as in surface loops leading into this cleft. These mutations usually result in large reductions in enzyme activity. The second group of mutations is located far from the active site in a region that is predicted to undergo a substrate-induced conformational change that results in closure of the active site cleft. These mutations show a small approximately 2-fold reduction in Vmax and a 5- to 10-fold increase in Km for glucose. The characterization of mutations in glucokinase that are associated with a distinct and readily recognizable form of NIDDM has led to the identification of key amino acids involved in glucokinase catalysis and localized functionally important regions of the glucokinase molecule.

Amino Acid Sequence↗