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Biomedical subjects

J Hagman

Publications and source records attributed to J Hagman.

36 records · Page 2Linked to original sources
PubMed1992

An inhibitory carboxyl-terminal domain in Ets-1 and Ets-2 mediates differential binding of ETS family factors to promoter sequences of the mb-1 gene.

The mb-1 gene is expressed only during the early stages of B-lymphocyte differentiation. Here we show that the mb-1 proximal promoter region contains a functionally important binding site for members of the ETS family of DNA-binding proteins. We found that both the E26 virus-encoded v-ets and the myeloid/B-cell-specific factor PU.1 bind efficiently to this site in vitro. By contrast, Ets-1, the lymphocyte-specific cellular homologue of v-ets, and the related, more ubiquitously expressed Ets-2 protein interacted weakly with this binding site. DNA binding by both Ets-1 and Ets-2, however, could be increased 20- to 50-fold by deleting as few as 16 carboxyl-terminal amino acids. The inhibitory carboxyl-terminal amino acid sequence is highly conserved between Ets-1 and Ets-2 but is not present in either v-ets or PU.1. Replacement of the carboxyl-terminal amino acids of v-ets with those of Ets-1 decreased DNA binding by v-ets drastically. Cotranslation of Ets-1 transcripts encoding proteins of different lengths suggested that Ets-1 binds DNA as a monomer. Therefore, the carboxyl-terminal inhibitory domain appears to interfere directly with DNA binding and not with homodimerization. Finally, the functional relevance of ETS factor binding to the mb-1 promoter site was evidenced by the stimulation of transcription through this site by a v-myb-v-ets fusion protein. Together, these data suggest that one or more ETS family factors are involved in the regulation of mb-1 gene expression.

Amino Acid Sequence↗
PubMed1991

A novel lineage-specific nuclear factor regulates mb-1 gene transcription at the early stages of B cell differentiation.

The mb-1 gene, which encodes a protein associated with membrane-bound antibody, is expressed only at the early stages of B cell differentiation. To gain insight into the mechanisms that underlie temporally regulated gene expression, we examined the mb-1 promoter region for interactions with cell type-specific DNA binding proteins. Here, we report the characterization of a novel nuclear factor that recognizes the mb-1 promoter. This DNA binding activity, termed Early B cell Factor, or EBF, is expressed in early stage B cells, but not in late stage B cells, T cells or non-lymphoid cells. EBF recognizes the nucleotide sequence 5'-CAAGGGAAT-3' in the mb-1 and major histocompatibility complex (MHC) class II A alpha d promoters. The binding of EBF to DNA was characterized by DNase I footprinting and by methylation interference analysis which indicated both major and minor groove contacts. The specificity of EBF binding is distinct from that of other nuclear factors expressed in hematopoietic cells. EBF appears to consist of at least two polypeptides of approximately 70-75 kDa and 80-85 kDa. The EBF binding site was important for maximal mb-1 promoter activity in early stage B cells. Moreover, the EBF binding site conferred correct lineage- and stage-specific transcriptional activity upon a heterologous promoter in a context-dependent manner. Thus, EBF appears to represent an important transcriptional regulator of B cell specific gene expression.

B-Lymphocytes↗
PubMed1991

Heterogeneously initiated transcription from the pre-B- and B-cell-specific mb-1 promoter: analysis of the requirement for upstream factor-binding sites and initiation site sequences.

The mb-1 gene, encoding a membrane immunoglobulin-associated protein, is developmentally regulated and expressed specifically in pre-B and mature B lymphocytes. Analysis of the TATA-less mb-1 promoter indicated that it directs initiation of transcription from multiple sites. Promoter sequences between -68 and +70 conferred the correct pattern of cell type-specific transcription upon a heterologous gene. Two nuclear factor-binding sites that are important for promoter function were identified between -59 and -38. Both sites interacted with ubiquitous nuclear factors in vitro. One of these factors was identified as Sp1. Multimerized copies of both factor-binding sites augmented expression from a heterologous minimal promoter in both lymphoid and nonlymphoid cells, suggesting that additional mb-1 promoter sequences are involved in determining the correct cell type specificity. Analysis of the heterogeneity of transcription initiation indicated that a mutation which increased the distance between upstream sequences and the region of initiation resulted in the utilization of a novel set of initiation sites. Moreover, an insertion of a TATA element into the mb-1 promoter at -30 biased initiation of transcription to +1 but did not abolish the use of the other sites. Mutation of an initiator sequence homology encompassing one of the major initiation sites had only a minor effect on its utilization. From these data, we conclude that upstream factor-binding sites in the TATA-less mb-1 promoter define a region in which initiation of transcription occurs at multiple sites.

Animals↗
PubMed1990

Abnormal EEG slow activity in left temporal areas in senile dementia of the Alzheimer type.

Resting 32-channel topographical measures of EEG slow activity were compared in 12 elderly controls and 12 patients with senile dementia of the Alzheimer type. The patients had higher amplitude delta and theta than controls, especially in the left temporal regions. This greater amount of low frequency EEG activity in the left temporal area is consistent with recent EEG, neuropsychological assessment, and positron emission tomography findings in SDAT patients. Five patients with mild-to-moderate dementia (as determined by the Folstein Mini-Mental State scale) primarily exhibited focal, abnormal slow activity in the left temporal regions. Seven patients with severe dementia exhibited increased slow activity across the head, which was still most abnormal in the left temporal regions.

Aged↗
PubMed1990

A novel enhancer in the immunoglobulin lambda locus is duplicated and functionally independent of NF kappa B.

As a first step toward defining the elements necessary for lambda immunoglobulin gene regulation, DNase I hypersensitive sites were mapped in the mouse lambda locus. A hypersensitive site found 15.5 kb downstream of C lambda 4 was present in all the B-cell but not in the T-cell lines tested. This site coincided with a strong B-cell-specific transcriptional enhancer (E lambda 2-4). This novel enhancer is active in myeloma cells, regardless of the status of endogenous lambda genes, but is inactive in a T-cell line and in fibroblasts. The enhancer E lambda 2-4 functions in the absence of the transcription factor NF kappa B, which is necessary for kappa enhancer function. No evidence could be found for NF kappa B binding by this element. Rearrangement of V lambda 2 to JC lambda 3 or JC lambda genes deletes E lambda 2-4; however, a second strong enhancer was found 35 kb downstream of C lambda 1, which cannot be eliminated by lambda gene rearrangements. The second lambda enhancer (E lambda 3-1) is 90% homologous to the E lambda 2-4 sequence in the region determined to comprise the active enhancer and likewise lacks the consensus binding site for NF kappa B. The data support a model for the independent activation of kappa and lambda gene expression based on locus-specific regulation at the enhancer level.

Animals↗
PubMed1990

Greater left cerebral hemispheric metabolism in bulimia assessed by positron emission tomography.

Eight women with bulimia and eight age- and sex-matched normal control subjects were studied with positron emission tomography using [18F]-fluorodeoxyglucose (FDG) as a tracer of brain metabolic rate. Subjects performed a visual vigilance task during FDG uptake. In control subjects, the metabolic rate was higher in the right hemisphere than in the left, but patients with bulimia did not have this normal asymmetry. Lower metabolic rates in the basal ganglia, found in studies of depressed subjects, and higher rates in the basal ganglia, reported in a study of anorexia nervosa, were not found. This is consistent with the suggestion that bulimia is a diagnostic grouping distinct from these disorders.

Adult↗
PubMed1989

Inhibition of immunoglobulin gene rearrangement by the expression of a lambda 2 transgene.

The rearrangement of Ig genes is known to be regulated by the production of H and kappa L chains. To determine whether lambda L chains have a similar effect, transgenic mice were produced with a lambda 2 gene. It was necessary to include the H chain enhancer, since a lambda gene without the added enhancer did not result in transgene expression. The lambda 2 transgene with the H enhancer was expressed in lymphoid cells only. The majority of the B cells of newborn transgenic mice produced lambda, whereas kappa + cells were reduced. Concomitantly, serum levels of kappa and kappa mRNA were diminished. By 2 wk after birth the proportion of kappa-expressing cells was dramatically increased. Adults had reduced proportions of B cells that produced lambda only, but the levels of lambda were still higher than in normal littermates. Also, kappa + cells were still lower than in normal mice. Analysis of hybridomas revealed that reduction of kappa gene rearrangement was the basis for the decreased frequency of kappa + cells. Furthermore, many cells also contained an unrearranged H chain allele. It was concluded that feedback inhibition by the lambda 2 together with endogenous H protein may have inhibited recombinase activity in early pre-B cells, leading to inhibition of both H chain and kappa gene rearrangement. Thus, lambda 2 can replace kappa in a feedback complex. The levels of serum lambda 1 and, to a lesser degree, of spleen lambda 1 mRNA were reduced in the lambda 2 transgenic mice. However, the proportion of hybridomas with endogenous lambda gene rearrangement was at least as high as in normal mice. It was therefore concluded that the suppression of functional lambda 1 may be a consequence of decreased selection of endogenous lambda-producing cells because of the excess of transgenic lambda. The escape of kappa-producing cells from feedback inhibition may be the result of several mechanisms that operate to varying degrees, among them: (a) kappa rearrangement during a period in which the recombinase is still active after appearance of a lambda 2/mu stop signal; (b) a B cell lineage that is not feedback inhibited at the pre-B cell stage; (c) subthreshold levels of transgenic lambda 2 in some pre-B cells; and (d) loss of the lambda 2 transgenes in rare pre-B cells.

Animals↗
PubMed1988

Ig lambda-producing B cells do not show feedback inhibition of gene rearrangement.

In order to study the regulation of expression of Ig lambda genes we have analyzed lambda-producing hybridomas derived from transgenic mice which harbor a functionally rearranged kappa transgene. We also analyzed lambda-producing hybridomas from nontransgenic mice. Surprisingly, all but one of the transgenic lambda-hybridomas co-produce kappa L chains. Also, in contrast to transgenic kappa-hybridomas, most lambda-hybridomas have rearranged endogenous kappa genes despite the presence of transgenic kappa-chains and endogenous H chains. Analysis of spleen cells and hybridomas from nontransgenic mice shows that about 20% of lambda-producing B cells in the spleen co-produce kappa, and a similar proportion of lambda-hybridomas from normal spleens produce both kappa- and lambda-chains. The data argue strongly against the strictly sequential expression of kappa and lambda genes. We present a new model for the regulation of kappa and lambda gene expression, whose key feature is the distinction between a kappa cell lineage in which Ig gene rearrangement is susceptible to feedback by a complete antibody molecule at the pre-B cell stage, and a kappa lambda B cell lineage which does not show feedback inhibition during B cell development.

Animals↗
PubMed1988

Cloning of a gamma 2b gene encoding anti-Pseudomonas aeruginosa H chains and its introduction into the germ line of mice.

A complete, functional gamma 2b gene (pVCM) was cloned from a mouse hybridoma (VD93) with antibody activity to Pseudomonas aeruginosa. DNA sequencing of the VDJ region of pVCM determined that the VH gene was a member of the J558 family rearranged to JH2. Upon transfection into myeloma cells the gamma 2b gene gave rise to high levels of gamma 2b mRNA and gamma 2b protein. The gamma 2b protein had the same IEF pattern as the parent hybridoma protein VD93 and the antibodies formed from a combination of the pVCM gamma 2b chains and the myeloma lambda-chains bound weakly to P. aeruginosa. However, the hybrid antibodies did not discriminate between the serotypes 2 and 3, whereas the parent protein was specific for serotype 3. Transgenic mice were produced with the pVCM gamma 2b gene which expressed the gamma 2b mRNA (both membrane and secreted forms) only in lymphoid organs. However, contrary to expectations, the gamma 2b mRNA levels were higher in T cells than in B cells in three different transgenic lines. The serum of the transgenic mice had no activity to P. aeruginosa indicating the importance of L chains for the conformation of the Ag binding site. These gamma 2b transgenic mice provide a convenient tool for the study of feedback inhibition of Ig gene rearrangement.

Animals↗
PubMed1987

Two diagnostic correlates of dexamethasone nonsuppression in normal weight bulimia.

Evaluations of neuroendocrine abnormalities and possible relationship to major affective disorder in normal weight bulimic women have utilized the Dexamethasone Suppression Test (DST). In our sample of 29 bulimic women, 59% showed DST nonsuppression (DSTNS). Two diagnostic correlates were significant in relation to DSTNS: prior history of anorexia nervosa and current clinical DSM III diagnosis of depression. Eating Attitudes Test (EAT) scores were also significantly higher in the DSTNS group. The findings suggest that more extensive psychiatric disorder and ingestive abnormalities may be present in this subgroup of normal weight bulimic women who exhibit DST nonsuppression.

Adolescent↗
PubMed1986

Serum salivary isoamylase levels in patients with anorexia nervosa, bulimia or bulimia nervosa.

Salivary isoamylase levels were studied in a sample of 35 women with bulimia, anorexia nervosa, or bulimia nervosa. Salivary isoamylase elevation was related to the presence of sham eating, evidenced by elevated isoamylase values in patients with bulimia nervosa or bulimia, and depressed isoamylase values in patients with anorexia nervosa. Salivary isoamylase levels may provide insight and have bearing on the functional interrelationship between appetite regulation and ingestive behavior in patients with eating disorders, as abnormalities may occur during both the cephalic as well as the oral phase of eating.

Adolescent↗
PubMed1985

Characterization of adrenocorticotropin receptors that appear when 3T3-L1 cells differentiate into adipocytes.

The binding of an 125I-labeled analog of ACTH, [125I]Tyr23,Phe2,Nle4-ACTH-(1-38), to differentiated 3T3-L1 fat cells was characterized. Time-dependent binding, which was inhibited by saturating concentrations of unlabeled ACTH (0.44 microM), could be demonstrated in the differentiated cells. Using 0.4 nM [125I]ACTH analog and increasing concentrations of ACTH, the half-maximal concentration for inhibition by ACTH was 4.3 nM. Scatchard analysis demonstrated a single class of ACTH binding. There were approximately 3500 binding sites/cell. The binding of [125I]ACTH analog was specific in that it could be displaced by ACTH, ACTH-(1-19), ACTH-(1-17), and N-acetyl-Ser1-ACTH, but not by high concentrations of insulin, beta-endorphin, or polylysine. There was an excellent correlation between the ability of ACTH and its analogs to inhibit [125I]ACTH analog binding and the ability of ACTH and its analogs to stimulate cAMP production. In contrast, no saturable binding could be demonstrated when undifferentiated 3T3-L1 fibroblasts, which are not responsive to ACTH, were studied. Thus, differentiation of 3T3-L1 cells into the adipocyte form is accompanied by the appearance of receptors for ACTH. These receptors allow the adipocytes to respond to ACTH.

Adipose Tissue↗
PubMed1984

The syndrome of bulimia. Review and synthesis.

This comprehensive review of the syndrome of bulimia outlines treatment modalities including response prevention, cognitive behavioral and group interventions, and antidepressant pharmacotherapy. The authors propose an etiologic model that synthesizes available data indicating that young women who are at risk for developing bulimia appear to have a biologic vulnerability to affective instability, have family environments that are conflicted and disorganized, and a variety of personality traits that result in low self-esteem and self-regulatory difficulties.

Adolescent↗
PubMed1982

Synthesis of human corticotropinyl-thiolglycine and its specific conjugation to bovine serum albumin.

Human corticotropin containing a thiolglycine residue at the carboxyl terminal (I) was synthesized by the solid-phase method. The citraconyl derivative of peptide I was coupled to either a model tetrapeptide or bovine serum albumin by reaction with silver nitrate/N-hydroxysuccinimide in water. The extent of reaction with bovine serum albumin was determined by radioimmunoassay, and the peptide-protein conjugate was shown to possess 12% of the steroidogenic activity of porcine adrenocorticotropin in isolated rat adrenal cells. Peptide I and its conjugate with the model tetrapeptide were fully active in the same system.

Adrenal Cortex↗
PubMed1981

Persistent activation of steroidogenesis in adrenocortical cells by photoaffinity labeling of corticotropin receptors.

Photolysis of rat adrenocortical cells in the presence of the photoreactive derivative [(2-nitro-5-azidophenylsulfenyl)Trp9]-adrenocorticotropic hormone (2,5-NAPS-ACTH) at 24 degrees C resulted in persistent activation of corticosterone production. The basal rate of steroidogenesis became maximal when photolysis was performed at 24 degrees C but remained the same as that of control cells when irradiation was performed at 0 degrees C. No increase in basal rate was observed with dark controls or cells photolyzed with [(2,4-dinitrophenylsulfenyl)Trp9]ACTH, a photoresistant analog of the hormone. Prephotolyzed 2,5-NAPS-ACTH failed to induce persistent activation. Both ACTH and 2,4-(dinitrophenylsulfenyl)Trp9-ACTH blocked the photo-induced activation of steroidogenesis elicited by 2,5-NAPS-ACTH. Under photolysis conditions which caused the basal rate of steroidogenesis to become maximal, a 3-fold increase in the basal rate of cAMP formation was observed.

Adrenal Cortex↗
PubMed1981

A sensitive radioimmunoassay for corticotropin using a fully biologically active 125I-labeled ligand.

The human corticotropin (ACTH) analog, Phe2,Nle4-ACTH-(1-38) was iodinated by the chloramine-T procedure and the product was purified by reverse phase high performance liquid chromatography. The specific radioactivity of [125I]Tyr23,Phe2,Nle4-ACTH-(1-38) was determined by comparing the antiserum binding curves of the iodinated peptide and [3H]ACTH of known specific activity. This method gave a value of 1800 +/- 75 Ci/mmol, which is close to the theoretical radioactivity expected for the introduction of a single 125I atom into the peptide. [125I]Tyr23,Phe2,Nle4-ACTH-(1-38) was as potent as ACTH in stimulating corticosterone production in isolated rat adrenocortical cells. The concentrations for half-maximal steroidogenesis were 36.5 +/- 6.1 pM for the 125I derivative and 37.6 +/- 6.7 pM for ACTH. By the use of this 125I-labeled ligand, a highly sensitive RIA capable of detecting 1 pg aCTH was developed.l The antiserum employed in this study appeared to be directed against residues 11-13 of ACTH.

Adrenocorticotropic Hormone↗