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Biomedical subjects

S M Ruben

Publications and source records attributed to S M Ruben.

At least 37 records · Page 2Linked to original sources
PubMed1995

The development of healthcare services for drug misusers and prostitutes.

With the advent of human immunodeficiency virus (HIV) and the increase of drug misuse in the UK, the Government wishes primary care to play a greater part in treating drug problems in the hope of preventing the spread of HIV. Drug misusers do not avail themselves of traditional services and many are not registered with general practitioners. In response to this Liverpool Health Authority and Family Health Service Authority commenced a new salaried post to provide primary care services to special groups such as injecting drug misusers and prostitutes. Judgemental attitudes towards drug misusers, their high mobility and being a transient population play a part in the reasons why drug misusers find it difficult to access primary healthcare. Drug misusers have high morbidity related to their drug misuse. Many of these conditions, if treated early, can prevent the need for more intensive intervention. Although drug misusers may present with a condition requiring immediate treatment, the opportunity is used to provide other healthcare such as hepatitis B vaccinations, sexually transmitted infection screening, contraception and HIV/hepatitis B testing. The sero prevalence of anti-HBc in injecting drug misusers is 45.5%. Due to their high morbidity and associated costs, the requirements of these groups may conflict with the objectives of budget-holding practices. If general practitioners are unable to respond to their problems, then health care providers and purchasers will have to consider similar schemes in areas which have a higher prevalence of drug misuse in order to provide appropriate healthcare for these vulnerable groups.

Adult↗
PubMed1995

An estimate of the prevalence of drug misuse in Liverpool and a spatial analysis of known addiction.

BACKGROUND: The objective of this study was to determine the prevalence and distribution of opiate and cocaine misuse in the City of Liverpool in 1991. The databases included residents of the city using opiates or cocaine, who were known to the Drug Dependency Units or the Infectious Diseases Unit, or who were arrested for possession of drugs in 1991. METHODS: A three-sample log-linear capture-recapture method was applied to databases containing details of drug users with City of Liverpool postcodes, to determine the prevalence of drug misuse in 1991. Linear regression analysis was performed to correlate the prevalence of known drug misuse with indices of material deprivation in each electoral ward. RESULTS: Data on 1427 individuals were analysed, producing an estimate of the drug-using population of 2344 [95 per cent confidence interval (CI) = 1972-2716] and a period prevalence of 5.2 per 1000 [95 per cent CI = (4.5-6.0) per 1000]. In the 15-29 year age group, the prevalence of drug abuse was 16.9 per 1000 [95 per cent CI = (13.9-19.9) per 1000]. There was a negative interdependence between the police and Drug Dependency Unit databases with attenders at the Unit being 7.2 (95 per cent CI = 4.6-11.4) times less likely to be arrested for possession than non-attenders. There was a strong correlation between the distribution of known drug use and material deprivation, as measured by the Townsend index (r = 0.75; p < 0.001). CONCLUSIONS: The capture-recapture method allows the prevalence of drug misuse to be estimated and provides more meaningful information than is available from the notification system. The study suggests that people in contact with drug services are less likely to commit crimes of possession of class A drugs than those not in contact with drug services. There is a strong association between drug abuse and deprivation, and therefore the purchasing of services for drug misusers should be focused on areas of deprivation.

Adolescent↗
PubMed1994

Mutations of two PMS homologues in hereditary nonpolyposis colon cancer.

Hereditary nonpolyposis colorectal cancer (HNPCC) is one of man's commonest hereditary diseases. Several studies have implicated a defect in DNA mismatch repair in the pathogenesis of this disease. In particular, hMSH2 and hMLH1 homologues of the bacterial DNA mismatch repair genes mutS and mutL, respectively, were shown to be mutated in a subset of HNPCC cases. Here we report the nucleotide sequence, chromosome localization and mutational analysis of hPMS1 and hPMS2, two additional homologues of the prokaryotic mutL gene. Both hPMS1 and hPMS2 were found to be mutated in the germline of HNPCC patients. This doubles the number of genes implicated in HNPCC and may help explain the relatively high incidence of this disease.

Adenosine Triphosphatases↗
PubMed1994

Mutation of a mutL homolog in hereditary colon cancer.

Some cases of hereditary nonpolyposis colorectal cancer (HNPCC) are due to alterations in a mutS-related mismatch repair gene. A search of a large database of expressed sequence tags derived from random complementary DNA clones revealed three additional human mismatch repair genes, all related to the bacterial mutL gene. One of these genes (hMLH1) resides on chromosome 3p21, within 1 centimorgan of markers previously linked to cancer susceptibility in HNPCC kindreds. Mutations of hMLH1 that would disrupt the gene product were identified in such kindreds, demonstrating that this gene is responsible for the disease. These results suggest that defects in any of several mismatch repair genes can cause HNPCC.

Adaptor Proteins, Signal Transducing↗
PubMed1993

The type 1 human immunodeficiency virus Tat binding protein is a transcriptional activator belonging to an additional family of evolutionarily conserved genes.

The type 1 human immunodeficiency virus Tat protein is a powerful transcriptional activator when bound to an RNA structure (TAR) present at the extreme 5' terminus of viral mRNA. Since transcriptional activation requires binding of Tat to RNA, it has been suggested that Tat enhances initiation or elongation through a direct interaction with cellular transcription factors. Here we show through protein fusion experiments that the previously identified cellular Tat binding protein, TBP-1, although unable to bind DNA, is a strong transcriptional activator when brought into proximity of several promoter elements. Transcriptional activity depends upon the integrity of at least two highly conserved domains: one resembling a nucleotide-binding motif and the other motif common to proteins with helicase activity. Our studies further reveal that TBP-1 represents one member of a large, highly conserved gene family that encodes proteins demonstrating strong amino acid conservation across species. Finally, we identified a second family member that, although 77% similar to TBP-1, does not activate transcription from the promoters examined. This finding, together with the observation that TBP-1 does not activate each promoter examined, suggests that this gene family may encode promoter-specific transcriptional activators.

ATPases Associated with Diverse Cellular Activitie↗
PubMed1993

Conservation of transcriptional activation functions of the NF-kappa B p50 and p65 subunits in mammalian cells and Saccharomyces cerevisiae.

The NF-kappa B transcription factor complex is composed of a 50-kDa (p50) and a 65-kDa (p65) subunit. Both subunits bind to similar DNA motifs and elicit transcriptional activation as either homo- or heterodimers. By using chimeric proteins that contain the DNA binding domain of the yeast transcriptional activator GAL4 and subdomains of p65, three distinct transcriptional activation domains were identified. One domain was localized to a region of 42 amino acids containing a potential leucin zipper structure, consistent with earlier reports. Two other domains, both acidic and rich in prolines, were also identified. Of perhaps more significance, the same minimal activation domains that were functional in mammalian cells were also functional in the yeast Saccharomyces cerevisiae. Coexpression of the NF-kappa B inhibitory molecule, I kappa B, reduced the transcriptional activity of p65 significantly, suggesting the ability of I kappa B to function in a similar manner in S. cerevisiae. Surprisingly, while the conserved rel homology domain of p65 demonstrated no transcriptional activity in either mammalian cells or S. cerevisiae, the corresponding domain in p50 was a strong transcriptional activator in S. cerevisiae. The observation that similar domains elicit transcriptional activation in mammalian cells and S. cerevisiae demonstrates strong conservation of the transcriptional machinery required for NF-kappa B function and provides a powerful genetic system to study the transcriptional mechanisms of these proteins.

Amino Acid Sequence↗
PubMed1993

Acquisition of NFKB1-selective DNA binding by substitution of four amino acid residues from NFKB1 into RelA.

The subunits of NF-kappa B, NFKB1 (formerly p50) and RelA (formerly p65), belong to a growing family of transcription factors that share extensive similarity to the c-rel proto-oncogene product. The homology extends over a highly conserved stretch of approximately 300 amino acids termed the Rel homology domain (RHD). This region has been shown to be involved in both multimerization (homo- and heterodimerization) and DNA binding. It is now generally accepted that homodimers of either subunit are capable of binding DNA that contains a kappa B site originally identified in the immunoglobulin enhancer. Recent studies have demonstrated that the individual subunits of the NF-kappa B transcription factor complex can be distinguished by their ability to bind distinct DNA sequence motifs. By using NFKB1 and RelA subunit fusion proteins, different regions within the RHD were found to confer DNA-binding and multimerization functions. A fusion protein that contains 34 N-terminal amino acids of NFKB1 and 264 amino acids of RelA displayed preferential binding to an NFKB1-selective DNA motif while dimerizing with the characteristics of RelA. Within the NFKB1 portion of this fusion protein, a single amino acid change of His to Arg altered the DNA-binding specificity to favor interaction with the RelA-selective DNA motif. Furthermore, substitution of four amino acids from NFKB1 into RelA was able to alter the DNA-binding specificity of the RelA protein to favor interaction with the NFKB1-selective site. Taken together, these findings demonstrate the presence of a distinct subdomain within the RHD involved in conferring the DNA-binding specificity of the Rel family of proteins.

Amino Acid Sequence↗
PubMed1992

Identification of a naturally occurring transforming variant of the p65 subunit of NF-kappa B.

Transcription factor NF-kappa B comprises two proteins, p50 and p65, that have sequence similarity to the v-rel oncogene. In primary hematopoietic cell populations an alternatively spliced form of NF-kappa B p65 mRNA was observed that encoded a protein designated p65 delta. Expression of the p65 delta cDNA in Rat-1 fibroblasts resulted in focus formation, anchorage-independent growth in soft agar, and tumor formation in athymic nude mice, effects not obtained with expression of p65 or a p65 delta mutant that contains a disruption within the transcriptional activation domain. Thus, p65 delta, which associated weakly and interfered with DNA binding by p65, may sequester an essential limiting regulatory factor or factors required for NF-kappa B function.

Animals↗
PubMed1992

I kappa B interacts with the nuclear localization sequences of the subunits of NF-kappa B: a mechanism for cytoplasmic retention.

NF-kappa B is an inducible transcription factor comprised of a 50-kD (p50) and a 65-kD (p65) subunit. Induction of NF-kappa B activity, which is a critical event in many signal transduction pathways, involves release from a cytoplasmic inhibitory protein, I kappa B, followed by translocation of the active transcription factor complex into the nucleus. Earlier studies suggested that I kappa B targets the p65 subunit of NF-kappa B. However, we demonstrate by in vitro and in vivo methods that the recently cloned I kappa B/MAD-3 interacts with both the p50 and p65 subunits of NF-kappa B, as well as c-Rel. Furthermore, an alternatively spliced, dimerization-deficient transforming variant of p65 (p65 delta) interacts extremely weakly with I kappa B/MAD-3, suggesting that dimerization is important for interaction. We demonstrate that the conserved nuclear localization sequences (NLSs) of NF-kappa B and c-Rel are the targets for I kappa B/MAD-3 interaction. Indirect immunofluorescence experiments demonstrate that I kappa B/MAD-3 expression retains both p65 and p50 in the cytoplasm. Furthermore, and most important, a p65 that contains an SV40 large T antigen NLS in addition to its own NLS is no longer retained in the cytoplasm in the presence of I kappa B/MAD-3. We propose that I kappa B/MAD-3 masks the NLSs of NF-kappa B and c-Rel and that this constitutes the mechanism for cytoplasmic retention of these proteins.

Alternative Splicing↗
PubMed1992

I-Rel: a novel rel-related protein that inhibits NF-kappa B transcriptional activity.

The NF-kappa B transcription factor complex is comprised of two subunits, p50 and p65, that share significant homology to the rel oncogene. We have isolated a cDNA encoding a novel 66-kD rel-related protein, designated I-Rel. Unlike other rel-related proteins, I-Rel does not interact with DNA. I-Rel forms heterodimers with p50, however, and greatly attenuates its DNA-binding activity--an effect probably resulting from the presence of a domain inhibitory to DNA binding present within the 121 amino-terminal residues of I-Rel. In contrast, I-Rel does not associate with p65. Transfection experiments demonstrate that I-Rel suppresses NF-kappa B-induced transcription, probably through its association with p50. Expression of I-Rel mRNA is induced by mitogenic stimulation and accumulates after the appearance of p50 transcripts. Our findings suggest that p50 and I-Rel are components of a feedback pathway where expression of I-Rel may modulate indirectly the expression of genes responsive to the NF-kappa B transcription factor complex.

Amino Acid Sequence↗
PubMed1992

Temazepam misuse in a group of injecting drug users.

It is well recognized that many injecting drug users are poly-drug users. The intravenous use of Temazepam has become popular recently. In response to the ease of misuse, the pharmaceutical industry produced a formulation that would be as 'resistant' as possible to injecting. The preparation is a gel-filled formulation, one proprietary name being Temazepam Gelthix. General Practitioners have been encouraged to prescribe gel-filled capsules to potential drug misusers in order to reduce the harm Temazepam can cause by its misuse. This study of 23 Temazepam injectors shows that the group still find the gel-filled preparation readily injectable. It appears to be more problematic in causing medical complications including superficial thrombophlebitis, abscesses and deep venous thrombosis. Temazepam misuse can cause drug users to become more chaotic. The study group recognize this and suggest there should be stricter control on the supply of Temazepam to drug dependents. General Practitioners, who are the main source of Temazepam prescribing, require additional training in prescribing to drug users.

Adult↗
PubMed1992

Selection of optimal kappa B/Rel DNA-binding motifs: interaction of both subunits of NF-kappa B with DNA is required for transcriptional activation.

Analysis of the p50 and p65 subunits of the NF-kappa B transcription factor complex has revealed that both proteins can interact with related DNA sequences through either homo- or heterodimer formation. In addition, the product of the proto-oncogene c-rel can bind to similar DNA motifs by itself or as a heterodimer with p50 or p65. However, these studies have used a limited number of known kappa B DNA motifs, and the question of the optimal DNA sequences preferred by each homodimer has not been addressed. Using purified recombinant p50, p65, and c-Rel proteins, optimal DNA-binding motifs were selected from a pool of random oligonucleotides. Alignment of the selected sequences allowed us to predict a consensus sequence for binding of the individual homodimeric Rel-related proteins, and DNA-protein binding analysis of the selected DNA sequences revealed sequence specificity of the proteins. Contrary to previous assumptions, we observed that p65 homodimers can interact with a subset of DNA sequences not recognized by p50 homodimers. Differential binding affinities were also obtained with p50- and c-Rel-selected sequences. Using either a p50- or p65-selected kappa B motif, which displayed differential binding with respect to the other protein, little to no binding was observed with the heterodimeric NF-kappa B complex. Similarly, in transfection experiments in which the selective kappa B binding sites were used to drive the expression of a chloramphenicol acetyltransferase reporter construct, the p65- and p50-selected motifs were activated only in the presence of p65 and p50/65 (a chimeric protein with the p50 DNA binding domain and p65 activation domain) expression vectors, respectively, and neither demonstrated a significant response to stimuli that induce NF-kappa B activity. These findings demonstrate that interaction of both subunits of the heterodimeric NF-kappa B complex with DNA is required for DNA binding and transcriptional activation and suggest that transcriptional activation mediated by the individual rel-related proteins will differ dramatically, depending on the specific kappa B motifs present.

Base Sequence↗
PubMed1992

Functional characterization of the NF-kappa B p65 transcriptional activator and an alternatively spliced derivative.

The NF-kappa B transcription factor complex is composed of two proteins, designated p50 and p65, both having considerable homology to the product of the rel oncogene. We present evidence that the p65 subunit is a potent transcriptional activator in the apparent absence of the p50 subunit, consistent with in vitro results demonstrating that p65 can interact with DNA on its own. To identify the minimal activation domain, chimeric fusion proteins between the DNA binding domain of the yeast transcriptional activator protein GAL4 and regions of the carboxy terminus of p65 were constructed, and their transcriptional activity was assessed by using a GAL4 upstream activation sequence-driven promoter-chloramphenicol acetyltransferase fusion. This analysis suggests that the boundaries of the activation domain lie between amino acids 415 and 550. Moreover, single amino acid changes within residues 435 to 459 greatly diminished activation. Similar to other activation domains, this region contains a leucine zipper-like motif as well as an overall net negative charge. To identify those residues essential for DNA binding, we made use of a naturally occurring derivative of p65, lacking residues 222 to 231 (hereafter referred to as p65 delta), and produced via an alternative splice site. Gel mobility shift analysis using bacterially expressed p65, p65 delta, and various mutants indicates that residues 222 to 231 are important for binding to kappa B DNA. Coimmunoprecipitation analysis suggests that these residues likely contribute to the multimerization function required for homomeric complex formation or heteromeric complex formation with p50 in that no association of p65 delta with itself or with p50 was evident. However, p65 delta was able to form weak heteromeric complexes with p65 that were greatly reduced in their ability to bind DNA. On the basis of these findings, we suggest that subtle changes within the proposed multimerization domain can elicit different effects with the individual Rel-related proteins and that a potential role of p65 delta may be to negatively regulate NF-kappa B function through formation of nonfunctional heteromeric complexes.

Amino Acid Sequence↗
PubMed1991

Isolation of a rel-related human cDNA that potentially encodes the 65-kD subunit of NF-kappa B.

The sequence reported in our 22 March 1991 report "Isolation of a rel-related human cDNA that potentially encodes the 65-kD subunit of NFkappaB" [Science 251, 1490 (1991)], contained some errors. Resequencing under strong denaturing conditions revealed three insertions at nucleotide positions 1194, 1212, and 1220, which changed the AA sequence from RSAR-PRLGP to QISQASALAP (residues 372 to 380), thus accounting for some of the divergence in this region. A corrected sequence has been sent to GenBank.

Amino Acid Sequence↗