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Biomedical subjects

J London

Publications and source records attributed to J London.

At least 37 records · Page 2Linked to original sources

DNA-binding activities in Streptococcus gordonii: identification of a receptor-nickase and a histonelike protein.

Extraction of Streptococcus gordonii cells with the mild chaotropic agent, LiCl, drastically decreased DNA transforming ability, had little effect on viability, and released both DNA nicking and binding activities. Both activities were Mg2+ and Ca2+ independent and were not competence specific. Southwestern blot analysis of the extract identified putative surface proteins of 56 kDa and 68 kDa in strain Challis and Wicky, respectively. Extracts also contained a 10-kDa DNA-binding protein, designated HSgo, that belongs to the eubacterial histonelike class of proteins.

Amino Acid Sequence↗

Natural genetic transformation in Streptococcus gordonii: comX imparts spontaneous competence on strain wicky.

Streptococcus gordonii Wicky becomes competent only after stimulation with conditioned medium from strain Challis as a source of competence factor (CF). A 3.2-kbp genomic fragment from Challis was found to impart spontaneous competence on Wicky by a complementation assay. Wicky clones containing the fragment secreted a heat-sensitive activity that induced competence in Wicky and in a comA insertion mutant of Challis. Activity was localized to a putative open reading frame, comX, with the potential to encode a 52-amino-acid peptide. comX had no similarity to known sequences, and a comX::ermAM insertion mutant of Challis transformed normally and secreted CF. These data suggest that a CF-independent pathway for competence induction exists in S. gordonii.

Amino Acid Sequence↗

Transgenic mice overexpressing the human Cu/Zn-SOD gene: ultrastructural studies of a premature thymic involution model of Down's syndrome (trisomy 21).

It has been suggested that the overexpression of copper-zinc superoxide dismutase (SOD-1) in Down's syndrome (DS) patients may be involved in expression of some of the phenotypic characteristics observed in these patients. To explore the possible role of SOD-1 overexpression in the premature thymic involution and immunologic disorders observed in DS patients, transgenic mice overexpressing the human SOD-1 gene have been generated and their thymuses have been studied at the ultrastructural level. Our observations show premature involution of the thymus in SOD-1 transgenic mice, with a strong modification of the thymic microenvironment starting at approximately 3-4 months of age. The thymic microenvironment in 7-month-old transgenic mice is similar to that observed in 20-month-old control mice. We suggest that these results are consistent with the role of SOD-1 overexpression in the early thymic involution observed in DS patients. These transgenic mice provide an interesting model to investigate the deleterious effect of increased dosage of some chromosome 21 genes such as SOD-1 in the pathogenesis of DS.

Animals↗

Iatrogenic accessory nerve injury.

Accessory nerve injury produces considerable disability. The nerve is most frequently damaged as a complication of radical neck dissection, cervical lymph node biopsy and other surgical procedures. The problem is frequently compounded by a failure to recognise the error immediately after surgery when surgical repair has the greatest chance of success. We present cases which outline the risk of accessory nerve injury, the spectrum of clinical presentations and the problems produced by a failure to recognise the deficit. Regional anatomy, consequences of nerve damage and management options are discussed. Diagnostic biopsy of neck nodes should not be undertaken as a primary investigation and, when indicated, surgery in this region should be performed by suitably trained staff under well-defined conditions. Awareness of iatrogenic injury and its consequences would avoid delays in diagnosis and treatment.

Accessory Nerve↗

Genomic organization of the human cystathionine beta-synthase gene: evidence for various cDNAs.

A CBS cDNA isolated from an adult liver cDNA library was cloned and sequenced. The 5' untranslated region (5'-UTR) contains a sequence which is only partially common (88nt) with that previously published (3). It is expressed as a 2.5kb species mostly in liver and pancreas and faintly in brain, heart, kidney and lung and as a 3.7 kb in pancreas and liver. The human cystathionine beta-synthase gene (CBS) was isolated from a cosmid genomic library and its structure was determined. The CBS gene is at least 23 kb long and is composed of 17 exons. The organization of the human gene is different from that of the rat especially in the 5'-UTR. In the rat gene the ATG is present in exon 1, conversely in the human gene first the ATG is present in exon 3 and second the 5'-UTR contains two different exons 1 (E1a and E1b) linked with exon 2.

Adult↗

Expression of the Prevotella loescheii adhesin gene (plaA) is mediated by a programmed frameshifting hop.

The 2.4-kb plaA gene, which encodes a Prevotella loescheii galactoside-specific adhesin, contains a programmed frameshifting hop. The frameshift region consists of two UAA termination codons, two repeats of four identical bases between the terminators, and a stem-loop structure that has the potential to form a pseudoknot located downstream from the second UAA. The stem-loop and pseudoknot are features found in a number of retroviruses where frameshifting is a more common occurrence. The terminators, sequence repeats, and secondary structures were identified in both the P. loescheii plaA gene and the mRNA transcript. An in-frame fusion of the entire plaA frameshift region between codons 9 and 10 of the lacZ gene permitted relatively efficient expression (4 to 25% of that of the control) of beta-galactosidase in Escherichia coli.

Adhesins, Bacterial↗

Psychoeducational group approach: HIV risk reduction in drug users.

In two trials of a small-group AIDS prevention approach, 50 methadone maintenance patients and 98 heroin abusers in outpatient detoxification were randomly assigned to experimental or comparison conditions. Experimental condition subjects received a 6-hour, small-group intervention that aimed to improve their knowledge and attitudes about AIDS, skills in syringe sterilization and condom use, and changing high-risk needle use and sexual behaviors. Comparison subjects received a set of written materials about AIDS. At posttest and 3-month follow-ups, experimental condition subjects in both maintenance and detoxification demonstrated greater knowledge of AIDS and risk reduction practices and improved skill in demonstrating condom use. Although outpatient detoxification subjects displayed considerably more risk behaviors at study outset, the intervention's effect appeared to be more robust in methadone maintenance patients. The relative lack of impact on subjects' behaviors points out that more potent, sustained interventions need to be developed to slow the spread of HIV among injecting drug users.

Adult↗

Adhesin degradation: a possible function for a Prevotella loescheii protease?

Prevotella loescheii PK1295 produces at least 3 proteases that are separable by isoelectric focusing. One of these proteases, an enzyme with an isoelectric point at 8.5 and an M(r) of 36,000, hydrolyzes the fimbria-associated adhesin on P. loescheii responsible for coaggregation with Streptococcus oralis 34, as well as gelatin, casein and fibrin. The action of this protease may contribute to the detachment of P. loescheii from its streptococcal coaggregation partner and provide a mechanism for bacterial relocation in dental plaque.

Adhesins, Bacterial↗

On the right path. Collaborative case management makes nurses partners in the care-planning process.

The quality improvement movement in healthcare has given nurses a greater role in developing and implementing collaborative case management processes. In the case management model, nurses no longer simply take orders but actively participate in designing a plan of care. At Mercy Health Center, Oklahoma City, nurses play a leading role in the development of "clinical pathways," plans of care for a single diagnosis as directed by a specific physician or group of physicians. The pathways promote multidisciplinary, interdepartmental cooperation in patient care. Since August 1992, Mercy has developed clinical pathways for five inpatient and outpatient procedures, and more are being considered. Once a plan has been created, its key points are rewritten in lay terms and printed in a brochure for the patient. During the treatment, nurses and other healthcare professionals document when specific steps in the plan have been completed. In follow-up evaluations Mercy's steering committee for the collaborative care process has found that the clinical pathways have maximized quality, improved efficiency, increased patient satisfaction, and enhanced collaborative team practice.

Documentation↗

The gene encoding a Prevotella loescheii lectin-like adhesin contains an interrupted sequence which causes a frameshift.

We cloned and sequenced the Prevotella loescheii gene plaA, which encodes a lectin-like adhesin that mediates the coaggregation of P. loescheii 1295 with Streptococcus oralis 34. A probe derived from the N-terminal amino acid sequence of the purified adhesin was used to identify the plaA gene from a P. loescheii genomic library constructed in lambda GEM-11. Sequence analysis of plaA indicates that the initial translation product contains a 22-amino-acid leader. The reading frame of the plaA gene is interrupted after amino acid 28 of the mature protein by a TAA termination codon. Amplification of the P. loescheii genomic DNA in the region surrounding this codon by the polymerase chain reaction followed by DNA sequencing of the cloned DNA fragment established that this stop codon was not an experimental artifact. A frameshift beginning 29 bp downstream of the ochre terminator was required to access the only large open reading frame in the gene. Amino acid sequences of six purified peptides derived by limited proteolysis of adhesin with endoproteinase Lys-C matched the downstream amino acid sequence derived by translation of the large open reading frame. The gene coding sequence of 2.4 kb contains sufficient information for the synthesis of an 89-kDa protein. A putative rho-independent terminator (delta G = -25.5 kcal/mol [ca. -107 kJ/mol]) was detected 38 bp downstream from the plaA stop codon.

Adhesins, Bacterial↗

The organization engine: virtual data integration.

The Organization Engine is an early example of Virtual Data Integration--providing the appearance of integration at the desktop without modifying existing infrastructure. Starting with the Organization Engine, eight programming days were needed to provide uniform desktop access to a CODASYL-compliant hospital information system and to a MUMPS-based radiology information system (the technique is equally effective for relational and other data bases). The resulting tool provides a seamless integration of these two systems, image storage, pre-recorded audio, and document storage. In addition to providing uniform access, the tool allows healthcare providers to organize the data to suit their individual needs. The ease of this integration lies in two simple techniques: the transformation of data from all sources into a single, homogeneous representation, and the use of simple customization files to describe new object types and formats. The approach is sufficiently general to allow the integration of applications which present external interfaces of radically different forms. Two such forms are discussed here: data map publication and transactions.

Computer Communication Networks↗

Erythrocyte glycophorin B deficiency may occur by two distinct gene alterations.

The genomic DNA from rare persons whose erythrocytes are deficient in glycophorin B (GPB) (S-s-U- phenotype), was examined by Southern hybridizations using glycophorin B probes and was subdivided into two main categories. In the type I variant (Fav., M.H., S.K.), we found that the S-s-U- condition is generated by a large gene deletion extending from exons B2 to B4 of glycophorin B gene. Conversely, in the type II variant (Del.), the entire gene is present, and its promoter is almost similar to common Glycophorin A (GPA) and GPB as well as to type I promoters, except for four-point mutations, which do not occur in potential cis-acting elements. We concluded that the same phenotypic glycophorin B deficiency may occur by different gene alterations, including either a gene deletion or a mutation that might alter transcription or translation of the gene.

Blotting, Southern↗

Adinazolam, diazepam, imipramine, and placebo in major depressive disorder: a controlled study.

In summary, the clinical results of this double-blind study clearly show that imipramine, as expected, demonstrated significant antidepressive properties in outpatients suffering from major depressive disorders. In contrast, adinazolam showed rather mild and weak antidepressive properties, and in no measures did its response differ significantly from that of diazepam. These findings are quite in contrast to those obtained by the authors in an earlier study with alprazolam (Rickels et al., 1987) in which alprazolam and imipramine produced rather similar results and both were significantly better than placebo, while diazepam was not. While the rather high dropout rate may well be considered a limitation of the study, the dropout rate is equally distributed between all four treatments. And since both decreasing sample size and endpoint analyses which include all patients with at least one week data, provide rather similar results, the findings can be considered as robust despite the high dropout rate. While the authors consider those findings the most robust in which endpoint and completer analyses results are rather similar, when high dropout rates occur, endpoint analyses should be given more weight than completer analyses as they are more representative of actual clinical practice. The present findings therefore suggest that adinazolam clearly possesses less antidepressive properties than imipramine and not more than diazepam and these findings are in agreement with other studies which found lack of significant antidepressant activity for such benzodiazepines as diazepam (Covi et al., 1974) and chlordiazepoxide (Lipman et al., 1986). The presence of only borderline antidepressive effects combined with rebound symptoms occurring already after only 6 weeks of therapy does not recommend adinazolam for use in depression.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Promoter sequence and chromosomal organization of the genes encoding glycophorins A, B and E.

The promoter and exon 1 sequences of the genes encoding erythrocyte glycophorins GPA, GPB and GPE were investigated in detail, both from a genomic clone sorted out of a human leukocyte library and from genomic clones obtained by polymerase chain reaction amplification of total genomic DNA from control individuals and from GAP and/or GPB deletion variants. The three exons 1 and upstream sequences were shown to be highly homologous with only a few point mutations that did not affect the potential cis-acting elements (CACCC, NF-E1 and NF-E2) that are present in the same position within the three genes. Moreover, these genes share the same transcription start point. Analysis of the exon 1 and promoter sequences together with the gene defects occurring in the GP variants indicate that unequal cross-overs between the three genes are responsible for deletions and the generation of hybrid gene structures in which the promoter of one gene is brought close to another gene of the family. On the basis of these studies, a model of the gene organization is proposed to explain the rearrangements occurring in the variants.

Base Sequence↗