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Biomedical subjects

C Hughes

Publications and source records attributed to C Hughes.

At least 253 records · Page 14Linked to original sources
PubMed1989

Microtitre plate measurement of platelet response to hypotonic stress.

The conventional method of assessing the platelet response to hypotonic stress (HSR) was adapted to allow microtitre plate technology to be used. After water is added to a platelet suspension two sequential readings are taken at 414 nM on a vertical microplate reader. The difference between the second (three minutes) and the first (one minute) was defined as the HSR. This method allowed the relation between platelet concentrate pH and viability to be confirmed, and an HSR value for use in quality control was established. The method correlated well with the conventional technique and permitted measurement of undiluted samples as well as of products with a high free haemoglobin concentration.

Blood Platelets↗
PubMed1989

Overview of supported employment.

This article traces the emergence of supported employment as a result of philosophical changes in expectations for persons with disabilities, based on scientific developments that challenged traditional service-delivery models. Supported employment program characteristics also are reviewed, and the influence of applied behavior analysis is outlined. Finally, areas for future research in supported employment are discussed.

Employment↗
PubMed1989

Teaching supported employees with severe mental retardation to solve problems.

Two individuals with severe mental retardation, employed by a janitorial supply company, were taught to use self-instruction in combination with multiple exemplar training to solve work-related problems. Use of the combined strategy resulted in generalization of the effects of independent variables, as well as generalization to nontrained problems. Use of the strategy is discussed in terms of promoting independent performance among supported employees.

Adult↗
PubMed1988

Expression of the E.coli hemolysin secretion gene hlyB involves transcript anti-termination within the hly operon.

The genes hly A and hly B dictating synthesis and secretion of hemolytic toxin by Escherichia coli are transcribed as part of an operon hly C, hly A, hly B but are separated by an inverted repeat and poly-T sequence characteristic of a rho-independent terminator. The hly A-hly B intergenic sequence caused a reduction of in vivo transcriptional read-through from the gal promotor into gal K when inserted in the pKG1900 terminator-probe vector and also in vitro 3' to the bacteriophage T7 luminal diameter 10 promotor. Hybridisation of mRNA generated by the hly determinant of recombinant DNA pBR202-312 to an antisense RNA probe spanning the hly intergenic sequence revealed specific termination of 80% of in vivo hly transcripts within the poly-T sequence, immediately preceding the hly B translation start. Extension of the hly determinant with 3.5kbp of hly promotor-proximal DNA sequence raised intracellular and cell-free hemolytic activity 3-fold and 20-fold respectively and increased markedly the secretion of the 107Kd hemolysin protein (HlyA). Parallel hybridisation of in vivo mRNA to hly A and hly B antisense probes revealed that levels of hly A and hly B mRNA were increased by approximately 3-fold and 90-fold. The dramatically enhanced level of hly B mRNA resulted primarily from specific suppression of transcription termination at the intergenic rho-independent terminator from 80% to 1%, thus allowing virtually all hly A transcripts to elongate into hly B.

Bacterial Proteins↗
PubMed1988

Identification of the promoters directing in vivo expression of hemolysin genes in Proteus vulgaris and Escherichia coli.

The hemolytic activity of Escherichia coli and Proteus vulgaris is determined by common contiguous genes encoding synthesis (hly C, hly A) and specific secretion (hly B, hly D) of active hemolysin. Nevertheless, the hly C-proximal DNA sequences directing production of the homologous hemolysins by the recombinant DNAs P. vulgaris pVU763-709 and E. coli pANN202-312 showed no extensive homology. Primer extension and S1 nuclease protection were used to define in the two sequences the 5' termini of hly transcripts synthesized in vivo and thus to infer the active hly promoters sequences. The E. coli hly C upstream region contained three separate promotors directing in vivo hly transcription, while the corresponding transcription of the P. vulgaris hly operon originated from a single distinct promotor, the -35 and -10 sequences of which formed part of an inverted repeat sequence. Elevated hemolytic activity caused by upstream Tn5 insertions in pVU763-709 resulted from increased transcription from this promotor.

Base Sequence↗
PubMed1988

Comparison of the haemolysin secretion protein HlyB from Proteus vulgaris and Escherichia coli; site-directed mutagenesis causing impairment of export function.

The hlyB secretion genes of Proteus vulgaris and Escherichia coli showed 81% nucleotide homology and similar E. coli-atypical codon usage. The deduced protein sequences differed in 54 of 707 residues and shared a previously unreported sequence which corresponds to the ATP-binding motif characteristic of protein kinases. The motif was also conserved in the HlyB of Morganella morganii. Of 4 oligonucleotide-directed substitutions introduced into the putative E. coli HlyB motif, 2 non-conservative changes caused radical reductions in the export of active haemolysin protein.

Amino Acid Sequence↗
PubMed1988

Nuclear factors binding to the mini-exon repeat of Trypanosoma brucei.

In trypanosomes and related kinetoplastida a common short 5' leader sequence is encoded by the highly repetitive mini-exon gene and added to all protein coding mRNAs by trans-splicing. To initiate a search for transcription factors associated with transcription of the mini-exon we have used an electrophoretic mobility shift assay to detect trypanosome nuclear factors which interact specifically with mini-exon DNA. A factor present in the nuclei of both infectious bloodstream forms and non-infectious culture forms of Trypanosoma brucei was shown by DNAase I footprinting and oligonucleotide competition to bind 5' to the transcription start site of the mini-exon. A second factor which bound to the mini-exon itself at a sequence conserved in other kinetoplastida was evident only in the nuclei of infectious bloodstream forms.

Animals↗
PubMed1988

Production and properties of haemolysins from clinical isolates of the Proteeae.

A collection of 198 clinical isolates of strains belonging to the tribe Proteeae was examined for haemolytic activity on blood agar and in Brain Heart Infusion Broth. The strains were of diverse bacteriocin and O-antigenic types and from a wide variety of sources. They included representatives of all species of Morganella, Proteus and Providencia. Approximately half of the M. morgani strains were haemolytic on blood agar. This activity was not associated with any particular bacteriocin type. The haemolysin was also produced during exponential growth in broth and was thermolabile and calcium dependent. All P. mirabilis strains and some P. vulgaris strains were non-haemolytic on blood agar. However, most strains of the Proteus spp., irrespective of their bacteriocin and antigenic type, produced, over a short period during exponential growth in broth, a heat-stable, cell-associated calcium-independent haemolysin. A smaller proportion of P. vulgaris and P. penneri strains produced, in addition, a thermolabile, calcium-dependent haemolysin which was associated with the formation of large haemolytic zones on blood agar. The relationship of these haemolysins to Escherichia coli haemolysin and their possible role in virulence is discussed. Haemolysin production was not found in any of the 74 strains of four species of Providencia.

Calcium↗
PubMed1987

H1 histone synthesis and phosphorylation in mouse mammary gland in vitro.

The synthesis and phosphorylation of H1 histones were studied in organ cultures of midpregnant mouse mammary glands exposed to various combinations of insulin, cortisol and prolactin over a 48-h period. The synthesis of specific H1 histone subtypes was changed only when all three hormones were present, and the effect was most pronounced during the first 24 h of culture, a period of cell replication. The 3-hormone combination also stimulated the phosphorylation of the N-terminal region of the H1 histone, and this also occurred maximally during the first 24 h of culture. The enhanced phosphorylation of the N-terminal region of the H1 histone included a site sensitive to phosphorylation by cyclic AMP-dependent protein kinase. Thus, hormones which stimulate mammary development in vitro influence the synthesis and specific phosphorylation of H1 histones during a period of cell replication preceding the expression of milk protein genes.

Animals↗
PubMed1987

Immunochemical studies on the synthesis and secretion of link protein and aggregating proteoglycan by chondrocytes.

Chondrocytes from pig laryngeal cartilage were maintained in culture, and the biosynthesis and secretion of link protein and proteoglycan were studied using immunochemical, biochemical and immunolocalisation techniques. In the presence of monensin there was a dose-dependent inhibition of link protein secretion which was very similar to that of aggregating proteoglycan, and suggested that they followed the same intracellular pathway during biosynthesis. In the presence of cycloheximide there was a similar dose-dependent inhibition of the secretion of both link protein and proteoglycan. Kinetics of secretion following inhibition of synthesis by cycloheximide showed that both proteins had similar intracellular pool sizes. Analysis of protein core and glycosaminoglycan biosynthesis showed that the time for synthesis and glycosylation of proteoglycan was 22 minutes, and this was quickly followed (within 6 minutes) by secretion. Intracellular electron microscopic immunolocalisation using protein A-gold showed link protein to be present in the Golgi cisternae and vesicles, and double-labelling experiments showed link protein only to be detected in vesicles that also labelled for proteoglycan protein core. When chondrocytes were maintained in monolayer culture for 10 days the rate of biosynthesis and secretion of proteoglycan increased although that of link protein remained constant. The control of their biosynthesis was thus shown to be independent. Within 4 hours of secretion a high proportion of link protein was incorporated into proteoglycan aggregates.

Animals↗
PubMed1987

Coinduction of glucose-regulated proteins and doxorubicin resistance in Chinese hamster cells.

The glucose-regulated protein (GRP) system in mammalian cells is induced by glucose deprivation, anoxia, the calcium ionophore A23187, and 2-deoxyglucose. In Chinese hamster ovary cells the major GRPs are approximately equal to 76, 97, and 170 kDa. Removal of each of these four GRP-inducing stresses leads to the coordinate repression of GRPs and induction of the major heat shock proteins at 70 and 89 kDa. The application of each of these four GRP-inducing conditions leads to a significant induction of resistance to the drug doxorubicin. Removal of each GRP-inducing condition results in the rapid disappearance of this resistance in a manner that correlates with the repression of the GRPs. The retention of doxorubicin by GRP-induced cells does not explain the induced drug resistance. When the RIF in vitro/in vivo tumor system is probed with an antibody against the 76-kDa GRP, a significant increase in this GRP is observed in cells obtained from the central regions of tumors. Since hypoxia and/or nutrient deprivation can occur during tumor development, a GRP-induced state in the tumor may confer resistance to doxorubicin treatment.

Animals↗
PubMed1987

The aftermath of rape. Profiles of immediate and delayed treatment seekers.

Seventy-eight sexual assault victims who sought treatment within 1 month of their assaults were compared with 40 victims who delayed seeking treatment. Demographic, rape situation, and psychiatric history characteristics were examined as were postrape symptom profiles and responses to treatment. More of the delayed treatment seekers were raped by a "friend," and fewer used physical means to defend themselves against the assailant. With respect to symptomatology, delayed treatment seekers reported considerable rape-related distress and were more anxious and significantly more fearful than were recent rape victims. Implications for clinical practice and for the tailoring of services for victims of sexual assault are suggested.

Anxiety Disorders↗
PubMed1987

The secreted hemolysins of Proteus mirabilis, Proteus vulgaris, and Morganella morganii are genetically related to each other and to the alpha-hemolysin of Escherichia coli.

Secreted hemolysins were extremely common among clinical isolates of Proteus mirabilis, Proteus vulgaris, and Morganella morganii, and hemolytic activity was either cell associated or cell free. Southern hybridization of total DNA from hemolytic isolates to cloned regions of the Escherichia coli alpha-hemolysin (hly) determinant showed clear but incomplete homology between genes encoding production of hemolysins in the four species. One of the two E. coli secretion genes, hlyD, hybridized only with DNA from P. vulgaris and M. morganii, which produced cell-free hemolysis, but not with that from P. mirabilis, which showed only cell-associated activity. Molecular cloning of the genetic determinants of cell-free hemolytic activity from P. vulgaris and M. morganii chromosomal DNA allowed their functional analysis via inactivation with the transposons Tn1000 and Tn5. Both hemolysin determinants were about 7.5 kilobase pairs and comprised contiguous regions directing regulation, synthesis, and specific secretion out of the cell. Transposon mutations which eliminated secretion of the Proteus and Morganella hemolysins could be complemented specifically by the E. coli hemolysin secretion genes hlyB or hlyD. Alignment of the physically and functionally defined hly determinants from P. vulgaris and M. morganii with that of the E. coli alpha-hemolysin confirmed a close genetic relationship but also indicated extensive evolutionary divergence.

Bacterial Proteins↗
PubMed1987

Growth study including stereophotogrammetry of a pair of monozygotic twins, one having a cleft lip and palate.

This report is a serial growth study of a pair of monozygotic twin boys, one of whom suffered from a bilateral cleft of the lip and a unilateral cleft of the palate. Annual records for height and weight were registered from seven years eight months to 18 years 0 months. Soft tissue facial growth was also measured annually using short base stereophotogrammetry (Burke, 1967). Growth and development of the dentition was recorded as orthodontic study models at less frequent intervals. Measurements derived from the facial maps allowed not only measurement of soft tissue growth changes in the face, but also of surgical change to both lips related to an Abbe flap procedure carried out for the cleft twin. All changes are compared with those occurring in his monozygotic twin.

Adolescent↗