Search PubMed⌕ Search

Biomedical subjects

A Wright

Publications and source records attributed to A Wright.

At least 325 records · Page 18Linked to original sources
PubMed1985

Epithelial dysplasia immediately adjacent to oral squamous cell carcinomas.

A number of workers have attempted to identify dysplastic features which may be predictors of malignant change, by prospective studies of dysplastic lesions. In the present study we have looked at dysplastic changes immediately adjacent to established squamous carcinomas in an attempt to determine whether any predictors can be identified in this way. Eighty cases were included in the study for whom information on tobacco usage was known. Clinical details were recorded. Histological features in epithelium immediately adjacent to the carcinoma were studied in representative sections. Eighteen specific histological characteristics were noted as present or absent. Data were transferred by Conversational Monitoring System (CMS) terminal, processed and analyzed by the Statistical Analysis System (SAS) Computer package. Only 8 patients were non-smokers (10%). Dysplastic changes in adjacent epithelium were frequently multicentric. Changes appear to occur first in the basal layer in the form of disturbance of polarity or basal cell hyperplasia, while other dysplastic features are absent. The feature referred to as basal cell hyperplasia appears, in fact, to represent disturbed epithelial maturation. In 80% of cases increased nucleo-cytoplasmic ratio appears to result from a decrease in cytoplasmic volume rather than increased nuclear size. A defect in RNA synthesis may be a factor. A sharp decrease in inflammatory cells in the lamina propria of adjacent epithelium, compared with that of the carcinoma, was observed. Russell bodies were noted in 5 of the 8 lesions in non-smokers (63%) and in 16 of 72 lesions in smokers (22%) (p less than 0.001; Chi2 17.65).

Adult↗
PubMed1985

Physical and genetic analysis of DNA regions encoding the immunoglobulin A proteases of different specificities produced by Haemophilus influenzae.

The structural gene for immunoglobulin A protease (iga) from Haemophilus influenzae serotype d was cloned in pBR322. The gene was used as a probe for Southern hybridization analysis of chromosomal DNA from the five other H. influenzae serotypes (a, b, c, e, and f). In most cases strains from a single serotype exhibited a distinct pattern of restriction fragment(s) homologous to the iga gene probe which was unique for that serotype. Serotype f strains were unique in that they gave two distinct patterns of homologous restriction fragments which correlated well with the production of two different protease types by members of this group. An iga mutant of H. influenzae serotype d was isolated by introducing a 4-base-pair insertion into the cloned iga gene and using the altered DNA for transformation of an H. influenzae recipient. The resulting iga- mutant produced no immunoglobulin A protease but was otherwise indistinguishable from its iga+ parent in growth characteristics. Transformation of mutant cells with chromosomal DNA isolated from either a serotype d or a serotype c strain gave rise to iga+ transformants. Those obtained with serotype d DNA produced a type 1 protease, whereas those obtained with serotype c DNA produced either a type 1 protease (characteristic of serotype d) or a type 2 protease (characteristic of serotype c). Southern analysis of the latter transformants, using the iga gene probe, indicated that the type 1 transformants had a serotype d pattern of restriction fragments whereas the type 2 transformants had either a serotype c or a novel pattern of restriction fragments. These results indicate that there is considerable homology between the iga genes of the various serotypes and that the homologous sequences identified with the serotype d probe are the immunoglobulin A protease-coding sequences in each case.

Bacterial Proteins↗
PubMed1985

Maintenance of plasmid pSC101 in Escherichia coli requires the host primase.

The abilities of three Escherichia coli strains with thermosensitive dnaG alleles to maintain plasmids pSC101 or pBR322 or an RP4 derivative were studied at elevated growth temperatures. Under these conditions, pSC101 segregated from cells to a greater extent than did pBR322. No segregation of the primase-encoding RP4 derivative was observed.

DNA Primase↗
PubMed1985

Ménière's syndrome.

A patient complaining of dizziness, deafness, and tinnitus often brings a feeling of despondency to the doctor. Together the symptoms may arise from Ménière's syndrome, a condition that eludes firm diagnosis, is without known cause, and cannot yet be cured. Consequently, discussion and disagreement about the disease is common and some of these aspects are outlined here.

Audiometry, Evoked Response↗
PubMed1984

Dimensions of the cochlear stereocilia in man and the guinea pig.

The tuning properties of the basilar membrane and the presence of acoustic emissions from the cochlea suggest that an energy consuming, mechanically active cochlear amplifier exists. Some models of this amplifier demand a mechanical resonator within the cochlea. The lengths of the stereocilia of the inner and outer hair cells in man and the guinea pig have been measured from scanning electron micrographs using a stereometric technique. In both species there is a linear increase in the length of the longest inner hair cell stereocilia with distance along the cochlea. There are, however, marked differences between the dimensions of the outer hair cell stereocilia in the two species. In man, there is an increase in length which is is a hyperbolic function of distance along the cochlear duct. The picture is more complicated in the guinea pig. This could account for some of the differences in auditory physiology between the two groups. The mechanical resonance properties of the human OHC stereocilia have been assessed, and, with certain assumptions, these properties are such that resonance of the stereocilia of the OHCs could form part of the cochlea amplifier, at least in man.

Animals↗
PubMed1984

Aflatoxin B1: effect on the synthesis and degradation of mitochondrial proteins in hepatocyte monolayers.

The effect of aflatoxin B1 (AFB1), a hepatocarcinogen, on mitochondrial and general protein synthesis and degradation has been studied. AFB1 (0.003, 0.03, 0.25 micrograms ml-1) inhibited total protein synthesis over a 5 h period by 30, 64 and 82%, respectively, measured by incorporation of [3H]leucine. After 24 h in the presence of AFB1 inhibition was 23, 77 and 100%, respectively. AFB1 inhibited total hepatocyte protein degradation in a concentration independent manner by approximately 50% i.e., from 1.4% h-1 to 0.7% h-1. The immediate effect of AFB1 on mitoribosomal and total mitochondrial protein synthesis and mitochondrial degradation has been assessed by two methods. Mitoribosomal synthesis of proteins was inhibited over a 5 h period by AFB1 in a concentration independent manner by approximately 43%. Total mitochondrial protein synthesis showed a 23 and 45% inhibition by AFB1 (0.003 and 0.03 micrograms AFB1 ml-1) over a 4 h period and 25 and 72% inhibition, respectively, after 24 h in culture. The rate of mitochondrial protein degradation was not altered. AFB1 inhibits dibutyryl cyclic AMP-induced tyrosine amino transferase (TAT) activity in hepatocytes by 57% at 0.003 micrograms ml-1 and 100% at 0.03 micrograms ml-1 over a 24 h period. Dibutyryl cyclic AMP increases the rate of degradation of proteins in hepatocyte monolayers from 1.4% h-1 to 2.7% h-1 and was inhibited at both concentrations of AFB1 used. AFB1 causes a rapid inhibition of total hepatocyte protein synthesis, synthesis of proteins in hepatocyte mitochondria and the synthesis of imported mitochondrial proteins. General hepatocyte and dibutyryl cyclic AMP-induced protein degradation are significantly inhibited by AFB1 whereas the degradation of mitochondrial proteins is unaffected.

Aflatoxin B1↗
PubMed1984

A cooperative organizational form for hospitals.

Hospitals face severe financial pressures at the same time that patients and physicians are demanding quality medical care and the latest technology, which is becoming increasingly costly. Hospitals must consider adopting and experimenting with a cooperative organization system, which groups physicians, nurses and administrators together in teams to plan jointly and allocate resources.

Budgets↗
PubMed1984

Examination of Haemophilus pleuropneumoniae for immunoglobulin A protease activity.

Haemophilus pleuropneumoniae, the etiological agent of porcine contagious pneumonia, was examined for the ability to produce an immunoglobulin A (IgA) protease specific for porcine IgA. No IgA protease activity against either porcine or human IgA was detected. Furthermore, no sequence homology was found between H. pleuropneumoniae chromosomal DNA and the gene which specifies IgA protease in Haemophilus influenzae.

Animals↗
PubMed1983

Chemically synthesized galactosyl ficaprenyl diphosphate as an intermediate in the biosynthesis of the Salmonella O-antigenic polysaccharide.

The membrane fraction from a mutant of Salmonella anatum deficient in UDPgalactose-4-epimerase, utilized synthetic ficaprenyl alpha-D-galactosyl diphosphate as a substrate in the biosynthesis of the O-polysaccharide portion of lipopolysaccharide which has a mannosylrhamnosylgalactose repeating sequence. The galactosyl lipid was prepared by chemical synthesis from D-galactose and ficaprenol extracted from Ficus elastica. Membrane preparations catalyzed the transfer of rhamnose from TDP-rhamnose onto membrane-bound ficaprenyl galactosyl diphosphate forming rhamnosylgalactosyl ficaprenyl diphosphate; the reaction was dependent on the prior insertion of the synthetic glycosyl-lipid into the membrane, and was proportional to incubation time up to 4 min at 29 degrees C. When both TDP-rhamnose and GDP-mannose were added, the product formed was O-polysaccharide. These results indicate that the chemically synthesized ficaprenyl galactosyl diphosphate can be an active substrate for the in vitro synthesis of the Salmonella O-polysaccharide.

Antigens, Bacterial↗
PubMed1983

Effects of aldosterone and corticosterone on cloacal water and electrolyte excretion of constantly-loaded intact and colostomized ducks (Anas platyrhynchos).

1. Doses of aldosterone (50, 100 and 200 micrograms per kg body wt) evoked similar changes in Na+ and K+ excretion by intact and colostomized ducks loaded with either distilled water or 0.5 isotonic saline (70 mM NaCl, 1.5 mM KCl); both antinatriuretic and antikaliuretic responses were observed. 2. The lowest dose of aldosterone had no effect on electrlyte excretion in intact and colostomized ducks loaded with a solution containing more K+ than Na+ (74 mM KCl, 36 mM NaCl) but the higher doses caused an antinatriuretic response in both groups; a retention of K+ occurred only in intact birds given this solution. 3. The lower dose of corticosterone (1.25 mg per kg body weight) caused both antidiuresis and antinatriuresis in intact birds, but in colostomized birds the decrease in Na+ excretion was not accompanied by an antidiuresis. 4. The higher dose of corticosterone (2.50 mg per kg body wt) caused a significant increase in K+ excretion in colostomized birds, whereas no kaliuresis was ever observed in intact birds. 5. Intact and colostomized birds loaded with 0.5 isotonic saline showed no responses to the lower dose of corticosterone, whereas the higher dose had an antikaliuretic effect in intact birds and an antinatriuretic effect in colostomized birds. 6. Corticosterone had no effect on cloacal water and electrolyte excretion by intact and colostomized birds given loads containing more K+ than Na+.

Aldosterone↗
PubMed1983

IgA1 proteases of Haemophilus influenzae: cloning and characterization in Escherichia coli K-12.

Haemophilus influenzae is one of several bacterial pathogens known to release IgA1 proteases into the extracellular environment. Each H. influenzae isolate produces one of at least three distinct types of these enzymes that differ in the specific peptide bond they cleave in the hinge region of human IgA1. We have isolated the gene specifying type 1 IgA1 protease from a total genomic library of H. influenzae, subcloned it into plasmid vectors, and introduced these vectors into Escherichia coli K-12. The enzyme synthesized by E. coli was active and had the same specificity as that of the H. influenzae donor. Unlike that of the donor, E. coli protease activity accumulated in the periplasm rather than being transported extracellularly. The position of the protease gene in H. influenzae DNA and its direction of transcription was approximated by deletion mapping. Tn5 insertions, and examination of the polypeptides synthesized by minicells. A 1-kilobase probe excised from the IgA1 protease gene hybridized with DNA restriction fragments of all H. influenzae serogroups but not with DNA of a nonpathogenic H. parainfluenzae species known to be IgA1 protease negative.

Cloning, Molecular↗
PubMed1983

The surface structures of the human vestibular apparatus.

The surface of the human vestibular apparatus has been examined in the scanning electron microscope following early post mortem fixation. Preservation of the fine structures of the maculae is good but of the cristae of the semi-circular canals is only fair. The surface features of the maculae do not differ from those seen in experimental animals. There appears to be an age related loss of ciliated sensory cells from the cristae. This might explain some of the age related changes in vestibular function.

Acoustic Maculae↗
PubMed1983

Scanning electron microscopy of the human organ of Corti.

The human cochlea has been preserved from post-mortem autolysis by perfusion with a fixative shortly after death. Subsequent staining with osmium permits dissection of this structure from the temporal bone. (Temporal bones were obtained from eight patients). When prepare for examination in the scanning electron microscope, the auditory sensory cells are found to be located in the band-like organ of Corti which extends the length of the cochlea. The sensory cells have a cluster of stereocilia projecting from their free upper surface and because of this are called hair cells. The hair cells are divided into two separate groups: a single row of inner hair cells, which show little variation in their surface appearance along the length of the cochlea, and three or four rows of outer hair cells whose cilia change in conformation and increase in length along the cochlea.

Adult↗