Biomedical subjects

R Nicholson

Publications and source records attributed to R Nicholson.

At least 19 recordsLinked to original sources

PubMed1997

Referral letters: are form letters better?

An essential mode of contact between general practitioners (GPs) and hospital staff is the referral letter. This must be clear and concise with sufficient information to aid the GP, the consultant and the patient. In order to ensure this, a proposal was made for the use of a structured or standardized referral letter: a form letter. This report shows that form letters were shorter than typed letters. Form letters were also proven to contain more information than nonform letters.

Correspondence as Topic↗

PubMed1996

Resection of the internal carotid artery and replacement with greater saphenous vein: a safe procedure for en bloc cancer resections with carotid involvement.

PURPOSE: Many patients who have advanced cancer of the neck will have involvement of the internal carotid artery. The management of this condition remains controversial, and a wide range of therapeutic options have been suggested including ligation, "shaving" the tumor off the carotid, or en bloc resection and replacement of the internal carotid artery by polytetrafluoroethylene, vein, or superficial femoral artery. We reviewed our experience with en bloc resections of the internal carotid artery in a consecutive series of patients who had malignancies involving the internal carotid artery at a single institution from 1989 to 1995. METHODS: We used a retrospective chart review based on a list of 20 patients generated by the Hospital Cancer Registry and our Vascular Surgery clinical database. RESULTS: All patients had their internal carotid artery removed and replaced with a greater saphenous vein while they were under general anesthesia. A resection of their cervical malignancy was also performed. Concomitant myocutaneous flaps were rotated over the carotid bypass in six (30%) patients. Eight (40%) of the bypass grafts were nonreversed, and 12(60%) were reversed, with a clear trend towards using nonreversed veins more recently. Shunts were used in 18(90%). Eighteen of the 20 patients had some form of intraoperative contamination including tracheostomies, pharyngostomies, or fistulas. Half of the patients had intraoperative radiation therapy, and 16(80%) patients underwent operation for recurrent cancer. During the follow-up period two (10%) patients had strokes (one minor and one major), and one patient had a graft blowout, which was treated by ligation without stroke. One patient had an asymptomatic occlusion of his graft. CONCLUSIONS: From these results we conclude that the use of the greater saphenous vein to replace the internal carotid artery after en bloc resection is not attended by a high rate of infectious complications or graft blowout even in the presence of intraoperative tracheopharyngeal contamination and that the greater saphenous vein is the conduit of choice for replacing an internal carotid artery after cancer resections.

Carcinoma, Squamous Cell↗

PubMed1995

A new immunohistochemical antibody for the assessment of estrogen receptor status on routine formalin-fixed tissue samples.

We describe a method for the immunocytochemical assessment of estrogen receptor (ER) status on routinely processed, formalin-fixed tissue using a recently developed commercially available monoclonal antibody (Dako 1D5) with a microwave antigen retrieval technique. A series of 90 cases of human breast carcinoma was analyzed and the staining was assessed using a semiquantitative microscopic scoring method and by assessment of the percentage of nuclei showing positive staining. The results were compared with assessment using another commercially available antibody (Abbott H222) and with clinical response to tamoxifen therapy. Direct comparison of the paired sets of H scores and the percentage of positively stained nuclei using the two different techniques showed a significant correlation. By assigning an arbitrary cut-off for positivity of H score = 50, assessment of ER status using DAKO 1D5 antibody was found to correlate with response to tamoxifen therapy with a sensitivity of 90% and a specificity of 51%, similar to values in previous studies using other methods. We conclude that assessment of ER status using this new antibody and technique gives accurate results on routinely processed, formalin-fixed tissue and may be used as an alternative to other methods.

Adult↗

PubMed1995

Assessment of the new proliferation marker MIB1 in breast carcinoma using image analysis: associations with other prognostic factors and survival.

The 'growth fraction' of tumours can now be assessed on paraffin sections of tissues using the monoclonal antibody MIB1 by a microwave antigen retrieval technique. The MIB1 labelling index was studied using a CAS 200 image analyser in 177 tumours from women with primary operable breast carcinoma in whom long-term follow-up data were known. Statistical analysis showed a strong association between the MIB1 labelling index and histological grade (P < 0.001), tumour size (P = 0.002), tumour type (P < 0.001) and also patient survival (P < 0.001). No association with lymph node stage (P = 0.974) or regional recurrence (P = 0.185), the presence or absence of distant metastases (P = 0.418), patient age (P = 0.309), menopausal status (P = 0.181) or oestrogen receptor status (P = 0.401) was found in this group of patients. In multivariate analysis for survival, when histological grade, lymph node stage and tumour size were included as well as the MIB1 labelling index, each was found to be of independent significance. If histological grade was not included, MIB1 replaced it as the most important variable predicting for survival in this group of patients. The results suggest that the tumour growth fraction, as assessed by the MIB1 labelling index, is an important predictor of survival.

Antibodies, Monoclonal↗

PubMed1994

Dual immunocytochemical analysis of oestrogen and epidermal growth factor receptors in human breast cancer.

Recent studies have demonstrated a consistent inverse relationship between oestrogen receptor (ER) and epidermal growth factor receptor (EGFR) levels in female human breast cancer. Serial cross-section studies have suggested that separate populations of ER+/EGFR- and ER-/EGFR+ cancer cells exist in tumours deemed by immunocytochemical assay (ICA) to be positive for both. We have developed a dual ICA that is able to stain for both ER and EGFR on a single 5 microns frozen section sample of breast tissue. Twenty-two samples of female human breast cancer tissue that exhibited positivity for ER and EGFR by ER-ICA using the H222 monoclonal antibody and EGFR-ICA using the EGFR1 monoclonal antibody underwent the dual ICA. There was a significant correlation in receptor positivity between the single and dual assays for both ER (rs = 0.801, P < 0.001) and EGFR (rs = 0.831, P < 0.001). Individual cancer cells exhibited one of three staining patterns: nuclear staining only (ER+/EGFR-), membrane-associated and cytoplasmic staining only (ER-/EGFR+) or no staining (ER-/EGFR-). No cancer cells exhibited both nuclear and membrane/cytoplasmic staining. This is the first description of a simultaneous dual immunocytochemical assay system for ER and EGFR in clinical breast cancer specimens. The results suggest that ER and EGFR expression are mutually exclusive within an individual breast cancer cell in vivo with separate populations of ER+/EGFR- cells, ER-/EGFR+ cells and ER-/EGFR- cells coexisting.

Adult↗

PubMed1994

The protease of adenovirus serotype 2 requires cysteine residues for both activation and catalysis.

Sequence analysis and site-directed mutagenesis were used to study the mechanisms of activation and catalysis of the adenovirus type 2 (Ad2) protease. Primary structure alignments of proteases from 12 serotypes and previously elucidated inhibition profiles were used to target residues for mutagenesis. All conserved serine and cysteine residues were mutated separately and following expression in Escherichia coli their activity in a synthetic peptide assay was compared to that of wild-type recombinant protease. Mutants containing altered serine residues were active while mutations to cysteine-104 and cysteine-122 reduced activity by more than 95%. These results taken together with the known inhibition profile of the adenovirus protease confirm that it is a cysteine protease and suggest that one of these residues provides the active site nucleophile while the other is a part of the thiol-disulphide interchange mechanism previously reported to be involved in its activation.

Adenoviruses, Human↗

PubMed1994

Ovulation induction and endometrial steroid receptors.

The endometrial morphology, endometrial steroid receptors and serum steroid hormone concentrations have been studied in 22 infertile women participating in an in-vitro fertilization, gamete intra-Fallopian transfer programme, including nine cases following treatment with gonadotrophin-releasing hormone analogue/human menopausal gonadotrophin/human chorionic gonadotrophin. All patients had normal ovulatory function before treatment and satisfactory response to ovulation induction. Endometrial biopsies were taken in spontaneous and treatment cycles on the fourth day after ovulation had been detected by ultrasound scanning, when endometrial receptors were measured using immunohistochemistry. Histological examination of biopsies in spontaneous cycles showed the majority (20/22) to be 'in-phase', while in two cases luteal phase defect was diagnosed. After ovulation induction, all the biopsies were still morphologically 'in-phase', although a significant reduction had occurred in the nuclear receptor level in both the glands and stroma for both progesterone receptors (gland P = 0.030, stroma P = 0.012 using microscopic analysis; gland P = 0.020, stroma P < 0.001 using a cell analysis system) and oestrogen receptors (gland P = 0.017, stroma P = 0.002 using direct microscopic analysis). This suggests that a reduction in steroid receptors in the endometrium occurs after ovulation induction in the presence of supraphysiological amounts of steroids, which is not associated with detectable morphological changes.

Adult↗

PubMed1991

The c-Ets oncoprotein activates the stromelysin promoter through the same elements as several non-nuclear oncoproteins.

The c-ets protooncogenes have recently been shown to code for transcription factors that activate the oncogene responsive unit of the polyoma virus enhancer. We show that transcription of the stromelysin gene, which is highly expressed in transformed cells and tumours, is efficiently activated by c-Ets-1 and -2 through two DNA elements. The distal element is a highly conserved palindrome composed of two strong binding sites for c-Ets-1. The proximal element does not bind c-Ets-1, but may be activated indirectly by increased synthesis of c-Jun and c-Fos. Both ets responsive elements mediate activation by the oncoproteins Ha-Ras, v-Src and v-Mos. These results suggest that c-Ets participates in the mechanisms by which stromelysin gene expression is deregulated in transformed cells and tumours.

Animals↗

PubMed1991

c-erbB-2 oncoprotein expression in primary and advanced breast cancer.

Immunoreactivity for c-erbB-2 oncogene product expression has been investigated in patients with breast cancer using the polyclonal antibody 21N. Three series of patients were studied, 602 presenting with primary operable cancer, 57 with stage 3 and 123 with stage 4 disease. Representative tissue sections of each primary tumour were stained using a standard immunoperoxidase technique. Invasive tumour membrane immunoreactivity was assessed and identified in 15% of patients with primary operable cancer and 20% in the advanced breast cancer group. The results demonstrate a relationship between poorer survival and oncogene expression in all three patient groups. Patients in the primary operable cancer group with membrane oncoprotein expression had a poorer outcome, 35% 10-year survival, compared with those in which membrane expression was absent, 55% 10-year survival. The median survival of patients with stage 3 disease with c-erbB-2 membrane positivity was 17 months compared to 24 months with membrane negativity. In stage 4 disease median survival with membrane expression was 8.8 months compared to 19.7 months with no membrane expression. In addition in the series of primary cancers a correlation existed between histological grade and membrane immunoreactivity. Multivariate analysis showed histological grade to be a more powerful prognostic factor than c-erbB-2 protein expression. In conclusion, this study demonstrates, in a large series of patients presenting to one centre, that c-erbB-2 protein expression is a prognostic indicator in patients with primary operable and advanced breast disease.

Breast Neoplasms↗

PubMed1991

The long term prognostic significance of oestrogen receptor analysis in early carcinoma of the breast.

The long term prognostic significance of oestrogen receptors was assessed in a prospective study of 767 patients presenting between the years 1975 and 1981 with stage 1 and 2 breast cancer treated by mastectomy with either full axillary dissection or nodal sampling. Oestrogen receptor binding was determined by a dextran coated charcoal method and median follow up was 11 years. Oestrogen receptors were present in 396 (54%) of tumours. Absence of oestrogen receptors was associated with tumours of high histological grade, but there was no relationship between nodal status or tumour size. Oestrogen receptor status did not predict survival for the group as a whole or when stratified by nodal status. In multivariate analysis both nodal status and tumour size were powerful independent prognostic factors, but oestrogen receptors failed to achieve statistical significance.

Analysis of Variance↗

PubMed1991

Structural and functional analysis of the ribosome landing pad of poliovirus type 2: in vivo translation studies.

The naturally uncapped genomic and mRNAs of poliovirus initiate translation by an internal ribosome-binding mechanism. The mRNA 5' untranslated region (UTR) of poliovirus is approximately 750 nucleotides in length and has seven to eight (depending on the serotype) AUG codons upstream of the initiator AUG. The sequence required for internal ribosome binding has been termed the ribosome landing pad (RLP). To better understand the mechanisms of internal initiation, we have determined the boundaries and critical elements of the RLP of poliovirus type 2 (Lansing strain) in vivo. By using deletion analysis, we demonstrate the existence of a core RLP in the poliovirus mRNA 5' UTR whose boundaries are between nucleotides 134 and 155 at the 5' end and nucleotides 556 and 585 at the 3' end. Sequences flanking the core RLP affect translational activity. The importance of several stem-loop structures in the RLP for internal initiation has been determined. Mutation of the phylogenetically conserved loop sequences in the proximal stem-loop structure of the RLP (stem-loop structure III; nucleotides 127 to 165) abolished internal translation. However, deletion of the second stem-loop in the RLP (stem-loop structure IV; nucleotides 189 to 223) reduced internal translation by only 50%. Internal deletions encompassing nucleotides 240 to 300, 350 to 380, or 450 to 480, predicted to disrupt stem-loop structure V and possibly VI, also abrogated internal initiation. Small point mutations within a short polypyrimidine sequence, highly conserved among all picornaviruses, abolished translation. A conservation of distance between the conserved polypyrimidine tract and a downstream AUG could play an important role in the mechanism of internal initiation.

Animals↗

PubMed1991

In vitro mutational analysis of cis-acting RNA translational elements within the poliovirus type 2 5' untranslated region.

Initiation of translation on poliovirus RNA occurs by internal binding of ribosomes to a region within the 5' untranslated region (UTR) of the mRNA. This region has been previously roughly mapped between nucleotides 140 and 631 of the 5' UTR and termed the ribosome landing pad. To identify cis-acting elements in the 5' UTR of poliovirus type 2 (Lansing strain) RNA that confer cap-independent internal initiation, we determined the in vitro translational efficiencies of a series of deletion and point mutations within the 5' UTR of the mRNA. The results demonstrate that the 3' border of the core poliovirus ribosome landing pad is located between nucleotides 556 and 585, whereas a region extending between nucleotides 585 and 612 confers enhanced translation. We studied two cis-acting elements within this region of the 5' UTR: a pyrimidine stretch which is critical for translation and an AUG (number 7 from the 5' end) that is located approximately 20 nucleotides downstream from the pyrimidine stretch and augments translation. We also show that the stem-loop structure which contains this AUG is not required for translation.

Base Composition↗

PubMed1991

Ureteric sludge syndrome.

Four cases of a form of obstructive uropathy previously unreported in children are described. All presented with oligoanuria and either flank pain or fluid retention and had evidence of crystalline sludge in their lower ureters. Three cases had an underlying crystalluria.

Adolescent↗

PubMed1991

Effects of alpha-thalassemia and sickle polymerization tendency on the urine-concentrating defect of individuals with sickle cell trait.

A defect in urine concentrating ability occurs in individuals with sickle cell trait (HbAS). This may result from intracellular polymerization of sickle hemoglobin (HbS) in erythrocytes, leading to microvascular occlusion, in the vasa recta of the renal medulla. To test the hypothesis that the severity of the concentrating defect is related to the percentage of sickle hemoglobin present in erythrocytes, urinary concentrating ability was examined after overnight water deprivation, and intranasal desmopressin acetate (dDAVP) in 27 individuals with HbAS. The HbAS individuals were separated into those who had a normal alpha-globin genotype (alpha alpha/alpha alpha), and those who were either heterozygous (-alpha/alpha alpha) or homozygous (-alpha/-alpha) for gene-deletion alpha-thalassemia, because alpha-thalassemia modulates the HbS concentration in HbAS. The urinary concentrating ability was less in the alpha alpha/alpha alpha genotype than in the -alpha/alpha alpha or -alpha/-alpha genotypes (P less than 0.05). After dDAVP, the urine osmolality was greater in patients with the -alpha/-alpha genotype than with the -alpha/alpha alpha genotype (882 +/- 37 vs. 672 +/- 38 mOsm/kg H2O) (P less than 0.05); patients with the -alpha/alpha alpha genotype had greater concentrating ability than individuals with a normal alpha-globin gene arrangement. There was an inverse linear correlation between urinary osmolality after dDAVP and the percentage HbS in all patients studied (r = -0.654; P less than 0.05). A linear correlation also existed for urine concentrating ability and the calculated polymerization tendencies for an oxygen saturation of 0.4 and O (r = -0.62 and 0.69, respectively). We conclude that the severity of hyposthenuria in HbAS is heterogeneous. It is determined by the amount of HbS polymer, that in turn is dependent upon the percentage HbS, which is itself related to the alpha-globin genotype.

Adult↗

PubMed1990

Expression of epidermal growth factor receptor in breast carcinoma.

A series of 90 patients with primary operable breast cancer and with up to 36 months of follow up were investigated for expression of epidermal growth factor receptor (EGFR) in their tumours by immunocytochemical staining with the monoclonal antibody EGFR 1. Tumour samples were snap frozen in liquid nitrogen immediately after resection and subsequently stained using a standard indirect immunocytochemical method. Tumour staining was assessed by two observers and scored on a four point scale (0-3). Thirteen (14%) tumours showed positive immunoreactivity. A strong correlation between distinct EGFR expression and short disease free interval was observed. Significant correlations were also shown with oestrogen and progesterone receptor expression and tumour nuclear size. No significant association was found with tumour size, lymph node stage, and histological grade. The association with disease free interval remained significant in multivariate analysis.

Antibodies, Monoclonal↗

PubMed1989

Human and rat malignant-tumor-associated mRNAs encode stromelysin-like metalloproteinases.

Rat transin and human stromelysin 2 mRNAs, which have been associated with malignant tumors, code for potential proteins with significant sequence homology to the metalloproteinases collagenase and stromelysin. We have used an expression system that allows easy purification of these proteins after transfection of COS cells with a vector containing the corresponding cDNA. This system has allowed us to prepare transin and stromelysin 2 as active proteinases that are inhibited by inhibitors of metalloproteinases. Further analysis of these enzymes indicates that they degrade several components of the extracellular matrix including collagen types III, IV, and V and fibronectin, as well as gelatins formed from several denatured collagen types. In addition, both transin and stromelysin 2 are capable of activating procollagenase in vitro. Thus, in malignant tumors these proteinases may act, both directly and indirectly, to degrade the extracellular matrix and permit tumor invasion of neighboring tissues.

Animals↗

PubMed1988

Structure-function relationships in the collagenase family member transin.

We have developed a system for studying the proteinase activity of a collagenase family member, transin. Cos cells transfected with a vector designed to direct synthesis of a secretable fusion protein between staphylococcal protein A and transin secrete a latent proteinase, activable by 4-aminophenylmercuric acetate, which binds to IgG-Sepharose. Treatment with 4-aminophenylmercuric acetate leads to cleavage of the fusion protein and elution of the active proteinase transin. Based on results obtained with this system we propose that transin comprises an N-terminal proteinase domain and an independent C-terminal hemopexin-like domain. The latter domain is not required for binding of inhibitors or for maintenance of transin in its inactive form. The sequence PRCGVPDV is present in the proenzyme forms of collagenase family proteinases just upstream from the N termini of the active enzymes. We show that mutations within this sequence lead to transin variants with a much increased tendency to undergo spontaneous activation. Finally, we show that mutations within a region of transin having sequence similarity to the zinc-binding site of bacterial metalloproteinases inactivate the proteinase activity of transin, lending support to the notion that this region represents part of transin's active site.

Amino Acid Sequence↗

PubMed1988

cis-acting translational effects of the 5' noncoding region of c-myc mRNA.

We have previously shown that the 5' noncoding region of mouse c-myc mRNA has a negative effect on translational efficiency in a rabbit reticulocyte lysate (A. Darveau, J. Pelletier, and N. Sonenberg, Proc. Natl. Acad. Sci. USA 82:2315-2319, 1985). We wanted to localize and characterize the inhibitory translational element(s) in the mRNA and to study its effect in other in vitro and in vivo systems. Here we report that the restrictive element is confined to a 240-nucleotide sequence of the 5' noncoding region of mouse c-myc mRNA and that this sequence acts in cis to inhibit the translation of a heterologous mRNA. In addition, we report that the cis-inhibitory effect is also exhibited in microinjected Xenopus oocytes and wheat-germ extracts but not in HeLa cell extracts. Transfection of corresponding plasmid DNA constructs into several established cell lines did not produce the cis-inhibitory effect. A model to explain these results is presented.

Animals↗