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Biomedical subjects

J Stewart

Publications and source records attributed to J Stewart.

At least 343 records · Page 19Linked to original sources
PubMed1991

Subareolar dissection for duct ectasia and periareolar sepsis.

Excision of the major duct system of the breast for symptoms owing to mammary duct ectasia may be curative, but recent reports have been less optimistic. A retrospective study (1978-1990) of 46 women (median age 38 years, range 18-78 years) who underwent subareolar dissection with antibiotic cover for symptoms associated with duct ectasia is presented. Thirty-three women presented without symptoms of overt sepsis (periareolar lump, nipple discharge or nipple retraction). Following subareolar dissection, six developed recurrent symptoms and five required further surgery. Thirteen women presented initially with abscesses. Eight abscesses recurred following incision and drainage, and one developed a mammillary fistula. Following subareolar dissection, six developed recurrent sepsis requiring further surgery.

Abscess↗
PubMed1991

Evaluation of accuracy of the wash impression technique to rebase and replace the resilient part of a soft-lined denture.

The dimensional inaccuracies that might be introduced during a wash impression technique within a heat-cured acrylic resin tray lined with a silicone resilient denture base material were investigated with the use of an electronic digitizer. Casts were poured from impressions of a machined metal die using a light- and heavy-bodied addition silicone in the soft-lined tray and compared with casts poured from impressions made in a hard-based tray and with the master die itself. The dimensions of the casts poured from the heavy-bodied impression in the soft-lined trays were significantly different from those poured from impressions in the hard-based tray when compared with the metal die. Those produced from the light-bodied material showed no statistically significant dimensional difference.

Acrylic Resins↗
PubMed1991

Correlation of M-bcr breakpoint with different chromosomal abnormalities in blast crisis Ph1-positive CML.

The molecular genetics of the Philadelphia (Ph1) chromosome, arising from a reciprocal translocation between chromosomes 9 and 22 and involving the genes abl and bcr, has been well characterized. However, the Ph1 chromosome is usually the sole cytogenetic abnormality during the chronic phase of the disease with additional karyotypic abnormalities arising prior to, or during the onset of the blast or acute phase. We have shown that patients with a breakpoint within the 5' region of the M-bcr of the bcr gene have a different sub-set of chromosomal bands involved in the cytogenetic abnormalities observed during the development of blast crisis than those patients with a 3' breakpoint. This suggests that different mechanisms of progression to blast crisis may be implicated for the subgroups groups of patients.

Blast Crisis↗
PubMed1991

Serological response to measles revaccination in a highly immunized military dependent adolescent population.

In the spring of 1986, there was a measles outbreak in the city of El Paso, Texas, with 92 cases reported to the City-County Health Department. Of those 92 cases, 31 (32%) occurred within a public high school's student population of 2524. A mass measles vaccination program was undertaken at that high school in order to limit the outbreak. The student enrollment included a military dependent population of 368 students. Despite documented histories of prior measles immunizations in this military dependent subgroup, three individuals contracted the disease. Since this subgroup of students represented a highly immunized adolescent population, it was of interest to serologically determine their immune status prior to and following reimmunization with the expectation that such a study would provide information relating to the level of "protective" immunity. Prevaccination and postvaccination sera were obtained from 95 students. Results of measuring anti-measles antibody activity by ELISA indicate that 13 (14%) students responded to revaccination and experienced a fourfold or greater rise in IgG antibody levels. There were no detectable IgM responses. All of the students who responded to revaccination produced an anamnestic response (IgG boost only). Since most of these individuals had received first immunizations at 15 months of age or older, these findings suggest that secondary vaccine failure (waning immunity) was responsible for the putative "lowered" immunity in these individuals, instead of primary vaccine failure (maternal antibody suppression). These findings support current recommendations for measles booster revaccination of school-age children and adolescents.

Adolescent↗
PubMed1991

Exacerbation of fibrous dysplasia associated with an adolescent pregnancy.

Fibrous dysplasia is a metabolic skeletal disorder in which the medullary spaces of affected bones are replaced by fibro-osseous tissue. Patients with fibrous dysplasia usually become symptomatic during childhood; the adolescent patient we describe is unusual because she was not known to suffer from fibrous dysplasia until she became pregnant and experienced a dramatic reactivation of the symptoms. The therapeutic implication of this case and reproductive counselling for young women with fibrous dysplasia are discussed.

Adolescent↗
PubMed1991

p53 in colorectal cancer: clinicopathological correlation and prognostic significance.

p53 protein was detected by immunohistochemistry in 42% of 52 colorectal adenocarcinomas. Positive tumours were significantly more frequent in the distal colon, and demonstrated a higher rate of cell proliferation. No correlation was found with tumour grade, Dukes' stage, presence of DNA aneuploidy or patient survival. The role of p53 in colorectal carcinogenesis is discussed with particular reference to differences between proximal and distal large bowel cancers.

Colorectal Neoplasms↗
PubMed1991

A community outbreak of epidemic keratoconjunctivitis in central Australia due to adenovirus type 8.

A large outbreak of epidemic keratoconjunctivitis occurred in Alice Springs, Australia, between July and September 1989. Initially, there was a large outbreak within two child care centers, followed by a more prolonged outbreak within the community. A simultaneous outbreak occurred among staff at the local hospital. Infected children developed mild conjunctivitis, whereas adults developed typical keratoconjunctivitis. Conjunctival swabs from 30 cases were cultured and adenovirus was recovered from 18, all of which were typed by neutralization assay as adenovirus type 8. DNA restriction fragment analysis of the genomes of 5 isolates revealed they were identical, distinct from prototype adenovirus type 8, and nearly identical to adenovirus genome type 8C (Ad-8C), which was previously reported in the southern United States in the early 1970s. Ad-8C was present in another region of Australia greater than or equal to 1 year before the epidemic.

Adenovirus Infections, Human↗
PubMed1991

Capture PCR: efficient amplification of DNA fragments adjacent to a known sequence in human and YAC DNA.

We have devised a procedure, termed capture PCR (CPCR), that permits the rapid isolation of DNA segments situated adjacent to a characterized nucleotide sequence. In this procedure, a DNA sample is restriction-digested and a linker, comprising two base-paired oligonucleotides, is added to the ends by ligation. Multiple extension reactions are performed using a biotinylated primer derived from the known sequence, permitting the subsequent isolation of extension products on a streptavidin-coated support. The enriched fragments are amplified exponentially using another specific oligonucleotide, hybridizing 3' to the biotinylated primer in combination with one of the linker oligonucleotides, now functioning as a PCR primer. The convenience of CPCR is greatly enhanced by using a novel streptavidin-coated manifold, which is constructed so that it projects into each individual well of a microtiter plate. The procedure permits the simultaneous isolation of fragments from large numbers of DNA samples and minimizes the risk of contamination between reactions. We have applied this method to identify DNA sequences located downstream of known sequences in the human genome. The technique has also been used to identify end fragments of sequences cloned in a yeast artificial chromosome (YAC) vector. The reactions can be initiated directly from yeast colonies and provide access to DNA sequence information for these end fragments in a minimal number of steps. With the aid of the present technique, we have isolated over 100 end fragments from YACs derived from the human X chromosome. Isolated end sequences have been used to order YAC clones into a contig.

Base Sequence↗
PubMed1991

A longitudinal study of New Zealand children's experience with alcohol.

A longitudinal study assessed the use of alcohol and related measures among New Zealand children aged 9, 11, 13 and 15 years. The proportion of children who were abstainers was at a similar level to the adult population by age 15 years. Those remaining abstainers were more likely to have infrequently drinking parents and to have been warned of the bad effects of alcohol by their parents. In terms of amount consumed and frequency of drinking, there was an increase with age and a marked increase between the ages of 13 and 15 years. Frequency of drinking was positively associated with the frequency of drinking by the mother and father. Girls drank less than boys until the age of 15 years, when they drank slightly more and a difference in terms of socio-economic status (SES) emerged at age 15 years with lower SES groups drinking more.

Alcohol Drinking↗
PubMed1991

Enlisting the eccentric photoscreener in a public hospital eye department.

We analysed retrospectively non-acute new referrals of children to Waikato Hospital over one year. It was found that children were required to wait unacceptably long to be seen. Almost half the children with established amblyopia were not seen until after the age of five years (42% were not referred until after that age). On the other hand, half the children seen had no significant pathology, and the high level of non-attendance also wasted clinic time. An attempt was made to address these problems by holding regular screening clinics using a photoscreener, assessing all children within three weeks of referral so that children with pathology could be examined and treated promptly. Preliminary investigations into mass community photoscreening produced an average recall rate of 11% (54% of whom fell into our definition of pathological). We feel that enlisting the photoscreener has provided a much more efficient paediatric service, which it is hoped will lead to a reduction in visual loss due to amblyopia.

Adolescent↗
PubMed1991

Alterations in monocyte receptor function in type 1 diabetic patients with ketoacidosis.

The level of expression of three monocyte cell surface receptors was studied in seven patients with Type 1 (insulin-dependent) diabetes admitted to hospital with ketoacidosis. After recovery of metabolic control the monocyte carbohydrate-binding ('lectin-like') receptors that recognize bacterial cell wall sugars and receptors for complement components were reduced in the patients compared with normal control subjects. This was in contrast to the expression of the receptor for the Fc portion of immunoglobulin which remained unaltered. Compared with the control subjects the level of 'lectin-like' receptors was reduced by 22.8 +/- 6.5% (p less than 0.05) on admission to hospital and 12.1 +/- 1.7% (p less than 0.001) 6 weeks later when metabolic control had been established. The expression of complement receptors was 33.8 +/- 8.1% (p less than 0.01) lower than normal subjects when the diabetic patients suffered from ketoacidosis and 8.6 +/- 1.6% (p less than 0.01) lower than control subjects when patients had recovered metabolic control. The increased susceptibility to infection seen in diabetic patients, and the high incidence of infection in patients with ketoacidosis, may be partially the result of these changes in monocyte recognition mechanisms.

Adult↗
PubMed1991

T cell receptor expression in Sjögren's syndrome.

T lymphocytes expressing the gamma/delta T cell receptor and B lymphocytes expressing CD5 are known to occur in expanded numbers in the peripheral blood of patients with primary Sjögren's syndrome. The cellular infiltrates for the surface phenotypic markers for alpha/beta and gamma/delta T cell receptors, CD4, CD8, CD45, and CD5 were examined in lip biopsy specimens from two patients with primary Sjögren's syndrome, six with secondary Sjögren's syndrome, and seven healthy controls. Most of the Sjögren's lip biopsy cellular infiltrates were T lymphocytes of the CD4 subset expressing the alpha/beta T cell receptor (mean 70%). The low prevalence of gamma/delta T cell receptor bearing cells in lip biopsy specimens is maintained in Sjögren's syndrome (mean 1.5%), and thus it seems unlikely that these lymphocytes bearing the gamma/delta T cell receptor have a major role in the immunopathology of Sjögren's syndrome. Over 70% of cells within the lesional infiltrate of primary and secondary Sjögren's syndrome expressed the CD5 and CD45 cell surface molecules.

Antigens, CD↗
PubMed1991

Severe congenital neutropenia: clinical effects and neutrophil function during treatment with granulocyte colony-stimulating factor.

We studied neutrophil function and clinical responses in seven patients with severe congenital neutropenia (SCN) after they received treatment with recombinant human granulocyte colony stimulating factor (rhG-CSF). Two subpopulations of patients with SCN were defined by their pattern of absolute neutrophil response, superoxide production, and cytochrome b559 levels. One group had an oscillating absolute neutrophil count and reduced ability to produce superoxide and cytochrome b559 (n = 4), and the second group had a relatively constant absolute neutrophil count response with normal superoxide and cytochrome levels (n = 3). Neutrophils from both groups had decreased surface expression of FcRIII and abnormal upregulation of the C3bi receptor (CR3). All patient neutrophils, however, had normal contents of the primary granule constituent, beta-glucuronidase, and the specific granule constituent, vitamin B 12 binding protein. The clinical response to rhG-CSF was evident by marked improvement in the degree of periodontitis and reduction in the number of oral ulcers in both groups of patients. Although neutrophil function is not completely normal in patients with SCN, it is likely that enough redundancy exists in neutrophil bactericidal capacity to promote normal host response to inflammation.

CD18 Antigens↗
PubMed1990

Chronic systemic administration of amphetamine increases food intake to morphine, but not to U50-488H, microinjected into the ventral tegmental area in rats.

Chronic intermittent administration of amphetamine (AMPH) sensitizes rats to the stimulatory effects on feeding produced by systemic injections of either morphine (MORPH) or the kappa-opiate receptor agonist, U50,488H (U50). Both morphine and the putative kappa-receptor endogenous ligand, dynorphin, have been reported to stimulate feeding when administered into the ventral tegmental area (VTA). To evaluate whether the VTA is the site where AMPH produces sensitization to the feeding effects of opiates, rats were given daily IP injections of either saline or AMPH (3 mg/kg). The amount of powdered food ingested during the 5 h following the injections was measured. After 9 days of AMPH or saline administration, twice weekly tests were begun of the effects of either saline, MORPH (1-10 nmol) or U50 (10 pmol to 10 nmol) injected into the VTA; AMPH administration was continued on intervening days. MORPH produced a statistically significant greater increase in food intake in rats chronically treated with AMPH than in saline treated rats. No statistically significant effects were produced by U50. However, when U50 was administered systemically to the same animals, food intake increased, and the effect was significantly greater in the AMPH-pretreated group. Thus the sensitization to the feeding effects of MORPH and U50 produced by chronic AMPH administration appears to involve different systems; the mesolimbic dopamine system appears to mediate sensitization to the effects of the predominately mu-receptor agonist, MORPH, but not of the kappa-receptor agonist, U50.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1990

Transcription pausing by Escherichia coli RNA polymerase is modulated by downstream DNA sequences.

Escherichia coli RNA polymerase pauses immediately after transcription of certain sequences that can form stable secondary structures in the nascent RNA transcript; pausing appears to be essential for several types of bacterial transcription attenuation mechanisms. Because base changes that weaken the RNA secondary structures reduce the half-life of pausing by RNA polymerase, nascent transcript RNA hairpins are thought to cause pausing at these sites. We show here that, for the well characterized trpL pause site, the determinants of transcription pausing are not limited to the RNA hairpin, but include the not-yet-transcribed sequence of DNA immediately downstream from the pause site. We show that this effect extends to bases up to fourteen nucleotides downstream from the pause site, that placement of a oligo(dT) tract in the nontranscribed strand in this region does not convert the pause site to a termination site, and that shifting the position of pausing by one nucleotide downstream almost eliminates pausing. From an analysis of many variants of this downstream sequence, we argue that the effect of downstream sequence is not related simply to its GC content. We suggest that these effects are mediated by altered interactions between RNA polymerase and the DNA template downstream from the enzyme's active site.

Base Sequence↗
PubMed1990

Amphetamine administered to the ventral tegmental area but not to the nucleus accumbens sensitizes rats to systemic morphine: lack of conditioned effects.

Different groups of rats received conditioning training with bilateral injections of amphetamine (2.5 micrograms/0.5 microliters/side) either into the ventral tegmental area (VTA) or the nucleus accumbens (NAC) and were tested on separate occasions for conditioned locomotor activity with saline and cross-sensitization to the locomotor activating effects of morphine (1.0 mg/kg, i.p.). Intra-VTA injections of amphetamine had no effect acutely but subsequently produced a sensitized locomotor response to morphine. On the other hand, intra-NAC amphetamine produced increased locomotion but with no evidence of sensitization either during training or on the test with morphine. No evidence for conditioning of the locomotor activating effects of amphetamine or for stimulus control of the expression of the sensitized response to morphine was obtained with either the intra-VTA or the intra-NAC injections. These results confirm earlier findings indicating that the site of action of amphetamine critical for the development of behavioral sensitization is the VTA and not the NAC and extend them to the case of cross-sensitization to morphine. They also demonstrate that behavioral sensitization can be obtained in the absence of conditioned effects and, therefore, that the two phenomena are distinct. Implications of the present findings for an understanding of the mode and site of action of amphetamine in the development of conditioned locomotor activity are discussed.

Amphetamines↗
PubMed1990

Dynamics of a class of immune networks. I. Global stability of idiotype interactions.

This paper establishes the conditions under which a class of differential equations which appear in the study of immune systems (Varela et al., 1988a, In: Theoretical Immunology Part II. New Jersey: Addison Wesley), are globally stable. This is proved by adapting a Liapunov functional originally proposed by Cohen & Grossberg (1983, IEEE Transac SMC 13, 815-826) for competitive systems. The global stability thus obtained is valid on the fast time scale where only idiotypic interactions are relevant, thus excluding both lymphocyte proliferation processes and repertoire change via recruitment from immature bone marrow B cells.

Animals↗