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Biomedical subjects

R Scott

Publications and source records attributed to R Scott.

At least 19 recordsLinked to original sources
PubMed1992

Hereditary conditions in which the loss of heterozygosity may be important.

Somatic mutations are a common event in multicellular organisms and, therefore, have a significant impact on health. They can lead to either heterozygosity or homozygosity. Since the multistep concept of carcinogenesis presupposes that mutations/deletions of several genes are acquired, the identification and location of the critical genes involved in this sequence is attempted either by the observation of cytogenetic or molecular abnormalities in tumorous tissue or by linkage analysis, or both. The retinoblastoma paradigm of loss of heterozygosity with respect to the loss of the only wild-type allele can be applied to familial neoplasias occurring in all organs as they are summarized in this review. The development of homozygosity in non-malignant tissue has not been extensively investigated. However, its study has contributed to the identification of new genetic phenomena such as parental unidisomy and genomic imprinting.

Genetic Diseases, Inborn↗
PubMed1992

Characterisation of a wound-induced transcript from the monocot asparagus that shares similarity with a class of intracellular pathogenesis-related (PR) proteins.

We report the isolation and characterisation of a wound-induced cDNA designated AoPR1 from a suspension of mesophyll cells that had been mechanically isolated from cladodes of light-grown Asparagus officinalis seedlings by grinding in a mortar and pestle. The transcript abundance is up-regulated following cell separation and in chopped mesocotyl tissue from dark-grown seedlings. The expression of AoPR1 was shown by northern analysis to be located around the site of damage. Sequence analysis revealed similarity between the predicted AoPR1 polypeptide and bean PvPR1 and PvPR2 proteins, the potato pSTH2 protein, the pea PI49 protein, the parsley PcPR1-1 protein and a major pollen allergen from birch (BetvI). These transcripts have been shown to be induced in response to microbial attack or fungal elicitation. To our knowledge, this is the first example of a monocot cDNA belonging to this class of intracellular pathogenesis-related proteins (IPRs).

Amino Acid Sequence↗
PubMed1992

The isolation and characterisation of the tapetum-specific Arabidopsis thaliana A9 gene.

The Brassica napus cDNA clone A9 and the corresponding Arabidopsis thaliana gene have been sequenced. The B. napus cDNA and the A. thaliana gene encode proteins that are 73% identical and are predicted to be 10.3 kDa and 11.6 kDa in size respectively. Fusions of an RNase gene and the reporter gene beta-glucuronidase to the A. thaliana A9 promoter demonstrated that in tobacco the A9 promoter is active solely in tapetal cells. Promoter activity is first detectable in anthers prior to sporogenous cell meiosis and ceases during microspore premitotic interphase. The deduced A9 protein sequence has a pattern of cysteine residues that is present in a superfamily of seed plant proteins which contains seed storage proteins and several protease and alpha-amylase inhibitors.

Amino Acid Sequence↗
PubMed1992

Quantitative evaluation of the growth of established cell lines on the surface of collagen, collagen composite and reconstituted basement membrane.

As a step in the development of a system for assessing growth of human urothelium and transitional cell carcinoma, the growth of two established cell lines on collagen-based membranes has been evaluated. HT1080 (metastatic human fibrosarcoma) and WI38 VA13 (virus-transformed human fibroblasts) were grown on substrates of collagen, collagen/hyaluronic acid or chondroitin sulphate and reconstituted basement membrane (Matrigel). Cell growth was quantified using a new fluorimetric assay utilizing carboxyfluorescein diacetate. There were differences in morphology between cells grown on collagen and those grown on polystyrene. There were, however, no differences in growth of the WI38 VA13 cells on collagen compared with polystyrene, but growth of the HT1080 cells was increased on membranes of collagen/2.5% hyaluronic acid and collagen/5% chondroitin sulphate, and decreased on Matrigel. Adequate growth on collagen substrates is dependent on cell line. The fluorimetric assay used was suitable for quantifying cell growth on such substrates.

Basement Membrane↗
PubMed1992

Collagen vicryl--a new dural prosthesis.

No ideal dural grafting material is currently available. Many materials have been evaluated in this role, and for many neurosurgeons cadaveric human lyophilized dura has been popular. Recently this material has been putatively associated with Creutzfeldt-Jakob disease. In this study we compared three degradable materials, collagen vicryl (Bovine collagen coated vicryl mesh), Zenoderm (Porcine dermis) and Lyodura (Lyophilized human cadaveric dura) as dural substitutes. In an experimental model using the New Zealand White Rabbit the materials were implanted into dural defects of dimensions 1.7 cm by 1 cm. In the control group the dura was not repaired. In total 47 animals were used and sacrificed at time intervals of 2, 4, 8, 12, and 24 weeks. On gross examination the collagen vicryl produced few adhesions to the cerebral cortex and was replaced by a neomembrane which showed good union with the host dura. In the control group no new layer was formed and there were severe cortical adhesions. Zenoderm and Lyodura remained undegraded and produced more adherence to the cerebral cortex than the collagen vicryl implant. The histological examination showed collagen vicryl to support ingrowth of fibroblasts and the production of a new collagen layer which by 3 months resembled the original host dura. The inflammatory response to the implant did not persist after 3 months. The other substitutes were revitalized by host cells but remained undegraded at 6 months with ingrowth of woven bone and persistence of inflammatory and foreign body response. The results show collagen vicryl to be a suitable dural substitute with potential advantages over other currently used degradable materials, and should be evaluated more fully, both in laboratory studies and clinically.

Animals↗
PubMed1992

Cognitive profiles of Japanese and Canadian kindergarten and first-grade children.

Japanese kindergarten and first-grade children were given the Canadian Cognitive Abilities Test (CCAT), with slight cultural modifications. Widely used in Canadian and American schools, the CCAT consists of three batteries: verbal, quantitative, and nonverbal. The sample consisted of 454 Japanese children (234 boys, 220 girls). Results were examined by 3-month age intervals (chronological age range, 60 to 87 months of age). Subjects' scores were compared with CCAT norms, based on the performance of 3,500 Canadian children at each age level. On each battery, the Japanese children outperformed their Canadian counterparts, but the differential was most apparent on the verbal battery. Moreover, on the nonverbal battery for kindergarten Japanese children (ages 60 to 72 months), significant differences appeared only with the 60- to 63-month age cohort. Results indicate that the higher achievement of Japanese children was apparent by the time they entered kindergarten and that higher Japanese educational productivity could not be solely attributed to schooling effects. Furthermore, the data indicate that the early academic advantage of Japanese children may widen as they progress through their first year of school. (Longitudinal replication studies are suggested for examination of the long-range impact of the early cognitive advantage of Japanese children.)

Achievement↗
PubMed1992

Crystalline lens power in myopia.

Growth of the eye shows a coordinated pattern whereby the reduction in refractive power of the cornea and crystalline lens tends to reduce the myopia that would otherwise result from the normal increase in axial length. There is some controversy as to whether the reduction in crystalline lens power is influenced by the refractive state of the eye, i.e., an active role in the emmetropization process, or is simply related to the changing lens dimension occurring with growth. We measured ocular dimensions and determined the crystalline lens powers in 19 myopes and 19 emmetropic subjects matched for age, gender, and ethnic origin. No significant difference was found in corneal radius of curvature for the two groups, but there was a significant difference (p < 0.05) in crystalline lens power of 2.30 D. These results suggest that greater compensation for axial elongation of the eye was afforded by the decrease in crystalline lens power than by corneal flattening.

Adolescent↗
PubMed1992

Premature dissolution of the microsporocyte callose wall causes male sterility in transgenic tobacco.

Male sterility in a petunia cytoplasmic male sterile line has been attributed to the early appearance of active callase, a beta-1,3-glucanase, in the anther locule. This leads to premature dissolution of the callose walls surrounding the microsporogenous cells. We have mimicked this aspect of the petunia line in transgenic tobacco by engineering the secretion of a modified pathogenesis-related vacuolar beta-1,3-glucanase from the tapetum prior to the appearance of callase activity in the locule. Plants expressing the modified glucanase from tapetum-specific promoters exhibited reduced male fertility, ranging from complete to partial male sterility. Callose appearance and distribution are normal in the male sterile transgenic plants up to prophase I, whereupon callose is prematurely degraded. Meiosis and cell division occur normally. The resultant microspores have an abnormally thin cell wall that lacks sculpturing. The tapetum shows hypertrophy. Male sterility is probably caused by bursting of the aberrant microspores at a time corresponding to microspore release. These results demonstrate that premature callose degradation is sufficient to cause male sterility and suggest that callose is essential for the formation of a normal microspore cell wall.

Base Sequence↗
PubMed1992

Comparison of three methods of evaluating glare.

A Humphrey Automatic Refractor Model 570 was used to measure the impairment of visual acuity for low contrast optotypes as a result of glare for normal subjects and for subjects with cataracts. This was compared with a direct measure of intraocular light scatter as measured by a compensating technique and with a subjective assessment of glare determined by a questionnaire. Only a weak correlation (r = 0.28) was found between the decrease in low contrast letter acuity and intraocular light scatter. The subjective assessment of glare sensitivity was not correlated with the decrease in low contrast letter acuity, but correlated to some extent (r = 0.55) with the measurement of intraocular light scatter.

Adult↗
PubMed1992

Academic learning problems and Rorschach indices: a Spanish replication.

This study compared the Rorschach responses of Spanish children who were and who were not judged by their teachers to be experiencing significant reading problems. With controls exacted on gender, social class, chronological age, and IQ, the responses of 15 pairs of subjects were examined; group differences in perceptual accuracy, self-concept, and reactivity were assessed. Consistent with American studies involving profiles of learning disabled and nonlearning disabled subjects, despite some differences being small, responses of children with reading problems were characterized by lower perceptual accuracy and lower self-concept; inconsistent findings appeared on measures of reactivity. Empirical problems in conducting cross-cultural investigations with the Rorschach are discussed.

Achievement↗
PubMed1992

Expression of Helenium virus S coat protein in Escherichia coli, in vitro in rabbit reticulocyte lysate and transgenic tobacco.

The coat protein open reading frame (ORF) sequence of Helenium virus S (HelVS) was cloned and expressed in E. coli, rabbit reticulocyte and transgenic tobacco. In E. coli the size of the protein was identical to that obtained for the coat protein from purified virus particles and less than that predicted for the fusion protein. This may be due to ribosome binding at a potential ribosome binding site present on the viral sequence, approximately 45 nucleotides upstream from the initiating methionine of the coat protein ORF. This region of HelVS, equivalent to the 1.5 kb subgenomic RNA, also produced high levels of protein when transcribed and translated in vitro. When introduced into Nicotiana tabacum by leaf disk transformation via Agrobacterium tumefaciens, high levels of stable coat protein were detected which were identical in molecular weight to that of HelVS coat protein and constituted approximately 0.1-0.5% of the total extracted protein.

Animals↗
PubMed1992

[Tumor diseases in families of 600 breast cancer patients with special reference to familial adenocarcinomatosis and the Li-Fraumeni-/SBLA syndrome].

In some families breast cancer aggregates as the predominant site-specific neoplasia and in others in association with defined malignancies. In the case of familial adenocarcinomatous (Lynch II-syndrome) it occurs together mainly with colorectal and endometrial carcinoma whereas in the case of the Li-Fraumeni/SBLA-syndrome it belongs to a wider spectrum including sarcoma, brain tumors, lung and laryngeal cancer, leukaemia and adrenocortical carcinoma. The occurrence of these malignancies is reported as they were observed in the families of 600 women suffering from breast cancer.

Adenocarcinoma↗
PubMed1992

Ultrasound evaluation of the common duct in symptomatic and asymptomatic patients.

We studied common duct (CD) diameter using real time ultrasound in 551 patients. The patients were divided into two groups: those referred for evaluation of the biliary tree [biliary-referred group (BRG)], and those referred for a problem unrelated to potential biliary tree pathology [non-biliary-referred group (NBRG)]. Potentially obstructed CDs were excluded from analysis. The CD diameter in the NBRG patients was found to increase after cholecystectomy (p less than 0.0003), but not in patients in this group with intact gallbladders and cholelithiasis. Dilation was observed in the BRG patients with either cholelithiasis (p less than 6 x 10(-7)) or cholecystectomy (p less than 4 x 10(-10)) compared to patients with intact gallbladders without cholelithiasis. To our knowledge, the former phenomenon has not been described in the literature. Our NBRG data suggest that the normal CD diameter should be set at 5 mm and 8 mm, respectively, for patients with intact gallbladders and patients post-cholecystectomy. No correlation was found between duct size and sex, age, or weight.

Adolescent↗