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Biomedical subjects

S Roberts

Publications and source records attributed to S Roberts.

At least 145 records · Page 8Linked to original sources
PubMed1997

Matrix metalloproteinases in the human intervertebral disc: role in disc degeneration and scoliosis.

STUDY DESIGN: Biochemical study of human intervertebral discs collected at surgery from patients with low back pain associated with disc degeneration or scoliosis. Matrix metalloproteinases were studied by quantitative zymography. OBJECTIVE: To determine whether changes in the expression of matrix metalloproteinases will bring about tissue remodelling that contributes to the progressive nature and pathology of these diseases of the intervertebral disc. SUMMARY OF BACKGROUND DATA: The diseases of the intervertebral disc, degenerative disc disease and scoliosis, are both characterized by changes in the extracellular matrix components that will affect the mechanical function of the tissue. Matrix metalloproteinases are known to have the capability of degrading all the known extracellular matrix components of the disc. METHODS: Matrix metalloproteinases 2 and 9 were detected by gelatin-gel zymography and quantified by laser scanning densitometry. Both pro and active forms of the enzymes were measured. Thirty-four discs from patients with low back pain and 29 from patients with scoliosis were investigated. RESULTS: A correlation was found between the increasing levels of matrix metalloproteinases 2 and 9 and the grade of degenerative disc disease. In addition, the levels of these enzymes show a differential expression across the scoliotic disc with the highest levels in samples taken from the convexity of the curve. CONCLUSIONS: The difference between the concave and convex side of the scoliotic curve indicates that mechanical loads might influence the expression of these enzymes. The increased expression of these enzymes in both degenerative disc disease and scoliosis strongly suggests that they may affect the progressive nature of these diseases.

Adolescent↗
PubMed1997

Uniqueness of the S-cone pedicle in the human retina and consequences for color processing.

The purpose of this study was to investigate more fully the shape and content of ribbons and synapses to second-order neurons in the short-wavelength cone (S-cone, blue cone) pedicle and to learn more concerning the uniqueness of the S-cone system in the primate retina. A piece of well-fixed peripheral human retina (10 mm, 35 degrees nasal to the fovea) was serially thick sectioned in the tangential plane from the level of the outer segments to the tops of the cone pedicles. Then serial electron microscope (EM) sections were collected through the whole depth of the pedicle-occupying region into the neuropil of the outer plexiform layer (OPL). The resultant EM micrograph montages of a large field of cone pedicles were perused, and S-cone pedicles were identified. Serial micrographs of a single S-cone pedicle, picked out of the montages, were digitized and reconstructed by computer three-dimensional methods. The S-cone pedicle arose from a slightly oblique axon and projected 0.5-1 microm more vitread in the OPL than other cone pedicles. It was bilobed in shape, with synaptic invaginations and ribbons in both lobes. No cone-contacting telodendria projected from the S-cone pedicle itself, but a small number of neighboring cones sent telodendria to its surface to make small gap junctions. Neighboring rod spherules also made small gap junctions. Four robust bipolar cell dendrites, most likely from S-cone-specific bipolar cells, made synapses at ribbons and basal (distal) junctions. A small number of other bipolar cell dendrites made narrow-cleft basal junction only. The majority of lateral elements were thought to be from HII horizontal cells, and a minority from HI horizontal cells. We conclude that the S-cone pedicle has a unique morphology and connectivity to second-order neurons that makes it quite different from the other two longer wavelength cone systems, and we speculate on the consequences for color processing in the visual system in general.

Adult↗
PubMed1997

The divergent 5' termini of the alpha human folate receptor (hFR) mRNAs originate from two tissue-specific promoters and alternative splicing: characterization of the alpha hFR gene structure.

The human KB cell or alpha folate receptor (alpha hFR) is a membrane glycoprotein of 42 kDa that participates in the internalization of folates and antifolates. Seven independent alpha hFR cDNA isoforms have been reported that contain unique 5' termini but share a common open reading frame (ORF). To investigate the molecular basis of these heterogeneous 5' sequences, we determined the sequence of the alpha hFR gene from two clones isolated from a human lymphocyte lambda DASH genomic library. The gene is composed of seven exons that span 6.8 kb. The ORF is encoded by exons 4 through 7 while the reported 5' termini of the cDNA isoforms (including two novel cDNAs designated KB2 and KB4) are encoded by exons 1 through 4. Using RNase protection assays, we demonstrate that transcripts corresponding to the KB1 and KB4 cDNAs originate from promoters upstream from exon 1 and exon 4, designated P1 and P4, respectively, and that these mRNA isoforms are the most abundant transcripts expressed in KB cells and selected normal tissues (including kidney, lung, and cerebellum). We observed a heterogeneous start site within exon 1 from the P1 promoter while transcripts from the P4 promoter originate from a single site. In addition, we detected tissue specificity for the P1 and P4 promoter utilization. Transcripts originating from the P1 promoter are the most abundant transcripts expressed by human cerebellum and kidney. In contrast, transcripts from the P4 promoter are the most abundant transcripts expressed by human KB cells and lung. Total RNA from KB cells also protects a 66 bp fragment of an exon 3 riboprobe that is consistent with an alternatively spliced transcript. To examine the functional activity of the predicted P1 and P4 promoters, alpha hFR promoter-CAT chimeric plasmids were constructed using sequences flanking exon 1 and exon 4. We observed a 7.5- and 10-fold increase in CAT activity in HeLa cells transiently transfected with the P1 and P4 promoter constructs, respectively. These data demonstrate that a single gene encodes the divergent 5' termini of the alpha hFR cDNAs and that the alpha hFR transcripts are transcribed from two promoters that are activated in a tissue-specific manner.

Alternative Splicing↗
PubMed1997

Does the thickness of the vertebral subchondral bone reflect the composition of the intervertebral disc?

Degeneration of the intervertebral disc, seen radiologically as loss of disc height, is often associated with apparent remodelling in the adjacent vertebral body. In contrast, maintenance or apparent increase in disc height is a common finding in osteoporosis, suggesting the properties of the intervertebral disc may be dependent on those of the vertebral body or vice versa. We have investigated this relationship by measuring the radiological thickness of the subchondral bone and comparing it to the chemical composition of the adjacent disc. Sagittal slabs were sampled from lumbar spines obtained at autopsy and X-rayed microfocally. The thickness of the subchondral bone was measured and correlated with the composition of the adjacent intervertebral disc. Eighty-three cadaveric endplates were studied from individuals aged 17-85 years. There was regional variation in thickness of the subchondral bone, being greater adjacent to the annulus than the nucleus, and the endplates cranial to the disc were thicker than those caudal. There was a positive correlation between the thickness of the subchondral bone and the proteoglycan content of the adjacent disc, particularly in the region of the nucleus. A weaker correlation was seen here between water content and thickness, whilst there was no significant correlation at the annulus or between the bone thickness and collagen content. The positive relationship between the radiographic thickness of vertebral subchondral bone and the proteoglycan content of the adjacent disc seen in human cadaveric material could be due to the bone responding to a greater hydrostatic pressure being exerted by discs with higher proteoglycan content than by those with less proteoglycan present. It is suggested that while this is true in "normal" specimens, the relationship becomes altered in disease states, possibly because of changes to the nutritional pathway of the disc, with resultant endplate-bone remodelling affecting the flow of solutes to and from the intervertebral disc.

Adolescent↗
PubMed1997

Acute pancreatitis complicating a bone marrow harvest.

A patient developing acute pancreatitis with pseudocyst formation after an uncomplicated bone marrow harvest is reported. The diagnosis was confirmed by elevated serum amylase and lipase, and by CT scan. We suggest that the pancreatitis may have been precipitated by spasm of the sphincter of Oddi secondary to opiates administered as premedication and for pain relief.

Abdominal Pain↗
PubMed1997

Transfusion- and community-acquired cytomegalovirus infection in children with malignant disease: a prospective study.

BACKGROUND: The use of cytomegalovirus (CMV)-"safe" blood has been recommended for CMV seronegative patients with newly diagnosed malignant disease for whom bone marrow transplantation is a future option. STUDY DESIGN AND METHODS: To evaluate this policy, 76 CMV-seronegative children with lymphoreticular malignancies or solid tumors were randomly assigned to receive either blood components that were not screened for CMV antibody or CMV-seronegative red cell (RBC) and platelet units. Subjects were followed for evidence of CMV infection by the use of enzyme-linked immunosorbent assays and virus isolation. Follow-up continued long after the blood transfusions to determine the risk of community-acquired CMV infection. RESULTS: No cases of transfusion-acquired CMV infection were documented. The prevalence of CMV IgG and IgM antibody in blood donors was 40.5 and 0.9 percent, respectively. Patients assigned to receive standard blood components and CMV-negative components were given a median (range) of 7 (1-30) and 9 (1-38) RBC units and 11 (0-123) and 14 (0-71) platelet units, respectively. The risk of transfusion-acquired CMV infection is estimated to be less than 1 in 698 donor exposures. Two patients developed asymptomatic community-acquired CMV infection, for an incidence of 1.7 percent per patient-year of follow-up. CONCLUSION: The risk of transfusion-acquired CMV infection in this population is low, largely because of the patients' low level of exposure to seropositive blood and the use of relatively white cell-reduced components for purposes other than CMV prevention. Such children at this center therefore continue to receive standard blood components. Strategies to prevent CMV seroconversion in these children should include parental education to minimize the risk of community-acquired infection.

Adolescent↗
PubMed1997

Improved perfusion with rt-PA and hirulog in a rabbit model of embolic stroke.

We conducted a study using diffusion-weighted (DWI) and perfusion-weighted (PWI) magnetic resonance imaging (MRI) to evaluate the efficacy of thrombolysis in an embolic stroke model with recombinant tissue plasminogen activator (rt-PA) and hirulog, a novel direct-acting antithrombin. DWI can identify areas of ischemia minutes from stroke onset, while PWI identifies regions of impaired blood flow. Right internal carotid arteries of 36 rabbits were embolized using aged heterologous thrombi. Baseline DWI and PWI scans were obtained to confirm successful embolization. Four animals with no observable DWI lesion on the initial scan were excluded; therefore, a total of 32 animals were randomized to one of three treatment groups: rt-PA (n = 11), rt-PA plus hirulog (n = 11), or placebo (n = 10). Treatment was begun 1 h after stroke induction. Intravenous doses were as follows: rt-PA, 5 mg/kg over 0.5 h with 20% of the total dose given as a bolus; hirulog, 1 mg/kg bolus followed by 5 mg/kg over 1 h. MRI was performed at 2, 3, and 5 h following embolization. Six hours after embolization, brains were harvested, examined for hemorrhage, then prepared for histologic analysis. The rt-PA decreased fibrinogen levels by 73%, and hirulog prolonged the aPTT to four times the control value. Posttreatment areas of diffusion abnormality and perfusion delay were expressed as a ratio of baseline values. Significantly improved perfusion was seen in the rt-PA plus hirulog group compared with placebo (normalized ratios of the perfusion delay areas were as follows: placebo, 1.58, 0.47-3.59; rt-PA, 1.12, 0.04-3.95; rt-PA and hirulog, 0.40, 0.02-1.08; p < 0.05). Comparison of diffusion abnormality ratios measured at 5 h showed trends favoring reduced lesion size in both groups given rt-PA (normalized ratios of diffusion abnormality areas were as follows: placebo, 3.69, 0.39-15.71; rt-PA, 2.57, 0.74-5.00; rt-PA and hirulog, 1.95, 0.33-6.80; p = 0.32). Significant cerebral hemorrhage was observed in one placebo, two rt-PA, and three rt-PA plus hirulog treated animals. One fatal systemic hemorrhage was observed in each of the rt-PA groups. We conclude that rt-PA plus hirulog improves cerebral perfusion but does not necessarily reduce cerebral injury. DWI and PWI are useful methods for monitoring thrombolysis.

Animals↗
PubMed1997

Mutational analysis of the human papillomavirus type 16 E1--E4 protein shows that the C terminus is dispensable for keratin cytoskeleton association but is involved in inducing disruption of the keratin filaments.

The function of the human papillomavirus (HPV) E4 proteins is unknown. In cultured epithelial cells the proteins associate with the keratin intermediate filaments (IFs) and, for some E4 types, e.g., HPV type 16 (HPV-16), induce collapse of the keratin networks. An N-terminal leucine-rich motif (LLXLL) is a conserved feature of many E4 proteins. In a previous study we showed that deletion of this region from the HPV-1 and -16 E4 proteins abrogated the localization of the mutant proteins to the keratin cytoskeleton in a simian virus 40-transformed human keratinocyte cell line (S. Roberts, I. Ashmole, L. J. Gibson, S. M. Rookes, G. J. Barton, and P. H. Gallimore, J. Virol. 68:6432-6445, 1994). The E4 proteins of HPV-1 and -16 have little sequence homology except at the N terminus. Therefore, to establish the role of sequences other than those at the N terminus, we have performed a mutational analysis of the HPV-16 E4 protein. The results of the analysis were as follows: (i) similar to findings for the HPV-1 protein, no mutation of HPV-16 E4 sequences (other than the N-terminal leucine motif) results in a mutant protein which fails to colocalize to the keratin IFs; (ii) the C-terminal domain (residues 61 to 92) is not essential for association with the cytoskeleton; and (iii) deletion of C-terminal sequences (residues 84 to 92; LTVIVTLHP) corresponding to part of a domain conserved between mucosal E4 proteins affects the ability of the mutant protein to induce cytoskeletal collapse, despite colocalization with the keratin IFs. Further analysis of this region showed that conserved hydrophobic residues valines 86 and 88 are important. In addition, we show that the HPV-16 E4 protein is detergent insoluble and exists as several disulfide-linked, high-molecular-weight complexes which could represent homo-oligomers. The C-terminal sequences (residues 84 to 92), in particular valines 86 and 88, are important in the formation of these insoluble complexes. The results of this study support our postulate that the E4 proteins include functional domains at the N terminus and the C terminus, with the intervening sequences possibly acting as a flexible hinge.

Amino Acid Sequence↗
PubMed1997

Adenovirus type 12 early region 1B 54K protein significantly extends the life span of normal mammalian cells in culture.

The life span of normal human cells in culture is extended by two to four total life spans following retrovirus-mediated transfer of the adenovirus type 12 E1B 54,000-molecular-weight protein (54K protein). This extension of the in vitro growth potential was accomplished without any of the obvious changes in morphology or growth properties that are usually associated with viral transformation. These 54K+ cells escape the normal senescence checkpoint (M1) and show a very extended secondary growth phase. The 54K+ human cells eventually enter crisis (M2), which does not appear to be due to either telomere attrition or the activation of the senescence-associated proteins p21SdilCipIWaf1 and p16INK4A. Even in the absence of telomerase activity, high-molecular-weight heterogeneous telomeres are produced and maintained in both 54K+ adult dermal fibroblasts and embryo kidney cells, indicating that the 54K protein may interfere with the normal metabolism of telomeric structures during cell division. These findings are discussed with reference to the known ability of the 54K protein to influence p53 function.

Adenovirus E1B Proteins↗
PubMed1997

Proteoglycan synthesis in the intervertebral disk nucleus: the role of extracellular osmolality.

Proteoglycans, through their polyelectrolyte properties, regulate the ionic composition and hence the osmotic pressure of the extracellular matrix. We measured the change in [35S]sulfate incorporation, a marker of proteoglycan synthesis, in explants of bovine nucleus pulposus. During incubation, nucleus slices swelled 200% and proteoglycans leached from the matrix, so that extracellular osmolality fell from 420-450 to approximately 300 mosmol/kg H2O. When in vivo extracellular osmolality was maintained either by adding 80 mM NaCl or 150 mM sucrose to the swollen tissue or by preventing swelling, synthesis rates were 260-280% greater than in swollen tissue. Synthesis rates also increased 200% in cells isolated from the nucleus pulposus by enzyme digestion when medium osmolality was raised from 280 to 430 mosmol/ kgH2O by sucrose addition. The cells, either in the tissue or isolated from it, swelled by more than 20% as osmolality fell from 430 to 280 mosmol/kgH2O and showed little regulatory volume decrease over 150 min. Synthesis rates thus appear to be regulated by extracellular osmolality rather than by the macromolecular composition of the matrix and correlated well with measured changes in cell volume.

Animals↗
PubMed1997

Molecular and functional heterogeneity of cholangiocytes from rat liver after bile duct ligation.

Cholangiocytes, the epithelial cells that line intrahepatic bile ducts, participate in bile secretion via basal and agonist-stimulated transport of solutes and water. On the basis of subtle structural differences between cholangiocytes lining small vs. large bile ducts, as well as known phenotypic variations among transporting epithelia in other organs, we demonstrated that cholangiocytes are functionally heterogeneous along the intrahepatic biliary tree of normal rats. In studies reported here, we confirm and extend the concept of functional heterogeneity of cholangiocytes by employing the bile duct-ligated (BDL) rat model of cholestasis associated with selective cholangiocyte proliferation. Using novel isolation and separatory techniques, we prepared subpopulations of pure small, medium, and large cholangiocytes from BDL rats and compared them with regard to gene expression and basal or agonist-responsive transport activities. Although transcripts for gamma-glutamyl transpeptidase and cytokeratin 19, two cholangiocyte-specific proteins, and glyceraldehyde-3-phosphate dehydrogenase, a housekeeping gene, were in all three subpopulations, genes for several proteins involved in solute transport [Cl-/HCO3- exchanger, cystic fibrosis transmembrane conductance regulator (CFTR), and secretin receptor] were expressed only in medium and large cholangiocytes. Consistent with these findings, secretin increased intracellular levels of adenosine 3',5'-cyclic monophosphate (cAMP) and 36Cl- efflux rates in medium and large cholangiocytes but not in small cholangiocytes. Also, forskolin/8-(4-chlorophenylthio)-cAMP stimulated 36Cl- efflux rates only in medium and large cholangiocytes, consistent with selective functional expression of CFTR in these subpopulations. These results support the molecular and functional heterogeneity of cholangiocytes within the intrahepatic biliary ductal system and are consistent with the notion that hormone-regulated transport of solutes after BDL occurs principally in medium and large cholangiocytes in a fashion similar to that observed in normal rat liver.

Animals↗
PubMed1997

Lunar cycle and consultations for anxiety and depression in general practice.

The influence of the moon on patient consultations for anxiety or depression in general practice was assessed through a retrospective survey based on general practice medical records and on lunar records detailing the dates and times of different phases of the moon. Seven-hundred-eighty-two patients continuously registered in a general practice in Beckenham, South London, between 1971 and 1988 were included in analyses. No statistically significant lunar effect was found by setting the expected surge in consultations one to three days after the full moon and the period of the sine-wave curve to 30 days. Similarly, no statistically significant lunar effect was found, when the period of the sine-wave curve was allowed to vary in order to best fit the data. The moon had little influence on when individuals consulted their general practitioner with anxiety or depression.

Adolescent↗
PubMed1997

What's up, Billy Jo? Deaf children and bilingual-bicultural instruction in east-central Texas.

Seven deaf children attended a bilingual-bicultural (bi-bi) prekindergarten, kindergarten, and first grade from 1993 to 1996 in an east-central Texas public school. The children had diverse backgrounds (African American, Hispanic, White) and various intellectual, cognitive, and linguistic abilities. We detail the backgrounds of the seven children and their families and describe three bi-bi classrooms. We present standardized test scores on cognition (Bracken Test of Basic Concepts) and academic achievement (Stanford Achievement Test, 9th edition, and Woodcock-Johnson Psycho-Educational Battery). When, with one exception, the children completed first grade, they all tested at grade level. (The exception was a younger child who had only completed kindergarten but who nonetheless tested at the first-grade level). We interpret our findings in light of theories of first- and second-language acquisition and discuss the feasibility of establishing bi-bi programs in areas where no large Deaf community exists. We also note our plans to evaluate the seven children again, at the end of second grade in spring 1997.

Child↗
PubMed1997

Negative and positive dimensions of schizotypal personality disorder.

The positive (perceptual-cognitive) and negative (social-interpersonal) dimensions of schizotypal personality traits were examined in biological relatives of individuals with Axis I disorder. The subjects were young adult offspring from three contrasting parental groups, including schizophrenic disorder, affective disorder, and normal controls. Cognitive correlates, including digit span (presumed to assess working memory) and P3 amplitudes, were also examined. Preliminary results showed that positive and negative dimensions were distinguished by different prevalence patterns in the offspring subjects, and by a different pattern of correlations with cognitive measures. Negative dimensions were more frequent in offspring from the schizophrenic parental group than in the offspring from affective disorder and normal control parental groups. Digits forward and backward, and P3 amplitude decrements, characterized a subset of offspring with negative features from the schizophrenic parental group. Positive dimensions did not differ between the psychiatric parental groups, and did not covary with digit span or P3 amplitude assessments. These results support the view that positive and negative dimensions may reflect separable pathophysiologic processes.

Adult↗
PubMed1997

TIA-1 expression in lymphoid neoplasms. Identification of subsets with cytotoxic T lymphocyte or natural killer cell differentiation.

TIA-I is a 15-kd cytotoxic granule-associated protein expressed in natural killer (NK) cells and cytotoxic T lymphocytes. TIA-1 expression was evaluated by paraffin immunohistochemistry in 115 T- or NK-cell neoplasms, 45 B-cell neoplasms, and 45 Hodgkin's lymphomas. TIA-1-positive granules were identified within the cytoplasm of neoplastic cells in 6/6 large granular lymphocytic leukemias, 11/11 hepatosplenic T-cell lymphomas, 15/15 intestinal T-cell lymphomas, 6/6 NK-like T-cell lymphomas of no special type, 2/2 NK-cell lymphomas, 8/9 nasal T/NK-cell lymphomas, 7/8 subcutaneous T-cell lymphomas, 4/5 pulmonary T- or NK-cell angiocentric lymphomas (lymphomatoid granulomatosis), 12/19 T-cell anaplastic large-cell lymphomas, 2/12 nodal peripheral T-cell lymphomas, 1/3 CD8+ cutaneous T-cell lymphomas, and 5/38 classical Hodgkin's disease. All B-cell neoplasms, nodular lymphocyte-predominant Hodgkin's disease (7 cases), CD4+ cutaneous T-cell lymphomas (6 cases), adult T-cell leukemia/lymphomas (3 cases), T-cell chronic or prolymphocytic leukemias (3 cases), and T-cell lymphoblastic leukemia/lymphomas (7-cases) were TIA-1 negative. These findings indicate that most large granular lymphocytic leukemias, hepatosplenic T-cell lymphomas, intestinal T-cell lymphomas, NK-like T-cell lymphomas, NK-cell lymphomas, nasal T/NK-cell lymphomas, subcutaneous T-cell lymphomas, pulmonary angiocentric lymphomas of T or NK phenotype, and anaplastic large-cell lymphomas are cytotoxic T-or NK-cell neoplasms.

Biopsy↗
PubMed1996

Cloning and functional characterization of the gene encoding the TFIIIB90 subunit of RNA polymerase III transcription factor TFIIIB.

The yeast RNA polymerase III (pol III) general transcription factor TFIIIB is composed of three subunits; the TATA-binding protein (TBP)1, the TFIIB-related factor (BRF1), and a third factor termed TFIIIB90 or B". Here we report the purification of yeast TFIIIB90, cloning of the gene encoding TFIIIB90, and reconstitution of TFIIIB from recombinant polypeptides. The TFIIIB90 open reading frame encodes a 68-kDa polypeptide and has no obvious similarity to any other known protein sequences. The gene encoding TFIIIB90 is essential for viability of yeast. Using recombinant TFIIIB subunits, we found that TFIIIB90 interacts weakly with TBP in the absence of BRF1, and that this interaction is enhanced at least 25-fold by BRF1. In addition, TFIIIB90 showed pol III specificity as it could not interact with the pol II-specific TFIIB-TBP-DNA complex. To localize the regions of the TBP-DNA complex that interact with BRF1 and TFIIIB90, we tested whether the pol II factors TFIIA and TFIIB interfered with the binding of BRF1 and TFIIIB90 to TBP-DNA. Our results suggest that the binding sites for BRF1 and TFIIIB90 on TBP-DNA both overlap the binding sites for TFIIA and TFIIB.

Amino Acid Sequence↗