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Biomedical subjects

B Lee

Publications and source records attributed to B Lee.

At least 271 records · Page 15Linked to original sources
PubMed1996

[Mortality of SMON patients in relation to their disabilities].

The relationship between mortality and disability, was studied in SMON patients, who had participated in the questionnaire survey in 1980, by following them for 10 years through municipal resident registration information offices. Eighty deaths were observed among 409 subjects during the follow-up period. The effect of each disability on the mortality of SMON was estimated by applying the Cox proportional hazard model. The presence of severe gait disturbance and low levels of activities of daily living (ADL) were associated with significantly higher risk of death after adjustment for age and sex. The relative risk of visual disturbance was not significant after adjusting for age, sex and other kinds of disability. Those who complained of continuous dysesthesia at the time of the initial survey showed better prognosis than those without such dysesthesia. Among subjects who died during the follow-up period, those who had reported low levels of ADL at the time of the initial survey had a greater proportion of deaths attributable to heart failure and pneumonia than those who had reported high levels of ADL.

Activities of Daily Living↗
PubMed1996

Oxytocin-stimulated insulin release in a clonal beta-cell line RINm5F: involvement of phospholipase C-dependent and -independent pathways.

AIM: To study the mechanisms underlying oxytocin (Oxy)-induced insulin release. METHODS: In a clonal pancreatic beta-cell line, RINm5F cells. RESULTS: Oxy increased insulin release and [Ca2+]i in a concentration-dependent manner. Oxy-induced insulin release was not altered by pretreatment with pertussis toxin (PT). U-73122 (2-8 mumol.L-1), a phospholipase C (PLC) inhibitor, concentration-dependently inhibited Oxy-induced increases in [Ca2+]i with IC50 value of 2.8 +/- 0.2 mumol.L-1. In addition, U-73122 diminished the Oxy-induced increase in intracellular concentration of inositol 1, 4, 5-triphosphate (IP3). U-73122 at 8 mumol.L-1 totally abolished the Oxy-induced increases in [Ca2+]i and IP3; however it reduced the Oxy-induced increase in insulin release only by 36% and 63% in the monolayer and suspended cell preparations, respectively. CONCLUSION: Oxy increases insulin release through both PLC and non-PLC mediated signal transduction mechanisms.

Animals↗
PubMed1995

Molecular cloning of the alpha 3 chain of human type IX collagen: linkage of the gene COL9A3 to chromosome 20q13.3.

Type IX collagen is composed of three polypeptides derived from the human genes COL9A1, COL9A2, and COL9A3 that assemble to form a mature collagen molecule with the structure alpha 1(IX)alpha 2(IX)alpha 3(IX). We have identified overlapping cDNA and genomic clones that encode for the entire alpha 3 chain of human type IX collagen. Tryptic peptides from the human alpha 3(IX) collagen chain were subjected to N-terminal amino acid sequencing, and a stretch of 124 contiguous amino acids that included the NC1, COL1, and NC2 domains was obtained. Degenerate oligonucleotide primers were designed based on the amino acid sequences of the human tryptic peptides as well as bovine peptides and sequences from chicken cDNA clones. These primers were used to amplify three overlapping PCR products that covered the majority of the human alpha 3(IX) collagen. PCR products were then used to identify overlapping cDNA clones from a human chondrocyte library. A lambda genomic clone was identified that contained the 5'-most exon that encodes the signal peptide to complete the entire structure of the human alpha 3(IX) collagen chain. Genomic amplification identified a single-strand conformational polymorphism in COL1 that was used to map COL9A3 to chromosome 20q13.3 by linkage analysis. The present study completes the structure of human type IX collagen, and linkage for COL9A3 completes the genomic mapping of cartilage collagen genes. These data will greatly assist the genetic screening of families with degenerative cartilage and eye diseases by allowing investigators to screen for a complete set of candidate collagen gene markers.

Amino Acid Sequence↗
PubMed1995

Purified CD34+ Lin- Thy+ stem cells do not contain clonal myeloma cells.

High-dose therapy with autologous marrow or peripheral blood stem cell (PBSC) rescue has been extensively applied in the treatment of multiple myeloma (MM) patients during the past 10 years resulting in improved event-free and overall survival when compared with standard chemotherapy. However, relapses are common and cure is unlikely in the majority of patients. Because both bone marrow and PBSCs are contaminated with myeloma cells it is conceivable that relapse after autotransplantation originates at least in part from autografted tumor cells. In this study, mobilized PBSCs were examined for the presence of myeloma cells based on immunophenotyping and sensitive polymerase chain reaction (PCR)-based techniques. In addition, CD34+ Lin- Thy+ stem cells were purified from mobilized PBSC harvests of 10 MM patients by sequentially using counterflow elutriation centrifugation, treatment with phenylalanine methylester, and flow sorting, using 5-parameter gating (propidium iodide, forward scatter, side scatter, CD34+ v Lin- and CD34+ v Thy+). Virtually all mobilized unsorted PBSC preparations contained myeloma cells in sufficient quantities (range, < 0.01 to > 10%) potentially causing a disease relapse. Stem cell purification led to an overall enrichment by about 50-fold in all 10 patients; approximately 90% of the final cell population expressed CD34+ Lin- Thy+ with no evidence of myeloma cell contamination based on flow cytometric analysis of CD38bright cells (< 0.1%). Quantitative PCR amplification of patient-specific complementarity determining region III (CDRIII) DNA sequences showed depletion of clonal B cells by 2.7 to 7.3 logs, with the highest log reduction noted in the samples initially containing the most tumor cells. Our results show that purification of CD34+ Lin- Thy+ cells depletes myeloma cells to undetectable levels from up to 10% present in unsorted PBSCs, thus offering a tool to investigate whether MM relapse after autotransplantation can be reduced markedly.

ADP-ribosyl Cyclase↗
PubMed1995

Ultrasonography and endocrinology of ovarian dysfunctions induced in heifers with estradiol valerate.

This study monitored the long-term follicular dynamics and changes in ovarian steroid hormones associated with an experimental model of cystic ovarian degeneration (COD) in the heifer. In the treated group (n = 7), Holstein heifers received a single injection of 500 microg of cloprostenol (prostaglandin F2a, PG) and 5 mg of estradiol valerate (EV) on either Day 17, 18 or 19 of the estrous cycle. The control group (n = 7) received only PG. Transrectal ultrasound was performed daily, beginning 8 to 10 d before injection and continuing until a return to normal cyclicity (40 to 74 d). Blood samples were taken twice daily over the same period. The EV disrupted the normal follicular development as well as the plasma progesterone and estradiol profiles of 6/7 heifers in the treated group. Two different types of responses were observed. The Type-I response (n = 2) was characterized by a premature ovulation followed by a corpus luteum (CL) which persisted for over 30 d. The Type-II response (n = 4) was characterized by anovulation followed by the emergence of a large ovarian structure which could further be subtyped. In Type- IIA (n = 2), this follicle ovulated at an exaggerated size of 19 or 24 mm (mean diameter of controls: 13.4 +/- 2.7 mm). The subsequent cavernous CL was very large at 35 and 37 mm (mean diameter of CL in controls: 23.8 +/- 2.0 mm). In Type- IIB (n = 1), the follicle present at the time of injection continued to grow and became a luteinized cyst. In Type-IIC (n = 1), several waves of follicular cysts developed and persisted for 52 d. This study suggests that EV induces a range of ovarian dysfunctions including different forms of COD. The individual differences in the stage of folliculogenesis at the time of injection of EV may be responsible for the different types of responses.

Journal Article↗
PubMed1995

Tuberculin sensitivity and the BCG scar in tuberculosis contacts.

SETTING: Tuberculosis clinic, St Vincents Hospital, Dublin. OBJECTIVE: To determine the influence of past BCG vaccination on tuberculin sensitivity in tuberculosis contacts. DESIGN: Prospective cohort study of tuberculin sensitivity using the Mantoux technique (5 TU). RESULTS: In 1050 contacts of 96 cases of tuberculosis, BCG scars were noted in 76% of the contacts. Approximately 50%, 30% and 20% of the contacts respectively had negative (0-4 mm), positive (5-14 mm) and strongly positive (15+ mm) Mantoux responses. The presence of a BCG scar was not found to significantly influence the degree of tuberculin sensitivity. The degree of tuberculin sensitivity increased after 20 years and decreased after 60 years of age. Contacts of sputum-positive cases of tuberculosis had larger Mantoux responses. CONCLUSIONS: The study suggests that age of the contact and sputum status of the index case are important determinants of the degree of tuberculin sensitivity. Attributing a 'positive' Mantoux response to past BCG vaccination may be encouraging a false sense of security in contacts recently exposed to an infectious case of tuberculosis. Contact management guidelines may need to be reviewed and perhaps modified to reflect this finding.

Adolescent↗
PubMed1995

Construction of a functional disulfide-stabilized TCR Fv indicates that antibody and TCR Fv frameworks are very similar in structure.

Disulfide-stabilized Fvs (dsFv) are recombinant Fv fragments of antibodies in which the inherently unstable VH-VL heterodimer is stabilized by an interchain disulfide bond engineered between structurally conserved framework positions. We now design and produce a disulfide-stabilized Fv of a T cell receptor. It is composed of V alpha and V beta variable domains of the 2B4 TCR stabilized by a disulfide bond between framework residues of the TCR Fv at a site corresponding to that used for disulfide stabilization of antibody Fvs. For ease of production and detection, the TCRdsFv was fused to a truncated form of Pseudomonas exotoxin (PE38). The TCR(dsFv) retains its native conformation and is much more stable than a TCR scFv. Moreover, it is functional in biological assays. Because successful disulfide stabilization of the TCR Fv by the positions used for antibody Fv stabilization would not occur unless the mutated residues in TCR Fv are at positions closely similar to those in antibody Fvs, most likely within less than 1.5 A, these results provide very strong experimental evidence for the structural similarity between immunoglobulin and TCR antigen-binding variable domains.

Amino Acid Sequence↗
PubMed1995

Cloning of the putative tumour suppressor gene for hereditary multiple exostoses (EXT1).

Hereditary multiple exostoses is an autosomal dominant disorder that is characterized by short stature and multiple, benign bone tumours. In a majority of families, the genetic defect (EXT1) is linked to the Langer-Giedion syndrome chromosomal region in 8q24.1. From this region we have cloned and characterized a cDNA which spans chromosomal breakpoints previously identified in two multiple exostoses patients. Furthermore, the gene harbours frameshift mutations in affected members of two EXT1 families. The cDNA has a coding region of 2,238 bp with no apparent homology to other known gene sequences and thus its function remains elusive. However, recent studies in sporadic and exostosis-derived chondrosarcomas suggest that the 8q24.1-encoded EXT1 gene may have tumour suppressor function.

Amino Acid Sequence↗
PubMed1995

Disulfide stabilization of antibody Fv: computer predictions and experimental evaluation.

Using molecular modeling technology we have recently identified positions in conserved framework regions of Fvs which can be used to stabilize antibody Fvs by an interchain disulfide bond engineered in between the structurally conserved framework positions of the variable domains of heavy (VH) and light (VL) immunoglobulin chains (disulfide-stabilized Fv; dsFv). The computer model indicated the existence of other potential sites in the framework regions that might be suitable for disulfide bond formation between VH and VL. The possibility of obtaining dsFvs using these positions is evaluated here experimentally by constructing dsFv immunotoxins in which the Fv moiety is fused to a truncated form of Pseudomonas exotoxin. We analyzed the extent of dsFv formation and the activity of the resulting dsFv immunotoxins, and compared various dsFv molecules with the scFv immunotoxin. Our results demonstrate that position H44-L105 is the only one which gives high production yields of active dsFv. All other positions gave either low yields and activity or completely failed to produce active dsFv. With one exception, the formation and activities of the dsFvs corresponded to the C alpha-C alpha distance between the VH and VL positions, with an optimal distance of 5.7 A producing the best dsFv. Distances of 6.0-6.9 A resulted in a low yield of protein that was still capable of binding antigen, whereas distances > 7.0 A resulted in molecules in which dsFv formation was not obtained.

Amino Acid Sequence↗
PubMed1995

Hydrophobic potential by pairwise surface area sum.

An approximate but rapid method for estimating hydrophobic energy is proposed. Aside from a scale factor, it is given by the pairwise sum of the surface area buried by each neighbor atom, but excluding those atoms in the same residue or in its sequence neighbor residues. This sum is found to be linearly related to the true buried area as calculated by the algorithm of Lee and Richards [1971, J. Mol. Biol., 55, 379-400], and to the contact potential of Miyazawa and Jernigan [1985, Macromolecules, 18, 534-552]. It correlates with experimental transfer free energies to approximately the same degree as that calculated using the true buried area. Furthermore, in a simple test of helix packing with ROP protein monomer, the new hydrophobic energy clearly discriminated one structure, with the lowest r.m.s. deviation from the crystal structure, against an exhaustive set of others.

Amino Acids↗
PubMed1995

Noninvasive central nervous system imaging in sickle cell anemia. A preliminary study comparing transcranial Doppler with magnetic resonance angiography.

PURPOSE: We evaluated the accuracy of transcranial Doppler (TCD) and magnetic resonance angiography (MRA) as a screening modality for cerebral infarct in patients with sickle cell disease. PATIENTS AND METHODS: Twenty-four patients with sickle cell disease were assessed for a cerebral infarct. Each patient underwent neurologic examination, psychometric evaluation, magnetic resonance imaging (MRI), MRA, and TCD. Presence of a cerebral infarct was determined by an MRI and supported by neurologic and neuropsychometric evaluation. All investigators were unaware of the patient's status. Cerebral vasculature by MRA was categorized as being occluded, stenotic, or normal. The maximum TCD velocity of the right and left middle cerebral artery were assessed. Various cutoffs were used to determine the sensitivity and specificity of TCD. RESULTS: MRA had a sensitivity and specificity of 100% and 92%, respectively. At a maximum velocity cutoff of 180 cm/s, the sensitivity and specificity of TCD were 20% and 67%, respectively. No maximum velocity on TCD produced both sensitivity and specificity > 50%. CONCLUSION: MRA is more sensitive than TCD when the middle cerebral artery for maximum velocity is compared. Prospective evaluation is warranted to determine if TCD is useful as a screening technique for cerebral infarction in children with SCD.

Anemia, Sickle Cell↗
PubMed1995

Effect of AVP and oxytocin on insulin release: involvement of V1b receptors.

We used a number of receptor antagonists to determine which receptors mediate the effect of arginine vasopressin (AVP) and oxytocin (OT) on insulin release. We found that OT (10(-7) M) and AVP (10(-8) M) increased insulin release from the perfused rat pancreas with similar magnitude. The antagonist with potent V1b receptor-blocking activity, dP[Tyr(Me)2]AVP (10(-7) M), abolished the effect of OT and AVP, whereas the highly selective OT receptor antagonist L-366,948 (10(-6) M) did not change the effect of OT, nor did a V1a receptor antagonist, d(CH2)5[Tyr(Me)2]AVP (10(-7) M), change the effect of AVP. The insulin-releasing potency of OT was estimated as 9-fold less than that of AVP in RINm5F cells. Selected AVP and OT antagonists were used to study their antagonism on AVP- and OT-induced insulin release from RINm5F cells, and the order of potencies of antagonists was estimated as dP[Tyr(Me)2]AVP > d(CH2)5[D-Phe2,Ile4]AVP > SR-49059 > d(CH2)5[Tyr(Me)2]AVP > desGly9d(CH2)5[Tyr(Et)2]VAVP (WK-3-6) approximately L-366,948. These results were consistent with the V1b receptor antagonistic activities of the antagonists. d[D-3-Pal]VP, a V1b receptor agonist, increased insulin release dose dependently (10(-9) to 10(-6) M), and this effect was antagonized by dP[Tyr(Me)2]AVP but not by WK-3-6 (10(-6) M). These results suggested that the stimulatory effect of both OT and AVP on insulin release from beta-cells may be mediated by V1b, but not by V1a or OT receptors.

Animals↗
PubMed1995

Adenosine inhibits arginine vasopressin-stimulated chloride secretion in a mouse IMCD cell line (mIMCD-K2).

Previously, we demonstrated that a mouse inner medullary collecting duct cell line (mIMCD-K2) secretes Cl- by an electrogenic mechanism via cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channels [N. L. Kizer, B. Lewis, and B. A. Stanton. Am. J. Physiol. 268 (Renal Fluid Electrolyte Physiol. 37): F347-F355, 1995; N. L. Kizer, D. Vandorpe, B. Lewis, B. Bunting, J. Russell, and B. A. Stanton. Am. J. Physiol. 268 (Renal Fluid Electrolyte Physiol. 37): F854-F861, 1995; D. Vandorpe, N. Kizer, F. Ciampolillo-Bates, B. Moyer, K. Karlson, W. B. Guggino, and B. A. Stanton. Am. J. Physiol. 269 (Cell Physiol. 38): C683-C689, 1995]. The objective of the present study was to determine whether adenosine, and adenosine A1 receptors (A1AR) specifically, regulate electrogenic Cl- secretion (IscCl) in mIMCD-K2 cells. Neither N6-cyclohexyladenosine (CHA), a specific A1AR agonist, nor 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), a specific A1AR antagonist, altered basal, unstimulated IscCl in monolayers of mIMCD-K2 cells mounted in Ussing-type chambers. In contrast, DPCPX increased arginine vasopressin (AVP)-stimulated IscCl, an effect that was reversed by CHA. Adenosine deaminase (ADA), which oxidatively deaminates adenosine to inosine, increased AVP-stimulated IscCl. CHA reversed the stimulatory effect of ADA on AVP-stimulated IscCl. These results suggest that adenosine, via A1AR, inhibits AVP-stimulated IscCl. To identify the source(s) of extracellular adenosine, we examined the effects of dipyridamole, an inhibitor of nucleoside transport, and alpha,beta-methyleneadenosine 5'-diphosphate (AOPCP), an inhibitor of ecto-5'-nucleotidase, on AVP-stimulated IscCl. Both compounds increased AVP-stimulated IscCl. CHA reversed the stimulatory effect of dipyridamole and AOPCP on IscCl. Neither ADA nor CHA had an effect on 8-(4-chlorophenylthio)-adenosine 3',5'-cyclic monophosphate (CPT-cAMP)-stimulated IscCl. Moreover, U-73122, an inhibitor of phospholipase C, failed to attenuate the increase in AVP-stimulated IscCl elicited by dipyridamole and AOPCP or the decrease in AVP-stimulated IscCl elicited by CHA. We conclude that adenosine, released by a nucleoside transporter and formed extracellularly by the breakdown of AMP, binds to A1AR, and decreases AVP-stimulated IscCl in mIMCD-K2 cells by reducing intracellular cAMP levels.

Adenosine↗
PubMed1995

[Pharmacological profiles of F-1322, a novel anti-asthmatic agent. (1). Mechanisms of action].

The pharmacological effects of N-[2-(4-(benzhydryloxy)piperidino)ethyl]-3-hydroxy-5-(3-pyridyl methoxy)-2- naphthamide (F-1322), a novel anti-asthmatic agent, was investigated in vitro. The results obtained were as follows: 1) In the isolated trachea of guinea pigs, F-1322 showed a markedly potent antagonistic action against the contraction induced by histamine, while it had little or no effect on 5-hydroxytryptamine-, acetylcholine-, leukotriene D4- or U-46619-induced contractions. 2) In rabbit platelets, F-1322 did not affect the platelet aggregation induced by platelet activating factor. 3) F-1322 significantly inhibited the thromboxane (TX) A2 synthetase (IC50 value: 1.7 x 10(-8) M) and 5-lipoxygenase (IC50 value: 9 x 10(-7) M) activities. 4) F-1322 had no effect on phospholipase A2, cyclooxygenase, Ca2+/calmodulin-dependent phosphodiesterase and phosphodiesterase activities. These in vitro studies suggest that the anti-asthmatic action of F-1322 is associated with histamine antagonism and an inhibitory action on TXA2 synthetase and 5-lipoxygenase activities.

Animals↗
PubMed1995

Molecular structure and function of autoantigens in systemic sclerosis.

Autoantibodies in systemic sclerosis target a limited set of nuclear proteins, principally those of the nucleolus and RNA transcription complexes. These antibodies have proved helpful in diagnosis of this disease, and have been used extensively as probes of nuclear structure and function. Despite these advances, the events that initially trigger autoantibody production in systemic sclerosis are not yet known. While these ANA are not known to disrupt cellular processes by entering living cells, or to cause tissue injury (in contrast to SLE, where autoantibodies may mediate tissue damage), it seems likely that they do not merely represent epiphenomena of the disease. Rather, it is logical to assume that their origin is in some manner tied to etiology of systemic sclerosis, since they segregate by syndrome within the spectrum of this disease (for example, anti-kinetochore antibodies occur in limited cutaneous disease, and anti-topoisomerase I and anti-RNA polymerase antibodies occur in diffuse disease), and since they are distinct from the ANA found in other connective tissue diseases in their selectivity for the nucleolus and RNA polymerases.

Antigens, Nuclear↗