Biomedical subjects
Publications and source records attributed to B Li.
A sharp dissection technique, using specially designed curved insulated scissors, is described for use in laparoscopic cholecystectomy. This technique is a suitable alternative to laser and electrocautery, and produced a significant shortening of operating time.
Angiogenesis plays critical roles in organ development during embryonic and fetal life, wound healing and in a variety of pathological conditions. Vascular endothelial growth factor (VEGF) is a secreted growth factor specific for vascular endothelial cells which induces angiogenesis in vivo. To gain a better understanding of the physiological role of VEGF, we have generated and characterized four murine monoclonal antibodies (mAbs) using the 165 amino acid species of recombinant human VEGF as immunogen. These mAbs (A3.13.1, A4.6.1, B4.3.1 and B2.6.2) belong to IgG1 isotype and have high affinities for VEGF (dissociation constants range from 2.2 x 10(-9) to 4 x 10(-10) M). Two different epitopes were detected with these mAbs. One epitope is recognized by mAbs A3.13.1 and B2.6.2, and the other recognized by mAbs A4.6.1 and B4.3.1. The epitope recognized by mAb A4.6.1 appears to be continuous while mAb B2.6.2 recognizes a discontinuous epitope. MAb A4.6.1 recognized three species of VEGF generated by alternative splicing, VEGF121, VEGF165 and VEGF189 while mAb B2.6.2 binds only VEGF165 and VEGF189. Results using an in vitro bovine adrenal cortex endothelial cell proliferation assay, in in vivo vascular permeability assay and an in vivo embryonic chicken angiogenesis assay showed that mAb A4.6.1 has potent VEGF neutralizing activities. MAb A4.6.1 was shown to block the binding of VEGF to its receptor(s) suggesting the inhibitory mechanism for VEGF activities. These well-defined mAbs should be very powerful tools to understand the structure-function relationship of various domains of VEGF and may have therapeutic potential.
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The cerebral arteries in seven cases of Moyamoya disease, demonstrated by angiography were observed by light, transmission and scanning electron microscopy. In two cases, the lumen of the terminal portion of the internal carotid artery was completely occluded by proliferated connective tissue. The characteristic pathologic change was extensive destruction of the smooth muscle cells and the elastica interna. Degeneration and necrosis of smooth muscle cells were obvious in the media. Many condensed organelles and other elements of cellular destruction were dispersed throughout the interstitium. The media was thinned. The proliferated smooth muscle cells in the intima showed the same destructive changes as in the media. The elastica interna was excessively infolded and was thickened or thinned, disrupted or disintegrated in some segments. Identical, but less severe and more localized changes were seen in three middle cerebral arteries (M2 and M5 segments) and two collateral arteries at the base of brain. These changes suggest that Moyamoya disease is a progressive disorder characterized by repeated destruction of smooth muscle cells occurRing over a long time period. The pathogenesis of these changes is discussed.
erb-B gene is an oncogene from avian leukosis virus. The carcinogenic capability of erb-B is due to the close similarity of expressional proteins to the epidermal growth factor receptor (EGFr). In this study the amplification and the over-expression of erb-B were found in human oral squamous (cell carcinomas by DNA and RNA dot blot hybridization). Results showed that erb-B was correlated with the oral epidermoid tumors but not with group of non-epidermoid tumors in the head and neck region. Southern blotting analysis showed that there were rearrangement of erb-B gene in the tumor genosomes, which is perhaps one of the ways to activate the proto-oncogene of erb-B.
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We describe here the technique of DNA probe directly labelled with horseradish peroxidase (HRP) and enhanced chemiluminescence (ECL) detection for determining DNA fingerprints. The patterns of DNA fingerprint were clear and with high distinction. The sensitivity of DNA fingerprint was 0.8 microgram, similar to the method of 32P labelling. The DNA fingerprints of 150 unrelated individuals were studied and showed that the probability of chance association of DNA fragments between random individuals was 3.7 x 10(-14). The method is stable, simple and quick, and can be used in individual identification and paternity test.
The regulation of mRNA encoding transforming growth factor beta (TGF-beta) and interleukin 2 (IL-2) in normal human T cells was explored using novel competitor DNA constructs in the quantitative polymerase chain reaction and accessory cell-independent T cell activation models. Our experimental design revealed the following: (a) TGF-beta mRNA and IL-2 mRNA are regulated differentially in normal human T cells, quiescent or signaled with the synergistic combinations of: sn-1,2-dioctanoylglycerol and ionomycin or anti-CD3 monoclonal antibody (mAb) and anti-CD2 mAb; (b) the steady-state level of TGF-beta mRNA in the stimulated T cells, in contrast to that of IL-2 mRNA, is increased by the immunosuppressant cyclosporine (CsA); and (c) the paradoxical effect of CsA on TGF-beta mRNA levels is also appreciable at the level of production of functionally active TGF-beta protein. Our findings, in addition to demonstrating the utility of the competitor DNA constructs for the precise quantification of immunoregulatory cytokines, suggest a novel and unifying mechanistic basis for the immunosuppression and some of the complications (e.g., renal fibrosis) associated with CsA usage.
The theme of this study is an evaluation of the involvement of cAMP and cAMP-dependent protein kinase (PKA) in the regulation of the human heat shock protein (hsp) 70 gene promoter. Expression of a highly specific protein inhibitor of PKA (pRSVPKI) inhibited the basal as well as heat- and cadmium-induced expression of the cotransfected pHBCAT, a human hsp 70 promoter-driven reporter gene; this inhibition was dependent on the amount of pRSVPKI used. The effect of an expression vector of the RI regulatory subunit of PKA, pMTREV, was similar to that of pRSVPKI; pMTREV inhibited both the basal as well as the heat-induced expression of pHBCAT. The specificity of effects of these expression vectors was demonstrated by the lack of effect of a mutant PKI gene and by the unaffected expression of a reference gene (pRSV beta gal) under these conditions. Analysis of the effects of dibutyryl cAMP (1 mM), forskolin (10 microM), and 8-Br-cAMP (1 mM) on the transient expression of pHBCAT showed that these cAMP-elevating agents stimulated the hsp 70 promoter activity, whereas cAMP (1 mM) was without effect. Chloramphenicol acetyltransferase gene constructs with truncated or mutated hsp 70 promoter were used to define the cis-acting DNA element(s) that confer this cAMP stimulation; the heat induced (42 degrees C) expression was used as a control. Mutation of the adenovirus transcription factor element (pLSN-40/-26) greatly reduced the basal level of expression; forskolin had little or no effect on this adenovirus transcription factor-minus promoter, although the promoter activity was very heat inducible. The absence of a functional heat shock consensus element (HSE) in the construct pLSPNWT rendered the promoter heat insensitive; this construct was forskolin responsive although the magnitude of this stimulation was reduced when compared with that of a control construct with HSE. These results were corroborated by studies using consensus sequence of ATF (ATFE) and HSE as competitors to titrate our cellular factors that may interact with these elements. We showed that cotransfection with ATFE and HSE depressed the basal (37 degrees C) expression of pHBCAT by 25 and 60%, respectively. The heat-induced expression of pHBCAT was not significantly affected by the cotransfection of ATFE and was reduced by 60% when HSE was cotransfected. ATFE and HSE reduced the forskolin-induced pHBCAT expression by 70 and 40%, respectively. The implications of these findings as they relate to the action of cAMP and cAMP-dependent protein kinase in the control of heat shock gene expression are discussed.
PATIENT: A 52-year-old woman with an eight-year history of gallstones who had twice declined to have a cholecystectomy. CLINICAL FEATURES: The patient presented as an emergency with severe abdominal pain, hectic fevers and rigors. Results of examination showed an enlarged, tender and easily palpable gallbladder. A diagnosis of empyema of the gallbladder was made. INTERVENTIONS: Intravenous administration of antibiotics was started immediately and a laparoscopic cholecystectomy was performed 36 hours after admission. OUTCOME: Postoperative recovery was uncomplicated. The patient was discharged after 72 hours and returned to normal activities within one week. CONCLUSION: Laparoscopic cholecystectomy seems a useful technique to treat gallbladder disease in emergency as well as elective situations.
Vibratory stimulus-related responses were recorded from monkey primary somatosensory cortical (SI) neurons while animals performed two tasks. In the movement task, vibratory stimuli served as the go-cue for wrist flexion or extension. In the no-movement task, movements normally made in response to vibratory stimuli were extinguished. Area 3a, 3b, and 1 neurons with deep receptive fields (RFs) exhibited greater stimulus-related activity during the movement task than during the no-movement task. Area 3b neurons with cutaneous RFs were similarly enhanced during the movement task, whereas area 1 neurons with cutaneous RFs were less responsive to vibratory stimuli during the movement task. These results suggest that motor-set and/or selective attention may modulate the responsiveness of SI neurons to peripheral stimuli and that changes in sensory responsiveness in SI neurons differ as a function of their cortical location and RF type.
Northern blot analysis and a highly sensitive methodology for mRNA phenotyping, polymerase chain reaction (PCR), were used to explore the basis for the synergism between CD3/alpha beta T cell receptor (TCR) and the CD2 antigen-derived signals in promoting proliferation of T cells. Northern blotting of RNA isolated from highly purified normal human T cells revealed that crosslinking of anti-TCR-1 (a mAb directed at a framework determinant of the TCR) and OKT11 (a mAb directed at the SRBC-binding epitope of the CD2 antigen) induced the expression of the interleukin-2 gene and the gene for IL-2 receptor alpha, mRNA phenotyping by PCR revealed that crosslinkage of TCR with the CD2 antigen, and not independent crosslinking of TCR or the CD2 antigen, results in the induction of IL-2, IL-2 receptors alpha and beta, and IL-4-specific transcripts. Highly purified CD4+ T cells, as well as CD8+ T cells proliferated by crosslinking TCR with CD2 antigen. Moreover, crosslinkage of TCR with the CD2 antigen and not of either antigen with the CD4 antigen (on the surface of CD4+ T cells) or the CD8 antigen (on the surface of CD8+ T cells) resulted in marked proliferation. Our demonstration that the CD2 antigen-derived signal(s) contribute to the expression of growth promoting genes elicited via the TCR, and that the CD2 antigen is more efficient compared with the CD4 or CD8 antigen in evoking T cell proliferation, suggests that autoimmunity as well as alloimmunity might be regulated by targeting the CD2 antigen.
Pathologic changes in superficial temporal arteries (STA) and middle meningeal arteries (MMA) biopsied from 15 patients with moyamoya disease (MD) who had undergone cerebro-temporal arterio-synangiosis were studied histologically, ultrastructurally and immunohistochemically. The main pathologic features were: proliferation of smooth muscle cells (SMCs) and thickening of the intima, degeneration and destruction of SMCs in the media and intima, and the presence of condensed organelles in necrosed SMCs or the interstitium among SMCs, or both outside and within the elastica interna (EI). The EI had become thin, porous, fragmented and was even absent in some segments. These changes are different from those of other forms of angiopathy, but identical with those at the ends of internal carotid arteries (ICA) reported by us previously, being pathognomonic for MD. These changes in the STA and MMA reveal that MD involves not only the ICA but also the intra- and extracranial branches of external carotid arteries. The medial necrosis of SMCs seems to be the primary injury of the arterial wall in MD. STA tissue blocks from two cases of MD were stained immunohistochemically. By electron microscopy, IgG-, IgM-, and C3-positive granules were observed on the ER of endothelial and intimal cells. Further studies on more cases are needed to determine whether an immunoreaction has occurred in these arteries.
The use of minimally invasive techniques of removing gallstones, and the gall-bladder, is an attractive option for patients who may be severely ill with pancreatitis. We describe here a patient with gallstone pancreatitis who was managed completely by endoscopic techniques consisting of endoscopic retrograde cholangiopancreatography (ERCP) followed by laparoscopic cholecystectomy.
A study was done to evaluate the performance of suction apparatus in the operating room. The investigation was prompted by perceived poor suction performance in a suite of new operating rooms built in accordance with Standards Australia (SA) specifications. SA performance tests were conducted on each of four suction outlets in nine operating rooms. All 36 outlets complied with SA standards for flow-rate (minimum 40 L/min) and occluded negative pressure (ONP; minimum -60 kPa). However, 24 collection units failed to comply with standards (ONP) of -40 kPa achieved in less than 4 s when a 4 L disposable suction apparatus was connected (mean time to ONP: 6.1 s, 95% confidence interval: 4.9, 7.3). When smaller capacity suction jars were substituted, more units met SA standards. The standards therefore need revision to include specification of the capacity of the collecting apparatus. Other factors that were found to degrade suction performance significantly were air leakage and defective shut-off valves. The physical principles involved in operating room suction are described. Surgeons and anaesthetists should understand these principles, and it is recommended that a simple pre-operative check of the suction apparatus should be carried out, as follows: (1) Turn the wall control knob fully on, and disconnect the suction apparatus. The gauge should register zero. (2) Connect the suction jars. If the indicated gauge pressure is in excess of -15 kPa, investigate the equipment for excessive resistance, particularly in the shut-off valve, which should be replaced with a new unit if necessary.(ABSTRACT TRUNCATED AT 250 WORDS)
The competition between two opposing influences on the phenotypic expression of skeletal muscle myosin were studied to determine which was the dominant regulator. Experimental hyperthyroidism, which induces fast myosin expression, was produced by subcutaneous implantation of a 40-day constant-time-release triiodothyronine pellet. Compensatory hypertrophy, which induces slow myosin expression, was produced by surgical removal of a synergistic hindlimb muscle. Hyperthyroidism increased the percentage of type II fibers and the fast myosin isoforms in both the plantaris and soleus muscles. Hypertrophy significantly increased the percentage of type I fibers and the slow myosin type in the plantaris and soleus muscles. However, with the simultaneous introduction of hyperthyroidism and hypertrophy, only the hyperthyroid effects were observed. Hyperthyroidism and not physiological demand was found to be the dominant regulator of skeletal muscle myosin expression.