Biomedical subjects

A Lai

Publications and source records attributed to A Lai.

At least 37 records · Page 2Linked to original sources

PubMed2001

Fire during thoracic surgery.

A 67-year-old male with bilateral lung lesions presented for median sternotomy. One-lung ventilation was complicated by arterial desaturation. Continuous positive airway pressure with oxygen was applied to the non-ventilated lung to relieve the hypoxaemia. However, the cotton gauze packed inside the operative site was ignited by the electrocautery. The burning gauze was immediately removed without any complication. We report a case of electrocautery-induced fire during thoracic surgery done in supine position and discuss its implication on the choice of oxygen enrichment therapy during one-lung ventilation.

Aged↗

PubMed2001

Effect of age on recovery from remifentanil anaesthesia.

In a prospective, randomized study, the effect of age on recovery from remifentanil anaesthesia was evaluated. Twenty consecutive patients classified as ASA 1 and 2 and having elective laparotomy were recruited to one of two groups based on age (Group 1 age <60 y and Group 2 age >60 y). Remifentanil boluses and infusion were used for induction and maintenance of anaesthesia. Dosage was titrated against clinical response to perioperative stimulation and the infusion was terminated at the end of the operation. Time intervals between termination of remifentanil infusion and 1) spontaneous respiration, 2) adequate respiration, 3) eye opening, 4) limb movement, 5) extubation, 6) Aldrete score >9, 7) discharge to recovery room and 8) discharge to the ward were recorded. Patient controlled analgesia with morphine was used for postoperative pain control. Student's t test was used to compare the differences in these time intervals between Groups 1 and 2. A P value <0.05 was taken as significant. We found that the younger age group regained spontaneous respiration (0.8+/-0.7 min vs 3.2+/-3.6 min), adequate respiration (3.4+/-3.7 min vs 7.6+/-5.8 min), opened their eyes (0.9+/-1.0 min vs 3.6+/-4.4 min), had their endotracheal tubes removed (5.0+/-4.6 min vs 9.0+/-6.5 min) and were discharged to recovery room (8.8+/-4.3 min vs 14.5+/-7.1 min) earlier than their older counterparts. In conclusion, age was a co-variate for recovery from remifentanil anaesthesia.

Adult↗

PubMed2000

Enzyme biosensor for studying therapeutics of Alzheimer's disease.

An electrochemical method for the investigation and comparison of anti-Alzheimer medications that is based on the inhibition of the acetylcholinesterase is presented. The developed amperometric biosensor determines the in-vitro inhibition of the acetylcholinesterase that is co-immobilized with choline oxidase on the working electrode surface of a three-electrode system using gel entrapment. The sensor has been applied to determine the IC50 values of two known and one newly developed Alzheimer remedy. A simultaneous measurement with the photometric standard method shows the applicability of our method for fast drug screening.

Acetylcholinesterase↗

PubMed2000

[Changes of nitric oxide and endothelin plasma levels and effects of hormone replacement therapy in postmenopausal women].

OBJECTIVES: To investigate the changes of plasma levels of nitric oxide(NO) and endothelin (ET) when the estrogen level dropped and to assess the effects of hormone replacement therapy (HRT) on NO, ET plasma levels in postmenopausal women. METHODS: Twenty-six women with regular menses (regular mense group), twenty-eight perimenopausal women with climacteric symptoms (perimenopausal group), seventy healthy postmenopausal women (postmenopausal group) were in duded in this study. Thirty postmenopausal volunteers received oral conjugated estrogen/medroxyprogesterone acetate (post menopause group I) and twenty others took only calcium (post menopause group II) for 6 months. Plasma NO, ET, follicle-stimulation hormone (FSH) and estradiol (E2) levels were measured for all the women. RESULTS: The levels of NO were significantly lower in perimenopausal group (23.8 +/- 15.1) mumol/L and postmenopausal group (20.0 +/- 12.1) mumol/L than those of regular mense group (33.2 +/- 15.5) mumol/L (P < 0.05, P < 0.01). The mean concentrations of ET were significantly higher in both of perimenopausal (59.3 +/- 14.2) pg/L and postmenopausal groups (65.3 +/- 16.2) pg/L than those of regular mense group (51.1 +/- 15.6) pg/L (P < 0.01). Plasma NO (32.9 +/- 16.1) mumol/L and E2(47.5 +/- 12.9) pg/L values were significantly higher, and ET (52.2 +/- 12.0) pg/L values significantly lower than baselines of NO (20.3 +/- 11.1) mumol/L, E2(7.9 +/- 4.8) ng/Land ET(62.6 +/- 18.9) pg/L, respectively, in menopause group I after treatment for 6 months (P < 0.01). There was no difference in NO, ET and E2 concentrations in menopause group II before and after taking calcium for 6 month (P > 0.05). E2 had a significant positive correlation with NO and significant negative correlation with ET and FSH. CONCLUSIONS: HRT results in an increased level of NO and decreased level of ET in postmenopausal women. This may be one of the mechanisms by which HRT provides cardiovascular benefit.

Adult↗

PubMed1999

The soluble sperm factor that causes Ca2+ release from sea-urchin (Lytechinus pictus) egg homogenates also triggers Ca2+ oscillations after injection into mouse eggs.

Cytosolic extracts of boar sperm contain a soluble phospholipase C (PLC) activity that induces Ca2+ release in sea-urchin (Lytechinus pictus) egg homogenates and an uncharacterized protein factor that causes Ca2+ oscillations when injected into mammalian eggs. In the present study we fractionated boar sperm extracts on three different FPLC chromatographic columns and found that the fractions that caused maximal Ca2+ release in sea-urchin egg homogenates were also the ones that triggered Ca2+ oscillations in mouse eggs. Our data suggests that the sperm factor which triggers Ca2+ oscillations in eggs contains a PLC and not the 33 kDa glucosamine deaminase previously suggested to be one its components.

Animals↗

PubMed1999

RBP1 induces growth arrest by repression of E2F-dependent transcription.

Growth arrest and cell cycle progression are regulated by the retinoblastoma tumour suppressor pRB and related proteins p130 and p107 that bind to and inhibit the E2F family of transcription factors. Although the precise mechanism of this inhibition remains to be established, previous studies indicated the presence of transcriptional repression activity in the 'pocket' of RB family members. We show here that RBP1, a known pRB pocket-binding protein, possesses transcriptional repression activity and associates with p130-E2F and pRB-E2F complexes specifically during growth arrest. Overexpression of RBP1 both inhibited E2F-dependent gene expression and suppressed cell growth. Thus repression of E2F-dependent transcription by RBP1 via RB family members may play a central role in inducing growth arrest.

Animals↗

PubMed1999

Cyclic pentapeptides of chiral sequence DLDDL as scaffold for antagonism of G-protein coupled receptors: synthesis, activity and conformational analysis by NMR and molecular dynamics of ITF 1565 a substance P inhibitor.

Under the hypotheses of a structurally related binding site for antagonists of G-protein coupled receptors and the ability of cyclic pentapeptides of chiral sequence D1L2D3D4L5 to form rigid structures with which probe the pharmacophoric specificity of these receptors, inhibitors of substance P were designed based on available structure-activity relationships. ITF 1565, cyclo[D-Trp1-Pro2-D-Lys3-D-Trp4-Phe5], antagonized substance P activity mediated by type 1 neurokinin receptor (NK1) whereas it acted weakly against NK2 and did not inhibit endothelin at all. The preferential conformation of the peptide was obtained from nmr spectroscopy and computer calculations, and shown to contain the same beta II-turn and gamma'-turn found in other cyclic pentapeptides with the same chiral sequence. The structure of the peptide was compared with that of the beta-D-glucose molecule that has been proposed as a semirigid scaffold for antagonists of G-protein coupled receptors. The gamma'-turn of the cyclic peptide superimposed well with beta-D-glucose in the chair conformation. Furthermore, when the side chains were considered, the aromatic groups of the two molecules were found to generally overlap. These results support the view of G-protein coupled receptors as possessing structurally similar binding sites for antagonists and suggest that cyclic pentapeptides of chiral sequence D1L2D3D4L5 may be useful as semirigid scaffolds for the design of antagonists of this family of receptors.

Animals↗

PubMed1999

Direct evidence for native CD4 oligomers in lymphoid and monocytoid cells.

CD4 is expressed by T lymphocytes and monocytes and is generally considered a monomer even though its structure was originally modelled on the REI Bence-Jones homodimer. However, native CD4 was demonstrated as both monomer and dimers of 55 and 110 kDa in lymphoid and monocytoid cells by immunoprecipitation and immunoblotting after solubilization with alkylating (iodoacetamide) or reducing (dithiothreitol, 2-mercaptoethanol) reagents. Full reduction yielded only the 55-kDa monomeric form. Purified CD4 oligomers from CEM-T4 cells were also resolved as homodimers by MALDI-Tof mass fingerprinting after tryptic digestion. Cell treatment with the membrane impermeable, free-thiol reactive, 5,5'-dithiobis-2-nitrobenzoic acid enhanced cell surface CD4 dimers and tetramers. The interaction sites producing dimerization were probably in the D4 domain as OKT4 inhibited self association of recombinant CD4 (rCD4). Oligomerization of rCD4 by glutathione and thioredoxin indicates that thiol exchange interactions were responsible. Enhanced CD4 dimer expression was also observed after PMA (20 ng/ml) activation of THP-1 cells. These findings demonstrate that different quaternary forms of CD4 such as monomers, homodimers and tetramers are expressed by T lymphocytes and monocytes/macrophages.

Amino Acid Sequence↗

PubMed1999

Recognition and quantitation of cis-vaccenic and eicosenoic fatty acids in olive oils by 13C nuclear magnetic resonance spectroscopy.

The presence of 11-cis monoenoic fatty acids was detected in olive oil samples by means of 13C nuclear magnetic resonance spectroscopy, and the positional isomery on the glycerol backbone was derived. The 11-cis vaccenic and eicosenoic fatty acid resonances were recognized and the amounts of the fatty acids quantified. For comparison purposes, a quantitative analysis was also made by gas chromatography.

Carbon Isotopes↗

PubMed1999

Traumatic optic neuropathy: result in 45 consecutive surgically treated patients.

The management of traumatic optic neuropathy remains controversial. In this report, we present the results of 45 patients treated with extracranial optic nerve decompression after at least 12 to 24 hours of corticosteroid therapy without improvement. Vision improved in 32 patients after surgery (71%), and the mean percentage of improvement from preoperative visual deficit was 40.7% +/- 6.9% (median improvement 41.2%). Worsening of vision occurred in none of the patients as a result of the surgery, and no intraoperative or postoperative complications were encountered. We present a treatment protocol for traumatic optic neuropathy with the use of megadose corticosteroids and optic nerve decompression.

Adolescent↗

PubMed1999

Uterine artery embolization for the treatment of uterine leiomyomata midterm results.

INTRODUCTION: The authors review their midterm experience with uterine artery embolization for the treatment of uterine fibroids. MATERIALS AND METHODS: Sixty patients were referred for permanent polyvinyl alcohol (PVA) foam particle uterine artery embolization during an 18-month period. Detailed clinical follow-up and ultrasound follow-up were obtained. RESULTS: Bleeding was a presenting symptom in 56 patients and pain was a presenting symptom in 47 patients. All patients underwent a technically successful embolization. One of the patients underwent unilateral embolization. Fifty-nine patients underwent bilateral embolization. Of all patients undergoing bilateral embolization, at last follow-up (mean, 16.3 months), 81% had their uterus and had moderate or better improvement in their symptoms. Ninety-two percent of these patients also had reductions in uterine and dominant fibroid volumes. Overall, the mean uterine and dominant fibroid volume reduction were 42.8% and 48.8%, respectively (mean follow-up, 10.2 months). One infectious complication that necessitated hysterectomy occurred. CONCLUSION: Uterine artery embolization for the treatment of uterine fibroids is a minimally invasive technique with low complication rates and very good clinical efficacy.

Adult↗

PubMed1999

RBP1 recruits both histone deacetylase-dependent and -independent repression activities to retinoblastoma family proteins.

Retinoblastoma (RB) tumor suppressor family proteins block cell proliferation in part by repressing certain E2F-specific promoters. Both histone deacetylase (HDAC)-dependent and -independent repression activities are associated with the RB "pocket." The mechanism by which these two repression functions occupy the pocket is unknown. A known RB-binding protein, RBP1, was previously found by our group to be an active corepressor which, if overexpressed, represses E2F-mediated transcription via its association with the pocket. We show here that RBP1 contains two repression domains, one of which binds all three known HDACs and represses them in an HDAC-dependent manner while the other domain functions independently of the HDACs. Thus, RB family members repress transcription by recruiting RBP1 to the pocket. RBP1, in turn, serves as a bridging molecule to recruit HDACs and, in addition, provides a second HDAC-independent repression function.

Binding Sites↗

PubMed1999

Extracranial optic nerve decompression: a 10-year review of 92 patients.

Over a 10-year period the authors have performed 92 transethmoidal optic nerve decompressions for the treatment of visual loss due to various pathological processes, including 45 cases of trauma, 32 cases of neoplasm, 2 cases of bacterial pansinusitis, 5 cases of sphenoethmoidal mucocele, 4 cases of aspergillosis (all were immunocompetent patients), 2 cases of Wegener's granulomatosis, and 2 cases of sarcoidosis. Forty-eight patients (52%) had preoperative visual acuity of light perception or better, and in 44 patients (48%) the preoperative vision was no light perception. Sixty-five patients (71%) achieved improvement of vision postoperatively. Twenty-four patients (26%) had no change in vision and 3 patients (3%) had deterioration of vision after surgery. The mean percentage of improvement was 40.7% +/- 6.9% in the trauma group, 61.6% +/- 23.2% in the neoplasm group, 66.4% +/- 25.2% in the infectious/mucocele group, and only one patient in the inflammatory group had slight visual improvement from no light perception to counting fingers. Extracranial optic nerve decompression can result in the improvement of visual function in some patients with optic nerve injury from various causes.

Adolescent↗

PubMed1998

Signal-dependent trafficking of beta-amyloid precursor protein-transferrin receptor chimeras in madin-darby canine kidney cells.

We have investigated the intracellular trafficking of a chimeric molecule consisting of the cytoplasmic domain of the beta-amyloid precursor protein (APP) and the transmembrane region and external domain of the human transferrin receptor (TR) in Madin-Darby canine kidney cells. Newly synthesized APP-TR chimeras are selectively targeted to the basolateral surface by a tyrosine-dependent sorting signal in the APP cytoplasmic tail. APP-TR chimeras are then rapidly internalized from the basolateral surface and a significant fraction ( approximately 20-30%) are degraded. Morphological studies show that APP-TR chimeras internalized from the basolateral surface are found in tubulo-vesicular endosomal elements, internal membranes of multivesicular bodies, and lysosomes. APP-TR chimeras are also found in 60-nm diameter vesicles previously shown to selectively deliver wild-type TR to the basolateral surface; this result is consistent with the fact that 90% of internalized chimeras that are not degraded are selectively recycled back to the basolateral surface. APP-TR chimeras internalized from the apical surface are selectively transcytosed to the basolateral surface underscoring the importance of basolateral sorting in the endocytic pathway for maintaining the polarized phenotype. Tyr-653, an important element of the YTSI internalization signal in the APP cytoplasmic domain, is required for basolateral sorting in the biosynthetic and endocytic pathways. However, the structural features for basolateral sorting differ from those required for internalization.

Amino Acid Sequence↗

PubMed1998

Expression of the fgl2 and its protein product (prothrombinase) in tissues during murine hepatitis virus strain-3 (MHV-3) infection.

Murine Hepatitis Virus Strain 3 (MHV-3) produces fulminant hepatitis with 80-90% mortality in Balb/cJ mice. Previous studies in our laboratory have shown that peritoneal macrophages from MHV-3 infected mice produce a procoagulant (PCA) which has the ability to cleave prothrombin to thrombin (prothrombinase) encoded by the gene fgl2 located on chromosome 5. PCA accounts for sinusoidal thrombosis and hepatic necrosis and the necrosis and mortality can be prevented by treatment of animals with a monoclonal antibody to PCA. These present studies were designed to examine the expression of this gene (mRNA by Northern analysis and in situ hybridization) and the gene product PCA (immunochemistry) in tissues recovered from MHV-3 infected Balb/cJ mice in an attempt to explain the liver specific nature of MHV-3 disease. Fgl2 gene expression was detected as early as 8 hours after MHV-3 infection which persisted to 48 hours in the liver, spleen and lungs whereas no gene expression was seen in the brain or kidneys despite the fact that equivalent viral titers were detected in all tissues at all times. In the liver, fgl2 gene expression was confined to endothelial and Kupffer cells with no expression in hepatocytes. Immunochemistry localized the PCA protein to Kupffer cells and endothelial cells and necrotic foci within the liver. No PCA protein was detected by immunochemistry in any other tissues at any time during the course of MHV-3 infection. These results explain the liver specific nature (fulminant hepatitis) of MHV-3 infection and provides further evidence for the role of PCA in the pathogenesis of fulminant hepatitis. MHV-3 induces selective transcription of the gene fgl2 and only hepatic reticuloendothelial cells produce functional protein (PCA) which is known to account for fulminant hepatic failure produced by MHV-3.

Animals↗

PubMed1998

Functional status and well-being in patients with glaucoma as measured by the Medical Outcomes Study Short Form-36 questionnaire.

PURPOSE: This study aimed to determine whether patients with glaucoma have different functional status and well-being than patients without glaucoma. DESIGN: Prospective case-control study. PARTICIPANTS: The study population was recruited from 2 university-based glaucoma clinical practices and a university-based general ophthalmology clinic and consisted of 121 patients with open-angle glaucoma, 42 with diagnosis of glaucoma suspect, and 135 with no chronic ocular conditions except cataract. INTERVENTION: Administration of Medical Outcomes Study 36-item short-form survey (SF-36) was performed. Demographic information, medical history, and responses to the SF-36 questionnaire were elicited by an interviewer. Medical record review was performed to obtain clinical examination data and to substantiate the medical and demographic data obtained by the interviewer. MAIN OUTCOME MEASURES: The SF-36 scores by diagnostic group, demographic characteristics, and medical history were examined. Secondary outcome measures were SF-36 scores in patients with glaucoma by visual field impairment and glaucoma medication use. RESULTS: Patients with glaucoma consistently had lower scores, control subjects had higher scores, and glaucoma suspects had scores intermediate between the two groups. After adjusting for the possible influence of all the other covariate factors, glaucoma was found to be a strong predictor of lower SF-36 scores. CONCLUSION: Patients with glaucoma have lower scores, indicating less-functional status, than patients without glaucoma as tested by the SF-36 survey questionnaire.

Adult↗

PubMed1998

23Na NMR studies of Na-DNA in the solid state.

23Na MAS, CP/MAS and quadrupole nutation NMR spectra and the 23Na spin-lattice relaxation times in Na-DNA with and without competing species (Mg2+, ethidium bromide and [Ru(phen)3]2+) reveal the presence of two sodium sites with different NMR parameters. While in the presence of Mg2+, sodium resides far from the surface of the DNA molecule, ethidium bromide and [Ru(phen)3]2+ displace sodium closer towards the surface.

Animals↗

PubMed1998

Repair of orbital blow-out fractures with nasoseptal cartilage.

The goals of reconstruction in orbital blow-out fractures are to restore floor continuity, provide support of orbital contents, and prevent fibrosis of soft tissues. Although ease of use has popularized alloplasts, autogenous material provides greater biocompatibility and results in low rates of infection, extrusion, and migration. Nasoseptal cartilage is an easily accessible, abundant, autogenous source that provides support to the orbital floor and minimal donor site morbidity. Thirteen patients who presented with orbital blow-out fractures underwent reconstruction with nasoseptal cartilage. Follow-up at 3 months to 4 years shows one patient with persistent manifest enophthalmos requiring further augmentation. There were no recipient or donor site complications. Nasoseptal cartilage is an underutilized and superior material for reconstruction of orbital blow-out fractures.

Adolescent↗