Behavioral calibration of eye movement recording systems using moving targets

Equipment used to measure eye movements must generally be calibrated to the individual subject. Some methods of measuring eye position are quite non-linear, requiring that the system's output be linearized. We describe an approach of behavioral calibration and linearization that utilizes tracking of moving targets. The key aspect of this approach is to use tracking of horizontally moving targets to calibrate vertical eye position and vice versa. This method is especially convenient for use with cats, whose fixation of eccentric stationary targets is often unreliable. It allows one to obtain an accurate calibration without having to judge whether or not tracking saccades reliably hit the target.

Molecular views and measurements of hemostatic processes using atomic force microscopy

Hemostasis and thrombosis are highly complex and coordinated interfacial responses to vascular injury. In recent years, atomic force microscopy (AFM) has proven to be a very useful approach for studying hemostatic processes under near physiologic conditions. In this report, we review recent progress in the use of AFM for studying hemostatic processes, including molecular level visualization of plasma proteins, protein aggregation and multimer assembly, and structural and morphological details of vascular cells under aqueous conditions. AFM offers opportunities for visualizing surface-dependent molecular and cellular interactions in three dimensions on a nanoscale and for sensitive, picoNewton level, measurements of intermolecular forces. AFM has been used to obtain molecular and sub-molecular, resolution of many biological molecules and assemblies, including coagulation proteins and cell surfaces. Surface-dependent molecular processes including protein adsorption, conformational changes, and subsequent interactions with cellular components have been described. This review outlines the basic principles and utility of AFM for imaging and force measurements, and offers objective perspectives on both the advantages and disadvantages. We focus primarily on molecular level events related to hemostasis and thrombosis, particularly coagulation proteins, and blood platelets, but also explore the use of AFM in force measurements and surface property mapping.

Coherent control of phonons probed by time-resolved x-ray diffraction

Time-resolved x-ray diffraction with picosecond temporal resolution is used to probe the product state of a coherent control experiment in which a single acoustic mode in a bulk semiconductor is driven to large amplitude or canceled out. It is demonstrated that by shaping ultrafast acoustic pulses one can coherently control the x-ray diffraction efficiency of a crystal on the time scale of a vibrational period, with application to coherent switching of x-ray beams.

CD4+ T helper 1 cells facilitate regression of murine Lyme carditis

Murine Lyme borreliosis, caused by infection with the spirochete Borrelia burgdorferi, results in acute arthritis and carditis that regress as a result of B. burgdorferi-specific immune responses. B. burgdorferi-specific antibodies can attenuate arthritis in mice deficient in both B cells and T cells but have no effect on carditis. Because macrophages comprise the principal immune cell in carditis, T-cell responses that augment cell-mediated immunity may be important for carditis regression. To investigate this hypothesis, we examined the course of Lyme carditis in mice selectively deficient in B cells or alphabeta T cells. Our results show that carditis regresses in B-cell-deficient B10.A(k) mice but not in alphabeta T-cell-deficient mice, independently of the mouse strain background. Despite prominent macrophage infiltrates, hearts from B. burgdorferi-infected alphabeta T-cell-deficient mice had less mRNA for tumor necrosis factor alpha as measured by reverse transcription-PCR compared to infected control mice. Anti-inflammatory cytokine mRNA levels were equivalent. Adoptive transfer of gamma interferon-secreting CD4+ T cells into infected alphabeta T-cell-deficient mice promoted carditis resolution. These results show that alphabeta T cells can promote resolution of murine Lyme carditis and are the first demonstration of a beneficial role for CD4+ T helper 1 cells in this disease.

Diagnostic efficacy of fluorescence cystoscopy for detection of urothelial neoplasms

BACKGROUND AND PURPOSE

A major problem diagnosing bladder cancer using conventional white-light cystoscopy is that flat and tiny papillary neoplasms can be overlooked. Fluorescence cystoscopy is based on the detection of protoporphyrin IX (PpIX)-induced fluorescence in urothelial neoplasms through the topical administration of 5-aminolevulinic acid (ALA). The diagnostic efficacy of fluorescence cystoscopy in urothelial neoplasms was evaluated in this study. The focus of this investigation was to ascertain whether fluorescence cystoscopy could make a major contribution to staging and improving the choice of adjuvant therapy after transurethral resection.

PATIENTS AND METHODS

A series of 62 patients with suspected bladder cancer were investigated by fluorescence cystoscopy. An intravesical instillation of ALA was conducted 2 hours prior to fluorescence. A total of 274 tissue samples were obtained from the fluorescing and nonfluorescing areas of the bladder.

RESULTS

The sensitivity and negative predictive value of fluorescence cystoscopy were 98.0% and 94.7%, respectively, but the specificity was low (42.9%). Among a total of 148 lesions of urothelial neoplasm, 58 foci (dysplasia in 5, carcinoma in situ in 19, stage Ta in 15, T1 in 15, above T2 in 4) that were invisible under white-light cystoscopy were detected by fluorescence cystoscopy. The final histopathologic status was changed in 45% of patients (28/62) according to this technique. Among these patients, eight (13%) needed additional therapy, including a radical cystectomy in one patient and intravesical therapy in 10.

CONCLUSIONS

The ALA-based fluorescence cystoscopy technique is a safe and simple procedure that enhances the detection of flat and papillary urothelial neoplasms. Moreover, it will be able to provide useful information that will enable proper staging and appropriate further treatment.

Structure of 4-diphosphocytidyl-2-C- methylerythritol synthetase involved in mevalonate- independent isoprenoid biosynthesis

The YgbP protein of Escherichia coli encodes the enzyme 4-diphosphocytidyl-2-C-methylerythritol (CDP-ME) synthetase, a member of the cytidyltransferase family of enzymes. CDP-ME is an intermediate in the mevalonate-independent pathway for isoprenoid biosynthesis in a number of prokaryotic organisms, algae, the plant plastids and the malaria parasite. Because vertebrates synthesize isoprenoid precursors using a mevalonate pathway, CDP-ME synthetase and other enzymes of the mevalonate-independent pathway for isoprenoid production represent attractive targets for the structure-based design of selective antibacterial, herbicidal and antimalarial drugs. The high-resolution structures of E. coli CDP-ME synthetase in the apo form and complexed with both CTP-Mg2+ and CDP-ME-Mg2+ reveal the stereochemical principles underlying both substrate and product recognition as well as catalysis in CDP-ME synthetase. Moreover, these complexes represent the first experimental structures for any cytidyltransferase with both substrates and products bound.

Molecular cloning, expression and characterization of the first three genes in the mevalonate-independent isoprenoid pathway in Streptomyces coelicolor

The mevalonate-independent biosynthetic pathway to isopentenyl diphosphate and dimethylallyl diphosphate, the universal precursors to the isoprenoids, operates in eubacteria, including Escherichia coli, in algae, and in the plastids of higher plants. A search of the Sanger Centre Streptomyces coelicolor genome database revealed open reading frames with ca. 40--50% identity at the deduced amino acid level to the first three E. coli enzymes of this pathway, corresponding to deoxyxylulose phosphate synthase, deoxyxylulose phosphate reductoisomerase and 2-C-methyl erythritol 4-phosphate cytidylyltransferase. The S. coelicolor genes have been cloned and expressed in E. coli, and the recombinant proteins characterized physically and kinetically. The presence of the corresponding enzyme activities in extracts of S. coelicolor CH999 further supports the operation of the mevalonate-independent pathway in this organism.

Effects of stimulation of AMP-activated protein kinase on insulin-like growth factor 1- and epidermal growth factor-dependent extracellular signal-regulated kinase pathway

AMP-activated protein kinase (AMPK) is tightly regulated by the cellular AMP:ATP ratio and plays a central role in the regulation of energy homeostasis. Previously, AMPK was reported to phosphorylate serine 621 of Raf-1 in vitro. In the present study, we investigated a possible role of AMPK in extracellular signal-regulated kinase (Erk) cascades, using 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR), a cell-permeable activator of AMPK and antisense RNA experiments. Activation of AMPK by AICAR in NIH-3T3 cells resulted in drastic inhibitions of Ras, Raf-1, and Erk activation induced by insulin-like growth factor 1 (IGF-1). Expression of an antisense RNA for the AMPK catalytic subunit decreased the AMPK activity and significantly diminished the AICAR effect on IGF-1-induced Ras activation and the subsequent Erk activation, indicating that its effect is indeed mediated by AMPK. Phosphorylation of Raf-1 serine 621, however, was not involved in AMPK-mediated inhibition of Erk cascades. In contrast to IGF-1, AICAR did not block epidermal growth factor (EGF)-dependent Raf-1 and Erk activation, but our results demonstrated that multiple Raf-1 upstream pathways induced by EGF were differentially affected by AICAR: inhibition of Ras activation and simultaneous induction of Ras-independent Raf activation. The activities of IGF-1 and EGF receptor were not affected by AICAR. Taken together, our results suggest that AMPK differentially regulate Erk cascades by inhibiting Ras activation or stimulating the Ras-independent pathway in response to the varying energy status of the cell.

Insulin-like growth factor-1 protects H9c2 cardiac myoblasts from oxidative stress-induced apoptosis via phosphatidylinositol 3-kinase and extracellular signal-regulated kinase pathways

Oxidative stress plays a critical role in cardiac injuries during ischemia/reperfusion. Insulin-like growth factor-1 (IGF-1) promotes cell survival in a number of cell types, but the effect of IGF-1 on the oxidative stress has not been elucidated in cardiac muscle cells. Therefore, we examined the role of IGF-1 signaling pathway in cell survival against H2O2-induced apoptosis in H9c2 cardiac myoblasts. H2O2 treatment induced apoptosis in H9c2 cells, and pretreatment of cells with IGF-1 suppressed apoptotic cell death. The antiapoptotic effect of IGF-1 was blocked by LY294002 (an inhibitor of phosphatidylinositol 3-kinase) and by PD98059 (an inhibitor of extracellular signal-regulated kinase (ERK)). The protective effect of IGF-1 was also blocked by rapamycin (an inhibitor of p70 S6 kinase). Furthermore, H9c2 cells stably transfected with constitutively active PI 3-kinase (H9c2-p110*) and Akt (H9c2-Gag-Akt) constructs were more resistant to H2O2 cytotoxicity than control cells. Although H2O2 activates both p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK), IGF-1 inhibited only JNK activation. Activated PI 3-kinase (H9c2-p110*) and pretreatment of cells with IGF-1 down-regulated Bax protein levels compared to control cells. Taken together, our results suggest that IGF-1 transmits a survival signal against oxidative stress-induced apoptosis in H9c2 cells via PI 3-kinase and ERK-dependent pathways and the protective effect of IGF-1 is associated with the inhibition of JNK activation and Bax expression.

No significant correlation exists between core promoter mutations, viral replication, and liver damage in chronic hepatitis B infection

Hepatitis B virus (HBV) core promoter mutants have been proposed to contribute to severe liver damage by increasing viral loads, but this has not yet been clearly shown. To examine the effects of core promoter mutants on viral load and liver damage, we first developed a polymerase chain reaction (PCR)-based semiquantitative HBV DNA detection method with a high sensitivity (able to detect as low as 10(3) molecules/mL). Then we cloned 12 predominant core promoter mutants from 41 chronic hepatitis B patients. The in vitro promoter and replication activities of these mutants were similar to those of wild-type virus. However, viral load was highly variable, and this was dependent on individual patients rather than mutant type. In addition, there was no mutant type that showed any unique correlation with alanine transaminase (ALT) levels. Viral load was not significantly correlated with ALT level in both cross-sectional and longitudinal studies. Quantitation of HBV levels also revealed no clear correlation between hepatitis B e antigen (HBeAg) status and viral load. Taken together, these results indicated that the replication activity of core promoter mutants has little effect on viral load, and that viral load does not correlate with the severity of liver damage or with HBeAg status.

Modulation of collagen-induced arthritis by IL-4 and dexamethasone: the synergistic effect of IL-4 and dexamethasone on the resolution of CIA

We investigated effects of IL-4, dexamethasone (DXM), and the combination of IL-4 and DXM, low- or high-dose, on collagen-induced arthritis (CIA) in DBA/1 mice and correlated severity of arthritis with changes in IL-10 and IFN-gamma. Compared with control mice, mice treated with IL-4 had increased IL-10 with the same degree of arthritis, whereas mice treated with high-dose DXM had decreased IL-10 and increased IFN-gamma production with less severe arthritis. Mice treated with low-dose DXM showed the absence of IL-10 and increased IFN-gamma production with a trend toward the resolution of arthritis. Mice treated with IL-4 and low-dose DXM had neither IL-10 nor IFN-gamma production but revealed less severe arthritis, compared with mice treated with low-dose DXM alone. These results suggest that the beneficial effects of high-dose DXM and the combination of IL-4 and DXM on CIA are independent of IL-10 and IFN-gamma.

A case of primary hepatic lymphoma with hepatitis C liver cirrhosis

Primary hepatic lymphoma is rare. The usual type is a large-cell, high-grade malignant B-cell lymphoma, although T-cell types have been described. Several cases of primary hepatic lymphoma of B-cell origin developing in patients with chronic hepatitis C virus infection have been reported. Recently, new findings have raised the question of the induction of lymphoma by hepatitis C virus. However, the causal relationship between hepatitis C viral infection and primary hepatic lymphoma remains obscure. This article reports a case of histologically proven primary hepatic lymphoma of T-cell origin, which was confined to the liver, in the setting of hepatitis C liver cirrhosis. This association has not previously been reported.

Crystal structure determination of aristolochene synthase from the blue cheese mold, Penicillium roqueforti

The 2.5-A resolution crystal structure of recombinant aristolochene synthase from the blue cheese mold, Penicillium roqueforti, is the first of a fungal terpenoid cyclase. The structure of the enzyme reveals active site features that participate in the cyclization of the universal sesquiterpene cyclase substrate, farnesyl diphosphate, to form the bicyclic hydrocarbon aristolochene. Metal-triggered carbocation formation initiates the cyclization cascade, which proceeds through multiple complex intermediates to yield one exclusive structural and stereochemical isomer of aristolochene. Structural homology of this fungal cyclase with plant and bacterial terpenoid cyclases, despite minimal amino acid sequence identity, suggests divergence from a common, primordial ancestor in the evolution of terpene biosynthesis.

Aristolochene synthase: purification, molecular cloning, high-level expression in Escherichia coli, and characterization of the Aspergillus terreus cyclase

Aristolochene synthase catalyzes the cyclization of farnesyl diphosphate (6) to (+)-aristolochene (1). The Aspergillus terreus enzyme has been purified 75-fold to homogeneity in six steps. Based on the sequence of 3 internal peptides obtained by Lys-C digestion of the native protein, a set of degenerate PCR primers was used to amplify a 550-bp segment of cDNA corresponding to a portion of the aristolochene synthase transcript. A second round of PCR using specific primers was used to prepare a (32)P-labeled 180-bp segment, which was used to screen an A. terreus cDNA library prepared using lambdaZapII, resulting in the identification and sequencing of the A. terreus aristolochene synthase cDNA. Aristolochene synthase was encoded by an open reading frame (ORF) of 960 bp, corresponding to a protein of 320 amino acids with a predicted M(D) of 36,480. Comparison of the A. terreus ORF with the sequence of the previously described aristolochene synthase from Penicillium roqueforti revealed a 66% of identity at the nucleic acid level and a 70% identity at the deduced amino acid level between the aristolochene synthases from the two different fungal sources. PCR was used to insert the A. terreus aristolochene synthase gene into the T7lac expression vector pET11a. Cloning of the resultant construct into Escherichia coli XL1-Blue and subcloning into the expression host E. coli BL21(DE3)/pLysS gave, after induction with IPTG, soluble aristolochene synthase as 5-10% of total protein. The recombinant aristolochene synthase, which was purified 13-fold to homogeneity, appeared to be identical in all respects with the native A. terreus enzyme, displaying essentially the same steady-state kinetic parameters, with a K(m) of 15 nM and k(cat) 0.015 s(-1). Using PCR to amplify the aristolochene synthase gene (Aril) from A. terreus genomic DNA revealed the presence of 2 introns, identical in relative location but different in both sequence and length compared to the corresponding Ari1 gene of P. roqueforti.

Properties of saccade-related neurons in the cat superior colliculus: patterns of movement fields and discharge timing

The discharge characteristics of saccade-related neurons in the superior colliculi (SC) of trained cats were investigated in order to understand the involvement of the SC in dynamic control of saccades. In particular, two aspects of saccade-related collicular activity in relation to visually guided saccades were quantitatively analyzed: the bounded pattern of amplitude tuning and the timing of neural activity in relation to saccade offset. In order to determine whether the amplitude tuning of SC cells is bounded or unbounded, we characterized it with a quantitative index, the unbounded-field (UF) index. Analysis of the characteristics of the distribution of this index, including the absence of unbounded fields for cells within the central 10 degrees, suggested that all cells form a single class and that apparent unbounded amplitude tuning is an artifact occurring when the range of gaze shift is truncated by restraining the head. This interpretation is supported by the results of a computer simulation based on truncation of gaze-shift range that closely replicated the experimental data. Analyses of relative location of peak motor activity in the spatial and temporal dimensions revealed that the peak discharge was more closely linked to the midpoint of the saccade than to the offset of saccade, regardless of the pattern of amplitude tuning. These results do not support the proposal advanced by the moving-hill hypothesis: the bounded pattern of amplitude tuning is inconsistent with rostral migration of the activity locus during execution of a saccade, and the relative location of the peak motor activity is inconsistent with the idea that the SC activity encodes dynamic motor error (the difference between desired and current gaze directions).

Paragonimus westermani: a cytosolic glutathione S-transferase of a sigma-class in adult stage

We purified cytosolic glutathione S-transferase (GST) of adult Paragonimus westermani monitoring its activity with 1-chloro-2,4-dinitrobenzene (CDNB). The enzyme was purified 18.4-fold to electrophoretic homogeneity with 21% recovery rate through a three-step procedure. The purified enzyme (Pw28GST) has a subunit molecular weight of 28 kDa with an isoelectric point at 4.6. Monoclonal antibody (anti-Pw28GST) against Pw28GST did not cross-react with GSTs from other helminths. cDNA library was constructed in lambdaZAP II bacteriophage and screened with anti-Pw28GST. The corresponding gene containing a single open reading frame of 804 bp encoded 211 amino acids. The predicted amino acid sequence exhibited a higher homology with catalytic domain near N-terminus of class sigma GSTs (58%) than with schistosome 28-kDa GSTs (45-41%) or with class sigma GSTs themselves (33-31%). The sequence contained both Tyr-6 and Tyr-10 that are highly conserved in mammalian and helminth GSTs. The apparent K(m) value of a recombinant enzyme was 0.78 mM. Both native and recombinant enzymes showed the highest activity against CDNB, relatively weak activity against ethacrynic acid and reactive carbonyls, and no activity against epoxy-3-(p-nitrophenoxy)-propane. The activities were inhibited by bromosulfophthalein, cibacron blue, and albendazole, but not by praziquantel. These findings indicate that adult P. westermani has a class sigma GST.

Anserine bursitis in patients with osteoarthritis of the knee

BACKGROUND

We sought to determine the frequency of anserine bursitis (AB) in Koreans with osteoarthritis (OA) of the knee and its relationship to age, sex, and radiographic severity of OA, and to evaluate its response to various forms of therapy.

METHODS

In a retrospective study, we reviewed the charts of patients with OA of the knee and graded the radiographic severity by the Kellgren-Lawrence grading scheme.

RESULTS

Of 62 patients, 29 had AB. No difference in age, sex, and radiographic severity was noticed between patients with AB and those without AB. Eleven of 12 patients who received a local injection of methylprednisolone plus lidocaine at the anserine bursa had relief, whereas 7 of 17 patients who received noninjection therapy for AB showed improvement.

CONCLUSIONS

Anserine bursitis is commonly found in Koreans with OA of the knee, and its presence is unrelated to age, sex, and radiographic severity. Local injection at the anserine bursa is more effective than noninjection therapy.

Time-resolved X-Ray diffraction from coherent phonons during a laser-induced phase transition

Time-resolved x-ray diffraction with picosecond temporal resolution is used to observe scattering from impulsively generated coherent acoustic phonons in laser-excited InSb crystals. The observed frequencies and damping rates are in agreement with a model based on dynamical diffraction theory coupled to analytic solutions for the laser-induced strain profile. The results are consistent with a 12 ps thermal electron-acoustic phonon coupling time together with an instantaneous component from the deformation-potential interaction. Above a critical laser fluence, we show that the first step in the transition to a disordered state is the excitation of large amplitude, coherent atomic motion.

Mannan-binding lectin (MBL)-associated plasma protein present in human urine inhibits calcium oxalate crystal growth

Mannan-binding lectin (MBL)-associated plasma protein (MAp19) is an alternatively spliced form of MBL-associated serine protease-2, a component of a complement activation cascade. We observed that MAp19 is excreted in human urine. Interestingly, the amount of MAp19 was higher in urine of renal cell carcinoma patients than healthy people. Pretreatment of urine dialysate with 50 mM EDTA increased the recovery of MAp19, suggesting that MAp19 is a calcium-binding protein. The recombinant MAp19 showed a strong inhibition of calcium oxalate crystal growth in vitro in a concentration-dependent manner. Thus, we conclude that MAp19 plays a role in the inhibition of calcium oxalate renal stone formation.

Phosphatidylinositol 3-kinase regulates differentiation of H9c2 cardiomyoblasts mainly through the protein kinase B/Akt-independent pathway

Phosphatidylinositol 3-kinase (PI3-kinase) is known to be a crucial regulator of muscle differentiation. However, its downstream pathway for this function is quite obscure. In this experiment we demonstrated the regulatory mechanism of the differentiation of H9c2 cardiomyoblasts, focusing on PI3-kinase, protein kinase B/Akt (PKB/Akt) and p42/44 mitogen-activated protein kinase (p42/44 MAPK). When H9c2 cells stably transfected with a constitutively active p110 (H9c2-p110*), a constitutively active PKB/Akt (H9c2-Akt), and an empty vector (H9c2-con) were induced to differentiate, H9c2-p110* cells differentiated fastest, followed by H9c2-Akt cells. H9c2-con cells differentiated at the slowest rate. Consistent with this result, LY294002 completely blocked differentiation of all these transfected cell lines, whereas PD098059 had no effect on their differentiation. When H9c2-p110* cells were transiently transfected with a dominant negative form of PKB/Akt, differentiation was not affected. Taken together, we concluded that PI3-kinase, but not p42/44 MAPK, regulates differentiation of H9c2 cardiomyoblasts mainly through the PKB/Akt-independent pathway.

The regulatory mechanism of phosphatidylinositol 3-kinase by insulin in 3T3 L1 fibroblasts: phosphorylation-independent activation of phosphatidylinositol 3-kinase

Phosphatidylinositol (PI) 3-kinase plays an important role in transducing the signals of various growth factor receptors. However, the regulatory mechanism of PI3-kinase activity by these growth factor receptors is not completely understood. Therefore, we attempted to clarify the regulatory mechanism of PI3-kinase using insulin and 3T3 L1 fibroblasts. Our results showed that insulin stimulated PI3-kinase activity seven-fold and concomitantly phosphorylated a p85 subunit at the tyrosine residue. However, this tyrosine phosphorylation was not significant in the activation of PI3-kinase as the PI3-kinase pulled down by the overexpressed GST-p85 fusion protein showed as high an activity as the immunoprecipitated one. The p110 subunit was phosphorylated at both serine and tyrosine residues without insulin treatment. Since the phosphorylation state was not changed by insulin. The results suggested that phosphorylation of the p110 subunit does not control PI3-kinase activity. Finally, it was shown that the insulin receptor substrate-1 (IRS-1) binding to PI3-kinase was not sufficient for full activation because the amount of IRS-1 pulled down by the GST-p85 fusion protein reached almost maximum, after incubation with insulin-treated cell lysates for 20 min, whereas PI3-kinase activity reached its maximum only after incubation for 5 h. All results suggest that the phosphorylation of p85 subunit at tyrosine residues and phosphorylation of p110 subunit at tyrosine or serine residues are not functionally significant in the regulation of PI3-kinase activity. They also suggest that P13-kinase is needed to bind to other protein(s) as well as the insulin receptor substrate-1 for full activation.

Cloning and characterization of novel disintegrins from Agkistrodon halys venom

Snake venom disintegrins act as potent inhibitors of platelet aggregation. In this report, we isolated genes encoding novel members of disintegrins through the screening of Agkistrodon halys venom gland cDNA library. Subsequent characterization of positives revealed the presence of distinct disintegrins named salmosinl, 2, and 3, each containing a characteristic RGD/KGD sequence essential for the binding to integrins. Whereas salmosinl was identical to previously described salmosin purified from A. halys venom, salmosin2 and salmosin3 were predicted to be a novel, 73 amino acid protein with a KGD sequence, and an 80 amino acid protein with an additional 7th disulfide bond, respectively. Taken together, this is the first report describing 3 unique disintegrins, namely, salmosinl with RGD, salmosin2 with KGD and salmosin3 with 7 disulfide bonds are found in a single species of venom. Subsequently, to compare the platelet aggregation inhibitory potential of the recombinant protein with that of natural protein, salmosinl was expressed in E. coli and purified to homogeneity. Recombinant and natural salmosin1 inhibited the binding of alphaIIbbeta3 to fibrinogen with an almost identical IC50 value of 2.2 nM and 4.5 nM respectively. Moreover, recombinant salmosinl displayed an IC50 value approximately 5-fold lower than flavoridin, which was previously described as the most potent venom disintegrin so far. In conclusion, we identified 3 disintegrins with distinct properties through the molecular cloning approach and found that the recombinant salmosinl retained one of the most potent alphaIIbbeta3 antagonist activity.

Evidence that acetyl-CoA carboxylase isoforms play different biological roles in H9c2 cardiomyocyte

The present work was performed to identify the possible roles of acetyl-CoA carboxylase isoforms (ACC-alpha and ACC-beta). Two forms show 70% amino acid identity, but N-terminal regions share no homology, indicating that these may be uniquely related to the specific role of each ACC form. Thus, we investigated whether introduction of the exogenous ACC N-terminus into H9c2 cardiomyocytes that express both ACC forms causes a noticeable change in a specific pathway of fatty acid metabolism. The effect of ACC-alpha N-terminus overexpression was specific to the fatty acid synthesis rate resulting in an 80% induction, whereas overexpression of the ACC-beta N-terminus increased fatty acid oxidation rate 50% without affecting the fatty acid synthesis rate. These results suggest that ACC-alpha and beta are involved in the regulation of fatty acid synthesis and oxidation, respectively, and that the N-terminus plays an important role in the process. We further demonstrated that novel proteins specifically bound to the ACC N-terminus. This interaction may mediate the involvement of each ACC form in different cellular activities.

Rapid increase of cytosolic content of acetyl-CoA carboxylase isoforms in H9c2 cells by short-term treatment with insulin and okadaic acid

Mammalian acetyl-CoA carboxylase (ACC) is present in two isoforms, alpha and beta, both of which catalyze formation of malonyl-CoA by fixing CO2 into acetyl-CoA. ACC-alpha is highly expressed in lipogenic tissues whereas ACC-beta is a predominant form in heart and skeletal muscle tissues. Even though the tissue-specific expression pattern of two ACC isoforms suggests that each form may have a distinct function, existence of two isoforms catalyzing the identical reaction in a same cell has been a puzzling question. As a first step to answer this question and to identify the possible role of ACC isoforms in myogenic differentiation, we have investigated in the present study whether the expression and the subcellular distribution of ACC isoforms in H9c2 cardiac myocyte change so that malonyl-CoA produced by each form may modulate fatty acid oxidation. We have observed that the expression levels of both ACC forms were correlated to the extent of myogenic differentiation and that they were present not only in cytoplasm but also in other subcellular compartment. Among the various tested compounds, short-term treatment of H9c2 myotubes with insulin or okadaic acid rapidly increased the cytosolic content of both ACC isoforms up to 2 folds without affecting the total cellular ACC content. Taken together, these observations suggest that both ACC isoforms may play a pivotal role in muscle differentiation and that they may translocate between cytoplasm and other subcellular compartment to achieve its specific goal under the various physiological conditions.

Heterogeneous HBV mutants coexist in Korean hepatitis B patients

Although many hepatitis B virus (HBV) mutants have been found in all open reading frames since the precore defective mutant was initially reported, systematic investigations of diverse HBV mutant populations in hepatitis B patients have not been performed. Therefore, we examined whether heterogeneous mutant populations simultaneously exist in Korean hepatitis B patients. In order to detect hepatitis B virus mutants, we amplified a conserved core region and a surface antigen region of HBV DNA by PCR from sera of 27 Korean chronic hepatitis B patients, and then performed single strand conformational polymorphism analysis followed by DNA sequencing analysis. The results showed that heterogeneous HBV mutants in both regions were present in a single as well as in various hepatitis B patients. Sequence analysis revealed a defective interfering particle with missense mutation in the core region. We also found that two subtypes of adr and adw coexisted in a single patient. In addition, a point mutation causing a stop codon in the surface antigen region was observed. We are further analyzing the clinical implications of HBV mutants to identify their roles in the pathogenesis of chronic hepatic disorders induced by HBV.

Modulation of murine Lyme borreliosis by interruption of the B7/CD28 T-cell costimulatory pathway

Recent studies have implicated cytokines associated with Th2 cells in the genetic resistance to murine Lyme borreliosis. Because the B7/CD28 costimulatory pathway has been shown to influence the differentiation of Th-cell subsets, we investigated the contribution of the B7 molecules CD80 and CD86 to the Th2 cytokine profile and development of arthritis in BALB/c mice infected with Borrelia burgdorferi. Effective blockade of CD86/CD28 interaction was demonstrated by elimination of interleukin 4 (IL-4) and upregulation of gamma interferon (IFN-gamma) responses by B. burgdorferi-specific T cells and by reduction of B. burgdorferi-specific immunoglobulin G. Despite the shift toward a Th1 cytokine pattern, which others have associated with disease susceptibility, the severity of arthritis was unchanged. Moreover, combined CD80/CD86 blockade by using anti-CD80 and anti-CD86 monoclonal antibodies or CTLA-4Ig enhanced IFN-gamma production over that seen with CD86 blockade alone, yet augmentation of this Th1-associated cytokine did not enhance disease. These results demonstrate that IL-4 production by T cells in B. burgdorferi-infected BALB/c mice is dependent upon CD86/CD28 interaction and that this cytokine does not contribute significantly to host resistance to the development of arthritis. In addition, combined CD80/CD86 blockade resulted in preferential expansion of IFN-gamma-producing T cells in B. burgdorferi infection, suggesting that costimulatory pathways other than B7/CD28 may contribute to T-cell activation during continuous antigen stimulation. These studies may provide insight into the role of the B7/CD28 pathway in other infectious and autoimmune diseases in which deviation of Th cell immune responses occurs and antigen is persistently present.

Insulin has a limited effect on the cell cycle progression in 3T3 L1 fibroblasts

Insulin has pleiotropic effects on the regulation of cellular growth, differentiation, and metabolism. The biochemical events ultimately leading to cell proliferation after insulin treatment have been demonstrated in detail by numerous research groups. However, depending on cell types, it has been shown that insulin has various effects on cell proliferation. Therefore, we attempted to more critically evaluate the effect of insulin on cell proliferation in 3T3 L1 fibroblasts. In this study, we investigated insulin's effect on cell proliferation by using [3H]thymidine incorporation, flow cytometry, and cell counting. In 3T3 L1 fibroblasts studied in 0.5% serum, insulin induced a two-fold increase in [3H]thymidine incorporation over at 48 h, and the maximal rate of DNA synthesis was observed during 8-12 h incubation. The flow cytometric analysis also showed that insulin increased the cell population in the S phase. After insulin treatment for 48 h, cell numbers increased approximately 45% in comparison with 0.5% serum control. Cell division was found to occur only once in 60 h after staining 3T3 L1 fibroblasts with carboxyfluorescein diacetate succinimidyl ester (CFSE). Taken together, this data indicates that insulin stimulated the transit from the G0/G1 to S phase, progressed the cell cycle through the G2/M phase, and increased the cell number. However, under our experimental conditions, cells divided only once in 60 h in the presence of insulin.

T-helper-cell cytokines in the early evolution of murine Lyme arthritis

Genetic susceptibility to murine Lyme arthritis has been correlated with the dominance of T-helper (Th1)- or Th2-cell-associated cytokines. To determine when commitment of the Th cell phenotype occurs, we examined the kinetics of gamma interferon (IFN-gamma) and interleukin-4 (IL-4) production by lymph node T cells of disease-susceptible C3H/HeN and disease-resistant BALB/c mice from days 2 through 30 of infection, a period encompassing the evolution of disease and early regression. BALB/c mice produced more IFN-gamma on day 2 of infection than did C3H/HeN mice, whereas IL-4 was first detected on day 14. In contrast, only IFN-gamma could be detected in C3H/HeN mice, and the levels steadily increased from day 2 to surpass those seen in BALB/c mice by day 14 of infection. Despite the difference in cytokine profiles, both BALB/c and C3H/HeN mice developed comparable arthritis assessed at 14 days of infection. Arthritis regressed by day 30 in BALB/c mice but persisted in C3H/HeN mice. These studies are the first to demonstrate that the Th2 response to Borrelia burgdorferi infection of BALB/c mice is preceded by a Th1 cytokine response. Moreover, the timing of the appearance of IL-4 suggests that its primary effect is not in preventing disease, as suggested by others, but, rather, in hastening the resolution of inflammation. The implications of these findings for the orchestration of host defense against B. burgdorferi infection are discussed.

Sensitive measurement of nonlinear refraction and two-photon absorption by spectrally resolved two-beam coupling

A simple and very sensitive method for determining refractive and absorptive nonlinearities based on spectral resolution of two-beam coupling is demonstrated. Nonlinear phase shifts as small as ~10(-6) rad and two-photon absorption coefficients as small as 10(-4) cm/GW are readily observed by use of this technique with nanojoule pulses from a mode-locked laser.

Primers determine the sensitivity of PCR-mediated hepatitis B virus DNA detection and pretreatment of PCR mixture with 8-methoxypsoralen eliminates false-positive results

Most methods for the diagnosis of hepatitis B virus (HBV) infection largely depend on viral DNA detection by polymerase chain reaction (PCR) or radioimmunological assay of viral antigens or antibodies. The quality assurance program recently established in Europe reported that PCR-mediated HBV DNA detection methods used in many laboratories produced a high rate of false-positive and false-negative results. Thus, we attempted to improve the conditions of current PCR methods for detection of HBV DNA. In the present study, we applied a recently developed method of releasing HBV DNA from virion by NaOH treatment of patient serum. Using four different primer sets specific to the HBV core region, we found that the sensitivity of first-round PCR can be improved by more than two orders of magnitude depending on the primers. The second round of PCR using nested primers was sensitive enough to detect up to 10(-6) pg of the HBV DNA, which is equivalent to approximately 3 copies of the HBV genome. Among the approximately 800 HBV-infected patient sera investigated in our laboratory, more than 60% of the tested samples gave positive results in the first-round PCR. The rate of positive results obtained using our experimental conditions is very high in comparison with other reports. The reamplification of the first-round PCR reaction mixture with the nested primers produced practically 100% positive results. For diagnosis of HBV infection, we routinely used 1 microliter of patient serum, which was found to be optimum in our laboratory. Surprisingly, from 20% of our positive results, even serum diluted to 1/100 (0.01 microliter) produced a stronger signal than 1 microliter. This observation suggests that direct PCR amplification of HBV DNA released from serum by NaOH treatment has to be compensated by other DNA detection methods for correct quantitation. In order to eliminate the false positive signal resulting from the carry-over due to massive screening of a large number of samples, PCR reaction mixture containing 8-methoxypsoralen was exposed to ultraviolet light prior to thermal cycle amplification. This exercise did not decrease the sensitivity of the detection method, but almost completely removed the false positive results caused by contaminated templates. We are in the process of improving PCR-mediated HBV DNA detection methods to attain more reliable and easily applicable methods.

G alpha(i-2) mediates renal LLC-PK1 growth by a Raf-independent activation of p42/p44 MAP kinase

The protooncogene G alpha(i-2) plays a pivotal role in signaling pathways that control renal cell growth and differentiation. Mitogen-activated protein kinases (MAPKs) are potential downstream effectors for G alpha(i-2) in these pathways. In predifferentiated LLC-PK1 renal cells, the temporal maximal expression of G alpha(i-2) coincided with maximal activation of MAPK(p42/p44). By contrast, pertussis toxin treatment of these cells inhibited cell growth and reduced MAPK(p42/p44) activity by 30%. These findings reflected upstream activation of MAPK kinase (MEK1), as transient transfection of cells with a plasmid encoding a constitutively active form of MEK1 increased MAPK(p42/p44) activity and cell growth, whereas treatment with PD-098059, an inhibitor of MEK1 activity, reduced MAPK(p42/p44) activity and cell growth. Expression of a guanosinetriphosphatase (GTPase)-deficient G alpha(i-2) in these cells increased MAPK(p42/p44) activity and correspondingly reduced cell doubling time from 24 to 10 h without altering the activity of Raf-1 or c-Jun/stress-activated protein kinases (SAPKs). By contrast, expression of a GTPase-deficient G alpha(i-3) in these cells reduced both their cell doubling time by 30% and MAPK(p42/p44) activity by 60%. As the known MEKK isoforms (MEKK1, -2, and -3) can also activate SAPKs, these findings suggest the GTP-charged G alpha(i-2) subunit transduces growth signals in renal cells via activation of MAPK(p42/p44) and that such activation may be linked to pathways containing novel MEKK isoforms that preferentially activate MEKs.

Inhibition of murine leukemia virus with poly-2'-O-(2,4-dinitrophenyl)poly[A]

Poly-2'-O-(2,4-dinitrophenyl)poly[A] (DNP-poly[A] is a potent inhibitor of reverse transcriptases from a variety of sources (I. Kang and J. H. Wang, J. Biol. Chem. 269:12024-12031, 1994). In the present study, its inhibitory effect on the reverse transcriptase (RT) from Moloney murine leukemia virus (MuLV) was investigated. DNP-poly[A] was found to enter the virus spontaneously and to completely inhibit the RT within 30 min at 0 degree C. The inhibitor was also spontaneously transported into isolated human lymphocytes and leukocytes at 37 degrees C. Animal studies have demonstrated the effectiveness of DNP-poly[A] as an antiviral drug when administered intraperitoneally at various doses from 1 to 100 mg/kg of body weight. MuLV-infected mice show the presence of RT in their blood as well as increased numbers of leukocytes. After the administration of DNP-poly[A] at a dosage of 100 mg/kg of body weight three times a week over a 3-week period, RT could no longer be detected by an ultrasensitive RT-PCR assay. Autopsy showed that the spleens of infected but untreated mice were enlarged 2- to 10-fold, with fused nodules and the proliferation of large abnormal lymphocytes, whereas the spleens of infected but treated mice resembled the normal spleens of uninfected control mice. These observations indicate that further study of DNP-poly[A] as a general antiretroviral agent is desirable.

Selective removal of ribonucleases from solution with covalently anchored macromolecular inhibitor

Poly[2'-O-(2,4-dinitrophenyl)]poly(A)[DNP-poly(A)] has been found to be a potent inhibitor in solution for RNases A, B, S, T1, T2 and H as well as phosphodiesterases I and II. Kinetic measurements with RNase B and RNase T1 showed DNP-poly(A) to be a reversible competitive inhibitor with K1 equal to 1.03 and 1.05 microM, respectively. Data on the quenching of fluorescence of RNase T1 by DNP-poly(A) indicate the existence of more than one RNase-binding site in each DNP-poly(A) molecule. By attaching each DNP-poly(A) molecule at one end covalently to oxirane acrylic beads, an affinity column was prepared for selective removal of RNases from aqueous solutions by simple filtration. It was found that a 1000-fold reduction in RNase concentration can be obtained by passing either 7.0 microM or 7.0 nM RNase A solution through a 5-cm-long column. The column can be saturated by passing through a concentrated RNase solution and subsequently regenerated by washing with salt solution. The regenerated column can be used repeatedly with no significant decrease in RNase-binding affinity and capacity. By titration of the derivatized beads with RNase, the first dissociation constant (Kd) and binding capacity for the bound enzyme can be determined. The (Kd) was found to be 0.66 microM for RNase B and 0.48 microM for RNase T1; the corresponding binding capacities were found to be 21.0 x (10)-8 and 9.6 x (10)-8 mol/g, respectively.

Design of structure-based reverse transcriptase inhibitors

Based on the crystallographic structure of the active site in the reverse transcriptase (RT) of human immunodeficiency virus (HIV), a group of hydrophobic polyadenylic acid (5') derivatives were designed and synthesized as inhibitors of the enzyme. These compounds were found to inhibit all six of the RTs tested, with IC50 = 10(-11)-10(-8) M, but did not inhibit either RNA polymerase II (even at 10(-5) M) or DNA polymerase I up to 10(-6) M inhibitor concentration. The underivatized poly(A) did not inhibit any of the RTs tested under the same conditions. In aqueous solutions of purified HIV-1 RT, poly-2'-O-(2,4-dinitrophenyl)-oligo(A) was found to inhibit the enzyme reversibly and compete with the primer-template poly(A)-(dT)12, whereas poly-2'-O-(3-fluoro-4,6-dinitrophenyl)-poly(A) was found to inactivate HIV-1 RT irreversibly by covalent labeling. A comparison of physicochemical properties of the hybrids poly(A)-poly(dT) and dinitrophenyl-poly(A)-poly(dT) shows that the hydrophobic dinitrophenyl groups stabilize double helical structures. These inhibitors were also found to be effective in keeping susceptible lymphocytes viable in the presence of HIV-1 (wild type). The effective inhibitor concentrations (EC50) were found to be 0.2-2.6 microgram/ml. No toxic effect on the host cells was found even at 100-1000-fold higher inhibitor concentrations.

Isolation and characterization of the promoter of the human GABAA receptor alpha 1 subunit gene

The GABAA receptor, as assessed by ligand binding and chloride flux measurement in vivo and in vitro, is down-regulated in response to chronic benzodiazepine exposure. The mRNA levels of the alpha 1 and gamma 2 subunits of the receptor are also reduced. We have isolated the promoter of the gene encoding the alpha 1 subunit of the GABAA receptor to elucidate the regulatory mechanism of its expression. A DNA segment 650 bp long has been isolated that includes 151 bp of untranslated 5' end of the cDNA sequence and 500 bp of potential promoter-enhancer region. The transcriptional activity of this DNA segment linked to the firefly luciferase gene showed a strong orientation specificity. The promoter activity was localized to a 60-bp segment by deletion mapping. Mobility shift binding assay results suggest that this segment may interact with one or more factors in HeLa cell nuclear extracts to form a transcriptional complex. Primary cultures of embryonic chick cortical cells transfected with the promoter-luciferase construct were treated chronically with lorazepam. Transcriptional activity of this promoter construct was strongly repressed by chronic administration of lorazepam.

Affinity labeling and measurement of DNA-induced conformation change in RNA polymerase II

The inhibition of RNA polymerase II by 8-azido-2'-O-(1-naphthalenesulfonyl)- ATP (AN-ATP) was found to be reversible in the dark and competitive with ATP, with KI = 2.2 +/- 0.2 microM and KATP = 20 +/- 0.5 microM, but noncompetitive with CTP and GTP, with dissociation constants KCTP = 4.4 +/- 0.4 microM and KGTP = 19.4 +/- 0.7 microM. Under UV irradiation the enzyme was irreversibly labeled by AN-[alpha-32P]ATP. A linear plot of the relative specific activities of labeled enzyme samples after gel filtration vs the number of labels per enzyme molecule shows that each covalent label completely inactivates an enzyme molecule. Therefore the labeling has maximal specificity at an essential specific ATP site which is not the substrate-binding site for the polymerization reaction. The fluorescent AN-ATP-labeled enzyme, with absorbance maximum at 310 nm and emission maximum at 370 nm, can still bind noncovalently a second ligand, 2'-O-dansyl-ATP, with absorbance maximum at 365 nm and emission maximum at 560 nm, at the substrate-binding site. Measurement of energy transfer between the two fluorescent labels gave R = 23.8 +/- 0.4 A as the average distance between them and Kd = 31 +/- 0.1 microM for the bound 2'-O-dansyl-ATP in the absence of DNA template. The addition of either thymus DNA or poly[d(A-T)] to the system changed these values to R = 25.6 +/- 0.4 A and Kd = 53 +/- 0.4 microM. These results indicate that the binding of RNA polymerase II to DNA template triggers a conformation change in the enzyme molecule.

Electroconvulsive shock alters GABAA receptor subunit mRNAs: use of quantitative PCR methodology

Electroconvulsive shock (ECS) may affect several neurotransmitter systems in brain, including the GABAergic inhibitory system. We used a quantitative PCR-based assay to evaluate mRNAs for five GABAa receptor subunits at 2 to 24 h after ECS. mRNAs for the alpha 1 and beta 2 subunits were significantly increased in cerebellum at 4 and 8 h after ECS, and returned to control levels at 24 h. No changes were observed in alpha 2, beta 3, gamma 1, or gamma 2 subunits, and no changes in any subunit evaluated were observed in cortex or hippocampus. These data corroborate prior results obtained for the alpha 1 subunit using Northern hybridization, and illustrate the utility of the PCR assay in quantitating low-abundance mRNAs.

Decreased GABAA receptor subunit mRNA concentrations following chronic lorazepam administration

Chronic benzodiazepine administration has been associated with alterations in binding and function at the GABAA receptor. To evaluate effects of chronic benzodiazepine exposure on messenger RNA (mRNA) concentrations for several GABAA receptor subunits, we treated mice with lorazepam, 2 mg kg-1 daily for 1-28 days and evaluated mRNAs for the alpha 1 and gamma 2 subunits by Northern hybridization. In cerebral cortex, concentrations of mRNA for the alpha 1 and gamma 2 subunits were unchanged from vehicle or control after 1-10 days of lorazepam. However, after 14 days of treatment mRNA concentrations for both subunits decreased to approximately 50% of control values and remained decreased at 28 days. In contrast, no significant alterations were observed for either subunit mRNA in hippocampus or cerebellum over the same time course. Alterations in mRNAs in cortex occur after the development of tolerance and receptor downregulation in this model.

Persistent elevation in GABAA receptor subunit mRNAs following social stress

Stress is associated with alterations in GABA/benzodiazepine binding and function. We evaluated effects of social stress on GABAA receptor subunit (alpha 1 and gamma 2) mRNAs by Northern hybridization. In cortex, no change was observed in either subunit mRNA immediately after stress, but a 4 hours mRNAs for both subunits were increased. These changes persisted for 72 hours after stress, and returned to baseline levels at 7 days. No changes in mRNAs were observed in sham-treated mice. No changes in either subunit mRNA were observed in stressed or sham-treated mice in cerebellum or hippocampus. In undefeated resident mice, mRNAs for both subunits in cortex were unaffected at 24 hours after the stress episode. Social stress is associated with increases in GABAA receptor alpha 1 and gamma 2 subunit mRNAs in cortex.

An insulin response element in the glyceraldehyde-3-phosphate dehydrogenase gene binds a nuclear protein induced by insulin in cultured cells and by nutritional manipulations in vivo

Two independent cis-acting insulin response elements (IREs) in the gene encoding glyceraldehyde-3-phosphate dehydrogenase [D-glyceraldehyde-3-phosphate: NAD+ oxidoreductase (phosphorylating), EC 1.2.1.12], designated IRE-A and IRE-B, are sufficient to direct insulin-inducible gene expression. Using the electrophoretic mobility shift assay, a 4-fold increase in the amount of IRE-A DNA bound to nuclear proteins was detected when extracts isolated from insulin-stimulated differentiated 3T3-L1 cells or from the liver of rats refed a high-carbohydrate/low-fat diet after a 72-hr fast were compared to control nuclear extracts. The points of contact between protein and IRE-A DNA may represent a sequence recognized by at least one class of insulin-sensitive transcription factor(s).

CII-dependent activation of the pRE promoter of coliphage lambda fused to the Escherichia coli galK gene

Using a cloning vector designed for the study of prokaryotic promoters by fusion to the Escherichia coli galactokinase gene (galK), we have constructed a plasmid in which the lambda pRE promoter controls galactokinase expression. A galK- host containing this plasmid has a Gal- phenotype since transcription from pRE requires activation by the lambda CII protein. When CII protein is provided by a prophage, galactokinase is synthesized at a rate dependent on the concentration of CII protein. A second plasmid was constructed in which the pRE promoter from phage 21 controls galactokinase expression. Transcription of the galK gene in this plasmid requires the phage 21 CII protein. Using this system, we demonstrate that the lambda and 21 pRE promoters are highly selective for their corresponding CII proteins. However, a cross-reaction between 21 pRE and the lambda CII protein was observed. In addition, we transferred the pRE-galK fusion unit from the plasmid to a phage, and then to the host chromosome in single copy. Galactokinase expression in this single copy pRE-galK system is also dependent on CII protein, which may be provided from a multicopy plasmid. The high concentration of CII protein provided by the plasmid results in maximal expression of the pRE-galK transcription unit. In this second system low levels of CII activity from CII- mutants are amplified and can be readily detected.

Silicone rubber band for laparoscopic tubal sterilization

In 1974, Yoon and associates (Am J Obstet Gynecol 120:132, 1974) described a new approach in which laparoscopic tubal occlusion was accomplished by utilizing the silicone rubber band technique. Recognizing the great advantages of the new technique in eliminating potential thermal injury associated with electrocoagulation, the authors have utilized the Yoon silicone rubber band technique in these institutions over the past 20 months. Thus far the procedure has been performed in 304 patients without any major complications. In the hope of eliminating and/or reducing possible pregnancy-failure rates, in 110 cases. In addition to application of the silicone band, the tube within the band was transected with non-electrical Seigler biopsy forceps. This, we believe, should provide an interesting long-term comparative study.