Electrochemical Bioconjugation of Tryptophan Residues: A Strategy for Peptide Modification

Interest in electrocatalytic bioconjugation reactions has surged, particularly for modifying tryptophan and tyrosine residues in proteins. We used a cost-effective graphite felt electrode and low-current methodology to achieve selective bioconjugation of tryptophan with thiophenols, yielding up to 92%. This method exclusively labeled tryptophan residues and incorporated fluorinated tryptophan for NMR analysis. Eight polypeptides, including lanreotide and leuprorelin, were effectively coupled, demonstrating the method's versatility and potential for novel diagnostic and therapeutic agents.

Methylboronic acid MIDA ester (ADM) as an effective additive in electrolyte to improve cathode electrolyte interlayer performance of LiNi0.8Co0.15Al0.05O2 electrode

We investigated the effectiveness of using methylboronic acid MIDA ester (ADM) as an additive in an electrolyte to enhance the overall electrochemical and material properties of an LNCAO (LiNi_0.8Co_0.15Al_0.05O₂) cathode. The cyclic stability of the cathode material measured at 40 °C (@ 0.2 C) showed an enhanced capacity of 144.28 mAh g^-1 (@ 100 cycles), a capacity retention of 80%, and a high coulombic efficiency (99.5%), in contrast to these same properties without the electrolyte additive (37.5 mAh g^-1, ~ 20%, and 90.4%), thus confirming the effectiveness of the additive. A Fourier transform infrared spectroscopy (FTIR) analysis distinctly showed that the ADM additive suppressed the EC-Li⁺ ion coordination (1197 cm^-1 and 728 cm^-1) in the electrolyte, thereby improving the cyclic performance of the LNCAO cathode. The cathode after 100 charge/discharge cycles revealed that the ADM-containing system exhibited better surface stability of the grains in the LNCAO cathode, whereas distinct cracks were observed in the system without the ADM in the electrolyte. A transmission electron microscopy (TEM) analysis revealed the presence of a thin, uniform and dense cathode electrolyte interface (CEI) film on the surface of LNCAO cathode. An operando synchrotron X-ray diffraction (XRD) test identified the high structural reversibility of the LNCAO cathode with a CEI layer formed by the ADM, which effectively maintained the structural stability of the layered material. The additive effectively inhibited the decomposition of electrolyte compositions, as confirmed by X-ray photoelectron spectroscopy (XPS).

[Stress, anxiety, depression and insomnia in adults outside Hubei province during the COVID-19 pandemic]

Objective: To investigate the severity of stress, anxiety, depression and insomnia during the novel coronavirus disease (COVID-19) pandemic in adults outside Hubei Province, China. Methods: An online survey of psychological and sleep by using Questionnaire Star program from 5th to 19th February 2020 was conducted. The Impact of Event Scale-Revised was used to assess COVID-19 outbreak-related stress symptoms. Meanwhile, Questionnaires of Generalized Anxiety Disorder-7, Patient Health Questionnaire-9 and the Insomnia Severity Index were respectively used to assess the severity of anxiety, depression and insomnia symptoms prior to and during the COVID-19 pandemic. Results: A total of 3 134 subjects were included. Among the included subjects, 15.5% (487), 24.9% (779), 28.7% (899) and 30.9% (968) of the subjects had COVID-19-related stress symptoms, anxiety, depression and insomnia after the COVID-19 outbreak, respectively. The severity levels of anxiety, depression and insomnia were significantly increased during the COVID-19 pandemic compared to prior to the outbreak (all P<0.01). Furthermore, the subjects' stress response to the COVID-19 outbreak was an independent risk factor for increased anxiety, depression and insomnia after the outbreak. Conclusion: The COVID-19 outbreak resulted in related stress response and widespread increase in anxiety, depression, and insomnia outside Hubei Province, China in the general population. The aggravation of anxiety, depression and insomnia is associated with stress levels. Our data demonstrate that the widespread psychological and insomnia problems in the general population need to be addressed at the early phase of the pandemic.

[Investigation on the awareness of snoring hazard and prevalence of obstructive sleep apnea among civil servants]

Objective: To investigate the awareness of snoring hazard and prevalence of obstructive sleep apnea (OSA) among civil servants. Methods: A cross-sectional survey was conducted to investigate the awareness of snoring hazards among in-service civil servants who had annual medical examination in a Guangdong provincial institution from September to November 2017. The high-risk group for OSA was screened and diagnosed by sleep monitoring. Results: 1 036 of 1 241 civil servants were enrolled in the study for integral data. 60.1% (623/1 036) of the subjects realized that snoring was harmful to health. The most common source to develop OSA awareness was network (59.6%, 371/623), followed by television (48.0%), relatives and friends (46.6%), newspaper (44.5%) and radio (18.9%). The awareness rate of snoring consequences was as follows: decreased sleep quality (71.9%, 448/623), sudden death (52.2%), daytime sleepiness (44.3%), cardiovascular and cerebrovascular diseases (42.9%), hypertension (24.4%) and sexual dysfunction (16.7%). 22.0% (228 / 1 036) of the cases were classified into high-risk OSA. The prevalence of OSA among high-risk group was 46.05%(105/228)and only 0.9% (2/228) of them had been diagnosed with OSA. Conclusion: Civil servants had awareness of snoring hazard to a certain extent. Among civil servants classified into high-risk OSA, the OSA perveance was high but the rate of diagnosis and treatment was very low.

[Efficacy and outcome of transcatheter closure of patent foramen ovale in patients with cryptogenic stroke]

Objective: To investigate the efficacy and outcome of transcatheter patent foramen ovale (PFO) closure in patients with cryptogenic stroke (CS). Methods: Sixty consecutive patients with cryptogenic stroke who undertook transcatheter PFO closure between May 2015 and September 2017 in Beijing Tiantan Hospital were enrolled in this prospective study.Transcranial Doppler (TCD) bubble test was performed and right-left shunt(RLS) was confirmed in all patients.Closure success rate,effective closure rate, complications, recurrence of ischemic stroke and new onset atrial fibrillation were evaluated. Results: A total of 60 patients (42 male,age range 24-68 (47±11)years) were included in the study.PFO size (motionless state) was (1.6±0.6)mm.RLS before closure was graded and 11 patients had moderate RLS and 48 patients had large RLS (include 41 patients who experienced shower or curtain effect).Closure success rate was 100% (60/60).No severe complications were observed.At 6 months,45 patients completed TCD bubble test.Of these, 4 patients suffered from moderate to large residual and thus effective closure rate was 91%(41/45).The mean follow-up period was 2-29 (median 12) months. During the follow-up, only 1 patient experienced recurrent cerebral infarction.New onset atrial fibrillation was not detected. Conclusion: Transcatheter PFO closure is effective,safe and related with a good outcome in reduction of recurrent CS for patients with PFO.

[A cross-sectional survey of treatment acceptance and influence factors in patients with obstructive sleep apnea]

Objective: To investigate the treatment acceptance in patients with obstructive sleep apnea (OSA) and its influence factors. Methods: This cross-sectional survey recruited OSA patients diagnosed at sleep center in Guangdong General Hospital from January 2014 to December 2015. By phone follow-up, a pre-designed questionnaire was performed for all adults, which composed of the following sections: treatment or none, treatment method, reason for non-treatment, revisit or none. Results: From 524 OSA patients with completed contact information, 480 (91.6%) valid questionnaires were collected. The apnea hypopnea index was (36.1±21.4) /h. The mild, moderate, severe OSA patients accounted for 12.5%(60 cases), 33.1%(159 cases), 54.4%(261 cases) respectively. For all 480 included subjects, 200 (41.7%) received treatment and among them 184 (92.0%) were treated by continuous positive airway pressure. The treatment rate was lower in mild OSA, non-obesity, female, and patients without daytime sleepiness. Receiving treatment was negative correlated to difficult falling asleep. The first reason of non-treatment was self-determined behavioral intervention and the second was self-concept of no requirement for treatment. The specialist revisit rate was 3.8%, which was slightly higher in treated patients and those with sudden awakening when feeling asphyxia. Conclusion: A majority of OSA patients do not receive treatment, primarily as a result of their self-determined behavior intervention and self-concept of no requirement for treatment.

[Effects of myocardial performance index on assessing left ventricular function in patients with primary hypertension]

OBJECTIVE

To investigate the value of myocardial performance index (MPI) in assessing LV function in patients with primary hypertension (HP).

METHODS

We studied 130 patients with HP (mean age 54.9±13.3 years)and 155 healthy control subjects (mean age 52.4±11.6 years). MPI was determined by tissue doppler imaging using the following formula: MPI=(isovolumic contraction time + isovolumic relaxation time)/ ejection time. The HP group was divided into hypertrophy subgroup( LVMI≥115 g/m(2) in males, or ≥95 g/m(2) in females) and normal mass subgroup(LVMI <115 g/m(2) in males, or<95 g/m(2) in females).

RESULTS

MPI was significantly different in control group, normal mass subgroup and hypertrophy subgroup(0.72±0.23 vs. 0.54± 0.17 vs. 0.45±0.11, P<0.001). Hypertrophy subgroup had significant higher MPI than normal mass subgroup(P =0.046), and both the groups had significant higher MPI than control group(all P<0.001). MPI was positively associated with age(r=0.369,P<0.001), Left ventricular end diastolic diameter(r=0.169, P<0.05), Sm(r=-0.211, P<0.001) and Em(r=-0.383, P<0.001) in control group. In multiple linear regression analysis, MPI was independently related to age (β=0.492, t=7.222,P<0.001) in control group. Among the HP patients, MPI was positively associated with left atrial area (r=0.293, P<0.001),intra ventricular septum(IVS) diameter (r=0.453, P<0.001), LVMI (r=0.453, P<0.001), relative wall thickness(r=0.458, P<0.001), and negatively associated with Sm(r=-0.414, P<0.001), Em(r=-0.508, P<0.001), left ventricular ejection fraction (r=-0.305, P<0.001) in bivariate analysis. In the multiple linear regression analysis, MPI was independently related to Em (β=0.401, t=4.256,P<0.001) and IVS diameter (β=-0.365, t=-3.878,P<0.001) in the HP patients.

CONCLUSION

The HP patients had elevated MPI, especially in the ones with LV hypertrophy. Tissue doppler imaging (TDI) derived MPI could be a useful index to evaluate the overall cardiac function in HP patients.

[Hyperkalemia-induced failure of pacemaker capture and sensing: a case report]

Hyperkalemia may induce serious cardiac arrhythmia, with possible life-threatening effects. It may cause cardiac pacemaker (PMK) malfunctioning due to a reduction of the electronegativity of the resting myocardial potential. We report the case of a 71-year-old woman who had a previous history of chronic heart failure, chronic renal failure and DDI pacemaker. She was admitted for disturbance of consciousness. During hospitalization, she was observed for extreme hypotension, acute hyperkalemia, ventricular escape rhythm, associated with failure of pacemaker capture and sensing. She was treated with calcium chloride injection, followed by insulin/glucose and sodium bicarbonate infusions; the electrocardiogram recordings showed an correction of the PMK malfunctioning and serial improvement of the intraventricular conduction. This case supports that hyperkalemia should be closely monitored in the chronic heart failure patients combined with chronic renal failure.

Polymorphisms of the angiotensin II type 1 receptor gene affect antihypertensive response to angiotensin receptor blockers in hypertensive Chinese

The renin-angiotensin-aldosterone system plays a key role in regulating blood pressure by maintaining vascular tone and the water/sodium balance. Many antihypertensive drugs target the renin-angiotensin-aldosterone system, but the effect differs considerably among hypertensive patients. We investigated whether genetic variants of the angiotensin II type 1 receptor are associated with blood pressure response to angiotensin II receptor blockers in hypertensive Chinese patients. After a 2-week single-blind placebo run-in period, 148 patients with mild-to-moderate primary hypertension received monotherapy with 80 mg/day telmisartan and then were followed up for 8 weeks. The 1166A/C, 573T/C, -810A/T, and -521C/T polymorphisms of the AT1R gene were determined through PCR and RFLP analysis. The relationship between these polymorphisms and changes in blood pressure was observed and evaluated after 8 weeks of treatment. Patients with the AT1R -521CC genotype had a significant reduction in diastolic blood pressure compared to those carrying the T allele. No significant reduction in blood pressure was found in individuals with the 1166A/C, 573T/C, or -810A/T polymorphisms of the AT1R gene. We conclude that only the AT1R -521CC genotype is associated with a significant decrease in blood pressure in response to telmisartan treatment in Chinese hypertensive patients.

A multidimensional micro gas chromatograph employing a parallel separation multi-column chip and stop-flow μGC × μGCs configuration

A dual-chip, multidimensional micro gas chromatographic module was designed, built and evaluated. Column chips were fabricated on a silicon wafer with an etched rectangular channel 100 μm (width) × 250 μm (depth) using a deep reactive ion etching (DRIE) process. The column chip for the first GC dimension was 3 m long and was coated with polydimethylsiloxane (DB-1) as the stationary phase. The columns on the second dimensional chip were etched with the same width and depth as the first chip, but the flow channel was split into three parallel columns, 1 m long, on the same sized silicon chip (i.e., 3 cm × 3 cm). These three parallel columns on the second chip were coated with polyethylene oxide (DB-Wax), trifluoropropylpolymethylsilicone (OV-210) and cyanopropylmethylphenylmethylpolysilicone (OV-225), accordingly, in order to provide diversified chromatographic retention. These two chips were connected via a stop-flow configuration to simultaneously generate multiple two-dimensional gas chromatograms for every analysis. This stop-flow μGC × μGCs design allowed the first column to function as a pre-separator and as a sequencing injector for the second parallel-separation chip. Fifteen volatile organic compounds with boiling points that ranged from 80-131 °C with various functional groups were tested using this μGC × μGCs module. Three discrete 2-D chromatograms were generated simultaneously, which demonstrated the advantages of simultaneously combining GC × GC with parallel separation GCs in microchip chromatography. The total traveling length in the column was only 4 m for each eluted peak and fully resolved separation was achieved through the cross reference among triplet 2-D chromatograms.

Nonlinear hydrodynamic effects induced by Rayleigh surface acoustic wave in sessile droplets

We report an experimental and numerical characterization of three-dimensional acoustic streaming behavior in small droplets of volumes (1-30 μl) induced by surface acoustic wave (SAW). We provide a quantitative evidence of the existence of strong nonlinear nature of the flow inertia in this SAW-driven flow over a range of the newly defined acoustic parameter F{NA}=Fλ/(σ/R_{d})≥0.01, which is a measure of the strength of the acoustic force to surface tension, where F is the acoustic body force, λ is the SAW wavelength, σ is the surface tension, and R{d} is the droplet radius. In contrast to the widely used Stokes model of acoustic streaming, which generally ignores such a nonlinearity, we identify that the full Navier-Stokes equation must be applied to avoid errors up to 93% between the computed streaming velocities and those from experiments as in the nonlinear case. We suggest that the Stokes model is valid only for very small acoustic power of ≤1 μW (F{NA}<0.002). Furthermore, we demonstrate that the increase of F{NA} above 0.45 induces not only internal streaming, but also the deformation of droplets.

Nonlinear hydrodynamic effects induced by Rayleigh surface acoustic wave in sessile droplets

We report an experimental and numerical characterization of three-dimensional acoustic streaming behavior in small droplets of volumes (1-30 μl) induced by surface acoustic wave (SAW). We provide a quantitative evidence of the existence of strong nonlinear nature of the flow inertia in this SAW-driven flow over a range of the newly defined acoustic parameter F{NA}=Fλ/(σ/R_{d})≥0.01, which is a measure of the strength of the acoustic force to surface tension, where F is the acoustic body force, λ is the SAW wavelength, σ is the surface tension, and R{d} is the droplet radius. In contrast to the widely used Stokes model of acoustic streaming, which generally ignores such a nonlinearity, we identify that the full Navier-Stokes equation must be applied to avoid errors up to 93% between the computed streaming velocities and those from experiments as in the nonlinear case. We suggest that the Stokes model is valid only for very small acoustic power of ≤1 μW (F{NA}<0.002). Furthermore, we demonstrate that the increase of F{NA} above 0.45 induces not only internal streaming, but also the deformation of droplets.

Neointimal coverage of bare-metal and sirolimus-eluting stents evaluated with optical coherence tomography

OBJECTIVE

To analyse the neointimal coverage of sirolimus-eluting stent (SES) and bare-metal stent (BMS) visualised in vivo by optical coherence tomography (OCT).

METHODS

OCT images were obtained in 26 coronary vessels of 24 patients at 5-93 months after SES or BMS deployment. The short-term BMS group (BMS1) consisted of eight BMS in seven patients at 5-10 months of follow-up, the long-term BMS group (BMS2) consisted of six BMS in six patients at 23-93 months of follow-up, and the SES group (SES) consisted of 13 SES in 10 patients at 6-12 months of follow-up. The strut apposition, strut coverage and mean maximal and minimal neointimal thicknesses (NIT) for both BMS groups and SES were compared.

RESULTS

OCT images were acquired successfully. Significant differences between completely apposed and malapposed stent struts (p<0.0001) and between covered and uncovered stent struts (p<0.0001) were found among the three groups. The mean maximal and minimal NIT in the SES group were all significantly less than those of the BMS1 or BMS2 group, the minimal NIT in the BMS1 group was significantly less than that of the BMS2 but the mean maximal NIT was no significant difference between the BMS1 and BMS2 groups. In an open bifurcation artery, 19 struts visualised by OCT had no discernible coverage or were surrounded by either thrombus or a thick tissue layer.

CONCLUSIONS

OCT imaging can clearly visualise stent apposition and neointimal coverage of stent struts. Incomplete strut apposition and lack of strut coverage occurred with a significantly higher frequency in SES than in BMS. These findings may explain the occurrence of late thrombosis in SES. Optical coherence tomography (OCT) is the optical analogue to ultrasound, measuring the back-reflection of infrared light instead of sound waves. The greatest advantage of OCT is its high resolution, which exceeds that of any currently available in vivo imaging technology. The resolution of catheter-based systems is in the range of 10-20 microm. Furthermore, resolutions as high as 4 microm have been achieved ex vivo with more sophisticated techniques that may be applicable to future catheter-based approaches. The main components of various atheromatous plaques can be identified in OCT images, and have been validated in a histology-controlled study. Several studies have demonstrated the feasibility of OCT imaging in patients undergoing percutaneous coronary intervention (PCI). The aim of the present study was to use OCT to analyse the neointimal coverage of sirolimus-eluting stents (SES), compared with that of bare-metal stents (BMS).

The concentrations of LH, FSH, oestradiol-17beta and progesterone in the blood plasma of the female Bactrian camel (Camelus bactrianus) before and after intramuscular injection of seminal plasma

The concentrations of LH, FSH, oestradiol-17beta and progesterone in the blood plasma of the female Bactrian camel (Camelus bactrianus) before and after intramuscular injection of seminal plasma.

[Linkage analysis and mutation detection of GRIA3 in Smith--Fineman--Myers syndrome]

To determine the role of GRIA3 in the etiology of Smith--Fineman--Myers syndrome (SFMS), polymorphic short tandem repeats within GRIA3 gene were genotyped by PCR and denaturing polyacrylamide gel electrophoresis to test linkage between GRIA3 and the gene responsible for SFMS. The open reading frame of GRIA3 was detected for mutation by PCR amplification and direct sequencing in affected and normal males from SFMS family. One of the two short tandem repeats was informative in SFMS family. Tight linkage between SFMS locus and GRIA3 gene was established by STR3 within GRIA3 gene. No disease--causing mutation was found within the open reading frame of GRIA3 gene. The disease in SFMS family from Shandong (China) is not caused by the mutation within open reading frame of GRIA3 gene.

Isolation of ovulation-inducing factors in the seminal plasma of Bactrian camel (Camelus bactrianus) by DEAE-cellulose chromatography

Ovulation in the Bactrian camel (Camelus bactrianus) depends upon the ovulation-inducing factor in the seminal plasma; however, little research has been conducted to isolate and identify the factor. The current study attempts to isolate and identify the bioactive fractions from the seminal plasma of Bactrian camel. The seminal plasma was fractionated by diethylamino-ethylcellulose (DEAE)-cellulose chromatography and five protein fractions were obtained. The bioactive of each fraction was estimated by rat pituitary tissue culture in vitro and by the intramuscular injection of the bioactive fraction to the female camels in vivo. The concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in the pituitary culture media before and 6 h after the addition of each fraction and in the peripheral blood plasma collected from the camel immediately before and hourly after the injection of the active fraction were measured by radioimmunoassay. The results demonstrated that the third fraction (L3) had the bioactive potential to stimulate the release of LH in vitro from 11.82 +/- 1.77 to 25.63 +/- 3.84 mIU/ml after the addition of L3 to the culture media. The in vivo concentrations of LH in the blood plasma of the camel increased from 6.43 +/- 0.14 before to 15.50 +/- 2.64 ng/ml 6 h after injection of L3. However, the concentrations of FSH did not show any significant changes either in vitro or in vivo. The results clearly demonstrated the existence of LH-releasing associated fractions in the seminal plasma that appears to be separated by DEAE-cellulose matrix and the isolated L3 fraction might be the ovulation-inducing factor or one of its components.

Preliminary observations on the concentrations of serum luteinizing hormone and follicle-stimulating hormone during gestation in bactrian camels (Camelus bactrianus)

The concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in the serum of the Bactrian camel (Camelus bactrianus) throughout pregnancy were analysed by radioimmunoassay. The samples were withdrawn at intervals of half a month. The serum LH concentrations varied significantly between 2.2+/-0.9 and 20.3+/-18.8 ng/ml during the pregnancy, with the highest value on the day of artificial insemination, which indicated that a preovulatory LH peak appeared. Thereafter, the LH concentration tended to fall, reaching a fairly constant low level by the eighth month of pregnancy. The serum FSH concentrations varied between 7.0+/-0.2 and 28.9+/-0.4 ng/ml during gestation, with the peak value being reached at 4.5 months, followed by a marked drop to 7.0+/-0.2 ng/ml at 7.5 months.

X-ray crystal structure of an anti-Buckminsterfullerene antibody fab fragment: biomolecular recognition of C(60)

We have prepared a monoclonal Buckminsterfullerene specific antibody and report the sequences of its light and heavy chains. We also show, by x-ray crystallographic analysis of the Fab fragment and by model building, that the fullerene binding site is formed by the interface of the antibody light and heavy chains. Shape-complementary clustering of hydrophobic amino acids, several of which participate in putative stacking interactions with fullerene, form the binding site. Moreover, an induced fit mechanism appears to participate in the fullerene binding process. Affinity of the antibody-fullerene complex is 22 nM as measured by competitive binding. These findings should be applicable not only to the use of antibodies to assay and direct potential fullerene-based drug design but could also lead to new methodologies for the production of fullerene derivatives and nanotubes as well.

Antigenicity of fullerenes: antibodies specific for fullerenes and their characteristics

The recent interest in using Buckminsterfullerene (fullerene) derivatives in biological systems raises the possibility of their assay by immunological procedures. This, in turn, leads to the question of the ability of these unprecedented polygonal structures, made up solely of carbon atoms, to induce the production of specific antibodies. Immunization of mice with a C60 fullerene derivative conjugated to bovine thyroglobulin yielded a population of fullerene-specific antibodies of the IgG isotype, showing that the immune repertoire was diverse enough to recognize and process fullerenes as protein conjugates. The population of antibodies included a subpopulation that crossreacted with a C70 fullerene as determined by immune precipitation and ELISA procedures. These assays were made possible by the synthesis of water-soluble fullerene derivatives, including bovine and rabbit serum albumin conjugates and derivatives of trilysine and pentalysine, all of which were characterized as to the extent of substitution and their UV-Vis spectra. Possible interactions of fullerenes with the combining sites of IgG are discussed based on the physical chemistry of fullerenes and previously described protein-fullerene interactions. They remain to be confirmed by the isolation of mAbs for x-ray crystallographic studies.

Serum progesterone and 17 beta-estradiol concentrations during pregnancy of Bactrian camel (Camelus bactrianus)

Serum progesterone and 17 beta-estradiol during pregnancy in the Bactrian camel were measured by radioimmunoassay. Serum progesterone concentrations increased by 15 d after artificial insemination (AI) and remained elevated throughout most of gestation, the mean concentrations (3.06 +/- 0.49 to 8.51 +/- 4.80 ng/mL) were similar to those reported for many species during the same stage of pregnancy. Serum 17 beta-estradiol increased significantly from 11 m.o. of pregnancy with peak mean concentrations of 617.47 +/- 32.56 pg/mL at the 11.5 m.o.

Antibodies to oxidative DNA damage: characterization of antibodies to 8-oxopurines

The 8-oxo-7,8-dihydropurines (8-oxopurines) are important cellular premutagenic lesions produced in DNA by free radicals. Specific antibodies were prepared to detect these lesions. For antigens, 8-oxo-7,8-dihydroadenosine (8-oxoAdo) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo) were synthesized from the bromonucleosides, and the immunogens were produced by conjugating these to either bovine serum albumin or rabbit serum albumin by the periodate method. Polyclonal antibodies specific for the haptens were elicited from rabbits immunized with the BSA conjugates. The antibodies to 8-oxoAdo (anti-8-oxoAdo) and 8-oxoGuo (anti-8-oxoGuo) precipitated the homologous antigens in an Ouchterlony gel diffusion assay and no cross-reactivity was observed toward the normal nucleosides or to the heterologous 8-oxopurine. Specificity was also examined by hapten inhibition of antibody reactivity with the homologous conjugates using ELISA. For anti-8-oxoAdo, the IC50 for 8-oxoAdo was 8 mumol/L and 8-bromoadenosine, guanosine, and inosine did not inhibit, even at concentrations of 1.25 mmol/L. Similarly, the IC50 for anti-8-oxoGuo for 8-oxoGuo was 0.1 mumol/L. 8-Methoxyguanosine also inhibited the reaction but was about 500-fold less effective than the eliciting hapten. Other nucleosides tested did not inhibit at concentrations up to 100 mumol/L. Both antibodies could easily detect the corresponding damage in x-irradiated f1 DNA at a dose of 7.5 Gy and both antibodies recognized the corresponding lesion in duplex DNA; however, with anti-8-oxoGuo the signal was reduced about 50% compared to single-stranded DNA. In order to determine the exact amount of each lesion produced in irradiated DNA, and to standardize the ELISA signal, both products were measured after alkaline phosphatase digestion of x-irradiated calf thymus DNA using high-pressure liquid chromatography (HPLC) coupled to an electrochemical detector. Anti-8-oxoGuo could detect ten 8-oxoG residues and anti-8-oxoAdo could detect two 8-oxoA residues per 10,000 nucleotides. Thus, these antibodies should be useful for the detection and measurement of 8-oxopurines in cellular DNA.