DNA adducts: mass spectrometry methods and future prospects

Detection of DNA adducts is widely used for the monitoring of exposure to genotoxic carcinogens. Knowledge of the nature and amounts of DNA adducts formed in vivo also gives valuable information regarding the mutational effects that may result from particular exposures. The power of mass spectrometry (MS) to achieve qualitative and quantitative analyses of human DNA adducts has increased greatly in recent years with the development of improved chromatographic interfaces and ionisation sources. Adducts have been detected on nucleic acid bases, 2'-deoxynucleosides or 2'-deoxynucleotides, with LC-MS/MS being the favoured technique for many of these analyses. Our current applications of this technique include the determination of N7-(2-carbamoyl-2-hydroxyethyl)-guanine, which was postulated to be found as a DNA repair product in urine following exposure to acrylamide, and of 8-oxo-7,8-dihydro-2'-deoxyguanosine and 8-oxo-7,8-dihydro-2'-deoxyadenosine, as markers of oxidative damage in human lymphocyte DNA. Higher sensitivity (with a detection limit of 1-10 adducts/10(12) nucleotides) may be achieved by the use of accelerator mass spectrometry (AMS), although this requires the presence of certain isotopes, such as [(14)C], in the material being analysed. In order to make this technique more amenable for studies of human exposure to environmental carcinogens, new postlabelling techniques, incorporating [(14)C] into specific DNA adducts after formation, are being developed. It is expected that combining the use of advanced MS techniques with existing (32)P-postlabelling and immunochemical methodologies will contribute greatly to the understanding of the burden of human exposure to environmental carcinogens.

Mucosal morphology in Barrett's esophagus: interobserver agreement and role of narrow band imaging

BACKGROUND AND STUDY AIMS

We have recently proposed a classification of mucosal morphology in Barrett's esophagus based on three criteria: regularity of mucosal pattern, regularity of vascular pattern, and presence of abnormal blood vessels. We aimed to evaluate the interobserver agreement with the proposed mucosal morphology classification and to assess the additional value of narrow band imaging (NBI) over high resolution white light endoscopy (HR-WLE).

PATIENTS AND METHODS

Five international experts in the field of Barrett's imaging and seven community endoscopists with no expertise in this field independently evaluated magnified still images from 50 areas, obtained with HR-WLE and NBI, in Barrett's esophagus patients. Visual analogue scales (VAS) were used for scoring imaging quality. Interobserver agreement for mucosal morphology and yield for identifying early neoplasia were assessed.

RESULTS

Imaging qualities of NBI were rated more highly than HR-WLE, when evaluated separately as well as in a side-by-side comparison. The interobserver agreement ranged from 0.40 to 0.56 and did not significantly differ between expert and non-expert endoscopists. The overall yield for correctly identifying images of early neoplasia was 81 % for HR-WLE, 72 % for NBI and 83 % for HR-WLE + NBI, with no significant difference between experts and non-experts.

CONCLUSION

Interobserver agreement for the classification of mucosal morphology was moderate. Although NBI was rated more highly than HR-WLE for imaging quality, this did not result in improved interobserver agreement or increased yield for identifying early neoplasia in Barrett's esophagus. This applied to non-expert as well as expert endoscopists.

Comparative disposition of [14C]ertapenem, a novel carbapenem antibiotic, in rat, monkey and man

1. The disposition and metabolism of ertapenem, a carbapenem antibiotic, was examined in rat, monkey and man. Sprague-Dawley rats and Rhesus monkeys were given, by intravenous administration, radiolabelled doses of ertapenem (60 and 30 mg kg(-1), respectively), and healthy normal volunteers received a single fixed dose of 1000 mg. Urine and faeces were collected for determination of total radioactivity. 2. In healthy volunteers, [14C]ertapenem was eliminated by a combination of hydrolytic metabolism to a beta-lactam ring-opened derivative and renal excretion of unchanged drug. Approximately equal amounts were excreted as a beta-lactam ring-opened metabolite and unchanged drug (36.7 and 37.5% of dose, respectively). A secondary amide hydrolysis product accounted for about 1% of the dose in man. About 10% of the administered radioactivity was recovered in faeces, which suggested that a minor fraction underwent biliary and/or intestinal excretion. 3. In animals, a greater fraction of the dose was eliminated via metabolism; excretion of unchanged drug accounted for 17 and 5% of dose in rats and monkeys, respectively. In monkeys, the beta-lactam ring-opened and amide hydrolysis metabolites accounted for 74.8 and 7.59% of the dose, respectively, whereas in rats, these metabolites accounted for 31.9 and 20% of dose, respectively. 4. In vitro studies with fresh rat tissue homogenates indicated that lung and kidney were the primary organs involved in mediating formation of the beta-lactam ring-opened metabolite. The specific inhibitor of dehydropeptidase-I, cilastatin, inhibited the in vivo and in vitro metabolism of ertapenem in rats, which suggested strongly that the hydrolysis of ertapenem in lung and kidney was mediated by this enzyme.

Pediatric and neonatal tetanus: a hospital based study at eastern Nepal

A prospective hospital based study of childhood (<15 yrs) and neonatal tetanus cases from July 2004 - May 2006 was done to study the demography, clinical features and outcome of pediatric and neonatal tetanus cases at BPKIHS. During the study, 24 cases of tetanus were admitted from 9 districts including 5 neonatal tetanus. Among children with tetanus, 31.5% received 3 doses of DPT and 10.5% received TT vaccine as tetanus prophylaxis. In 16.0% children there was no recognizable injury preceding the disease. Otitis media preceded tetanus in 16.0%. All neonatal tetanus cases occurred following umbilical sepsis. Despite their mothers receiving 2 doses of TT during pregnancy, 2 neonates developed tetanus. A neonate delivered in hospital also developed neonatal tetanus. Average incubation period was 7.7 days and average onset time was 16.9 hours. Short onset time predicted the favorable outcome (p=0.005). Generalized tetanus cases were 75.0%, neonatal tetanus 21.0% and cephalic tetanus 4.0%. Generalized spasm was present in all cases. Common autonomic dysfunctions were fever, tachycardia and hypotension. Respiratory failure, aspiration pneumonia, rhabdomyolysis and seizure were common complications. Only one case received Intensive Care Unit (ICU) care. Survival rate was 21.1% for childhood tetanus and 40.0% for neonatal tetanus. Respiratory failure was the cause of death in majority. Study finds tetanus as an important disease in eastern Nepal, with substantial morbidity and mortality, primarily affecting the unvaccinated and inadequately vaccinated individuals. Despite lack of adequate resources, we can still manage tetanus cases with comparable outcome to other case series reported in the literatures.

Decreased fertility with increasing parity in lactating dairy cows

The relationships of parity and progesterone (P4) concentrations during the bred cycle with pregnancy rate (PR) were examined in this study. Breeding records of 163 Holstein heifers and cows (in 1st parity, 2nd parity, and 3rd or 4th parity) from the Uuniversity of British Columbia Dairy Education and Research Centre were used to compare PR among heifers, 1st, 2nd and 3rd/4th parity cows. Blood or milk samples collected from 10 animals of each treatment group were assayed to compare P4 concentrations among treatment groups. Statistical analysis showed that the heifers' first insemination PR (67.9%) was higher (P < 0.05) from 1st parity (42.9%), 2nd parity, (20.0%) and 3rd/4th parity cows (11.9%). P4 concentrations were not significantly different (P > 0.05). Key words: Pregnancy rate, progesterone, parity, cows, heifers

Sero-prevalence of Bovine Johne's disease in buffaloes and cattle population of North India using indigenous ELISA kit based on native Mycobacterium avium subspecies paratuberculosis ‘Bison type’ genotype of goat origin

Present pilot study is the first attempt in the country to estimate sero-prevalence of Bovine Johne's disease (BJD) by screening cattle and buffaloes representing large population belonging to farmer's and farm herds in the home tracts (Uttar Pradesh (UP) and Punjab) of Hariana cattle and Murrah buffaloes in North India. Indigenous and in-house plate ELISA kit (using protoplasmic antigen from native Mycobacterium avium subsp. paratuberculosis 'Bison type' strain of goat origin), originally developed for goats and sheep was standardized in bovines and used for screening. For this study, 33 villages of south and west UP were randomly selected and surveyed from 2001 to 2003. There were 7943 farmer's families having 38,251 livestock, including cattle, buffaloes, goats and sheep (per family 4.8% livestock). Numerically, buffaloes and cattle were 54.7% and 22.1%, respectively. Serum samples were collected from 726 animals (4.2% of 16, 981 livestock with 4375 farmer's families) located in 33 randomly surveyed villages. Serum samples (699), submitted to Epidemiology Department of Veterinary College (Punjab Agricultural University, Ludhiana), in the year 2004 by farmer's and organized farm herds (Buffaloes, 372, Cattle, 327), were screened by this ELISA kit. Soluble protoplasmic antigen was prepared from Map (S 5) 'Bison type' strain isolated from a terminally sick goat with Johne's disease. Of the total 1425 bovine (Buffaloes and cattle) serum samples screened using indigenous ELISA kit, sero-prevalence of Johne's disease was 29.0% (28.6% in buffalo and 29.8% in cattle) in Northern India. State-wise sero-prevalence was 31.9% and 23.3% in UP and Punjab, respectively. In UP, of the 601 randomly sampled buffaloes, sero-prevalence was 40.3% (16.6% in young and 40.9% adults) and 25.5% (10.5% in young and 26.3% adults) in south and west UP, respectively. Of the 125 cattle screened, sero-prevalence was 42.6% (nil in young and 44.4% adults) and 30.0% (nil in young and 30.6% adults) in south and west UP, respectively. Of the 699 serum samples screened from Ludhiana, Punjab, sero-prevalence of BJD was 23.0%. Sero-prevalence was 23.3% (12.1% in young and 24.4% in adults) and 26.9% (27.2% in young and 26.8% in adults) in buffaloes and cattle, respectively. High prevalence of BJD in buffaloes in native tract of Murrah breed, and Hariana breed of cattle correlated with poor per-animal productivity and BJD may be the major cause. Indigenous ELISA kit was rapid, economic and sensitive test for large-scale screening of buffaloes and cattle population against incurable BJD.

Pentoxifylline as an adjuvant to surgery and antibiotics in the treatment of perforation peritonitis: a prospective, randomised placebo-controlled study

INTRODUCTION

In animal models and human trials, pentoxifylline has shown beneficial pharmacological effects in the treatment of septic shock. We evaluated the role of pentoxifylline in the treatment of perforation peritonitis, as an adjuvant to surgery and standard antibiotic treatment.

METHODS

A prospective, randomised placebo-controlled trial was conducted on 50 patients with perforation peritonitis. 25 patients were randomised to the test group and 25 patients to the control group. In addition to standard treatment, the test group of patients received pentoxifylline 200 mg per day as an adjuvant for three days. The endpoints of the study were to evaluate the condition of the wound in the postoperative period, APACHE II score and total duration of hospital stay.

RESULTS

Both groups were comparable in all aspects. There were 23 male and two female patients in the test group, and 20 male and five female patients in the control group (p-value is 0.021). Mean age was 37.9 +/- 10.5 years in the test group and 33.8 +/- 11.0 years in the control group (p-value is 0.186). The APACHE II score in the test group and in the control group was statistically not significant (p-value is 0.661). In the test group, seven (28 percent) patients had wound infection and in the control group, 13 (52 percent) patients had wound infection (p-value is 0.083). The mean postoperative hospital stay in the test group was 6.8 +/- 2.1 days and in the control group, it was 11.2 +/- 5.2 days (p-value is 0.001).

CONCLUSION

Pentoxifylline improved the outcome by significantly decreasing the length of the hospital stay and the rate of wound infection.

Mini-incision dynamic condylar screw fixation for comminuted subtrochanteric hip fractures

PURPOSE

To review the results of indirect reduction and mini-incision dynamic condylar screw (DCS) fixation for comminuted subtrochanteric femoral fractures.

METHODS

29 men and 14 women aged 25 to 65 (mean, 44) years with comminuted subtrochanteric femoral fractures underwent indirect reduction and mini-incision DCS fixation. Fractures were classified according to the AO classification (10 type 32B and 33 type 32C) and Seinsheimer classification (6 type III, 15 type IV, and 22 type V). Functional outcomes were assessed using the Harris hip score and Merle d'Aubigne score.

RESULTS

The mean time to full weight bearing was 11 (range, 8-19) weeks. The mean time to union was 16 (range, 13-22) weeks. There were no cases of non-union or implant failure after a mean follow-up period of 25 (range, 18-30) months. Seven patients had a mean limb length discrepancy of 1.5 (range, 1-2) cm. Two patients had coxa vara and persistent limp. According to the Harris hip score, functional results were excellent in 12 and good in 31 patients. The mean Harris hip score was 88 (range, 80-99) and the mean Merle d'Aubigne score was 17 (range, 14-18). There was no deep infection or avascular necrosis of the femoral head. Restriction of knee flexion beyond 90 degrees was noted in 2 patients.

CONCLUSION

Results of indirect reduction and mini-incision DCS fixation for comminuted subtrochanteric femoral fractures are favourable. Proper planning and execution of the technique is required to achieve good functional outcomes and avoid complications. Preservation of vascularity of the medial fragments leads to rapid callus formation and early union and hence avoids implant failure and secondary bone grafting.

Left molar approach improves laryngeal view in patients with simulated limitation of cervical movements

BACKGROUND

Immobilized cervical spine, because of either diseases or stabilizing devices, poses considerable difficulties with endotracheal intubation due to poor laryngoscopic view. The left molar (LM) approach has been shown to be useful in difficult sporadic intubation cases. We evaluated efficacy of this approach of laryngoscopy to improve laryngeal view in patients with simulated limitation of cervical movements.

METHODS

Thirty patients of American Society of Anesthesiologists grade I/II, who were scheduled to undergo routine surgical procedures under general anaesthesia and endotracheal intubation, were studied. A two-piece semi-rigid cervical collar was used to immobilize the cervical spine. Under standardized anaesthesia and neuromuscular blocking agent, conventional laryngoscopy using a curved Macintosh blade was performed and glottic view was recorded with and without optimal external laryngeal manipulation (OELM). Subsequently, in the same subjects the laryngoscope blade was withdrawn and re-inserted through the LM approach and glottic view was recorded with and without OELM followed by tracheal intubation.

RESULTS

With the conventional approach, laryngeal view was recorded as grade II in five patients, grade III in 24 patients, and grade IV in one patient. However, with the LM approach, laryngeal view was grade I in 25 patients, grade II in five patients, and grade III or IV in none (P<0.001). Tracheal intubation with the LM approach required the use of a flexible stylet to guide the tube tip into the larynx.

CONCLUSIONS

The laryngeal view is improved by the LM approach in patients with simulated limited cervical movements with a high success rate of tracheal intubation, but requires orientation for negotiation of the tube through the narrow oropharyngeal space available.

Basidiobolomycosis: a rare case report

We report a rare case of basidiobolomycosis seen in an 11-year-old girl from North-Eastern part of India. She presented with complaints of bilateral nasal block and nasal discharge for seven-eight months. CT scan of sinuses revealed polypoidal mass in all the sinuses with extradural extension. The tissue biopsy examined histopathologically and microbiologically, revealed Basidiobolus ranarum.

Narrow-band imaging with magnification in Barrett's esophagus: validation of a simplified grading system of mucosal morphology patterns against histology

BACKGROUND AND STUDY AIMS

Validation of a simplified classification of mucosal morphology in prediction of histology in Barrett's esophagus using narrow-band imaging with magnification (NBI-Z) and assessing its reproducibility by endoscopists experienced in the use of NBI (NBI-experts) and by endoscopists who were new to NBI (non-NBI-experts).

PATIENTS AND METHODS

In a prospective cohort study of 109 patients with Barrett's esophagus at a single tertiary referral center, mucosal patterns visualized in Barrett's esophagus on NBI-Z were classified into four easily distinguishable types: A, round pits with regular microvasculature; B, villous/ridge pits with regular microvasculature; C, absent pits with regular microvasculature; D, distorted pits with irregular microvasculature. The NBI-Z grading was compared with the final histopathological diagnosis, and positive (PPV) and negative predictive values (NPV) were calculated. The reproducibility of the grading was then assessed by NBI-expert and non-NBI-expert endoscopists, and interobserver and intraobserver agreement were calculated using kappa statistics.

RESULTS

Per-biopsy analysis: In 903 out of 1021 distinct areas (87.9%) the NBI-Z grading corresponded to the histological diagnosis. Per-patient analysis: The PPV and NPV for type A pattern (columnar mucosa without intestinal metaplasia) were 100% and 97% respectively; for types B and C (intestinal metaplasia) they were 88% and 91% respectively, and for type D (high-grade dysplasia) 81% and 99% respectively. Inter- and intraobserver agreement: The mean kappa values in assessing the various patterns were 0.71 and 0.87 in the non-expert group; 0.78 and 0.91 in the expert group.

CONCLUSIONS

This study has validated a simplified classification of the various morphologic patterns visualized in Barrett's esophagus and confirmed its reproducibility when used by NBI-expert and non-NBI-expert endoscopists.

The in vivo effects of Tulbhagia violacea on blood pressure in a salt-sensitive rat model

AIM OF THE STUDY

The in vivo effects of Tulbhagia violacea on systemic arterial blood pressure and on the renin-angiotensin system in a Dahl salt-sensitive rat model were investigated.

MATERIALS AND METHODS

Animals were treated for 14 days intraperitoneally as follows: Tulbhagia violacea (Tvl) (50mg/kg b.w.), captopril (Cap) (10mg/kg b.w.) or DMSO (Con). Baseline blood pressures were recorded prior to the commencement of the study and biweekly during the experimental period. Urine volume and sodium concentration were measured during the experimental period. On day 15, animals were anaesthetized (sodium thiopentane, 50mg/kg, i.p.), blood samples for aldosterone levels were taken and the kidneys removed for determining AT1a mRNA expression.

RESULTS

Cap and Tvl groups showed significantly reduced AT1a mRNA expressions by 3.11- and 5.03-fold, respectively, when compared to the Con group (p<0.05). When compared to baseline blood pressures (day 0); Cap and Tvl showed reductions in systolic blood pressure (SBP) of 7.76+/-0.41% and 9.12+/-0.31%, respectively (mean% decrease from day 0 to day 14). In contrast, in the Con group the systolic blood pressure increased from day 0 to day 14 by 4.66+/-0.56%. Blood pressure changes in all treated groups differed from Con significantly. Systolic blood pressure decreased with the decrease in AT1a mRNA expressions in these groups. When comparing day 0 to day 14, urine output increased in the Cap and Tvl groups. In the Con group, urinary volume was reduced by day 14 as compared to day 0. Urinary sodium excretion was increased in the treated groups by day 14.

CONCLUSION

It can be concluded that Tulbhagia violacea reduces systemic arterial blood pressure in the Dahl rat by decreasing renal AT1 receptor gene expression and hence modulating sodium and water homeostasis.

Gonadotropin releasing hormone receptor gene and protein expression and immunohistochemical localization in bovine uterus and oviducts

Recently GnRH, GnRH-R systems has been demonstrated in various extrahypothalamic and extrapituitary reproductive tissues in different mammalian species, where GnRH acts in an autocrine and or paracrine manner and modulates different biological processes. GnRH-R mRNA has also been demonstrated in bovine ovaries (follicle and corpus luteum) and normal and carcinogenic human endometrium/endometrial cells. This is the first study elucidating presence of GnRH-R mRNA and GnRH-R protein in bovine uterus and oviducts in follicular and luteal phases of the estrous cycle and further localizing the receptors to endometrial and oviductal epithelial cells. To our knowledge this is the first report demonstrating GnRH-R mRNA and protein in mammalian oviducts. We used gene-specific primers and monoclonal GnRH-R antibody to test GnRH-R mRNA and GnRH-R protein through RT-PCR and immunobloting. Immunohistochemistry was employed to localize these receptors to endometrial and oviductal epithelial cells. GnRH-R mRNA and receptor protein were expressed at expected molecular weights of 920bp and 60kD, respectively. Densitometry analysis revealed that expression levels for GnRH-R protein in uterus and oviducts were similar to bovine pituitary. The presence of GnRH receptors in bovine uterus and oviducts is intriguing and it would be imperative to examine the functional role of this system in the regulation of reproductive processes.

Clinical relevance of HBV DNA load in patients with chronic hepatitis B infection

BACKGROUND

Hepatitis B virus (HBV) DNA detection and quantification are now playing an increasing role in the assessment of disease activity and response to therapy. However, viraemia levels which define various stages of HBV infection have not yet been established.

AIM

To define viraemia levels which describe various stages of chronic hepatitis B virus infection.

METHODS

In a retrospective study, stored sera samples of chronic hepatitis B virus (CHB) infected patients registered at AIIMS liver clinic, from January 1996 to June 2005 were subjected to competitive, quantitative PCR analysis.

RESULTS

The median HBV DNA load was lowest among carriers and highest among patients with chronic hepatitis B [0 (0-8) vs. 7 (0-12) log10 copies/ml, respectively; p<0.05]. As compared to chronic hepatitis patients the DNA load was also lower among cirrhotics [7 (0-12) vs. 4.5 (0-8) log10 copies/ml, respectively; p<0.05] and hepatocellular cancer patients [ 7(0-12) vs. 0 (0-8) log10 copies/ml, respectively; p<0.05]. Patients with carriers had a DNA load which was significantly lower than e antigen negative CHB [0 (0-8) vs. 6 (0-10) log10 copies/ml; p<0.05] or e antigen positive CHB [0 (0-8) vs 8 (0-12) log10 copies/ml; p<0.05]. A threshold of 3.5 log10 copies/ml had sensitivity and specificity of 83% and 58% respectively in differentiating carriers from e antigen negative CHB. There was a strong positive correlation of HBV DNA load with inflammatory grade (R=0.334; p=0.0001), fibrosis stage (R=0.276; p=0.001) and ALT levels (R=0.378; p=0.0001). 82% (9/11) of those who lost e antigen had a decline in HBV DNA levels to <5 log10 copies/ml, whereas only 12.5% (1/8) of those who did not lose e antigen had a decline in DNA load below this level.

CONCLUSIONS

HBV DNA viraemia levels correlate positively with the inflammatory grade, fibrosis stage and ALT levels. Most patients who loose e antigen have a decline in DNA load to below 5 log10 copies/ml. Further prospective studies employing repeated measurements are required to define a threshold to differentiate between HBV carriers and e antigen negative CHB.