Predictive profiling of gram-negative antibiotics in CagA oncoprotein inactivation: a molecular dynamics simulation approach

Gastric cancer (GC) is the fifth most prevalent form of cancer worldwide. CagA - positive Helicobacter pylori infects more than 60% of the human population. Moreover, chronic infection of CagA-positive H. pylori can directly affect GC incidence. In the current study, we have repurposed FDA-approved antibiotics that are viable alternatives to current regimens and can potentially be used as combination therapy against the CagA of H. pylori. The 100 FDA-approved gram negative antibiotics were screened against CagA protein using the AutoDock 4.2 tool. Further, top nine compounds were selected based on higher binding affinity with CagA. The trajectory analysis of MD simulations reflected that binding of these drugs with CagA stabilizes the system. Nonetheless, atomic density map and principal component analysis also support the notion of stable binding of antibiotics to the protein. The residues ASP96, GLN100, PRO184, and THR185 of compound cefpiramide, doxycycline, delafloxacin, metacycline, oxytetracycline, and ertapenem were involved in the binding with CagA protein. These residues are crucial for the CagA that aids in entry or pathogenesis of the bacterium. The screened FDA-approved antibiotics have a potential druggability to inhibit CagA and reduce the progression of H. pylori borne diseases.

Radial Long Sheath Angioplasty for Proximal Severe Flow Limiting Radial Artery Spasm Utilizing the Dotter Technique

BACKGROUND

Although studies continue to demonstrate the advantages of transradial access (TRA) for neurointerventions, radial artery spasm (RAS) remains a frequent cause of TRA failure. Dotter initially described a technique to dilate areas of peripheral vascular stenosis by advancing sequentially larger catheters across the lesion over a wire. We present our institutional experience performing a modified Dotter technique utilizing long radial sheaths to dilate areas of proximal flow limiting RAS.

OBJECTIVE

To review the use of the Dotter technique for alleviating RAS in patients undergoing TRA for neurointerventions.

METHODS

A retrospective review of all patients undergoing TRA for neurointerventions at our institution from 2018-2020 was performed to identify patients with proximal flow limiting RAS. In identified patients, a modified Dotter technique was employed to dilate the stenosis. Demographic and periprocedural data were assessed to identify any adverse outcomes.

RESULTS

Four patients with severe proximal flow limiting RAS were identified. In each case, a hydrophilic long radial sheath and vascular dilator were sequentially advanced through the stenosis. In all cases, repeat angiography demonstrated improvement of the spasm and final radial angiograms demonstrated persistent improvement in caliber and regularity of the vessel. Each procedure was also completed via TRA with no periprocedural complications.

CONCLUSIONS

Our modified Dotter technique is effective in bypassing areas of severe proximal flow limiting RAS thus obviating the need for access site conversion. Additional studies are warranted to understand the implication of the angioplasty-like effects seen within the radial artery following removal of the long radial sheaths.

Polymeric Micelles of Modified Chitosan Block Copolymer as Nanocarrier for Delivery of Paclitaxel

Background:

Polymeric micelles are being used as successful nanocarriers for the delivery of diverse drug molecules due to properties like solubilization, selective targeting, P-glycoprotein inhibition, altered drug internalization route and subcellular localization etc.

Objective:

The present investigation was planned to prepare and characterize novel polymeric micelles derived from self assembly of amphiphilic chitosan-bile salt derivative (CS-mPEG-DA) as nanocarrier and evaluate their potential in delivery of an anticancer drug, paclitaxel.

Method:

Paclitaxel, a diterpenoid compound, useful in clinical treatment of several solid tumors such as ovarian cancer, breast cancer and lung cancer suffers from limitations like low aqueous solubility and bioavailability and subsequently was used as the model drug.

Results:

Paclitaxel was successfully incorporated into polymeric micelles using dialysis and emulsion method with encapsulation efficiency up to 95% having particle size in nanometer range (<200 nm). Paclitaxel loaded micelles were found to release the drug in a sustained manner up to 96 h in PBS containing 0.1% (w/v) tween 80 at 37&#176;C. The micelles powders subjected to stability studies for a period of 90 days were found to be stable at 4 &#177; 2&#176;C with respect to particle size and drug content. In vivo cytotoxicity assay confirmed that paclitaxel encapsulated in polymeric micelles showed higher cytotoxicity against cultured MCF-7 breast cancer cells than paclitaxel alone.

Conclusion:

Polymeric micellar systems derived from copolymerization of chitosan exhibit a great potential in successful delivery of poorly water soluble or low bioavailable drugs like paclitaxel.

NEED OF IRON SUPPLEMENTATION IN GESTATIONAL DIABETES MELLITUS

Objective

Gestational diabetes mellitus (GDM) increases the foetal morbidity and mortality and there is also risk of development of type II diabetes for the mother. In pregnancy iron supplementations are given to all the females in India. Data are not available on the relationship between serum ferritin and GDM in Indian populations.

Material & Methods

Case control study was done on 90 women (30 GDM patients approx 28 weeks of gestation and 60 control subjects without GDM) referred to the tertiary care hospital at New Delhi. Ferritin was analysed by ELISA kit. They were analyzed for the correlation of ferritin with blood glucose in GDM patients.

Results

On comparison with blood glucose the levels of ferritin were statistically significantly high in GDM cases as compared to controls (p value 0.008). There was a negative correlation of ferritin with blood glucose level (r value -0.039, p value 0.794).

Discussion

Pregnancy is an equivalent of an inflammatory state and the high levels of ferritin can help in determining the need of iron supplementation given in pregnant females. Women who had high serum ferritin had the greatest risk of GDM.

Conclusion

This study suggests a possible link between elevated serum ferritin and low-grade inflammation. Further studies in larger populations are required to establish this study.

QSAR analyses of DDT analogues and their in silico validation using molecular docking study against voltage-gated sodium channel of Anopheles funestus

DDT has enjoyed the reputation of a successful pesticide in disease control programme and agricultural practices along with the serious opposition and ban later on due to its biomagnification and toxic action against non-target organisms. The present work was carried out to develop QSAR models for analysing DDT analogues for their pesticidal activity and in silico validation of these models. A 2D-QSAR model was generated using stepwise with multiple regression, and the model with a value of r(2) = 0.7324; q(2) = 0.6215; pred r(2) = 0.7038, containing five descriptors, was selected for further study. The 3D QSAR with CoMFA analysis showed that steric contribution of 21% and electrostatic contribution of about 79% were required for larvicidal activity of DDT analogues. A set of 3430 molecules was generated using the basic DDT skeleton as template, and these were evaluated for their mosquito larvicidal activity using the generated QSAR models and DDT as standard. Eleven molecules were selected for in silico validation of these models. For this, a docking study of the selected molecules against the homology-modelled voltage-gated sodium channel of Anopheles funestus was conducted. The study showed that the activities of these analogues as predicted by 2D-QSAR, 3D-QSAR with CoMFA and dock score were observed to be well correlated.

Knowledge and use of personal protective measures against mosquito borne diseases in a resettlement colony of delhi

Background:

Mosquito borne diseases (MBDs) are major public health problem in India. State of Delhi is endemic for dengue and other MBDs. The increasing incidence of MBDs in Delhi in recent years warrants a pro-active approach for their prevention. Knowledge and use of personal protective measures (PPMs) presents an effective strategy for prevention and control of MBDs.

Aim:

The present study was conducted to assess the knowledge and use of PPMs against MBDs in an urban resettlement colony of Delhi.

Subjects and Methods:

It was a cross-sectional study carried out in a resettlement colony of Delhi. A total of 100 families were selected by systematic random sampling. Data was collected using semi-structured questionnaire and supplemented by spot survey by the investigator in the community. The results were analyzed in SPSS version 16.0 (Chicago Illinios, USA).

Results:

Out of the 100 respondents, 65% (65/100), 58%(58/100) and 13% (13/100) had heard about dengue, malaria and chikungunya, respectively. Nearly, one-fifth (20/100; 20%) of the participants reported incorrect breeding sites for mosquitoes. The knowledge regarding PPMs was very high (93/100; 93%) and about (90/100; 90%) families were actually using at least one of the PPMs. However, very few families were using them correctly (1/90; 1.1%) and adequately (5/90; 5.6%). The most common PPM being used by the study population was liquid vaporizers (54/90; 60%). Nearly one-third (29/90; 32.2%) of the participants reported side-effects due to PPMs with irritation to smell being the most common reported side-effect. On house visit, adult mosquitoes were seen in 67% (67/100) of the houses, while potential mosquito breeding sites were found in and around 56% (56/100) houses.

Conclusions:

There were crucial gaps in knowledge and practices of participants with regard to prevention and control of MBDs. Thus, there is a need to intensify efforts toward creating public knowledge and mobilizing community about correct use of preventive measures against MBDs.

Antimicrobial resistance profiles of common mastitis pathogens on Canadian dairy farms

Monitoring of antimicrobial resistance (AMR) in bacteria has clinical and public health significance. The present study determined prevalence of AMR in common mastitis pathogens Staphylococcus aureus, including methicillin-resistant Staph. aureus (MRSA; n=1,810), Escherichia coli (n=394), and Klebsiella species (n=139), including extended-spectrum β-lactamase (ESBL)-producing E. coli and Klebsiella species, isolated from milk samples on 89 dairy farms in 6 Canadian provinces. Minimum inhibitory concentrations (MIC) were determined using the Sensititer bovine mastitis plate (Trek Diagnostic Systems Inc., Cleveland, OH) and a National Antimicrobial Resistance Monitoring System gram-negative panel containing antimicrobials commonly used for mastitis treatment and control. Denim blue chromogenic agar and real-time PCR were used to screen and confirm MRSA, respectively. Resistance proportion estimates ranged from 0% for cephalothin and oxacillin to 8.8% for penicillin in Staph. aureus isolates, and 15% of the resistant Staph. aureus isolates were multidrug resistant. One MRSA isolate was confirmed (prevalence: 0.05%). Resistance proportion estimates ranged from 0% for ceftriaxone and ciprofloxacin to 14.8% for tetracycline in E. coli, and 0% for amikacin, ceftiofur, ciprofloxacin, and nalidixic acid to 18.6% for tetracycline in Klebsiella species isolates. Further, 62.8 and 55% of the resistant E. coli and Klebsiella species isolates were multidrug resistant, respectively. Resistance to >5 and >2 antimicrobials was most common in E. coli and Klebsiella species isolates, respectively, and no ESBL producers were found. Prevalence of AMR in bovine mastitis pathogens was low. Most gram-negative udder pathogens were multidrug resistant; MRSA was rarely found, and ESBL E. coli and Klebsiella species isolates were absent in Canadian milk samples.

Antimicrobial use on Canadian dairy farms

Antimicrobial use (AMU) data are critical for formulating policies for containing antimicrobial resistance. The present study determined AMU on Canadian dairy farms and characterized variation in AMU based on herd-level factors such as milk production, somatic cell count, herd size, geographic region and housing type. Drug use data were collected on 89 dairy herds in 4 regions of Canada, Alberta, Ontario, Québec, and the Maritime provinces (Prince Edward Island, New Brunswick, and Nova Scotia) for an average of 540 d per herd. Dairy producers and farm personnel were asked to deposit empty drug containers into specially provided receptacles. Antimicrobial use was measured as antimicrobial drug use rate (ADUR), with the unit being number of animal defined-daily doses (ADD)/1,000 cow-days. Antimicrobial drug use rates were determined at farm, region, and national level. Combined ADUR of all antimicrobial classes was 14.35 ADD/1,000 cow-days nationally. National level ADUR of the 6 most commonly used antimicrobial drug classes, cephalosporins, penicillins, penicillin combinations, tetracyclines, trimethoprim-sulfonamide combinations, and lincosamides were 3.05, 2.56, 2.20, 1.83, 0.87, and 0.84 ADD/1,000 cow-days, respectively. Dairy herds in Ontario were higher users of third-generation cephalosporins (ceftiofur) than in Québec. Alberta dairy herds were higher users of tetracyclines in comparison to Maritimes. Antimicrobial drug use rate was higher via systemic route as compared with intramammary and other routes of administration (topical, oral, and intrauterine). The ADUR of antimicrobials used intramammarily was higher for clinical mastitis treatment than dry cow therapy. For dry cow therapy, penicillin ADUR was greater than ADUR of first-generation cephalosporins. For clinical mastitis treatment, ADUR of intramammary penicillin combinations was greater than ADUR of cephapirin. Herd-level milk production was positively associated with overall ADUR, ADUR of systemically administered ceftiofur, cephapirin administered for dry cow therapy, and pirlimycin administered for clinical mastitis treatment. Herd size and ADUR of systemically administered ceftiofur were also positively associated. In conclusion, β-lactams were most commonly used on Canadian dairy farms. Among antimicrobials of very high importance in human medicine, the use of fluoroquinolones was rare, whereas third-generation cephalosporins and penicillin combinations containing colistin were used very frequently on Canadian dairy farms.

Madurai Area Physicians Cardiovascular Health Evaluation Survey (MAPCHES)--an alarming status

BACKGROUND

Studies have shown that South Asians are highly susceptible to cardiovascular diseases (CVDs). There is very little information available about the prevalence of risk factors for CVD in the physician population, a group that might be expected to be more aware of cardiovascular risk and health status.

AIM

To evaluate the prevalence of cardiovascular risk factors - including metabolic, dietary and behavioural - among the physician population in southern India.

METHODS

Approximately 4000 physicians of differing specialties from eight southern districts in Tamilnadu, India, in and around the city of Madurai were listed. Of these, 1600 were randomly selected to participate in a cross-sectional survey, of which 1514 physicians agreed to participate. The survey included demographic questionnaires, objective measurements of blood pressure, fasting blood sugar, fasting lipids and waist circumference, and questionnaires about their dietary and behavioural habits.

RESULTS

Complete data were available for 1433 physicians. Using a blood pressure cut-off value of 130/85 mmHg or higher, the study recorded a prevalence of 41% among men and 23% among women. On applying the International Diabetes Federation criteria for the metabolic syndrome for the South Asian population, the present study identified 49% of female physicians and 41% of male physicians as having the metabolic syndrome. Only 17% were physically active. Less than one-half of them consumed vegetables. Nearly 31% of male physicians were smokers.

CONCLUSION

Analysis of these data suggests that the risk for CVD and stroke is at epidemic proportions in a cohort of well-educated physicians who are in the highest quintile of income.

Anti-inflammatory and anthelmintic activities of Solanum khasianum Clarke

In order to scientifically appraise some of the folkloric uses of Solanum khasianum Clarke (Solanaceae), the present study was undertaken to examine the anti-inflammatory and anthelmintic properties of the berries of ethanol extract. Anti-inflammatory activity was tested in carrageenan induced rat hind paw edema method at three dose level of 200, 300, and 400 mg kg(-1) respectively, Diclofenac sodium (100 mg kg(-1)) was used as the reference standard. The anti-inflammatory activity of the extract was compared with standard and control. The anthelmintic activity of the extract was tested on tape worm, liver fluke, thread worm, and hook worm using two different concentrations, 100 and 200 mg mL(-1) respectively. Time taken for the inhibition of motility was noted and compared with the standard drug, Piperazine citrate 15 mg mL. The plant extract significantly (p < 0.01) reduced the inflammation of the rats when compared to the control group. Also, the ethanol extract of the plant paralyzed the worms followed by death, which was comparable with that of the standard. This study supports the folk claim.

Tunable optical properties of colloidal quantum dots in electrolytic environments

The absorption spectra of colloidal cadmium sulfide quantum dots in electrolytic solutions are found to manifest a shift in the absorption threshold as the concentration of the electrolyte is varied. These results are consistent with a shift in the absorption threshold that would be caused by electrolytic screening of the field caused by the intrinsic spontaneous polarisation of these würtzite structured quantum dots. These electrolyte-dependent absorption properties provide a potential means of gaining insights on the variable extracellular and intracellular electrolytic concentrations that are present in biological systems.

Wood-smoke exposure: an unusual cause of miliary mottling on X-ray chest

A case of wood smoke inhalation related lung disease presenting with miliary mottling on radiography is described. Transbronchial lung biopsy showed the presence of coal macules.

Mediastinal widening in a patient of ulcerative colitis

A case of ulcertaive colitis on long-term corticosteroid therapy presenting with mediastinal widening and diagnosed to have mediastinal lipomatosis an thoracic computed tomography is presented.

Tuberculous parotitis: a series of five cases diagnosed on fine needle aspiration cytology

Parotid gland tuberculosis is still a rare entity and has mostly been diagnosed after parotidectomy. We present five cases which were diagnosed on fine needle aspiration cytology (FNAC) and managed medically avoiding surgical intervention.

Activation of the Ras-GRF/CDC25Mm exchange factor by lysophosphatidic acid

The Ras-GRF exchange factor can activate Ras-dependent responses following the activation of heterotrimeric G-protein and calcium signalling. In stable lines of NIH-3T3 fibroblasts that express Ras-GRF, the agonist lysophosphatidic acid (LPA) increases the phosphorylation state and activity of Ras-GRF. The stimulation of Ras-GRF can be demonstrated in vitro, in an assay using recombinant Ras substrate, and in situ, by a selective increase in the ability of LPA to stimulate mitogen-activated protein (MAP) kinase. The increase in Ras-GRF phosphorylation state, which occurs on serine residues, and the increase in exchange factor activity are blocked by pretreatment with pertussis toxin. Activation of Ras-GRF by LPA can also be inhibited by chelation of intracellular calcium and treatment of the Ras-GRF with protein phosphatase 1 (PP1), supporting a model in which Ras-GRF serves to integrate signals from multiple transduction pathways.

Poisoning in children: Indian scenario

The retrospective data on childhood poisoning from eight regional hospitals in India has been reviewed. The demographic features and types of poisonings encountered have been compared. The analysis of the data indicated that pediatric poisonings constituted 0.23-3.3% of the total poisoning. The mortality ranged from 0.64-11.6% with highest being from Shimla. Accidental poisoning was common involving 50-90% of children below 5 years of age and males outnumbered the females. Suicidal poisoning was seen after 13 years of age and was due to drugs and household chemicals. One of the hospitals in Delhi recorded a very high incidence (66.6%) of drug poisoning in children. The drugs consumed belonged to phenothiazines, antiepileptics and antipyretics. Iron poisoning was seen in younger children. Kerosene was one of the causes of accidental poisoning at all hospitals except Shimla and rural Maharashtra were probably wood charcoal is widely used. Pesticide poisoning was more prevalent in Punjab and West Bengal whereas plant poisoning was very common in Shimla. Significant number of snake envenomation has been recorded from rural Maharashtra. Other less common accidental poisonings in children included alcohol, corrosives, heavy metals, rodenticides, detergents and disinfectants. Thus various regions in the country showed some variation in types and frequency of childhood poisoning which could be attributed to different geographical and socio-economic background.

Attitudes of future mothers regarding infant feeding

Attitudes of 2500 urban college girls from Ludhiana city, aged 15 to 20 years were assessed towards infant feeding using a standardized Likert Scale (r = 0.82). The influence of subject opted in college and the presence of a child less than 3 years in the family on the attitudes was also studied. The overall attitudes of the whole group towards infant feeding were negative. Science students had better attitude scores on most of the themes tested (p < 0.05). The presence of a child aged less than 3 years in the family had no significant influence on the attitudes of girls towards infant feeding. Most of the girls were desirous of studying the concepts of infant feeding in their college curriculum. It is recommended that efforts should be made to incorporate these concepts in the formal educational curriculum so that girls grow up with positive attitude towards infant feeding.

EEG bispectrum predicts movement during thiopental/isoflurane anesthesia

OBJECTIVE

The objective of our study was to test the efficacy of the bispectral index (BIS) compared with spectral edge frequency (SEF), relative delta power, median frequency, and a combined univariate power spectral derivative in predicting movement to incision during isoflurane/oxygen anesthesia.

METHODS

A total of 42 consenting patients were assigned to 3 groups, isoflurane 0.75, 1.0, and 1.25 minimal alveolar concentration (MAC). Anesthesia was induced with thiopental and maintained with the appropriate end-tidal concentration of isoflurane. The electroencephalogram (EEG) was recorded using a microcomputer system, and data were analyzed off-line. The EEG during the 2 min before incision was analyzed. Following skin incision, each patient was carefully observed for 60 sec to detect occurrence of purposeful movement.

RESULTS

For all groups combined, there was a statistically significant difference for BIS (p < 0.0001) and also for relative delta power (p < 0.016) between movers and nonmovers. There was a statistically significant difference between movers and nonmovers at 1.25 MAC isoflurane for BIS (p < 0.01). There were no other significant differences for any other EEG variable at any concentration of isoflurane. No EEG variable showed a relationship to isoflurane concentration.

CONCLUSIONS

When bispectral analysis of the EEG was used to develop a retrospectively determined index, there was an association of the index with movement. Thus, it may be a useful predictor of whether patients will move in response to skin incision during anesthesia with isoflurane/oxygen.

New Macrocyclic Ligands. VII. The Synthesis of Mixed-Donor Spiro-Linked Macrocycles

The syntheses of five new spiro -linked bis-macrocyles, incorporating four ether oxygen and four or six secondary nitrogen heteroatoms , are reported. Two strategies were employed-the first involved the condensation of a spiro tetraaldehyde with 2 equiv. of ethane-1,2-diamine or propane-1,3-diamine or 2,2′-diaminodiethylamine followed by in situ reduction of the resulting intermediate tetraimines . The second procedure began with pentaerythrityl tetraamine [C(CH2NH2)4] which was then condensed with 2 equiv. of a dialdehyde moiety in which two ether oxygen atoms, bridged by either two or three methylene groups, were incorporated in its backbone. A related in situ reduction step to that employed in the first procedure then yielded the required double-ring macrocycles. For use in comparative studies, the corresponding single-ring macrocycles were also synthesized where they had not been reported previously.

Developing and standardizing a scale for measuring attitudes towards infant feeding

A Likert type scale was designed to assess the attitudes of urban college girls towards infant feeding. The scale was administered to a sample population of 50 girls and the scores thus obtained were used to calculate the internal consistency of the scale. The scale had a reliability of 0.82 (p < 0.01 at df 48).

Detection of antibodies to phenolic glycolipid by ELISA in leprosy patients

Antibody (IgM) response to PGL-1, a surface glycolipid unique to Mycobacterium leprae has been studied in 25 cases each of lepromatous and tuberculoid leprosy and in 25 healthy controls. The absorbance value at 488 nm was expressed as antibody titre. Serum antibody titre was found to be significantly higher in patients than controls. Results confirm that antibody response in leprosy patients depend upon bacterial load.

Acute respiratory infections in children: a study of knowledge and practices of mothers in rural Haryana

In the present study, data were collected on knowledge and practices of mothers in two villages of Block Beri of district Rohtak for devising a standard management plan. In all 304 mothers were interviewed. About 23 per cent mothers recognised pneumonia by fast breathing and 11.2 per cent recognised severe pneumonia by chest indrawing. Only 1.3 per cent mothers knew infective origin of ARI. Although most of them were convinced about continuation of breast feeding, 70 per cent of them were advising food restriction. Use of herbal tea in ARI was widely prevalent and so was the practice of putting warm mustard oil in ear for curing ear pain. Primary Health Centre was the most frequented place for treatment of ARI and mother-in-law was the most important person in taking management decisions for the child.

Comparative effects of the opioids fentanyl and buprenorphine on ventricular vulnerability during acute coronary artery occlusion

Fentanyl, a mu selective opioid agonist in wide clinical use, raises the ventricular fibrillation threshold in the normal canine myocardium. We have previously shown that this effect is amplified by haemorrhagic stress. In order to determine if mu receptor activation is antifibrillatory during acute myocardial ischaemia, we compared the effects of two mu selective agents, fentanyl and buprenorphine, in open chest chloralose anaesthetised dogs. Each drug was administered intravenously in two doses 1 h apart (fentanyl 30 micrograms.kg-1.dose; buprenorphine 0.3 mg.kg-1.dose). Ventricular fibrillation threshold was measured during right ventricular pacing using the single stimulus technique. The threshold was determined before and during a 10 min left anterior descending coronary artery occlusion. Prior to fentanyl administration, ventricular fibrillation threshold decreased from a control value of 19(SEM 2) mA to 12(1) mA during coronary artery occlusion. After the first dose of this drug an attenuation in the ischaemia induced fall in fibrillation threshold from 23(4) mA to 15(2) mA was observed. After the second dose of fentanyl the decline in fibrillation threshold was significantly blunted at 22(4) mA during control and 18(3) mA during occlusion, p less than 0.05 compared to no drug. In an additional series of experiments atropine sulphate abolished the antifibrillatory action of fentanyl, indicating that vagal efferent activation is responsible for the protective effect of the drug during acute myocardial ischaemia. This is in contrast with its mode of action during haemorrhage, when it enhances vagal afferent inhibition of sympathetic tone, and atropine pretreatment is without effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Encainide and flecainide: are they interchangeable?

Encainide and flecainide are two recently released class IC antiarrhythmic agents that have been reported to be highly effective for suppressing all forms of ventricular arrhythmias. Both drugs are potent blockers of the sodium channel and produce marked slowing of conduction within the His-Purkinje system and myocardium. To establish if the response to one agent predicts the response to the other, the antiarrhythmic effect of the two drugs was compared in a group of 18 patients with malignant ventricular arrhythmia. Fourteen patients had sustained ventricular tachycardia and four patients had ventricular fibrillation. The average ejection fraction of this group was 37%. All patients had a high density of spontaneous ventricular arrhythmia and were evaluated noninvasively. Both drugs significantly reduced all forms of spontaneous arrhythmia. By Holter monitoring criteria, the effect of the two drugs was concordant in 61% (p = NS). By exercise criteria, the concordance rate was 50% (p = NS). Overall, 12 patients (67%) responded to encainide and eight (44%) patients responded to flecainide (p = NS). Only 10 of 18 (56%) patients had the same response to both agents (p = NS). There was no significant difference in ejection fraction or in average daily dose of drug between responders and nonresponders. Thus despite their similar electrophysiologic profile, the clinical antiarrhythmic effect of these two agents was different. For the noninvasive management of patients the response to one agent should not be used to predict the response to the other.

Reproducibility of exercise-induced ventricular arrhythmia in patients undergoing evaluation for malignant ventricular arrhythmia

In patients with malignant ventricular arrhythmia, the utility of exercise testing for exposing arrhythmias and guiding antiarrhythmic drug selection and dosage is not yet generally accepted. A major reservation relates to the issue of reproducibility of arrhythmia provocation. This prospective study comprised 28 patients referred for evaluation of ventricular arrhythmia. In half of these subjects the clinical arrhythmia was sustained ventricular tachycardia or ventricular fibrillation. Maximal exercise testing adhering to a Bruce protocol was performed on 2 separate days. No antiarrhythmic drugs were administered at the time of testing. Of the 28 patients, 27 had an increase in arrhythmia with exercise. The prevalence rates of arrhythmia were greater than 80% and did not significantly differ between test 1 and test 2. Excluding infrequent single ventricular premature complexes, the reproducibility of a test with positive outcome was 76%. Similarly, test-retest agreement, a bidirectional measure of reproducibility, was greater than 74%. Kappa coefficients ranged from 0.26 to 0.36 for all grades of arrhythmia, indicating that reproducibility was consistently greater than by chance alone. Linear regression analysis of arrhythmia frequency in the 2 tests yielded R values of 0.76 to 0.96 and slopes of 0.82 to 1.2. No patient had enough spontaneous variability in repetitive forms to suggest spurious efficacy or aggravation. For ventricular premature complexes there was an 8 to 14% incidence of spurious efficacy and a 4 to 7% incidence of spurious aggravation. These results suggest that exercise-induced ventricular arrhythmia is sufficiently reproducible to serve as an adjunct method in the evaluation and management of patients with potentially life-threatening ventricular arrhythmias.

Antifibrillatory action of the narcotic agonist fentanyl

Morphine, an opiate alkaloid with mixed mu- and delta-agonist properties, raises the ventricular fibrillation threshold in anesthetized dogs by altering autonomic tone. To elucidate further underlying structure-activity relationships, the effect of fentanyl, a nonalkaloid, mu-selective agonist in wide clinical use, was studied. Fentanyl (30 micrograms/kg) was given intravenously to 27 chloralose-anesthetized dogs, and ventricular fibrillation threshold was measured by means of the single-stimulus technique. In the baseline state fentanyl raised the ventricular fibrillation threshold by 14%. When the dogs were subjected to hemorrhagic stress, this effect was amplified to 29% (p less than 0.0001). Bilateral cervical vagotomy abolished fentanyl's antifibrillatory effect, but neither atropine sulfate (0.4 mg/kg/hr) nor atropine methylnitrate (0.5 mg/kg/hr) did so. Fentanyl's influence on the fibrillation threshold during hemorrhage was significantly reduced by bilateral stellate ganglionectomy (p less than 0.005). It is concluded that fentanyl raises the ventricular fibrillation threshold by its known sympathoinhibitory action rather than by its vagal efferent activating effect. The facts that an intact vagus is required and that hemorrhage amplifies the effect suggest that the antifibrillatory effect of fentanyl is mediated through the afferent component of the baroreflex arc.

Clinical significance of short-term variability computed from heart-rate waveforms

The significance of short-term variability (STV) of the baseline fetal heart rate (FHR) as a prime indicator of fetal well-being is well recognized. It is obvious that for consistently reliable assessment of short-term variability, objective quantification is a necessity. This paper presents a retrospective clinical evaluation of a new technique of STV quantification in terms of beats per minute derived from the slowly varying instantaneous FHR waveform rather than from the relatively rapidly varying fetal ECG. FHR signals from 45 patients, internally monitored during labor, were digitized onto IBM-compatible 9-track digital magnetic tape using a PERKIN-ELMER model 7/32 minicomputer at a sampling rate of 240 milliseconds. The digitized signals were then analyzed off-line for STV and FHR. For each patient about 600 clinical variables were entered into the computer and these data were utilized to comprehensively evaluate the neonatal outcome according to HOBEL's neonatal risk assessment system. The values of mean STV ranged from 1.21 b.p.m. to 6.47 b.p.m. with a median value of 2.75 b.p.m., which was used to divide the patient population into a low-variability (less than or equal to 2.75 b.p.m.) and a high-variability (greater than 2.75 b.p.m.) group. This was found to be justified as the STUDENTS's t-test on mean baseline STV values for these two populations showed them to differ significantly (P less than 0.001). Analysis of the results (Fig. 1) showed that 28.7% of the low-variability population were associated with a poor outcome compared with 4.3% in the high-variability group.(ABSTRACT TRUNCATED AT 250 WORDS)