Biomedical subjects
Publications and source records attributed to P K Mittal.
A technique that allows construction of a modified Blalock-Taussig shunt using a polytetrafluoroethylene graft in neonates and infants through an axillary vertical minimal access thoracotomy is described. It is a simple, safe, cosmetically acceptable, and efficient approach even when used during emergency situations. It was successfully performed in 5 neonates and infants.
Absent conal septum in tetralogy of Fallot (TF) is usually noted intraoperatively when the ventricular septal defect (VSD) is found abutting the pulmonary valve, its superior rim being nearly inaccessible transatrially, and the posterior rim being separated from the tricuspid valve (TV) by a muscular ridge. The authors retrospectively analyzed angiograms of 208 consecutive patients with TF seen at their center from July 1989 to December 1995 for absence of the conal septum and the presence of an interval between the TV and the margin of the VSD in 30 degrees right anterior oblique view. In 13 (6%) patients, angiograms were inadequate or of poor quality for assessment and were excluded. Twenty-two of the remaining 195 (11%) patients had a large muscular interval between the tricuspid annulus and the margin of the VSD, which was associated with an absent conal septum in 14 (7.2%) and a diminutive septum in 8 (4%) patients. Nine of the 14 patients with an absent conal septum at angiography underwent surgery, and this finding was confirmed in all. The authors conclude that absent conal septum is not uncommon in TF and constitutes an important variation in its anatomy that can be identified preoperatively at angiography for optimal surgical management.
Residual efficacy of deltamethrin 2.5 wp on various types of surfaces was tested against Anopheles culicifacies under field conditions using WHO standard procedure. Deltamethrin was most effective on the thatched surface and produced 100% mortality of An. culicifacies adults up to 12 weeks, even when exposed at the lowest dose /12.5 mg/m2. It was least effective on brick surface and 100% mortality was observed only for three weeks. The efficacy was observed for 8 and 7 weeks on mud and cement surfaces, respectively. However, at the higher rate of application, i.e. 25 mg/m2, 100% mortality of this species was obtained for 12, 10, 9 and 12 weeks on mud, cement, brick and thatch surfaces, respectively.
Biocontrol potential of Mesocyclops thermocyclopoides against first instar larvae of Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus was studied under laboratory conditions. It was found that M. thermocyclopoides had the highest predation efficacy against Ae. aegypti followed by An. stephensi and Cx. quinquefasciatus. There was a significant reduction in the predation efficacy of M. thermocyclopoides against Cx. quinquefasciatus in the presence of alternate food (p < 0.01). The cage simulation trial indicated that M. themocyclopoides has the potential to control Ae. aegypti breeding effectively in a container type of habitat.
Various devices for transcatheter ASD closure are undergoing clinical trials. Each new device claims advantages in terms of safety and efficacy over earlier devices. We report three cases in which a new investigational device--the Das angel wings--failed. Emergency operations were necessary for device retrieval and defect closure. The possible mechanisms of the event and the options in management are discussed with a review of literature on all devices.
Laboratory evaluation revealed that the Spherimos and Vectolex formulations of Bacillus sphaericus produced 97 and 100% larval mortality respectively in Culex quinquefasciatus at a dose as low as 0.008 ml/sq m as against 93 and 97% mortality respectively at 1 ml/sq m in Anopheles stephensi. However, in An. culicifacies similar level of mortality was not observed even at 10 ml/sq m of these formulations. Field evaluation revealed 100% reduction of Cx. quinquefasciatus larvae for 2-3 weeks in pools and wells with single application of Spherimos @ 2 ml/sq m as against 95.4% reduction @ 10 ml/sq m in irrigation channel for one week. Vectolex @ 10 ml/sq m provided 99-100% reduction of Cx. quinquefasciatus larvae up to 9 weeks in wells and 1 week in channels.
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Toxicity of certain mosquitocidal compounds (both larvicides and adulticides) to the larvivorous fish Poecilia reticulata was determined in the laboratory. Among the various chemical insecticides tested, the synthetic pyrethroid deltamethrin was most toxic to fish (LC50 = 0.016 ppm), while the organophosphorus insecticide abate was least toxic (LC50 = 34 ppm). The bioinsecticides Spherix (Bacillus sphaericus) and Bactoculicide (Bacillus thuringiensis H-14) showed highest safety for the fish (LC50 > 1000 mg/litre). Integrated use of larvivorous fish and bioinsecticide in vector control has been suggested.
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The rare occurrence of anomalous origin of the left pulmonary artery in an adult as an isolated malformation and normal pressures in the pulmonary artery arising from the right ventricle are described. The possible implications of surgery are also discussed.
Two bioinsecticide preparations, viz. Spherix (Bacillus sphaericus) and Bactoculicide (Bacillus thuringiensis H-14), were tested in the laboratory against larvae of Anopheles culicifacies, Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti at different temperatures. The LCs50 of Spherix against III instar larvae of these species at 27 +/- 2 degrees C were 2.0, 0.19, 0.05 and > 40 mg/litre, respectively and those of Bactoculicide were 0.32, 0.16, 0.06 and 0.03 mg/litre, respectively. The toxicity of two bioinsecticides, especially Spherix, varied to a great extent when the tests were repeated at 21 +/- 2 degrees C and 31 +/- 2 degrees C. At 21 +/- 2 degrees C, Spherix was almost non-toxic against larvae of An. culicifacies and An. stephensi (LC50 > 10 mg/l) but at 31 +/- 2 degrees C the bioinsecticide was highly toxic against An. culicifacies (LC50 = 0.48 mg/litre) and An. stephensi (LC50 = 0.04 mg/litre). A similar effect of the temperature was also observed with Bactoculicide.
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Spherix, a powder formulation of Bacillus sphaericus strain B-101, serotype H5a 5b, was evaluated against larvae of Anopheles stephensi and Culex quinquefasciatus in both the laboratory and field. In laboratory tests the formulation @ 0.1 g/sq m produced 100% mortality against larvae of both mosquito species at room temperature (28-32 degrees C). The larvicidal activity of Spherix against An. stephensi @ 0.5 g/sq m persisted for over 12 weeks under laboratory conditions. Field evaluation of Spherix @ 0.25-2.0 g/sq m produced 95-100% reduction in the larval density of both An. stephensi and Culex quinquefasciatus within 48 h in different habitats, and the larvicidal activity persisted for 2-4 weeks in water habitats.
Fifty-three patients with osteomyelitis were grouped according to the duration of the disease at presentation, the bone and the part involved, the aetiology, activity, severity and stage of disease. Sera from these patients was estimated for IgA, IgM and IgG levels and in 23 matched controls. The results were compared with the normal range, and correlative studies were carried out between serum immunoglobulin levels and the different clinical parameters. Serum levels of the 3 immunoglobulins were found, in general, to fail to rise above the normal in the presence of infection. Furthermore, the levels did not show significant variation with the clinical parameters. These findings suggest that there is an intrinsically subdued immune response to osteomyelitis in most of the patients, partly confirming the suspicion of an immunodeficient state.
Earlier authors have shown the improved left ventricular (LV) function after chordae-preserving mitral valve replacement (MVR) in follow-up studies. Seventy-nine consecutive patients undergoing MVR were studied preoperatively and pre-discharge with M-mode and two-dimensional Color Doppler echocardiography for early LV morphometric changes. Conventional MVR was performed in 42 patients (Group 1) and the posterior leaflet-chordae-papillary muscle complex was preserved in 37 patients (Group 2). Both cohorts were similar in age, sex, preoperative NYHA class and valve pathology. Four St. Jude bioprostheses, 9 Medtronic and 66 Sorin prostheses were implanted. The intraoperative and perioperative management protocol was uniform for both groups. The median left atrial dimension in both groups decreased to better physiological levels (53 to 46 mm in group 1, 52.5 to 46 mm in group 2). The median LV enddiastolic dimension increased from 47 to 48 mm in group 1 while it decreased from 56.5 to 49 min in group 2. The median LV endsystolic dimension remained unchanged in group 1 but decreased in group 2 (37.6 to 36 mm). Echocardiographic documentation of such early changes in the LV dimensions after modified MVR indicates that the beneficial effects of chordal preservation become evident early in the postoperative period and may explain the improved perioperative LV function after modified MVR compared to conventional MVR.
A total of 40 patients with endoscopically proved reflux esophagitis were treated in a randomised study. Treatment was given for six weeks and consisted of daily doses of either 1 gm sucralfate four times a day or one, 150 mg ranitidine tablet twice daily. Twenty patients received each drug. Clinical evaluation was done weekly and endoscopic evaluation after six weeks. Forty percent patients on ranitidine and 50% patients on sucralfate became asymptomatic at six weeks. Fifty percent patients on ranitidine and 60% patients on sucralfate were endoscopically healed. The results did not show any difference in the effect of ranitidine and sucralfate treatment (p > 0.05). Overall tolerance and compliance in the two forms of treatment was good. Though ranitidine has a more convenient dose schedule and is more cost effective, sucralfate needs further clinical trials.
Forty patients with endoscopically proved reflux oesophagitis were treated in a randomised study. Treatment was given for six weeks and consisted of either 1 g sucralfate four times a day or 150 mg ranitidine tablet twice daily. Twenty patients received each drug. Clinical evaluation was done weekly and endoscopic evaluation after six weeks. Eight patients on ranitidine and ten patients on sucralfate became asymptomatic at six weeks. Ten patients on ranitidine and twelve patients on sucralfate were endoscopically healed. There was no difference in the effect of ranitidine and sucralfate treatment (p greater than 0.05). Overall tolerance and compliance with the two forms of treatment were good. Though ranitidine has a more convenient dose schedule and is more cost-effective, sucralfate needs further clinical evaluation.
Acute toxicity of certain organochlorine, organophosphorus, synthetic pyrethroid and microbial insecticides to the mosquito fish Gambusia affinis were determined to collect baseline data for selecting the resistant strains of the fish. The synthetic pyrethroid, Lambdacyhalothrin was most toxic to the fish (LC50 = 0.0022 ppm), followed by deltamethrin, cypermethrin and fenvalerate. Organochlorine insecticides, DDT and gamma-HCH, were less toxic than the pyrethroids, and these were followed by organophosphorus insecticides, malathion, fenthion, monocrotophos and temephos. The last two insecticides were least toxic among the different chemical insecticides (LC50 greater than 80 ppm ai). The microbial insecticide ABG-6262 (Vectolex 2.5 AS), a Bacillus sphaericus preparation, was totally harmless to the fish at 2500 microliters/l up to one week.