A method for reducing salts in tissue extracts containing low molecular weight compounds.
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Biomedical subjects
Publications and source records attributed to R K Saxena.
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Some novel lipophilic derivatives of N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) have been prepared and rigorously evaluated by spectroscopic means. Fast atom bombardment and field desorption mass spectrometry provided information about both molecular weight and structural detail. The new MDP derivatives have been tested in guinea pigs for immunoadjuvant activity using egg albumin as the model antigen. Amongst these derivatives, 6-O-[3-(5-cholesten-3 beta-yloxycarbonyl) propionyl]-N-acetylmuramyl-L-alanyl-D-isoglutamine (CSMDP), 6-O-[3-1,2-dipalmitoyl-sn-glycero-3-carbonyl) propionyl]-N-acetylmuramyl-L-alanyl-D-isoglutamine (GSMDP) and N-palmitoyl muramyl-L-alanyl-D-isoglutamine (PMDP) possessed significantly better activity than MDP, as judged by the antigen-specific antibody and delayed hypersensitivity responses in the immunized animals. In addition, CSMDP was found to induce strong delayed hypersensitivity response even in saline. These three active compounds were also tested for their pyrogenic response in rabbits, and were found to be lesser pyrogenic than MDP. Some of these MDP derivatives hold promise as adjuvants in immunization.
Varieties of Biomedical Equipment (BME) are now used for quick diagnosis, flawless surgery and therapeutics etc. Use of a malfunctioning BME could result in faulty diagnosis and wrong treatment and can lead to damaging or even devastating aftermath. Modern Biomedical Equipments inevitably employ highly sophisticated technology and use complex systems and instrumentation for best results. To the best of our knowledge the medical education in India does not impart any knowledge on the theory and design of BME and it is perhaps not possible also. Hence there is need for a permanent mechanism which can maintain and repair the biomedical equipments routinely before use and this can be done only with the help of qualified Clinical Engineers. Thus there is a genuine need for well organized cadre of Clinical Engineers who would be persons with engineering background with specialization in medical instrumentation. These Clinical engineers should be made responsible for the maintenance and proper functioning of BME. Every hospital or group of hospitals in the advanced countries has a clinical engineering unit that takes care of the biomedical equipments and systems in the hospital by undertaking routine and preventive maintenance, regular calibration of equipments and their timely repairs. Clinical engineers should be thus made an essential part of modern health care system and services. Unfortunately such facilities and mechanism do not exist in India. To make BME maintenance efficient and flawless in India, study suggests following measures and remedies: (i) design and development of comprehensive computerized database for BME (ii) cadre of Clinical engineers (iii) online maintenance facility and (iv) farsighted managerial skill to maximize accuracy, functioning and cost effectiveness.
Malaria endemicity in lower Myanmar has been studied to identify the causes for the prevalence of malaria in Yeasitkan village of lower Myanmar. Vector mosquitoes were collected by mosquito net in cattlesheds and in human dwellings (indoor and outdoor) by biting and catching procedure for the identification of species, insecticide susceptibility test and sporozoites detection. Larvae of mosquitoes were also collected in and around the village for vector identification and for breeding sources. Malaria infection in humans was examined by blood examination and blood antibody detection by ELISA method. Results showed that malaria infection was 43.2% in children under 10 years of age and An. dirus and An. minimus were found as main vectors. Total parasite positive rate was found to be 41.28% and in this 78.87% were P. falciparum infections and remaining 18.31% were of P. vivax. Spleen positive rate has been found very high in children between 2 and 9 years (52.94%). Study indicates that villages near to dam areas are more prone to malaria infection.
A glycophospholipid (GPL) antigen isolated from Plasmodium falciparum culture supernatant has been tested for its antigenicity. Detection of malaria positive known blood samples and unknown field samples from endemic and non-endemic areas were compared. In this study laser light scattering immunoassay (LIA) was used for the detection of P. falciparum malaria. Test results of control (malaria negative samples from Surat) were compared with known positive samples and unknown malaria positive field samples. A positive correlation has been observed (97%) in falciparum positive samples from laboratory and unknown samples from endemic area (Haldwani) by LIA method using GPL antigen. From the results of the study it was found that GPL antigen has a better antigenic property and can detect almost all the cases of Pf malaria by LIA method.
In the present study, allergenic significance of thirteen species of Aspergillus and their allergenic and antigenic relationship was studied. Of the 3025 ID tests performed with the 13 species of Aspergillus on 289 patients suffering with allergic respiratory diseases, 627 (20.7%) were positive (1+ to 4+), 386 (12.8%) being significantly positive (2+ to 4+) . Of the 64 patients eliciting a positive cutaneous response to at least one species, 42(65.6%) were positive to 5 or less number of species while others showed a broad spectrum of positive skin reactivity to different Aspergillus extracts. In RAST inhibition assays using pooled sera ofpatients sensitive to A. tamarii dose related inhibition was produced by homologous as well as 5 of the 12 heterologous species. Similarly, in A. terreus RAST inhibition was observed with homologous and A. tamarii extracts only. Our results suggested the presence of both species specific as well as shared allergenic components among different Aspergillus species. In TDIEP experiments using rabbit antisera to A. tamarii and A. terreus extracts multiple precipitin bands were observed with the homologous extracts. However, only 1-2 bands were produced by 6 heterologous Aspergillus species in each system. Collectively, these results gave evidence that there is heterogeneity of immune response in the patients with allergic respiratory diseases to different species of Aspergillus and also in rabbits immunized with Aspergillus extracts.
The cardiac-output (Q) of seven young healthy Indians with common physical characteristics at rest and after a single bout of exercise of 600 kpm for 10 min on a bicycle ergometer was ascertained by the Indirect Fick Principle. The end tidal alveolar Co2 pressure was obtained at the end of a normal expiration and PvCo2 was obtained by the help of the exponential rise (Defares method) in Co2 concentration during rebreathing from an initially low Co2 in O2 mixture (3-4%). The standard Co2 dissociation curve of oxygenated blood was used to find out the corresponding arterial and venous Co2 content, assuming the Hb content of these individuals to be normal. The mean value of the Cardiac-Output so obtained during rest is 4.21 liters/min when Co2 rebreathing time does not exceed 10 secs, and 17.33 litres/min., 2 to 3 breaths after exercise, when rebreathing time did not exceed 5 to 7 secs. Repeated studies and better training of the subjects will perhaps improve the resting values, while after exercise and during recovery our values are better reproducible.
P815 tumor cells (10(7] were administered intraperitoneally to DBA/2 mice. As the ascites tumor grew in the syngeneic host, a decline leading to a total loss of host spleen natural killer (NK) activity could be demonstrated. Removal of T and B cells or macrophages from the tumor-bearing (TB) mouse spleen cells did not raise the level of NK activity. Spleen cells from TB mice did not inhibit the NK activity of normal spleen cells. Comparable target (YAC cells) binding capacity could be demonstrated in spleen cells derived from normal or TB mice, but interferon failed to significantly stimulate the NK activity of TB mouse spleen cells. In adoptive transfer experiments, transfer of spleen or bone marrow cells from TB mice resulted in the development of significant levels of spleen NK activity in lethally X-irradiated recipient DBA/2 mice. These results indicate that the impairment of NK cell differentiation pathway rather than active suppression at the level of effector cells may be the mechanism of loss of NK activity in P815 TB DBA/2 mice.
The changes in the osmotic resistance of red blood cells (RBC), due to various pathological conditions like exposure to heat, anemia as well as the effect of storage and anticoagulants have been investigated. The results have shown that exposure to a temperature of 50 degrees C makes the red blood cells fragile to osmotic pressures. Also, red blood cells from the patients suffering from anemia exhibited decreased osmotic resistance. Storage upto 9 days showed a marginal increase in the osmotic fragility of the RBC and beyond that, there was no significant effect upto 15 days. Also, exposure to anticoagulants like citrate, ammonium oxalate, and EDTA increased the osmotic fragility of the cells. The present study shows that the various traumas investigated will affect the mechanical properties of the red blood cell membrane.
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