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Biomedical subjects

R K Gupta

Publications and source records attributed to R K Gupta.

At least 253 records · Page 14Linked to original sources
PubMed1996

Stabilization of respiratory syncytial virus (RSV) against thermal inactivation and freeze-thaw cycles for development and control of RSV vaccines and immune globulin.

A high-titered and stable respiratory syncytial virus (RSV) is essential for the development of RSV vaccines and quality control of vaccines and RSV immune globulin. We increased the virus titer of RSV seed stock, and virus preparations made from this seed stock, 100 times by removing defective interfering particles using limiting dilution procedure. RSV preparations made from the new seed stock had infectivity titers ranging from 10(7.6) to 10(8.2) TCID50 per ml for five lots made over a period of 3 years. Unstabilized RSV lost most of its infectivity at -86 degrees C within 2-3 weeks, at 37 degrees C within 24 hr, at 56 degrees C within 3 min and after five freeze-thaw cycles. The high titered virus was stabilized at -86 degrees C for 3 years, at 37 degrees C for 3 days, at 56 degrees C for 6 min and against five freeze-thaw cycles. Most effective stabilizers included 25% sucrose, 10% trehalose and 45% fetal bovine serum (FBS) in Medium 199 whereas 3.5% dimethyl sulfoxide, > or = 45% FBS in phosphate buffered saline, 40% glycerol and 10% sorbitol also stabilized RSV to lesser and variable degrees. A mixture of 0.5% gelatine and 0.3% sodium glutamate stabilized the virus for a short period whereas 0.1 M MgCl2 and 25% FBS did not stabilize the virus. The stabilized high-titered virus is very useful for achieving reproducibility in serologic assays. A broad spectrum of stabilizers, such as those evaluated in this study, would be useful in choosing the most suitable formulation for stabilizing a live RSV vaccine.

Cryopreservation↗
PubMed1996

Stabilization of tetanus toxoid in poly(DL-lactic-co-glycolic acid) microspheres for the controlled release of antigen.

Sustained release of antigenically active tetanus toxoid (TT) for several weeks from biodegradable poly (DL-lactic-co-glycolic acid) (PLGA) microspheres is very important for the development of a single dose vaccine. With a view to developing such a formulation, we evaluated in the vitro release of antigenic TT from TT-containing PLGA films and microspheres stabilized with gelatin or human serum albumin. Without stabilizer, TT-containing PLGA films released low levels of antigenic TT whereas TT-containing PLGA microspheres (average size 50 microMs) released 18% of antigenic TT in 4 weeks. Inclusion of gelatin and human serum albumin increased the amount of antigenic TT released from PLGA films and microspheres. As the concentration of gelatin increased from 0.08% to 2.2% in PLGA films, release of antigenic TT also increased. Similar results were found with gelatin-stabilized TT-containing microspheres. But the significant increase by higher concentration of gelatin was on the initial burst during the first week. A concentration of 0.2% gelatin was found suitable for getting approximately 40% of antigenic TT in 4 weeks. The proportion of antigenic TT to total protein was higher during the first 2 weeks of the release studies (50% during the first week and 23% during the second week). After 2 weeks, the proportion of antigenic TT was approximately 10% for the next 2 weeks. TT-containing microspheres stabilized with gelatin and human serum albumin showed stability of antigenic TT release when these microspheres were stored at 37 degrees C for 4 weeks. Gelatin appears to be a good stabilizer for TT-containing microspheres, but further studies are required to increase the proportion of antigenic TT beyond 2 weeks.

Antigens↗
PubMed1996

Pulsed controlled-released system for potential use in vaccine delivery.

Biodegradable polymeric devices intended to provide a viable route for single-dose vaccination were developed using controlled-release technology. One of the main challenges in the development of these devices was to overcome several water-mediated inactivation processes that occur in conventional polymeric systems. Our strategy was focused on the prevention of antigen exposure to environmental conditions. For this purpose a microencapsulation process was designed and optimized to provide an inert and insulated environment for the bioactive material inside controlled-release systems. Tetanus toxoid (TT) was used as a model antigen. The systems consist of core-wall microcapsule structures in which the antigenic protein is entrapped into oil-based cores of TT surrounded by outer polymer shells made of poly(D,L-lactide-co-glycolide), thus potentially protecting the bioactive material against deleterious conditions. Furthermore, using these microcapsules, pulses of immunochemically detected TT were programmed to release at two different times (3 and 7 weeks), as corroborated by in vitro release studies. The engineering of these specific antigen release properties was possible by careful selection of the copolymer composition and molecular weight. The final formulations were characterized with respect to morphology, structure, size distribution, and amount of immunochemically detected TT encapsulated. The new systems offer the potential to control the manner and timing of delivery. Over 92% of the TT released over a 63 day period from these microcapsules was immunochemically detected.

Capsules↗
PubMed1996

The role of cytology in the diagnosis of Paget's disease of the nipple.

Although rare, eczematous skin changes ascribed to Paget's disease of the nipple nevertheless warrant timely diagnosis. However this may occasionally be delayed due to a reluctance to proceed to traditional diagnostic techniques of wedge biopsy, surgical excision or punch biopsy. In this communication we describe 11 cases of unilateral mammary Paget's disease, in which an unequivocal cytodiagnosis was made from nipple scrapings. In five of these cases an underlying ductal carcinoma of the breast was simultaneously diagnosed by fine needle aspiration (FNA) cytology of a palpable breast lump. All 11 cases were subsequently proven histologically to be Paget's disease. Despite the fact that the use in dermatology of scrape smears and fine needle aspiration cytology remains somewhat unpopular, it is suggested that the screening of any eczematous skin change of the nipple should be considered using the simple, reliable and non-invasive technique of scrape cytology.

Adult↗
PubMed1996

Diagnosis of human sarcocystis infection from biopsies of the skeletal muscle.

Sarcocystis is an uncommon parasitic infection. We report four cases that presented with lumps, pain in the limbs or a discharging sinus of unknown etiology. Microscopic examination of the excised tissue in all cases showed characteristic cysts of the sarcocystis parasite. A discussion of the identification and recognition of this uncommon infection from muscle biopsies is given.

Adolescent↗
PubMed1996

Diphtheria antitoxin levels in US blood and plasma donors.

Plasma samples from 500 blood donors were titrated for diphtheria antitoxin (DAT) by the toxin neutralization (TN) test. Only 1.6% of donors had <0.01 IU/mL DAT, the minimum protective level against diphtheria; 15% had levels between 0.01 and <0.1 IU/mL, indicating basic protection, and 83.4% had levels > or =0.1 IU, indicating full protection. Three hundred fifty samples were studied by ELISA for diphtheria toxoid IgG antibodies to assess the utility of the assay as a quick, convenient method for evaluating diphtheria immunity. Although the correlation between TN and ELISA titers for the 350 samples was high (r = .80), there was no correlation (r = .07) for samples with antitoxin titers <0.1 IU/mL, the level of special interest for serosurveys for protection. Titration of 62 immune globulin samples (prepared from 1957 to 1994) showed that DAT levels in Massachusetts blood donors increased concurrently with increased use of tetanus-diphtheria vaccine in the state.

Animals↗
PubMed1996

Current management of follicular lymphoma.

Follicular lymphoma is the most common histological subtype of so-called indolent lymphomas. Despite the high rate of initial response to treatment, these low-grade B-cell non-Hodgkin's lymphomas follow a fluctuating (indolent) clinical course of regression and progression with an overall median survival of 8 to 10 years. Localized disease may be cured by radiotherapy, although in the majority of patients, the disease is already disseminated at the time of presentation. Current therapies include the use of single agents, such as the established drugs chlorambucil or cyclophosphamide, or the newer purine analogues, such as fludarabine. Combination chemotherapy, including the recently developed regimens based on fludarabine, is often advocated in those with more advanced disease or at subsequent recurrences. High-dose myeloablative therapy with autologous support has become a consideration for most patients whom are eligible or suitable for such treatment. Allogeneic transplantation may also be beneficial to a select group. The management of patients with this group of illnesses, however, may be heavily influenced in the future by the emerging immunologically oriented therapies, ie, monoclonal antibodies and idiotype vaccination.

Antineoplastic Agents↗
PubMed1996

Ringlike structures in fine needle aspirates from the breast.

Spherical ringlike structures of various sizes resembling Liesegang rings (LRs) are described in four fine needle aspirates (FNAs) from breast lesions over a period of 13 years. A characteristic finding in these structures was a distinct double layer outer wall with striations and an amorphous central nidus. Under polarized light they were non-refractile and no birefringence was noted in Congo red. Immunohistochemical stains for calcium, iron, mucus, glycogen, amyloid, cytokeratin and epithelial membrane antigen in all the cases were found to be negative. Since LRs can be mistaken for ova or parasites, their presence in aspirates of breast should be kept in mind to avoid misdiagnosis.

Adult↗
PubMed1996

Cellular ions in NIDDM: relation of calcium to hyperglycemia and cardiac mass.

OBJECTIVE: To investigate the role of hyperglycemia in mediating the clinical association of NIDDM with hypertension and left ventricular dysfunction and hypertrophy. RESEARCH DESIGN AND METHODS: Since hyperglycemia elevates cytosolic free calcium (Cai) both in myocardial and vascular smooth muscle cells, we utilized nuclear magnetic resonance (NMR) spectroscopy to measure erythrocyte Cai levels and compared them with serum ionized calcium (Caio), glucose, and insulin values before and following an oral glucose tolerance test (OGTT) and with previously obtained cardiac structural indexes in normotensive and hypertensive NIDDM (n = 32) and normal control subjects (n = 35). RESULTS: Compared with control subjects, normotensive NIDDM subjects had higher Cai (31.5 +/- 2.3 vs. 24.3 +/- 1.9 nmol/l, P = 0.05), lower intracellular free magnesium (Mgi) (200 +/- 10 vs. 225 +/- 7 mumol/l, P = 0.05), and greater posterior wall thickness (0.98 +/- 0.04 vs. 0.86 +/- 0.03 cm, P = 0.05). Hypertensive NIDDM subjects exhibited a further increase in Cai (43.1 +/- 4.4 nmol/l, P = 0.05 vs. control subjects) and left ventricular mass (LVM) (201.5 +/- 12.2 vs. 155.8 +/- 7.7 g, P = 0.05 vs. control subjects). For all subjects, significant relationships were observed between Cai and fasting blood glucose (r = 0.510, P < 0.01), HbAic (r = 0.389, P < 0.05), and the glycemic response to OGTT (the area under the curve [AUC] for glucose; r = 0.519, P < 0.01) and to systolic (r = 0.504, P < 0.01) and diastolic (r = 0.624, P < 0.01) blood pressure. Left ventricular mass index (LVMI) was related to fasting glucose levels (r = 0.406, P < 0.01) and the AUC for glucose (r = 0.380, P < 0.01), but not to fasting insulin or insulin responses to an OGTT. The LVMI was best related to Cai (r = 0.516, P < 0.01), while being inversely related to Caio (r = -0.486, P < 0.01). Multivariate regression indicated the contribution of glucose to LVMI was independent of age, BMI, insulin, and blood pressure but demonstrated a significant interaction with Cai. CONCLUSIONS: Altogether, these data suggest that glucose-related excess Cai is a fundamental lesion in diabetes that contributes to the elevated blood pressure and cardiac mass in this disease.

Blood Glucose↗
PubMed1996

Gastrointestinal bleeding from a false aneurysm of the hepatic artery after cholecystectomy.

Acute gastrointestinal bleeding due to penetration of a partially thrombosed hepatic artery aneurysm into the duodenal bulb is rare but has been reported. Ultrasound, computed tomography, and angiography are the methods of choice for aneurysm detection. If clinical review and endoscopy are inconclusive in determining the cause of upper gastrointestinal bleeding, and no usual diagnosis can be established, a search for arteriointestinal fistula must be initiated.

Adult↗
PubMed1996

Nocardiosis in renal transplant recipients in Kuwait.

BACKGROUND: Nocardiosis has emerged as an important bacterial disease among renal transplant recipients, leading to considerable morbidity and mortality. Apart from the increasing problem of resistance in pathogenic nocardiae, the spectrum of species causing disease has enlarged in recent years. There are no published reports on nocardiosis from Middle-East countries. METHODS: A retrospective review of case records of 513 renal transplant recipients between January 1989 and January 1995 was done in the transplant unit of our hospital. Information was collected on clinical details, type of donor, immunosuppressive therapy, prophylaxis, and outcome. Isolation of Nocardia species from appropriate clinical specimens was the sole criterion for diagnosis. RESULTS: Nocardiosis was diagnosed in six recipients with a disease incidence of 1.2%. Four patients had received unrelated kidneys. Co-morbid conditions were diabetes mellitus (3), viral hepatitis (2) and neutropenia (1). Clinical manifestations included deep-seated skin abscesses and pulmonary disease in three each. Cerebral abscess and meningitis were found in two patients with pulmonary disease. Pathogens were Nocardia asteroides in four and N. otiti discaviarum and N. farcinica in one each. In contrast to in vitro susceptibility results, clinical response was different in that five patients who received trimethoprim-sulphamethoxazole (TMP-SMX) alone (2) or in combination with cefuroxime (3) responded well. CONCLUSIONS: The study stresses a high index of suspicion for nocardiosis in susceptible hosts who present with cutaneous abscess, pulmonary infiltrative lesions, and cerebral manifestations. TMP-SMX in combination with cefuroxime seems to be a highly effective therapy. It does not appear mandatory to reduce or discontinue immunosuppressive therapy during treatment of nocardiosis.

Adult↗
PubMed1996

Evaluation of controlled-release mosquito repellent formulations.

Eight polymer and 9 microcapsule formulations of deet were tested on laboratory rabbits against Aedes aegypti and Anopheles albimanus. Several formulations were significantly more effective than simple (unformulated) deet at the same strength for periods up to 24 h. Best results were obtained with a polymer formulation containing a high molecular weight fatty acid and 3 microcapsule formulations containing lanolin, gum arabic, gelatin, tannic acid, stearic acid, polypropylene glycol, water, and a commercial lotion in the microcapsule and carrier fractions.

Aedes↗
PubMed1996

Evaluation of the laboratory rabbit model for screening topical mosquito repellents.

The laboratory rabbit was evaluated as a model for screening topical mosquito repellents, using data obtained in tests of deet (N,N-diethyl-3-methylbenzamide) against Aedes aegypti on humans and rabbits. Host-specific differences in the action of the test material were quantified by multiple regression analysis. The test material was less effective but more persistent in tests on rabbits, and responses of the mosquito test population were more variable.

Animals↗
PubMed1996

Use of in vitro Vero cell assay and ELISA in the United States potency test of vaccines containing adsorbed diphtheria and tetanus toxoids.

Current United States (US) regulations for potency testing of vaccines containing adsorbed diphtheria and tetanus toxoids require in vivo toxin neutralization (TN) tests on the pooled sera of immunized guinea pigs. To reduce the number of animals required for testing, two in vitro tests have been evaluated, the Vero cell assay for diphtheria antitoxin and ELISA for IgG antibody to tetanus toxin; these have been correlated with in vivo TN tests. In the Vero cell method, diphtheria antitoxin titres of the guinea pig sera, obtained four weeks after immunization as per US potency requirements, were markedly dependent on the toxin dose level used in the assay. A toxin dose level termed the Lcd/1 dose (limit of cytopathic dose at a IU/ml) for Vero cells gave comparable estimates of antitoxin activity to the in vivo TN test performed at L+/1 dose of toxin. When lower dose levels of toxin were used in the Vero cells (Lcd/10 to Lcd/1000), diphtheria antitoxin levels in four weeks guinea pig sera were two to 11.7 times lower than with the Lcd/1 dose level. The most likely reason for these differences is that guinea pig sera a 4 weeks are of lower avidity than the equine antitoxin standard. Antibodies of low avidity bind antigen less well at low reactant concentrations. Therefore, to obtain similar estimates of diphtheria antitoxin in the Vero cell method and in vivo TN test, the use of toxin dose for the Vero cell method similar to that for the in vivo TN test is suggested. Another alternative, in which any dose of toxin may be used for the Vero cell method, is the use of a reference guinea pig serum (calibrated in IU/ml by the in vivo TN test at L+/1 level of toxin) that has similar avidity or similar immunization status as the test sera (i.e. 4 week serum). IgG antibodies to tetanus toxin in guinea pig sera were found early in the course of immunization when tetanus antitoxin could not be detected by TN test. Tetanus toxin IgG antibody levels of guinea pig sera calculated in IU/ml against an ELISA guinea pig reference serum (calibrated in IU/ml by TN test) depended upon the immunization status of the animals. To obtain similar estimates of tetanus antibodies in IU/ml by TN and ELISA, the ELISA reference guinea pig serum should have similar immunization status (and presumably similar avidity) as the test serum (i.e. six week serum). We propose that the Vero cell method and ELISA deserve further evaluation to determine whether they can replace in vivo TN tests for titration of diphtheria and tetanus antitoxins in the US potency test.

Animal Testing Alternatives↗