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Biomedical subjects

H M Patel

Publications and source records attributed to H M Patel.

53 records · Page 3Linked to original sources
PubMed1983

Lytic effect of heparin on liposomes: possible mechanism of lysis of red blood cells by heparin.

Heparin causes lysis of the multilamellar liposomes of all three charges, positive, neutral, and negative, and thus releases the entrapped [3H]glucose or chromate. The lytic effect of heparin is also observed in liposomes prepared from the lipids extracted from human red blood cells. Heparin is found to interact with the phospholipid bilayers, which suggests that the reported lytic effect of heparin on the red blood cells may be mediated through the membrane phospholipid components of these cells.

Blood Glucose↗
PubMed1982

Prolonged hypoglycemic effect in diabetic dogs due to subcutaneous administration of insulin in liposomes.

The biologic action of insulin entrapped in liposomes (phospholipid vesicles) has been investigated following subcutaneous injection to dogs made diabetic with a combination of alloxan and streptozotocin. The fats of the liposomally entrapped material was determined by injecting rats subcutaneously with either 125I-insulin or the labeled polysaccharide 14C-inulin, incorporated in liposomes labeled with 3H-cholesterol. Injection of liposome insulin (0.75 U/kg) to five diabetic dogs resulted in a mean (+/- SEM) blood glucose fall from 16.4 +/- 0.8 to 2.9 +/- 0.4 mmol/L. The glucose level had still not returned to baseline after 24 h and, correspondingly, immunoreactive insulin (IRI) could still be detected in frozen and thawed plasma 24 h after injection. In contrast, the hypoglycemic effect of the same dose of free insulin with or without empty liposomes virtually ended within 8 h and IRI levels returned to baseline by 3 h after injection. In experiments on rats with liposomally entrapped 125I-insulin or 14C-inulin the proportion of the injected dose of tracer recoverable by excision of the injection site remained constant after about 1 h and 70% of the dose was still fixed in subcutaneous tissue for at least 5 h thereafter. When the plasma collected 3 h after subcutaneous injection of labeled liposomes containing 125I-insulin was passed through a column of Sepharose 6B, 50-75% of the 125I-activity was found in the fractions associated with intact liposomes. One possibility for the persistence of the hypoglycemic effect and of measurable IRI following injection of liposome insulin could be the presence of intact liposomes in the circulation for many hours after adsorption had ceased.

Animals↗
PubMed1982

Computed tomography of sellar and parasellar lesions: indications for metrizamide cisternography.

Sixty-four patients with intrasellar and suprasellar lesions on conventional computed tomography (CT) have been studied retrospectively to determine the indications for metrizamide CT cisternography (MCTC). Enhancing or calcified lesions, like a craniopharyngioma, pituitary adenoma, meningioma or aneurysm are adequately evaluated by conventional CT and MCTC is usually not needed. Determination of the exact suprasellar extent of an enhancing pituitary adenoma is best accomplished with coronal thin-section conventional CT alone. However, for isodense or hypodense suprasellar and intrasellar lesions, MCTC is indicated if conventional CT does not define their extent accurately. Differentiation of an empty sella from the occasional entirely lucent pituitary adenoma or other low density intrasellar lesions remains difficult by conventional CT at times, especially when the infundibulum is not identified. Then MCTC will also be indicated.

Adenoma↗
PubMed1981

The effect of reticuloendothelial blockade on the blood clearance and tissue distribution of liposomes.

The blood clearance and tissue distribution of liposomes have been studied in mice subjected to reticuloendothelial blockade with dextran sulphate or carbon. The liposomes have been labelled in the lipid membranes with [3H]-cholesterol, [14C]phosphatidylcholine and/or 99mTc and the content with [14C]inulin. Reticuloendothelial blockade has been shown to slow the rate of clearance of neutral, positively and negatively charged liposomes and of both small unilamellar vesicles and large multilamellar vesicles. In normal animals, the liver uptake accounted for only 20-55% of the total injected radioactivity, the amount varying with the charge and size of the liposomes. Following blockade, the liver uptake of charged and neutral multilamellar liposomes was depressed. This was also true for negatively charged small unilamellar vesicles. The degree of depression of hepatic uptake was between 25-50%, which contrasts with the 80-90% reduction in uptake of a wholly phagocytosed particle (sheep red cells). This difference suggests that mechanisms other than Kupffer cell phagocytosis are also responsible for the normal uptake of liposomes into the liver. In the case of neutral and positively charged small unilamellar vesicles, delayed clearance due to blockade was not associated with 'depressed' hepatic uptake. The site of action of blockading agents for these preparations is not clear. With all preparations of liposomes, blockade produced a slight and variable increase in uptake in the lung and spleen. The alteration of distribution of liposomes by reticuloendothelial blockade is therefore not great and the value of the technique in modifying the tissue distribution of substances within liposomes may be limited.

Animals↗
PubMedDate not supplied

Current progress and future prospects of liposomes in dermal drug delivery.

Liposomes were introduced first in 1980 for topical drug delivery and since then have attracted considerable interest and generated many speculative claims concerning their potential utility both as a drug carrier and reservoir for controlled release of drugs within various layers of the skin. A number of clinical studies have now demonstrated the superiority of liposomal drug formulations over conventional delivery systems. In this respect, liposomal formulations have been successful in treatment of a number of dermatological diseases and disorders such as psoriasis, mycoses, idiopathic hirsutism and cutaneous infections. This review emphasizes the evaluation of topically applied liposomal formulation both at experimental and clinical levels. Mechanism(s) by which liposomes facilitate deposition of drugs in various layers of the skin is also discussed.

Administration, Topical↗