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Biomedical subjects

A Karim

Publications and source records attributed to A Karim.

At least 145 records · Page 8Linked to original sources
PubMed1985

Food-induced changes in theophylline absorption from controlled-release formulations. Part II. Importance of meal composition and dosing time relative to meal intake in assessing changes in absorption.

Theo-24 (G. D. Searle & Co.) is an ultra-slow-absorbing formulation of theophylline suitable for once-a-day dosing in slow and normal metabolizers of theophylline. Relative to fasting conditions, increased rate and extent of theophylline absorption occur when this product is administered immediately after a breakfast with a high fat content. Our study demonstrated that factors such as meal composition (fat content) or dosing time relative to meal intake can modify the high fat-induced changes in absorption. For consistent, slow absorption, patients taking high doses (greater than or equal to 900 mg) of Theo-24 once a day should take this product in the morning under fasting conditions or with a breakfast containing less than or equal to 10 gm fat. If a high-fat breakfast (greater than 55 gm fat) is taken, then Theo-24 should be administered at least 1 hour before the meal.

Absorption↗
PubMed1985

A serologic epidemiological study of parainfluenza 1, 2, and 3 viruses in beef cattle and calves in Illinois.

Beef cattle and calves in four Illinois populations were studied. Serum was tested by the hemagglutination-inhibition (HI) test for antibodies to parainfluenza viruses (PIV) 1, 2, and 3. In all but group 3 a low level of antibody to PIV-1 and 2 was demonstrated. The highest prevalence and incidence of HI-antibodies was found for PIV-3, followed by PIV-1. There may have been a cross-reaction between PIV-1 and -3 in Group 1 calves. The low level of HI antibodies to PIV-1 and 2 may have resulted from infections early in life or colostral antibodies that decreased with age.

Age Factors↗
PubMed1984

A radioautographic study of the incorporation of iron 55 by the ameloblasts in the zone of maturation of rat incisors.

This study was designed to study the time course of the incorporation of 55Fe into the ameloblasts of maturation in rat incisors. Male Sherman rats (100 +/- 5 gm) were injected intravenously with 0.9 mCi of 55Fe and sacrificed in pairs by perfusion at various time intervals from 5 min to 7 days after injection. The incisors were demineralized in 4.13% disodium EDTA, postfixed in 1% osmium tetroxide in veronal acetate buffer, and embedded in Epon. Incisors from control rats injected with only physiological saline were treated in the same way. Sections from blocks of tissue in the zone of maturation were prepared for light microscope radioautographic observations. The greatest incorporation of iron occurred at 9 mm within the zone; at this site the ameloblasts contained few pigment granules. About 5 mm deeper into the zone the activity fell off to zero, as observed at 2.5 hr after injection of 55Fe. Between 1 day and 7 days after injection the 55Fe labeling was found over the cells containing many pigment granules, while the initial labeling over the cells within 9 mm of the zone had diminished. These data have shown that at any given time, from 30 min to 4 hr, the iron enters the maturation ameloblasts over a wide extent of the zone, reaching a maximum at about 9 mm from the onset of maturation. However, at longer times (1 day to 7 days) the labeling curve shifts and shows the greatest activity beyond 9 mm within the zone.

Ameloblasts↗
PubMed1983

Transdermal absorption of nitroglycerin from microseal drug delivery (MDD) system.

A recent important advance in biopharmaceutics has been the utilization of controlled delivery of drugs to the systemic circulation through the intact skin. With the conventional tablet and capsule dosage forms, the amount of drug absorbed through the gastrointestinal (GI) tract varies depending on the quantity and types of food in the stomach, on the GI motility and transit time. Acid and/or alkaline labile drugs may be deactivated prior to absorption from the GI tract while some drugs also get deactivated by GI microbial flora. In the case of drugs with a high hepatic extraction ratio, the absorbed drug may be largely deactivated by first-pass metabolism before reaching the systemic circulation. Drug absorption through the GI tract can therefore result in variable and/or unpredictable blood levels. Some of this variability can be minimized by administering controlled-release tablet or capsule formulations. However, these dosage forms cannot eliminate the inherent variability associated with first-pass metabolism.

Administration, Topical↗
PubMed1983

A randomized, double-blind, parallel group comparison of disopyramide phosphate and quinidine in patients with cardiac arrhythmias.

This report summarizes the results of a randomized, double-blind, parallel group, multicenter study which compared the antiarrhythmic activity and safety of oral disopyramide phosphate and oral quinidine sulfate. A total of 124 outpatients, whose pretreatment rates of ventricular and/or supraventricular arrhythmias were documented by ambulatory ECG recordings, were randomly assigned to receive either oral disopyramide or oral quinidine for the eight-week course of the study. Every two weeks, ten-hour ambulatory ECG recordings were obtained from each patient and blood was drawn to determine serum concentrations of assigned drug.

Administration, Oral↗
PubMed1983

Current status of an oral B subunit whole cell cholera vaccine.

Purified B subunit of cholera toxin retains membrane-binding capacity and protective immunogenicity and yet has no toxic activity as tested in animals. These properties suggest that B subunit might be a promising immunogen, particularly as an oral vaccine, for stimulating protective antitoxic immunity against cholera in man. A method has been elaborated which allows preparation of +/- 10 grams of pure B subunit per fermentor culture cycle. As tested in both Swedish and Bangladeshi volunteers purified B subunit alone or in combination with conventional whole cell vaccine gives no side-effects at all when given orally and only very mild local reactions after parenteral administration. A single peroral or intramuscular immunization with B subunit has given significant intestinal IgA antitoxin antibody formation in 75-85% of Bangladeshi women tested; however, the duration of the response was longer after the oral route. The preliminary results of a recent study (Svennerholm, A.M., Jertborn, M., Gothefors, L., Karim, A., Sack, D. and Holmgren, J., to be published) have further shown that two peroral immunizations of Bangladeshi volunteers with a combined B subunit--whole cell cholera vaccine give rise to mucosal IgA antitoxin as well as anti-lipopolysaccharide antibody formation which closely resemble these antibody responses in cholera convalescents. The combined vaccine also evoked a local immunologic memory comparable to that induced by clinical disease.

Antibody Formation↗
PubMed1979

The effect of colcemid on the structure and secretory activity of ameloblasts in the rat incisor as shown by radioautography after injection of 3H-proline.

Enamel secretion by ameloblasts was investigated in the incisors of 100 gm normal and colcemid-injected male rats. Morphological studies were done on rats given a single intraperitoneal injection of 0.1 mg (1.25 mM) of colcemid and sacrified 1 to 4 hours after injection. Protein synthesis and secretion were investigated with radioautography in normal and colcemid-treated rats injected with 3H-proline and sacrificed at intervals between 0.5 and 3.5 hours after injection. Colcemid was injected 0.5 hours prior to 3H-proline in each experimental rat. Electron microscopic examination revealed several morphological alterations between 1 and 4 hours after injection of colcemid. These changes included fragmentation of the normally elongated rough endoplasmic reticulum into shorter profiles; a disorganization of the normally tubular configuration of the Golgi apparatus into a number of seples and profiles of smooth endoplasmic reticulum from Tomes' processes; and the accumulation of secretion granules at the mature face of the Golgi stacks, as well as in the infranuclear cytoplasm where thye are normally not found. Radioautography revealed that protein synthesis by the rough endoplasmic reticulum had continued in colcemid-altered ameloblasts. Labeled secretion granules were found at the mature surface of the Golgi stacks and in the infranuclear cytoplasm, however they did not migrate into Tomes' processes. Consequently, labeled enamel matrix did not appear extracellularly at the same time as in normal controls. Quantitative radioautography in the light microscope revealed that the effect of colcemid, although reversed within 4 hours, had temporarily inhibited normal migration, and exocytosis of secretion granules.

Ameloblasts↗
PubMed1979

Immunohistochemical localization of procollagens. II. Electron microscopic distribution of procollagen I antigenicity in the odontoblasts and predentin of rat incisor teeth by a direct method using peroxidase linked antibodies.

In an attempt to locate procollagen I in rats odontoblasts, antibodies raised in rabbits were purified by affinity methods and linked to peroxidase. They were then incubated with chopped slices from the growing end of rat incisor teeth. The antibodies binding to the antigens in the slices were visualized by reacting the peroxidase moiety with diaminobenzidine in the presence of hydrogen peroxide. The slices were then embedded in Epon and sectioned for ultrastructural study. Within odontoblasts, the immunostaining indicative of procollagen I antigenicity is moderate in rough endoplasmic reticulum cisternae, strong in spherical and cylindrical Golgi distensions, intense in secretory granules, and variable in lysosomal structures. In predentin, immunostaining is intense close to the odontoblast layer, but decreases gradually in a distal direction. Hence, procollagen I (and/or substances endowed with similar antigenicity such as pro alpha (I) chains and procollagen fragments) is present: 1) along the intracellular pathway of collagen precursors where its concentration gradually increases to reach a maximum in secretory granules; 2) in predentin, into which it is released from the granules for transformation into nonimmunoreactive collagen I; and 3) in lysosomal structures where some of it is hydrolyzed.

Animals↗
PubMed1977

Spironolactone: relationship between concentrations of dethioacetylated metabolite in human serum and milk.

The concentration of canrenone, a principal metabolite of spironolactone, was determined in human serum and milk. The milk to serum concentration ratios of this metabolite were 0.72 at 2 hr and 0.51 at 14.5 hr after ingestation of spironolactone. It was estimated that the maximum quantity of canrenone ingested daily by a human infant via its mother's milk would be approximately 0.2% of the daily dose of spironolactone given to the mother.

Adult↗