Biotin transport in the human intestine: inhibition by anticonvulsant drugs.

The effect of the anticonvulsant drugs carbamazepine and primidone on the transport of biotin in the human intestine was examined with purified brush border membrane vesicles (BBMVs) and basolateral membrane vesicles (BLMVs). Both agents inhibited biotin transport in BBMV in a concentration-dependent manner. The inhibition by both carbamazepine and primidone was competitive (inhibition constant [Ki] of 4.

Intestinal transport of pyridoxine in experimental renal failure.

Renal failure (RF) has been shown to alter intestinal transport of a number of nutrients. We studied jejunal absorption of pyridoxine (B6) in rats rendered azotemic by subtotal nephrectomy (RF group) and compared the results with those obtained in normal rats subjected to sham operation (controls) and animals pair-fed (PF) with their RF counterparts. In vivo recirculating perfusion and in vitro everted sac techniques were employed.

Transport characteristics of glutamine in human intestinal brush-border membrane vesicles.

Transport of glutamine (Gln) across the brush-border membrane of the human intestine was examined using the brush-border membrane vesicle (BBMV) technique. Osmolarity and temperature studies indicate that the uptake of Gln by BBMV is mostly the result of transport of the substrate into the intravesicular space. Transport of Gln was Na+ gradient dependent (out greater than in) with a distinct "overshoot" phenomenon.

Biotin transport in rat intestinal brush-border membrane vesicles.

Transport of biotin across rat intestinal brush-border membrane was examined using the brush-border membrane vesicle (BBMV) technique. Uptake of biotin by BBMV is the result of transport of the substrate into the intravesicular space with negligible binding to membrane surfaces. In the presence of a Na+ gradient (out greater than in), transport of biotin was higher with a transient 'overshoot' phenomenon.

Tumefactive fibroinflammatory lesion of the head and neck.

The term tumefactive fibroinflammatory lesion is used to describe an unusual fibrosclerosing disorder that behaves in a malignant way clinically but is histologically benign. Lesions in the head and neck are believed to be part of the broader fibrosclerosing syndrome which include pseudotumour of the orbit, Reidel's thyroiditis, sclerosing cholangitis and mediastinal fibrosis. Clinical diagnosis is often difficult and relies heavily on histopathology.

Biotin transport in the human intestine: site of maximum transport and effect of pH.

Previous studies from our laboratory have characterized the transport process of biotin across the brush border membrane and the basolateral membrane of the human intestine. In this study we further characterized biotin transport in the human intestine by examining the vitamin's transport process in different areas of the small intestine (duodenum, jejunum, and ileum) and the effect of pH on the transport process using a brush border membrane vesicle technique. In all areas examined, the transport of biotin as a function of concentration was saturable in the presence of a Na+ gradient (out greater than in) but was linear and lower in the presence of a choline gradient (out greater than in).

Intestinal uptake of retinol in suckling rats: characteristics and ontogeny.

Uptake of retinol in the developing intestine of suckling rats (14-15 day old) and its maturation in adult rats (90 day old) was examined using intestinal everted sacs. Uptake of retinol (0.06 microM) in the jejunum of suckling and adult rats was linear for 5 min incubation and occurred at a rate of 31.

Rhabdomyosarcoma of the middle ear and mastoid in children.

Three cases of embryonal rhabdomyosarcoma in the middle ear and mastoid in children are presented. Diagnosis was confirmed by histopathology. A multidisciplinary approach employing surgery, chemotherapy and radiation therapy is the method of choice in the management of this rare and highly lethal condition.

Transport of glycyl-L-proline in intestinal brush-border membrane vesicles of the suckling rat: characteristics and maturation.

Transport of the dipeptide glycine-L-proline (Gly-L-Pro) in the developing intestine of suckling rats and its subsequent maturation in adult rats was examined using the brush-border membrane vesicles (BBMV) technique. Uptake of Gly-L-Pro by BBMV was mainly the result of transport into the intravesicular space with little binding to membrane surfaces. Transport of Gly-L-Pro in BBMV of suckling rats was: (1) Na+ independent; (2) pH dependent with maximum uptake at an incubation buffer pH of 5.

Biotin transport in basolateral membrane vesicles of human intestine.

The characteristics of the exit process of biotin from the enterocyte, i.e., transport across the basolateral membrane, was determined using an enriched basolateral membrane vesicle preparation of human intestine.

Mucoepidermoid carcinoma of the trachea (a case report).

A case of mucoepidermoid carcinoma of the trachea in a 26-year-old female is presented. Diagnosis was confirmed by histopathology. On the basis of the clinical and histological picture, the tumour is classified as a low grade mucoepidermoid carcinoma.

Ontogenesis of the intestinal transport of biotin in the rat.

Developmental aspects of the intestinal transport of biotin were examined in suckling (16 day old) and weanling (24 day old) rats using the everted sac technique. The results were compared with those of adult rats previously reported by us using the same intestinal preparation. Transport of biotin was linear for 20 min of incubation in all age groups.

Folate transport in ileal brush border-membrane vesicles following extensive resection of proximal and middle small intestine in the rat.

Uptake of folic acid (PteGlu) was examined in remnant ileum of rats after resection of 65% of the small intestine with the brush border-membrane vesicle technique. The results were compared to that of sham-operated rats. In both rat groups transport of PteGlu was linear for approximately 40 s of incubation and was similar in the presence of a Na+ and a K+ gradient (out greater than in).

Studies on the intestinal surface acid microclimate: developmental aspects.

The existence and general characteristics of the intestinal surface acid microclimate (ISAM) in the developing intestine of suckling and weanling rats were examined. ISAM pH measurements were performed in vitro using a sensitive glass pH-microelectrode. The results showed that the ISAM does exist in both suckling and weanling rat intestine.

A carrier-mediated, Na+ gradient-dependent transport for biotin in human intestinal brush-border membrane vesicles.

Transport of biotin across human intestinal brush-border membrane (BBM) was examined using brush-border membrane vesicle (BBMV) technique. Uptake of biotin by BBMV is mostly the result of transport of the substrate into an active intravesicular space with little binding to membrane surfaces. The transport of biotin was carrier mediated and was 1) Na+ (but not K+) gradient dependent with a distinct "over-shoot" phenomenon, 2) saturable as a function of concentration in the presence of a Na+ (but not a K+) gradient with an apparent Km and Vmax for the Na+ gradient-dependent system of 5.

A carrier-mediated transport for folate in basolateral membrane vesicles of rat small intestine.

The mechanism of exit of folate from the enterocyte, i.e. transport across the basolateral membrane, is not known.

The microfibrillar proteins of human hair: separation by high-performance liquid chromatography and isolation of some proteins enriched in glycine and tyrosine.

The microfibrillar proteins of human hair have been studied by reversed-phase high-performance liquid chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A chromatographic procedure which isolates the microfibrillar proteins from other hair-matrix proteins and separates them into collectable fractions has been introduced. These fibrous proteins fall into two major subgroups which are resolved into six components.

Persistently low blood retinol levels during and after parenteral feeding of very low birth weight infants: examination of losses into intravenous administration sets and a method of prevention by addition to a lipid emulsion.

Very low birth weight infants have little storage of hepatic retinol and are, therefore, highly dependent upon an exogenous supply. The recent association between low serum retinol level and bronchopulmonary dysplasia and the persistently low serum levels of retinol during total parenteral nutrition prompted a prospective study to evaluate serial changes in serum retinol levels during 1 month of total parenteral nutrition (retinol dose 455 micrograms/d) and again during 1 month of total enteral feeding (retinol dose 200 to 300 micrograms/d) in the same infants. Infants were divided into two groups.

Intestinal glucose transport in suckling rats fed artificial milk with and without added epidermal growth factor.

Epidermal growth factor (EGF), a potent mitogen present in milk, is postulated to play an important physiologic role in the ontogeny of the intestine. An artificial rat milk, free of EGF, was developed and fed to newborn rats in an effort to evaluate the physiologic role of EGF on intestinal glucose transport. Comparisons were made between mother-fed (group 1) and artificially fed pups (group 2).

Aging-associated increase in intestinal permeability to polyethylene glycol 900.

Effect of aging on the intestinal permeability to medium size [3H]polyethylene glycol (PEG 900) was examined in vivo by gavage and in vitro in intestinal everted sacs of rats ranging in age from 5 to 102 weeks. Rats were gavaged with PEG 900 solution and urinary recovery of PEG 900 was measured for 6 hr in order to assess its absorption. Young rats, 5-15 weeks of age, absorbed 1-1.

Folate transport by human intestinal brush-border membrane vesicles.

Transport of folic acid (Pte-Glu) across the brush-border membrane of human intestine was studied using brush-border membrane vesicle (BBMV) technique. The transport of Pte-Glu was higher in BBMV prepared from the jejunum than those prepared from the ileum (0.70 +/- 0.