Search PubMed⌕ Search

Biomedical subjects

L Howard

Publications and source records attributed to L Howard.

At least 127 records · Page 7Linked to original sources
PubMed1983

Development of cell junctions in sea-urchin embryos.

The development of cell junctions in sea-urchin embryos has been investigated using thin sections, lanthanum-tracer and freeze-fracture techniques. Three types of desmosomes are present: belt desmosomes and spot desmosomes, which attach cells to each other, and hemi-desmosomes, which attach cells to the basement membrane. Two types of septate junctions are present: the straight, unbranched, double-septum septate, which is present in epithelial cells throughout embryogenesis, and the pleated, anastomosing, single-septum septate. The latter is formed only on cells that have invaginated to the interior of the embryo to form the digestive tract. The pleated junctions are shown to replace the straight junctions that were originally present before the cells migrated to the interior. It is suggested that these pleated septates may be specialized for digestive processes, since they are developed just prior to feeding and are retained in the adult intestine. Tricellular junctions, which join the bicellular junctions of three adjoining cells, have been identified in the embryo and in the adult intestine. Evidence for the presence of gap junctions was not obtained, but there are indications of their presence.

Animals↗
PubMed1982

Reversible neurological symptoms caused by vitamin E deficiency in a patient with short bowel syndrome.

The effect of vitamin E deprivation on the fully developed human nervous system is not known. In children with fat malabsorption from various causes neuropathological and neurological changes have been ascribed to vitamin E deficiency. Herein we described a neurological deficit that occurred in a 64-yr-old man with chronic steatorrhea leading to severe vitamin E deficiency. long-term supplementation with vitamin E resulted in clinical improvement beginning a few months after normalization of his vitamin E status.

Ataxia↗
PubMed1982

Discontinuous counterimmunoelectrophoresis in the diagnosis of antibiotic-associated colitis.

Discontinuous counterimmunoelectrophoresis (DCIE) was employed to detect the toxin of Clostridium difficile, etiologic antibiotic-associated colitis (AAC), in bacteria-free stool filtrates from 51 patients with diarrhea. Stool samples from 31 patients contained C. difficile toxin as determined by tissue-culture assay. A positive result was obtained by DCIE in 20 of the 31 patients (65%) and was influenced by the titer of toxin present. When toxin was present by tissue-culture assay in a dilution of less than or equal to 10(-2) (11 samples), DCIE was positive in only 2 (18%). However, DCIE yielded positive results in 18 of the 20 samples (90%) containing toxin titers greater than or equal to 10(-3). The combination of DCIE and sigmoidoscopy of colonoscopy was superior to either alone in the diagnosis of AAC irrespective of the toxin titer. Nine of 11 patients (82%) whose stool samples contained C. difficile toxin in a dilution of less than or equal to 10(-2) were recognized by DCIE, endoscopy, or both. In stool samples containing toxin in titers greater than or equal to 10(-3), no false-negative results were encountered (sensitivity equals 100%). Thus, 29 of 31 patients whose stool samples contained C. difficile toxin were identified when the results of DCIE and endoscopical examination were combined (sensitivity 93.5%). Neither endoscopical examination nor DCIE yielded positive results in the 20 patients whose stool samples lacked C. difficile toxin (specificity equals 100%). DCIE is a rapid, moderately sensitive, and specific method for detecting C. difficile toxin. When DCIE is combined with endoscopy, the vast majority of patients requiring specific therapy for AAC can be identified.

Anti-Bacterial Agents↗
PubMed1979

Dietary heme iron absorption. A discussion of possible mechanisms for the absorption-promoting effect of meat and for the regulation of iron absorption.

Two main findings are reported. 1) The absorption of heme iron from a composite meal was very little if at all influenced by the subject's iron status at doses in the usual physiological range, but at high doses of heme iron there was a strong correlation with the subject's iron status. A hypothesis is presented to explain the regulation of iron absorption, so as to account for the impact of the subject's iron status, which is always evident with non-heme iron absorption but occurred only at high doses with heme iron. 2) Meat enhanced the absorption of heme iron. A probable explantation for the influence of meat on the separate absorbing mechanisms is that meat may stimulate the digestion of food, so that iron in either form is more efficiently released and made available for absorption.

Absorption↗
PubMed1978

A comparison of administering protein alone and protein plus glucose on nitrogen balance.

It has been suggested previously that in the fasting state the administration of amino acids alone would be more effective in sparing protein than the administration of amino acids plus small amounts of glucose. In the present study we have examined the effect of administration of amino acids alone (1 g/kg per day) and of the same regimen supplemented with 100 g glucose daily, on the nitrogen balance in 10 subjects, six of whom were obese and four undernourished. Mean cumulative nitrogen balance over a 5-day study period was -12.4 g on amino acids alone and +0.5 g when glucose was added (P less than 0.01). It thus appears that the addition of glucose may be beneficial rather than harmful in subjects receiving amino acid therapy.

Adult↗