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K T Smith

Publications and source records attributed to K T Smith.

At least 55 records · Page 3Linked to original sources
PubMed1989

The preferential inhibition of Bacillus subtilis spore outgrowth by chloroquine.

Chloroquine inhibited the outgrowth of Bacillus subtilis spores at a 10-fold lower concentration than that required to prevent vegetative growth. Analysis of macromolecular synthesis in outgrowing spores and vegetative cells in the presence of chloroquine indicated that it acted preferentially on transcription. Differential sensitivity of outgrowing spores and vegetative cells to chloroquine was not due to changes in the specificity of the RNA-polymerase, since RNA-polymerase activity measured in permeabilized cells was not affected differently by the drug. The preferential inhibition of spore outgrowth was not evident at pH 8.0, at which the majority of chloroquine is in a monovalent, more lipophilic, form. In the presence of inhibitors affecting membrane potential, vegetative cells were as sensitive to chloroquine as outgrowing spores. Measurement of [14C]-chloroquine uptake showed that early outgrowing spores accumulated twice as much drug as resistant late outgrowing spores and seven times more than vegetative cells. Treatment of vegetative cells with metabolic inhibitors led them to accumulate chloroquine to the levels found in outgrowing spores. Therefore, the preferential inhibition of outgrowing spores by chloroquine is the result of increased uptake of the drug, reflecting differences in energy metabolism from vegetative cells.

Bacillus subtilis↗
PubMed1989

Calcium bioavailability and iron-calcium interaction in orange juice.

We have determined the effects of orange juice on calcium bioavailability from CCM (a combination of CaCO3, citric acid, malic acid, 5:1:1, mol/mol/mol) and iron-calcium interaction by using whole body isotope retention techniques in rats. The mean calcium retention values from CCM were 42.8% from orange juice and 33.0% from water, a control. Orange juice significantly (p less than 0.05) improved calcium bioavailability. This enhancement of calcium absorption is independent of orange juice's pH and citric acid. Iron absorption from orange juice with CCM (36.7%) was also significantly higher than that from control (water) plus CCM (12.3%). Ascorbic acid at levels naturally present in orange juice failed to improve iron retention (12.3% vs 12.5%) from water plus CCM. In contrast, citric acid (at orange juice level) significantly (p less than 0.05) promoted iron absorption in the presence of CCM (8.0% vs 23.7%). The benefit of citric acid on iron-calcium interaction is enhanced by ascorbic acid. In the presence of both citric acid and ascorbic acid, at orange juice levels, iron absorption from water plus CCM (37.6%) was comparable to that from water without CCM (34.5%). These results show orange juice can deliver bioavailable calcium from CCM with minimal inhibition of iron absorption. Citric acid and ascorbic acid are likely the major orange juice components that contribute to the alleviation of iron absorption inhibition by CCM.

Absorption↗
PubMed1989

Meal effects on calcium absorption.

The effect of coingestion of a meal on calcium absorption efficiency was investigated using Ca carbonate, milk, and a new Ca delivery system, CCM. Six experiments with 168 rats and two experiments with 46 normal young women showed that coingestion of a light meal of varied composition enhanced absorption efficiency from all three sources by 10-30% above levels achieved when the test load was ingested without other foods. The differences taken as a whole were highly statistically significant.

Adult↗
PubMed1989

Amplification of specific DNA sequences in C127 mouse cells transformed by bovine papillomavirus type 4.

A rearranged bovine papillomavirus type 4 DNA fragment, present in a line of transformed C127 cells, was molecularly cloned into lambda GT 10. The rearranged viral fragment was found to consist of two separate sequences of 3.8 kb each. Clone A comprised 3.3 kb of host DNA linked to 0.5 kb of BPV-4 DNA. Clone B consisted of 2.2 kb of host DNA linked to 1.5 kb of BPV-4 DNA. The AB locus was found to be amplified and rearranged in a number of different BPV-4 transformed C127 cell lines, irrespective of the presence of viral DNA. The rearranged amplified locus was transferred and maintained in second and third round transformants. We propose that the altered AB locus is involved in the maintenance of the transformed phenotype in the absence of the BPV-4 DNA, and may act as an activated oncogene.

Animals↗
PubMed1988

"Hit and run" transformation of mouse C127 cells by bovine papillomavirus type 4: the viral DNA is required for the initiation but not for maintenance of the transformed phenotype.

Morphological transformation of C127 mouse fibroblasts by bovine papillomavirus type 4 (BPV-4) DNA depends on additional factors, including cell density, the presence of TPA, the concentration of fetal calf serum, and the physical state of the input DNA. Low cell density or the presence of TPA allows the achievement of full transformation, suggesting that disturbance of cell-to-cell contact may be necessary for the expression of the malignant phenotype. TPA also induces a burst of viral DNA synthesis and transcription. The frequency of focus formation is fivefold higher in the presence of high serum than in low serum, indicating that growth factors are required during the early stages of transformation. Although the same number of foci is obtained with either circular or linear DNA, the cells transfected with linear DNA are at a more advanced stage of transformation, being capable of anchorage-independent growth and tumorigenic in nude mice; only 5 out of 21 of these cell lines contain viral DNA in integrated and rearranged forms. In contrast cells transfected with circular DNA are anchorage-dependent but tumorigenic in mice, and do not contain any viral DNA. The linear DNA has an interrupted E1 ORF and fully transformed cells are obtained also with a subgenomic viral DNA fragment containing part of the L1 ORF, the complete E6, E7, and E8 ORFs, and the truncated E1 ORF under the control of the BPV-4 regulatory region; viral DNA is not maintained in any of these cell lines. In total, only 15% of the transformed cell lines contains viral DNA. These results are discussed in the light of the "hit and run" model of cell transformation.

Animals↗
PubMed1987

Calcium absorption from a new calcium delivery system (CCM).

Absorption of calcium from a highly soluble form of calcium, a mixed calcium citrate-malate salt (CCM), was tested against calcium carbonate and milk in both rats and humans. The rat method estimated absorption from the 6-day retention of an oral tracer, and the human method employed the standard double-isotope procedure. CCM was given both as a dry powder and in an orange juice beverage. In two experiments in rats calcium from CCM was absorbed at least as well as, if not better than from calcium carbonate or milk. In two separate experiments in humans, calcium from CCM was absorbed significantly better than from calcium carbonate or milk. We conclude that CCM exhibits excellent bioavailability and that this formulation is a useful addition to the forms of calcium now available either for direct supplementation or for food fortification.

Absorption↗
PubMed1987

The nucleotide sequence and genome organization of bovine papillomavirus type 4.

The nucleotide sequence of bovine papillomavirus type 4 (BPV-4) was determined. The viral genome is 7261 base pairs long. Several overlapping open reading frames (ORFs) have been identified both on the basis of amino acid comparison with other papillomaviruses and on their transcriptional pattern. Eight early ORFs (E1 to 8) were recognized, coding for DNA replication and cell transformation functions, and three late ORFs (L1 to 3), coding for structural proteins. Like the E5 ORF of human papillomavirus type 6 the E5 ORF of BPV-4 is discontinuous. Unlike other papillomaviruses, the non-coding region upstream of the early ORFs (ncr-1) is short (385 base pairs), but there is another non-coding region (ncr-2) of nearly 500 base pairs between the L2 and L1 ORFs. Most of the putative regulatory sites are located in the ncr-1, although potential controlling elements are also found in other parts of the genome. Polyadenylation sites are present at the 3' end of both the early and the late transcription units. Comparison between the polypeptides of BPV-4 and other papillomaviruses showed that BPV-4 is evolutionarily closer to the epitheliotropic human and rabbit viruses than to BPV-1.

Animals↗
PubMed1986

Transcriptional organization of bovine papillomavirus type 4.

Seven virus-specific RNA transcripts have been identified in tumours induced by bovine papillomavirus type 4 (BPV-4). The RNAs measured 4.2, 3.6, 3.0, 2.8, 1.9, 1.6 and 1.0 kilobases (kb). They were mapped on the viral genome by Northern blot hybridization to subgenomic probes, by cDNA hybridization to viral DNA fragments and by S1 analysis of unlabelled and 3' and 5' end-labelled DNA fragments. All the RNA species are transcribed from the same DNA strand, are polyadenylated and with the exception of the 1.0 kb RNA internally spliced. The 3.0, 1.9, 1.6 and 1.0 kb RNAs share the same 3' polyadenylation site at nucleotide 4009 whereas the 4.2 kb RNA and the 2.8 kb RNAs terminate near a polyadenylation site at nucleotide 7187. The 4.2 kb and the 2.8 kb RNAs are transcribed from the late open reading frames and encode the structural polypeptides; the 3.0, 1.9, 1.6 and 1.0 kb RNAs are transcribed from the early open reading frames and are the transcripts involved in viral replication and cellular transformation.

Animals↗
PubMed1985

Papillomaviruses and their involvement in oncogenesis.

Papillomaviruses have been identified as the causative agents of benign epithelial proliferation in many animals including man. Recent evidence has shown that each viral type will only infect a specific species and tissue. Furthermore, certain papillomavirus types have been found associated with lesions capable of malignant conversion, particularly in response to secondary physical or chemical factors. Many advances have been made in identifying particular papillomavirus types inducing papillomas capable of progression and in the identification of the virally encoded functions involved in viral replication and cellular transformation.

Animals↗
PubMed1984

Sharpening radiographs.

This article describes a method for clarifying and sharpening radiographs. The method uses convolution with a computed tomography reconstruction kernel and a noise elimination procedure to control the noise amplification of the convolution. The effect is to flatten global variations and to sharpen and magnify local variations. Examples from industry and medicine are included.

Humans↗
PubMed1984

Papillomavirus research: a growth area.

Recent advances in papillomavirus research have revealed a fascinating picture of diversity among viral types, specificity of tissue infected, and oncogenic potential. Fine mapping of the viral functions may prove invaluable in furthering our understanding of the mechanisms of their interaction with, and transformation of, the host cell.

Animals↗
PubMed1983

The genomes of bovine papillomaviruses types 3 and 4 are colinear.

The 7.2 kb genomic DNA of bovine papillomavirus type 3 (BPV-3) was molecularly cloned using its unique EcoRI site, and the 7.3 kb genome of BPV-4 was cloned using its single BamHI site. The viral genomes were compared by liquid hybridization, Southern blot hybridization and heteroduplex mapping. Low stringency hybridization conditions revealed that the genomes are colinear but the sequences are extensively mismatched. The relative alignment of the restriction endonuclease maps of the two viral genomes has been determined. It was found that the genomes as linearized for cloning are out of phase by 1.7 kb, so that the single EcoRI site of BPV-3 appears to coincide with the BPV-4 EcoRI site at 0.22 map units. It is concluded that the genomes of BPV-3 and BPV-4, both of which cause true epithelial warts, share the same physical organization but exhibit sequence divergence.

Base Sequence↗
PubMed1983

Community cooperation among a university, a community college, a hospital, and a high school: a new model for allied health education.

The University of Texas Health Science Center at Dallas, School of Allied Health Sciences, has designed and established a linkage plan that could help solve the health personnel shortages in many cities. This plan joins several schools to (1) stimulate the implementation of programs to provide limited numbers of trained health professionals, (2) establish a coordinated system whereby technologists and technicians can be trained, (3) prepare qualified persons to staff the local hospitals, and (4) provide a ladder for advancing motivated and qualified health professionals. Coordination of efforts among the university, the seven-member Dallas Community College District, and the Dallas Independent School District's High School for Health Professions facilitates solid academic instruction at these institutions, which is followed by well-supervised clinical experiences in the local hospitals under highly qualified professionals. To date, the program includes the education of nuclear medicine technologists, radiation therapy technologists, electroencephalographic technologists, and histologic technicians. This mode of education is one solution to the health professional shortage.

Allied Health Personnel↗
PubMed1980

Zinc-binding properties of bovine and human milk in vitro: influence of changes in zinc content.

The total zinc content of samples of fat-free human and bovine milk was 3.5 and 3.6 micrograms/ml, respectively. The total protein content was 5.3 and 29.0 mg/ml, respectively, Sephadex G-75 gel filtration chromatography of bovine milk revealed no evidence of zinc associated with low molecular weight fractions (less than 2000 daltons). However, chromatography revealed that 10% of the zinc in human milk was associated with these fractions. When the zinc content of these milks was raised by adding Zn2+ in vitro, chromatography of milk from both species revealed the presence of zinc with the low molecular weight fractions. More zinc was associated with these fractions from human milk than from bovine milk. Recovery of zinc was nearly 100% for all columns. It is proposed, based upon these binding data, that the association of zinc with low molecular weight components of milk is related in part to both protein content and composition and the relative zinc concentrations. These binding differences might influence the bioavailability of zinc from milk.

Animals↗
PubMed1980

Quantitative aspects of zinc absorption by isolated, vascularly perfused rat intestine.

Quantitative measurements of zinc absorption were made using the isolated, vascularly perfused rat intestine as a model. The perfused intestine retains the ability to discriminate between absorption processes for calciu, copper, iron and zinc. Measurements of zinc absorption by the perfused intestine, using atomic absorption spectrophotometry, indicated the presence of a zinc pool within intestinal mucosal cells. The zinc concentration in the lumen of the perfused intestine was directly related to the amount of zinc that appeared in the vascular perfusate. Intestines obtained from zinc-deficient animals exhibited an ability to process greater quantities of zinc which resulted in enhanced absorption. The maximal rate of zinc absorption was 229 nmoles per hour with intestines from rats fed adequate amounts of zinc and 627 nmoles per hour when a zinc-deficient diet was fed. Administration of zinc to rats before isolation and perfusion of the intestine resulted in greater intracellular retention of zinc taken up from the lumen and correspondingly lesser amounts (75 nmoles per hour) transferred to the vascular supply. These data provide quantitative evidence that the perfused intestine retains its ability to exercise homeostatic control over the zinc absorption process and that the intestinal cell is a major site of regulation.

Animals↗
PubMed1979

Identification of albumin as the plasma carrier for zinc absorption by perfused rat intestine.

The isolated vascularly perfused rat intestine exhibits an obligatory need for a protein carrier in order to absorb zinc. Therefore this system is ideal for use as a model to identify the plasma carrier during zinc absorption. Affinity chromatography on Blue Sepharose CL-6B was employed to separate the major serum zinc-binding proteins in the portal effluent of the perfused intestine. It was found that 94% of newly absorbed 65Zn was transported in the portal serum-containing perfusate as an albumin-65Zn complex. The identity of albumin as the plasma carrier was confirmed by polyacrylamide-slab-gel electrophoresis. This evidence suggests that albumin is the plasma protein that is involved in removal of zinc from intestinal-mucosal cells and subsequent transport of the metal in portal blood to the liver.

Animals↗