[Etiology of post-traumatic osteomyelitis].
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Adolescent↗
Biomedical subjects
D Lin
Publications and source records attributed to D Lin.
Effect of cellulose in the diet on the recovery of dietary plant sterols from the feces.
In one normal subject, J.S., fed several formula diets in a sterol balance study, only 25-58% of the ingested plant sterols were recovered from the stool. The dietary plant sterols were completely recovered from the stools of five other men. Plant sterol recovery was complete in all men when a diet of mixed general foods was consumed. Since the chief differences in composition of the formula and the diet of mixed general foods were related to the different contents of cellulose and lactose, these components were added to the formula diet of J.S., and plant sterol balance studies were then carried out. The addition of fresh celery or pulverized cellulose to the formula diet partially corrected the usual fecal loss of plant sterols (80% being recovered). Lactose in the formula was only slightly corrective. However, the addition of both cellulose and lactose led to complete recovery of the ingested plant sterols in the feces. Bacterial cultures of stools were incubated with added cholesterol-4-(14)C, and a linear relationship between losses of sterol during balance studies and in vitro incubations was observed; that is, a considerable loss of the labeled cholesterol from cultures after the formula diet, but not after the diet of mixed general foods. This in vitro loss was also corrected by the addition of cellulose and lactose to the formula diet. The loss of the sterol nucleus in the intestinal tract may occur at times because of the lack of certain dietary constituents. It is hypothesized that the metabolism of intestinal tract bacteria is altered when certain constituents are not present in the diet, and that these bacteria may then degrade the sterol nucleus.
Carbon Isotopes↗
Hypoxia after prenatal cocaine attenuates striatal dopamine and neurotrophic activity.
We have previously shown that newborn rabbits exposed to cocaine prenatally have an altered cardiorespiratory response to hypoxia. We report the effect of postnatal hypoxia on brain DA and neurotrophic activity in New Zealand White rabbit pups (n = 41) born to cocaine-exposed does (30 mg/kg/day SC from days 7-15 of a 32-day gestation = COCaine) and control does (sterile H2O = VEHicle). Four to 6-day-old pups were exposed to 20 min of room air (0.21 fractional inspired oxygen tension, FIO2). One third of each group was then exposed to 20 min of either 0.15 (moderate hypoxia) or 0.08 (severe hypoxia) FIO2. Immediately following hypoxic challenge the pups were sacrificed. Striatal tissue extracts were subsequently assessed for DA and striatal trophic activity by monitoring the number of neuron specific enolase immunoreactive (NSEir) cells in mesencephalic culture following incubation with striatal extracts. Increasing the severity of hypoxia increased DA content (p < 0.005), but reduced DA activity (p < 0.0001) and trophic activity (p < 0.001). Cocaine exposure reduced striatal DA (p < 0.005) as well as NSEir (p < 0.001) in all conditions relative to vehicle-treated controls. These data suggest that prenatal cocaine exposure enhances the vulnerability of the DA system to the stress of hypoxia, possibly through alterations in neurotrophic activity.
3,4-Dihydroxyphenylacetic Acid↗
Analysis for N2-(pyridyloxobutyl)deoxyguanosine adducts in DNA of tissues exposed to tritium-labeled 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and N'-nitrosonornicotine.
The tobacco-specific carcinogens 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN) are metabolically activated to DNA binding intermediates, partially via 4-(3-pyridyl)-4-oxobutanediazohydroxide (7) or related carbonium ions. Previous studies have shown that generation of 7 from 4-(carbethoxynitrosamino)-1-(3-pyridyl)-1-butanone (11) in the presence of deoxyguanosine yields a major adduct identified as 2'-deoxy-N-[1-methyl-3-oxo-3-(3-pyridyl)propyl]guanosine (adduct 1). These results suggested that adduct 1 should be present in DNA of tissues that can metabolically activate NNK and NNN. In the present study, we evaluate the formation of adduct 1 and its structurally related straight-chain analogue 2'-deoxy-N-[4-oxo-4-(3-pyridyl)butyl]guanosine (adduct 2) in DNA of tissues of rats treated with [5-3H]NNK or [5-3H]NNN, and in DNA of nasal mucosa that had been cultured in medium containing [5-3H]NNK or [5-3H]NNN. Hepatic DNA from rats treated with [5-3H]NNK was enzymatically hydrolyzed to deoxyribonucleosides and analyzed by HPLC. One of the radioactive peaks, peak E, coeluted with adduct 1. However, treatment of peak E with NaBH4 resulted in the formation of products different from those produced by NaBH4 treatment of adduct 1, demonstrating that adduct 1 could not be detected under these conditions. Hydrolysis of peak E with acid produced 4-hydroxy-1-(3-pyridyl)-1-butanone (9), suggesting that peak E might be adduct 2. Therefore, adduct 2 was synthesized by reaction of deoxyguanosine with 1-(3-pyridyl)butane-1,4-dione (5) in the presence of NaCNBH3.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Identification of N-(Deoxyguanosin-8-yl)-2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine as the major adduct formed by the food-borne carcinogen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, with DNA.
The covalent binding of the N-acetoxy-, N-hydroxy-, and nitro derivatives of the food-borne carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) to 2'-deoxyribonucleosides or DNA was investigated in vitro and in vivo. N-Acetoxy-PhIP reacted with deoxyguanosine (dG), but not with the other deoxyribonucleosides, to form N-(deoxyguanosin-8-yl)-PhIP (dG-C8-PhIP), whose structure was determined by NMR and mass spectral analyses and by ultraviolet absorption and pH-solvent partitioning characteristics. While reaction of N-acetoxy-PhIP with calf thymus DNA at pH 5.0 yielded 5.38 +/- 1.16 nmol of bound PhIP residues/mg of DNA, N-hydroxy-PhIP gave only 0.13-0.23 nmol binding/mg of DNA under identical reaction conditions. Nitro-PhIP produced no detectable binding under these conditions. HPLC analysis of 1-butanol extracts of enzymatically hydrolyzed DNA that had been modified by N-acetoxy-PhIP in vitro showed a major adduct which coeluted with and had an ultraviolet absorption and a mass spectrum that were identical to that of authentic dG-C8-PhIP. 32P-Postlabeling analysis of DNA isolated from colon, pancreas, lung, heart, and liver of rats treated orally with PhIP revealed the presence of a major PhIP-DNA adduct. This adduct had chromatographic properties identical to that of the 32P-labeled bis(phosphate) derivative of dG-C8-PhIP and represented 35-45% of the total adducts.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Analysis of DNA adducts of 2-amino-1-methyl-6-phenylimidazo[4,5- b]pyridine in rat and human tissues by alkaline hydrolysis and gas chromatography/electron capture mass spectrometry: validation by comparison with 32P-postlabeling.
A sensitive and specific method has been developed to measure levels of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) adducted to DNA in tissues. The method is based on alkaline hydrolysis of PhIP from DNA, followed by organic solvent extraction, derivatization to form the electron-capturing bis(pentafluorobenzyl) derivative, and analysis by gas chromatography/electron capture mass spectrometry (GC/MS) using a deuterium-labeled internal standard. The method can detect PhIP-DNA adducts at levels down to 0.03 fmol of PhIP/micrograms of DNA (1 PhIP adduct/10(8) normal nucleotides) for a 100 micrograms sample of DNA. The method is reproducible for sample sizes ranging up to at least 1000 micrograms of DNA. A series of 20 DNA samples from 5 tissues of rats treated with a single oral dose of PhIP were analyzed both by alkaline hydrolysis-GC/MS and by 32P-postlabeling. Results from the two methods were highly correlated (r2 = 0.83), with adduct levels determined by alkaline hydrolysis-GC/MS averaging about 60% of the levels determined by 32P-postlabeling. A pilot survey of 24 individual human tissue DNA samples, including pancreas (n = 12), colon mucosa (n = 6), and urinary bladder epithelium (n = 6), was carried out by alkaline hydrolysis-GC/MS and 32P-postlabeling. Both methods provided evidence for PhIP-DNA adducts in two of the colon samples, but not in the samples from human pancreas or urinary bladder.
Animals↗
Quantitative immunohistochemical analysis of 4-aminobiphenyl-DNA in cultured cells and mice: comparison to gas chromatography/mass spectroscopy analysis.
Two monoclonal antisera, 4C11 and 3C8, recognizing 4-aminobiphenyl (4-ABP)--DNA adducts were developed and characterized by competitive enzyme-linked immunosorbent assay (ELISA). Both antisera are highly specific for 4-ABP-DNA and, at the highest concentration tested, do not recognize the DNA adducts of several other aromatic amines tested including 1-aminopyrene, 8-nitro-1-aminopyrene, and 6-nitro-1-aminopyrene. An immunohistochemical method for detecting adducts was developed in R52 cells, a mouse NIH3T3 cell line expressing high levels of cytochrome P450 1A2. Quantitation of fluorescence labeling indicated a dose-related increase in staining in cells treated with 0, 6, 30, 60, and 300 microM 4-ABP. To apply the method to tissue samples, Balb/c mice were treated with 0, 4, 10, 20, 40, and 80 mg/kg 4-ABP and liver, bladder, and lung tissue analyzed by immunohistochemical staining of tissue sections. There was a dose-related increase in specific nuclear staining in liver and bladder tissues with no detectable staining in lung tissue. DNA from liver tissue was also analyzed by alkaline hydrolysis of 4-ABP, derivatization with pentafluoropropionic anhydride, and gas chromatography/mass spectroscopy analysis. A good correlation (r = 0.98, p < 0.0001) was found between DNA damage levels determined by the two methods. Based on adduct levels determined by GC/MS in both R52 cells and liver tissue, the immunohistochemical method has a limit of sensitivity of approximately 1 adduct/10(7-8) nucleotides. Immunohistochemistry should be useful for analysis of 4-ABP-DNA adducts in human tissue biopsies as well as exfoliated cells from the oral mucosa and urinary bladder.
3T3 Cells↗
Random amplified polymorphic DNA for strain delineation within Candida tropicalis.
Candida tropicalis DNA was used as a template in a polymerase chain reaction (PCR) utilizing a 10-mer primer to generate random amplified polymorphic DNA (RAPD). RAPD patterns associated with 25 primers were obtained for six epidemiologically-unrelated isolates, then a subset of six primers were selected to screen a panel of 18 isolates of C. tropicalis and six isolates of Candida paratropicalis, a species that resembles C. tropicalis but has a sucrose-negative phenotype. The panel, which included nine epidemiologically-related isolates from an outbreak of sternal wound infections, was typed without knowledge of each isolate's origin. The RAPD profiles of the epidemiologically-related isolates were identical to very similar; in contrast, the profiles of most unrelated isolates showed more dissimilarity. While RAPD profiles of C. albicans and Candida parapsilosis differed substantially from those of C. tropicalis, the profiles obtained for C. paratropicalis were consistent with it being a variant of C. tropicalis.
Base Sequence↗
Small subunit ribosomal RNA sequence of Henneguya exilis (class Myxosporea) identifies the actinosporean stage from an oligochaete host.
Several transmission studies, as well as recent molecular data, have indicated that the two classes Myxosporea and Actinosporea represent different life cycle stages of Myxozoa. To evaluate the life cycles of myxozoa in catfish aquaculture systems, the small subunit (18S) ribosomal RNA gene sequences of Henneguya exilis, a myxosporean from channel catfish Ictalurus punctatus, and an actinosporean (previously designated as Aurantiactinomyxon janiszewskai) from the aquatic oligochaete Dero digitata were determined. The sequences were identical, indicating that H. exilis and the actinosporean are alternate life stages of a single species. This is the first report identifying the actinosporean stage of the genus Henneguya.
Animals↗
Physical and cDNA mapping in the DBH region of human chromosome 9q34.
Chromosome 9q34 has been extensively studied and mapped due to the presence of known disease genes, principally tuberous sclerosis 1 (TSC1), in this region. During the course of our mapping of this region we constructed a 555-kb contig beginning approximately 50 kb proximal to the dopamine-beta-hydroxylase (DBH) gene and extending, with one small deletion, distal to the D9S114 marker. The contig consists of 11 P1 clones, four PAC clones, one BAC clone and six cosmid clones and contains 27 new nonpolymorphic STSs. We have found the region to be unstable in P1, PAC and BAC cloning vehicles and have identified several deleted genomic clones. In addition, we have isolated and mapped the 3' portions of three putative genes located within or immediately distal to the DBH gene, including one large gene that runs on the opposite strand to DBH and utilizes portions of two DBH exons. The genomic clones of the contig, cDNAs and new STSs will be useful reagents for the further study and mapping of this region.
Base Sequence↗
Isolation and manipulation of rostral mesencephalic tegmental progenitor cells from rat.
A technique for isolating mitotic progenitor cells from the embryonic rostral mesencephalon is described. Culture of the progenitor cells in complete media with subsequent staining for neuron specific enolase (NSE) revealed that only 0.6% of the cells were NSE immunoreactive. Co-culturing the progenitor cells with established striatal cultures did not result in conversion of any of the cells to the dopamine neuron phenotype (tyrosine hydroxylase immunoreactive (THir) neurons). In contrast, co-culture of progenitor cells with established mesencephalic cultures produced a statistically significant, and in some cases (three of twelve), dramatic increase in the number of THir cells. The THir cells that were present had more pronounced process extension than those observed in mesencephalic mono-cultures. Culturing progenitor cells in transwell baskets that were continuously exposed to media but physically separated from established mesencephalic cultures growing underneath the baskets led to the conversion of only a few progenitor cells to THir neurons in four of twelve transwell studies suggesting that cell-cell contact between progenitor cells and mesencephalic cells is required for the conversion. This co-culture technique also increased the number of THir neurons in the mesencephalic cultures although the increase was not profound enough to explain the increase observed in traditional co-culture. These data suggest that mitotic progenitor cells can be isolated from fetal rat tissue and successfully converted to the dopamine neuron phenotype.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
A newly developed porcine heart valve bioprosthesis fixed with an epoxy compound. An experimental evaluation.
Concerns with currently available bioprostheses are calcification, long-term durability, and functional and hemodynamic performance. It has been well known that these concerns are all more or less related to the fixatives, glutaraldehyde or formaldehyde, used in preserving bioprostheses. To address these concerns, we undertook the development of a porcine bioprosthesis fixed with an epoxy compound. It was discovered that the porcine leaflets fixed with the epoxy compound appeared more natural than those preserved with glutaraldehyde. The performance of this newly developed epoxy compound bioprosthesis (three samples) was evaluated in a juvenile sheep model. The results were compared to those of its glutaraldehyde counterpart (three samples). Two-dimensional echocardiographic inspection of the valvular leaflet motion indicated that the epoxy compound leaflets were more pliable than their glutaraldehyde counterparts. In addition, the epoxy compound valve appeared to open more widely than the glutaraldehyde valve. Color Doppler flow mapping demonstrated that the blood flow distal to the epoxy compound valve was slightly broader than that observed distal to the glutaraldehyde valve. Moreover, at retrieval, less calcium and pannus ingrowth were observed in the epoxy compound valve than its glutaraldehyde counterpart. The results of this preliminary evaluation indicated that the performance of this newly developed epoxy compound valve was at least equivalent to its glutaraldehyde counterpart, if not better.
Animals↗
Comparison of the cross-linking characteristics of porcine heart valves fixed with glutaraldehyde or epoxy compounds.
The concerns about currently available bioprosthetic heart valves are calcification, long-term durability, and functional and hemodynamic performance. These concerns are all more or less related to the cross-linking reagents, glutaraldehyde or formaldehyde, used in fixing bioprostheses. To address these concerns, the authors undertook the development of a porcine heart valve cross-linked with an epoxy compound. This study compared the cross-linking characteristics, shrink temperature, and moisture content of porcine heart valves fixed with epoxy compounds or glutaraldehyde. Two types of epoxy compounds, Denacol EX-313 and EX-810, or a 0.625% glutaraldehyde were used to fix the porcine aortic valves procured from a slaughter house. Samples of each group were removed at various elapsed fixation times. The shrink temperature and moisture content of the valvular leaflet and distinct layers of aortic wall of each sample were measured. Fresh porcine aortic valve was used as a control. It was found that the shrink temperature of the glutaraldehyde leaflet was the highest, whereas the moisture content of the EX-313 leaflet was the greatest among the three test groups. No significant difference in shrink temperature was observed among the epoxy compound fixed inner, middle, outer, and entire aortic walls. This implied that the cross-linking density of the epoxy compound valve was uniform throughout the entire aortic wall. The same also was observed for the glutaraldehyde fixed aortic wall.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗