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Biomedical subjects

R Chandler

Publications and source records attributed to R Chandler.

At least 19 recordsLinked to original sources
PubMed1999

Examination of psoralens-induced photodermatitis in Wistar rats under scanning electron microscopy.

The psoralens are photoactivated plant biosynthetic compounds which are found in several plant families, including common fruits and vegetables. Synthetic forms of the psoralens bergapten (5-methoxypsoralen) and xanthotoxin (8-methoxypsoralen) are extensively used in skin chemotherapy in combination with long-wave ultraviolet radiation (PUVA). Side effects of PUVA therapy are not, however, desirable, and this therapy has been linked with increased incidence of skin cancer in humans. The psoralens are known to be carcinogenic, mutagenic and teratogenic, and to cause photodermatitis. The main objective of this study was to document the effect of PUVA on the epidermis of rats. Female Wistar rats were administered dietary bergapten and/or xanthotoxin (0-200 mg/kg body) and exposed to UVA radiation (45 min./day) for four weeks. At the end of the four-week period the rats were sacrificed; skin samples were taken from the ears and the top part of the tail and fixed for examination by Scanning Electron Microscopy. The animals subjected to PUVA had significantly smaller scales on the tail epidermis (mean scale size for the control 926 mu vs. 725 to 805 mu for the psoralen treatment groups. The rats that received dietary psoralens also had significantly less hair on the ears compared with the control animals (mean number of hairs per millimeter over the ear edge for the control 54.9 vs. 2.00 to 10.7 for the treatment groups). The two compounds were synergistic in their ability to reduce scale size on the tail epidermis.

5-Methoxypsoralen↗
PubMed1998

Drosophila nerve cord culture: a tool for studying neural development.

The culture of explanted neural tissues has been a useful tool for the study of cellular and molecular neurobiology in vertebrates. We have developed a technique for the culture of explanted ventral nerve cords from Drosophila embryos. We have examined the morphology and dynamic behaviour of the growth cones that extend from these nerve cords, and the effect of calcium deprivation on the bundling of axons that are regenerated from the explanted tissue. This technique offers a unique opportunity to combine in vitro techniques for neuronal cell culture with the powerful techniques of genetic analysis that are available with Drosophila.

Animals↗
PubMed1998

Acquisition of iron by Gardnerella vaginalis.

Six Gardnerella vaginalis strains were examined for the ability to utilize various iron-containing compounds as iron sources. In a plate bioassay, all six strains acquired iron from ferrous chloride, ferric chloride, ferrous sulfate, ferric ammonium citrate, ferrous ammonium sulfate, bovine and equine hemin, bovine catalase, and equine, bovine, rabbit, and human hemoglobin. All six strains also acquired iron from human lactoferrin, but not from human transferrin, as determined by a liquid broth growth assay. Siderophore production was detected in eight G. vaginalis strains by the chrome azurol S universal chemical assay. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the cytoplasmic membrane proteins isolated from G. vaginalis 594 grown under iron-replete and iron-restricted conditions revealed several iron-regulated proteins ranging in molecular mass from 33 to 94 kDa. These results indicate that G. vaginalis may acquire iron from iron salts and host iron compounds.

Bacterial Proteins↗
PubMed1995

Phosphorylation with protein kinases modulates calcium loading of terminal cisternae of sarcoplasmic reticulum from skeletal muscle.

We previously found in single channel studies that ryanodine receptor (RyR) channel activity can be made insensitive to block by Mg2+ when terminal cisternae of sarcoplasmic reticulum, incorporated into planar bilayers, are treated with protein kinase A (PKA) or Ca2+/calmodulin dependent protein kinase type II (CamPK II), and then again made sensitive by treatment with protein phosphatases [Hain J. Nath S. Mayrleitner M. Fleischer S. Schindler H. (1994) Phosphorylation modulates the function of the calcium release channel of sarcoplasmic reticulum from skeletal muscle. Biophys. J., 67, 1823-1833]. In this study, modulation by protein kinases and phosphatases on net Ca2+ uptake by TC is presented. Phosphorylation of TC vesicles with PKA, CamPK II, or protein kinase C (PKC) reduced the calcium loading rate of TC vesicles 3-fold, 2.1-fold and 1.7-fold, respectively, measured in the presence of 1 mM MgCl2. There is no effect when AMP-PNP is substituted for ATP. Phosphorylation of the RyR was also measured by incorporation of [gamma-32P]-phosphate from ATP. A phosphorylation stoichiometry of 1.94 +/- 0.1 (32P/RyR) for PKA, 0.89 +/- 0.08 for CamPK II and 0.95 +/- 0.16 for PKC was obtained under these conditions. A study of the time dependence of phosphorylation with PKA and CamPK shows a direct correlation of reduction in calcium loading rate with increased phosphorylation of the ryanodine receptor. Treatment with protein phosphatase 1 enhanced the calcium loading rate again, after it was reduced by PKA phosphorylation. Investigation of the magnesium dependency shows that even at higher [Mg2+] (6 mM), PKA phosphorylated TC vesicles have a 2.3-fold reduced calcium loading rate indicating insensitivity to block by Mg2+.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Imidodiphosphate↗
PubMed1995

Site progression of loss of attachment over 5 years in 14- to 19-year-old adolescents.

The aims of this study were (1) to monitor the progression and patterns of progression of loss of attachment > or = 1 mm on a site basis over a 5-year period in adolescents, and (2) to relate the presence of oral deposits and inflammation to the subsequent development and progression of loss of attachment on a site basis. 167 subjects were examined at ages 14, 16 and 19 years. Loss of attachment > or = 1 mm, plaque, subgingival calculus, gingival bleeding and gingival colour change were assessed on the mesio-buccal sites of the 1st molars, 1st premolars and central incisors. Each site was treated separately in the analysis to avoid the problem of within-subject site dependence. Sites were classed as progressing, non-progressing or fluctuating according to the probing attachment level measurements at each of the 3 examinations. During the 5 years of this study, a total of 542 sites in 128 subjects progressed; 1136 sites in 162 subjects did not progress; 43 sites in 30 subjects had fluctuating attachment level measurements. Sites which subsequently progressed had significantly more plaque, subgingival calculus and gingival inflammation than non-progressing sites at the baseline examination and throughout the study (p < 0.001). Between 55-57% of the maxillary 1st molars and 46-49% of the mandibular incisors progressed. In contrast, there was no progression of loss of attachment on over 80% of the maxillary central incisors and mandibular 1st premolars.

Adolescent↗
PubMed1994

Anesthesia in the emergency setting: Part II. Head and neck, eye and rib injuries.

Anesthesia for procedures of the head and neck includes ear field blocks, supraorbital and supratrochlear nerve blocks, infraorbital, mental, mandibular and posterosuperior alveolar nerve blocks. Topical ophthalmic anesthesia is useful in treating a variety of ocular injuries, including corneal abrasion and laceration, chemical/thermal burns, and injuries caused by foreign bodies and contact lenses. The intercostal nerve block is used to manage the pain of rib fractures, thus improving patient comfort, tidal volume and ventilation, and pulmonary toilet.

Craniocerebral Trauma↗
PubMed1994

Anesthesia in the emergency setting: Part I. Hand and foot injuries.

Topical application and local infiltration of anesthetic agents are useful for localized areas, while a circular field block provides superficial anesthesia within the encircled area. Regional anesthesia is accomplished by injecting the anesthetic agent near a nerve or nerve group. Useful anesthetic techniques for repair of hand injuries include wrist blocks, intermetacarpal blocks and local infiltration anesthesia. Median nerve block, ulnar nerve block, radial nerve block or a combination of these blocks provides satisfactory anesthesia without inducing muscle paralysis in the anesthetized region. Intermetacarpal digital blocks are used to anesthetize any finger. Local infiltration is useful for closing minor lacerations. For foot injuries, the posterior ankle block is used to anesthetize the sole. The anterior ankle block is used for the dorsum of the foot.

Anesthesia, Local↗
PubMed1994

Isolation and partial amino acid sequence of a 78 kDa porcine gastrin-binding protein.

1. A 78 kDa protein (p78) has been partially purified from washed membranes isolated from the corpus of porcine gastric mucosa. The purification was monitored by covalent cross-linking of iodinated [Nle15]-gastrin. 2. A single N-terminal sequence extending for 33 amino acids was obtained from the p78 preparation. Partial sequences totalling 192 amino acids were also obtained from 14 tryptic and 3 Staphylococcal V8 peptides. 3. 10 peptides plus the N-terminal sequence were derived from a previously unsequenced protein which was distantly related to the product of the E. coli fadB gene (Baldwin G. S. (1993) Comp. Biochem. Physiol. 104B, 55-61). The remaining 7 peptides were derived from the beta-subunit of the gastric H+/K(+)-ATPase. 4. The gastrin-binding activity remained in association with p78, and could be separated from the beta-subunit of the gastric H+/K(+)-ATPase, during chromatography on tomato lectin-Sepharose. 5. We conclude that p78 binds gastrin, and is a novel member of the enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase family of enzymes.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1991

Randomized study of preoperative versus postoperative radiation therapy in advanced head and neck carcinoma: long-term follow-up of RTOG study 73-03.

This is a report of a 10-year median follow-up of a randomized, prospective study investigating the optimal sequencing of radiation therapy (RT) in relation to surgery for operable advanced head and neck cancer. In May 1973, the Radiation Therapy Oncology Group (RTOG) began a Phase III study of preoperative radiation therapy (50.0 Gy) versus postoperative radiation therapy (60.0 Gy) for supraglottic larynx and hypopharynx primaries. Of 277 evaluable patients, duration of follow-up is 9-15 years, with 7.6% patients lost to follow-up before 7 years. Loco-regional control was significantly better for 141 postoperative radiation therapy patients than for 136 preoperative radiation therapy patients (p = 0.04), but absolute survival was not affected (p = 0.15). When the analysis was restricted to supraglottic larynx primaries (60 postoperative radiation therapy patients versus 58 preoperative radiation therapy patients), the difference for loco-regional control was highly significant (p = .007), but not for survival (p = 0.18). In considering only supraglottic larynx, 78% of loco-regional failures occurred in the first 2 years. Thirty-one percent (18/58) of preoperative patients failed locally within 2 years versus 18% (11/60) of postoperative patients. After 2 years, distant metastases and second primaries became the predominant failure pattern, especially in postoperative radiation therapy patients. This shift in the late failure pattern along with the increased number of unrelated deaths negated any advantage in absolute survival for postoperative radiation therapy patients. The rates of severe surgical and radiation therapy complications were similar between the two arms. Because of an increased incidence of late distant metastases and secondary primaries, additional therapeutic intervention is required beyond surgery and postoperative irradiation to impact significantly upon survival.

Adult↗
PubMed1990

Isolation of transferrin from porcine gastric mucosa: comparison with porcine serum transferrin.

1. An iron-binding glycoprotein has been purified to homogeneity from porcine gastric mucosa. 2. The molecular weight (80,000), amino acid composition, carbohydrate content, N-terminal amino acid sequence, tryptic map, stoichiometry of iron binding (2 mol/mol), visible absorption spectrum of the ferric complex and chromatographic behaviour of the gastric protein are all strikingly similar to the corresponding properties of porcine serum transferrin. 3. The quantity of the gastric protein (1.3 mg/g wet weight) present in the gastric mucosa suggests that it is not serum transferrin (plasma concentration 1.8 mg/ml) contaminating the tissue. 4. A role for transferrin in the uptake of dietary iron by the gastrointestinal tract is proposed.

Amino Acid Sequence↗
PubMed1988

DNA analysis by flow cytometry.

Accurate quantification of DNA from cells of several species is possible with flow cytometry. When one species is used as a reference, cytometric readings from two or more different species can be compared to obtain relative percent DNA or DNA indices. Differences in DNA from the male and female of the same species also can be measured. The method allows rapid screening of chromosomal abnormalities among large clinical populations, and evaluation of errors of sex determination such as XY sex reversal.

Animals↗
PubMed1987

Structural studies on a 75-kDa glycoprotein isolated from porcine gastric mucosal membranes: close homology with the 78-kDa glucose-regulated family of proteins.

A 75-kDa glycoprotein (P75) has been purified to homogeneity from washed membranes isolated from the corpus of porcine gastric mucosa. The purification procedure employed chromatography on concanavalin A-Sepharose and DEAE-Sepharose, and preparative polyacrylamide gel electrophoresis. Reversed-phase microbore high-performance liquid chromatography was employed to fractionate and purify a number of tryptic peptides generated from approximately 1100 pmol purified P75. The use of reversed-phase microbore (2.1 mm internal diameter) columns facilitated the purification of subnanomole amounts of polypeptides in small volumes (40-60 microliter) suitable for loading onto the gas-phase sequencer without further concentration. N-Terminal amino acid sequence analyses were performed on the intact polypeptide and on 13 tryptic peptides and one Staphylococcus protease V8 peptide, yielding 170 unique assignments; this corresponds to approximately 26% of the molecule. A comparison of this amino acid sequence information with the cDNA-deduced primary structure of a 70-kDa heat-shock-related protein (P72), which is expressed in normal rat liver reveals that these protein sequences are almost identical, differing in only 1 of the 170 positions positively assigned thus far. The probable correspondence of P72 with the 78-kDa glucose-regulated protein (GRP78) isolated from hamster fibroblasts has been reported.

Amino Acid Sequence↗
PubMed1986

Identification of a gastrin binding protein in porcine gastric mucosal membranes by covalent cross-linking with iodinated gastrin.

A gastrin binding protein (GBP) has been identified in detergent extracts of porcine gastric mucosal membranes by covalent cross-linking to 125I-[Nle15]gastrin with disuccinimidyl suberate. The apparent molecular weight of the cross-linked complex (80,000) is uneffected by reduction suggesting that the GBP is not composed of disulfide-bonded subunits. Subtraction of the molecular weight of 125I-gastrin indicates that the molecular weight of the GBP is 78,000. A similar molecular weight has been observed previously for the gastrin receptor (74,000) on intact canine parietal cells and plasma membranes therefrom, and for the receptor for the related hormone cholecystokinin (76,000-85,000) on pancreatic acinar membranes under reducing conditions. The similarity in molecular weight between the gastrin receptor and the solubilized GBP suggests that the latter protein is probably the gastrin receptor. However, the concentration (2 microM) of [Nle15]gastrin required for 50% inhibition of cross-linking of gastrin to the GBP solubilized in 0.1% Triton X-100 is 200-fold greater than the value (10 nM) observed for the gastrin receptor on isolated canine gastric parietal cells. A lower concentration (0.3 microM) of [Nle15]gastrin was required to inhibit cross-linking in a milder detergent (0.4% digitonin, 0.08% cholate). Thus, the reduced affinity for gastrin of the putative solubilized form of the gastrin receptor appears to be a result of detergent extraction.

Animals↗
PubMed1986

Binding of gastrin to gastric transferrin.

Binding of 125I-gastrin to porcine gastric transferrin has been demonstrated by covalent cross-linking with disuccinimidyl suberate. The concentration of gastrin required to reduce cross-linking by 50% was approx. 100 microM. The occurrence of both gastrin and gastric transferrin in porcine gastric mucosa and lumen suggests a novel synergistic role for the observed interaction in the uptake of dietary iron.

Animals↗