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Biomedical subjects

C W Jones

Publications and source records attributed to C W Jones.

At least 73 records · Page 4Linked to original sources
PubMed1983

Radium retention in mature beagles injected at 5 years of age.

Retention of 226Ra was substantially lower in mature beagles injected at 5 years of age compared to corresponding values for young adult beagles injected at 17 months of age. As with young adults, the percentage retention in mature dogs given about 10 microCi/kg exceeded that in mature dogs given 4 microCi/kg or less. Percentage retention, R, at t days after the injection of 10 microCi/kg in mature beagles could be represented by the equation, R = 64.1e-0.233t + 13.0e-0.0048lt + 22.9e-0.000329t, and for mature beagles given 4 microCi/kg or less, R = 38.8e-0.40t + 30.6e-0.0424t + 11.9e-0.00567t + 18.7e-0.000352t. Measured 222Rn/226Ra ratios in bone were similar in mature and young adults. Roughly 66% of the injected radium was excreted by mature dogs during the first 3 weeks, about two-thirds of the total excretion appearing in the feces. Distribution of 226Ra within the skeleton was similar in mature and young adult beagles.

Age Factors↗
PubMed1983

Radium retention and dosimetry in juvenile beagles.

Retention of administered 226Ra was substantially greater in beagles injected as 3-month-old juveniles than as 1.4-year-old young adults, but the measured 222Rn/226Ra ratio in bone was significantly less in juveniles for about the first 600 days after injection. An equation that describes the total-body biological retention R in beagles injected with 226Ra at 3 months of age at any time t (in days) after injection during the first 6.6 years is R = 0.331e-0.206t + 0.245e-0.00374t + 0.424e-0.000114t. The rate constant of the final term in the equation for juveniles is similar to that for young adults, suggesting that this component reflects the net turnover rate in the slowly remodeling component of adult bone. Compared to young adult beagles, animals injected as juveniles had a greater fraction of their retained 226Ra in parts of the skeleton containing much cortical bone, such as paws, and a smaller fraction in those parts containing much trabecular bone.

Age Factors↗
PubMed1983

Radium retention and dosimetry in the St. Bernard.

The percentage total-body retention (R) of 226Ra was determined in 14 young adult St. Bernards for the first 4 years after injection to be represented by the equation, R = 34.8 e-0.165t + 24.6 e-0.00537t + 40.6 e-0.000503t, where t is the time after injection in days. It was found that the 222Rn/226Ra ratio in the skeleton was similar to that measured previously for young adult beagles given 226Ra. Excretion of injected 226Ra averaged about 32% in the first 2 weeks, with about 2/3 of the total appearing in the feces. St. Bernards appear to retain more 226Ra than do beagles injected at the same age. The last two terms of the retention equation were used to calculate the average skeletal radiation dose rate and cumulative radiation dose normalized to each dog's individual retention measurements. Allowance was made in the calculations for the changing skeletal retention of 222Rn and its radioactive daughters as a function of time.

Alpha Particles↗
PubMed1982

Vitreous fluorophotometry in the alloxan- and streptozocin-treated rat.

Since serum fluorescein levels are altered in various experimental states, we examined the relationship between serum and vitreous fluorescein levels. We also injected streptozocin, alloxan, and alloxan with glucose pretreatment do determine whether alterations in the blood-retinal barrier are directly attributable to drug toxicity. When corrected for serum levels, one- and two-hour vitreous fluorescein levels increased above prediabetic values two days after streptozocin or alloxan administration; two-hour readings were higher. Rats treated with alloxan plus glucose did not become diabetic or show elevated vitreous fluorescein levels. Insulin treatment of alloxan-induced diabetic rats resulted in normal vitreous readings without normoglycemia. These results suggest that vitreous readings should be corrected for serum levels and that observations at two hours could be more sensitive than at one hour. Furthermore, the observed alterations in blood-retinal barrier function are not attributed to drug toxicity.

Alloxan↗
PubMed1982

Accepted mutations in a gene family: evolutionary diversification of duplicated DNA.

We report and compare the DNA sequences of 14 silkmoth (Antheraea polyphemus) chorion genes, derived from either cDNA or chromosomal DNA clones. Seven of these genes are members of the A multigene family, and seven are members of the B family. Where available, the previously reported (Jones and Kafatos 1980) intronic and extragenic flanking DNA sequences are also considered. Closely related sequences are compared, revealing the types of spontaneous mutations that were fixed during paralogous evolution. Segmental mutations (i.e. mutations other than substitutions) are nearly always interpretable as small duplications or deletions, related to small direct repeats. Segmental mutations are strongly constrained in the coding regions, although they do occur. Nucleotide substitutions also appear to be under selective constraints: relatively few substitutions leading to amino acid replacements are accepted, silent substitutions leading to some codons (especially purine-terminated ones) are disfavored, and different compositional biases are maintained in different parts of the sequences. Other sequence differences can be interpreted as indicative of neutral drift, including most differences in non-coding regions and most T/C transitions in third-base positions. In the non-coding regions, which are thought to be only loosely constrained by selection, transitions are observed more frequently than might be expected: they account for 52% of all substitutions, and they appear to be favored two to threefold over transversions when allowance is made for the skewed base composition of these regions.

Base Sequence↗
PubMed1982

A comparison of stapled and sutured anastomoses in colonic operations.

Stapled colonic anastomoses can be performed both above and below the peritoneal reflection with complication rates that are comparable with those achieved when these anastomoses are sutured by hand. The new circular stapling instrument may facilitate the performance of a lower colorectal anastomosis than can be done by hand. Operative time, return of intestinal activity and postoperative hospital stay are not significantly affected by the anastomotic technique used.

Adenocarcinoma↗
PubMed1981

Respiration-linked proton translocation in the obligate methylotroph Methylophilus methylotrophus.

The stoicheiometries of respiration-linked proton translocation in Methylophilus methylotrophus were determined by using both the oxygen-pulse and initial-rate methods. The latter has also been used to determine leads to charge/O quotients (measured as yield K+/O quotients) in order to ascertain whether the leads to H+/O quotients might be underestimated by H+/anion symport. The results suggest that 6H+/O are translocated during NADH oxidation, and that 2H+/O are translocated during the oxidation of methanol to formaldehyde. There was no evidence for underestimation of the leads to H+/O quotients due to H+/anion symport, except by the movement of formic acid during formate oxidation. By comparing these results with the known growth efficiencies of this organism, an leads to H+/ATP quotient of close to 2 g-ions of H+/mol of ATP can be calculated. It is proposed that the respiratory chain in Methylophilus methylotrophus is arranged such that there are three sites of energy conservation for NADH oxidation, each translocating 2H+ and each linked to the synthesis of one molecule of ATP. Only the third site of energy conservation is involved in methanol oxidation.

Electron Transport↗
PubMed1981

Energy conservation in the terminal region of the respiratory chain of the methylotrophic bacterium Methylophilus methylotrophus.

Reduced + CO minus reduced difference spectra of respiratory membranes prepared from methanol-limited cultures of Methylophilus methylotrophus confirm the presence of three CO-binding cytochromes i.e. cytochromes aa3, o and cco. The kinetics of cyanide inhibition indicate that the respiratory chain of this organism is branched at the level of cytochrome c to two major terminal oxidases, viz. cytochromes aa3 and o; cytochrome cco is probably not a physiologically significant oxidase. Determination of proton and charge translocation stoichiometries (leads to H+/O and leads to K+/O quotients) during oxidation of ascorbate-N,N,N',N'-tetramethyl-p-phenylenediamine shows that the terminal oxidase system of this organism exhibits a net inward translocation of 2e-, but no net proton translocation, when a pair of electrons are passed from cytochrome c to oxygen. The use of appropriate concentrations of cyanide to selectively inhibit cytochrome o indicates that the overall translocation stoichiometries are achieved by the two oxidases, aa3 and o, functioning similarly. These and other results suggest that methanol oxidase is organised as a simple redox arm with the methanol oxidation site and oxygen consumption site(s) on the periplasmic and cytoplasmic faces of the inner membrane respectively.

Cell Membrane↗
PubMed1981

Linkage and evolutionary diversification of developmentally regulated multigene families: tandem arrays of the 401/18 chorion gene pair in silkmoths.

The coordinately expressed silkmoth chorion genes, 401 and 18, are closely linked as a pair, in divergent orientation. Analysis of overlapping clones (chromosomal "walk") demonstrated that each of the multiple copies of this gene pair is embedded within a larger deoxyribonucleic acid unit, which is tandemly repeated in a few arrays or possibly a single array. Southern analysis and examination of clones from a single individual moth demonstrated that the repeat units are extensively polymorphic in restriction sites, length, and possibly number, no differential amplification was evident during choriogenesis. Intron and 5'-flanking sequences were shown to be specific for the 401/18 gene pair and not to be present elsewhere in the genome. The spatial distribution of variations in the genes and their flanking sequences were examined.

Animals↗
PubMed1980

Clinicopathologic study of blood-retinal barrier in experimental diabetes mellitus.

Rats with experimental diabetes (induced by streptozocin [Streptozotocin]) were studied by vitreous fluorophotometry and horseradish peroxidase tracer technique. Vitreous fluorescein sodium concentration notably increased four to eight days after a single dose of streptozocin. No leakage from the retinal vasculature could be demonstrated by the horseradish peroxidase tracer study, but three types of retinal pigment epithelial (RPE) lesions were observed. The RPE lesions seemed to be partially responsible for the increase of vitreous fluorescein concentration.

Animals↗
PubMed1980

Structure, organization and evolution of developmentally regulated chorion genes in a silkmoth.

We describe in detail two cloned chromosomal DNA segments from Antheraea polyphemus, each bearing multiple chorion genes. Two types of genes are found per segment, each in two or three copies: they belong to both major chorion multigene families (A and B), but are expressed during the same developmental period (middle choriongenesis in one segment, late in the other). A and B genes alternate and are paired, lie in divergent transcriptional orientation and are in very close proximity to each other (mRNA cap sites are separated by a 5' flanking sequence 264 or 325 bp long). Each AB pair is embedded within a large, tandemly repeating unit. Within that unit, the homologous 3' flanking sequences that separate gene pairs evolve rapidly and are frequently interrupted by long segments representing inserts (or deletions). These segments would decrease unequal crossing-over, facilitating rapid evolution of the chorion multigene families. A total of 10.4 kb of DNA has been sequenced, permitting detailed comparisons of genes, their introns, 5' flanking and immediately 3' flanking regions. Genes range over two orders of sequence similarity, from highly releated to very disparate (gene copies; members of the same multigene family; members of different families). Among their universal features are a common cap-site sequence, a single intron invariably located at the same position within the signal peptide-encoding region, and a Hogness box 21 to 23 nucleotides upstream from the cap site. Features of possible paired promoters occupying the short 5' flanking region are discussed. Genes evolve both by base substitutions and by segmental mutations, which are almost invariably deletions/insertions related to small, direct repeats.

Animals↗
PubMed1980

A simple microassay for the estimation of renin concentration in plasma.

A simple assay for the measurement of renin concentration and renin substrate concentration in microliter quantities of rat plasma is described. In the plasma renin concentration assay 5 microliter of rat plasma was incubated for 2 hr at 37 degrees C in the presence of 20 microliter renin substrate (plasma from nephrectomized rats) and 5 microliter inhibitor-buffer solution pH 7.4. At the end of the enzymic incubation the generated angiotensin I was estimated by radioimmunoassay. Angiotensin I antisera and iodinated angiotensin I were added to the same tube and left to equilibrate at 45 degrees C for 15 hr. EDTA, dimercaprol, and 8-hydroxyquinoline were used to inhibit converting enzymes and angiotensinases. Reproducibility of the assay was good, and recovery of added angiotensin I complete. The normal range of plasma renin in rats was between 7 and 15 pmol angiotensin l/ml/hr.

Angiotensin I↗
PubMed1980

Long-term study of flunisolide treatment in perennial rhinitis with special reference to nasal mucosal histology and morphology.

Ten patients with allergic perennial rhinitis completed a 3-month course of reatment with flunisolide nasal spray. Biopsy of the nasal mucosa was carried out before the initiation of treatment and at the end of the treatment period. The flunisolilde was administered as a 0.025% solution twice daily at a total daily dose of 200 micrograms. No histological abnormalities which could have been attributed to the effects of the drug were found in the post-treatment biopsies. Comparison of the pre- and post-treatment histological features showed either that there had been no apparent changes or that there had been a reduction in the oedema and/or cellular infiltration which had been present initially. All except one patient improved clinically and in this case the pre-treatment nasal biopsy demonstrated features of atrophic rhinitis.

Adolescent↗