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R C Duhamel

Publications and source records attributed to R C Duhamel.

32 records · Page 2Linked to original sources
PubMed1981

A charcoal cartridge for the removal of anionic detergent and electrophoresis stains.

Instructions are given for the construction of a charcoal-containing cartridge that allows the rapid recirculation through charcoal of any fluid in which the cartridge is submerged; recirculatory flow is achieved by magnetic stirring of the fluid by a stirring bar placed under the cartridge. The device is assembled from nylon mesh and conical sections cut from polypropylene beakers. The device can be used to accelerate the destaining of electrophoresis gels and to remove SDS (sodium lauryl sulfate) from SDS gels. The removal of SDS prior to staining is essential for the staining of SDS gels with Coomassie Brilliant Blue G-250.

Charcoal↗
PubMed1980

Metachromatic staining with Coomassie Brilliant Blue R-250 of the proline-rich calf thymus histone, H1.

In this report, we show that calf thymus histone 1 stains metachromatically with Coomassie Brilliant Blue R-250. Histone 1 gel bands appear red instead of the more familiar blue color characteristic of the vast majority of proteins. The red color and the spectral properties of histone 1 bands are qualitatively similar to those of collagen and procollagen bands which, as previously shown by others, also stain metachromatically (Micko, S. and Schlaepfer, W.W. (1978) Anal. Biochem. 88, 566-572 and McCormick, P.J., Chandrasekhar, S. and Millis, A.J.T. (1979) Anal. Biochem. 97, 359-366). In contrast to histone 1, histones 2A, 3 and 4 stain blue; histone 2B also stains predominantly blue, but with a faint red tint. Both red and blue bands display an absorption maximum in the vicinity of 560 nm, but red bands display an additional maximum in the vicinity of 530 nm. There are quantitative differences between the red bands; the 530 nm peak is more prominent in the spectrum of the collagen band than in the spectrum of the histone 1 band. The spectra of the blue bands are all very similar except that the spectrum of the histone 2B band is shifted slightly toward lower wavelengths. To account for the spectral differences between protein bands, we propose a model in which closely-spaced proline residues are responsible for the chromotropic effect. Localized concentrations of proline residues are present in both collagens and histone 1 and a small cluster is also present in histone 2B.

Animals↗
PubMed1980

A simple procedure for the purification of bovine fibrin from clotted blood by the use of detergents.

A rapid and simple procedure for the preparation, directly from clotted whole blood, of bovine fibrin free of cell membrane contaminants is described. The procedure exploits the ability of detergents to solubilize and extract cell membrane proteins from homogenized clot fragments. The non-denaturing detergents, TX-100 and DOC, used in sequence, or the denaturing detergent, SDS, used alone, proved equally effective. The resulting fibrin has the solubility properties and the subunit composition on SDS gels of highly cross-linked fibrin.

Animals↗
PubMed1980

Rabbit glomerular and tubular basement membranes: morphology and differential solubilization.

Rabbit glomeruli and tubules were obtained by retrograde perfusion of magnetite into the lower aorta as previously described for the isolation of rat glomeruli. In addition, an alternative method of separating rabbit glomerular and tubular basement membranes from a single renal cortex preparation was developed. These preparations, which represent the Triton X-100-insoluble material, were extracted in sequence with deoxycholate, dodecyl sulfate in the presence and absence of 2-mercaptoethanol at 8 degrees C and again in the latter at 100 degrees C. The polypeptides solubilized at each step of this sequence were characterized by electrophoresis. The final extract consisted almost exclusively of red-staining, presumably collagenous bands, while the earlier extracts consisted of blue-staining, presumably noncollagenous bands. No significant differences were found between the glomerular and tubular basement membrane extracts.

Animals↗
PubMed1979

pH gradient elution of human IgG1, IgG2 and IgG4 from protein A-sepharose.

Pooled human serum having a normal IgG subclass content was chromatographed on a column of protein A-Sepharose. The immunoglobulins that bound to the column at pH 7.0 were eluted with a pH gradient generated by 3 equal volumes of citrate/phosphate buffer at pH 5.0, 4.5 and 2.2. The elution pattern consisted of two major overlapping peaks centered 0.4 pH units apart in the pH gradient; on average the first peak centered at pH 4.7, and the second centered at pH 4.3. Upon second passage of each component, single major peaks centered at the appropriate pH were seen. The subclass distributions of the re-chromatographed peaks were as follows: the high pH-eluting IgG contained less than 1% IgG1, 95% IgG2 and 5% IgG4; the low pH-eluting IgG contained 90% IgG1, 6% Ig2 and 5% IgG4. IgG3 does not bind to protein A and was thus absent from the pH gradient fractions. Chromatography on protein A-Sepharose provides a means for separating normal human IgG1 from IgG2 and may therefore prove useful as an additional tool for studying the relative biological role of these IgG subclasses.

Animals↗
PubMed1978

A molting rhythm for serum proteins of the cockroach, Blatta orientalis.

1. Polyacrylamide gel electrophoresis (PAGE) in 4% gels of Blatta orientalis larval hemolymph revealed 4 major proteins. 2. Maximum incorporation of [14C]-leucine into total hemolymph protein occurs within 24 hr and is followed by negligible turnover in the next 24 hr. 3. Quantitative PAGE was used to monitor concentration changes during the molting cycle in synchronously molting cultures. 4. All 4 proteins show the same temporal rhythm of variation but different amplitudes. 5. The widely differing concentrations achieved are accounted for by different rates of synthesis.

Animals↗
PubMedDate not supplied

Holocene age of the Yuha burial: direct radiocarbon determinations by accelerator mass spectrometry.

The view that human populations may not have arrived in the Western Hemisphere before about 12,000 radiocarbon yr BP has been challenged by claims of much greater antiquity for a small number of archaeological sites and human skeleton samples. One such site is the Homo sapiens sapiens cairn burial excavated in 1971 from the Yuha desert, Imperial County, California. Radiocarbon analysis of caliche coating one of the bones of the skeleton yielded a radiocarbon age of 21,500 +/- 1,000 yr BP, while radiocarbon and uranium series analyses of caliche coating a cairn boulder yielded ages of 22,125 +/- 400 and 19,000 +/- 3,000 yr BP, respectively. The late Pleistocene age assignment to the Yuha burial has been challenged by comparing the cultural context of the burial with other cairn burials in the same region, on the basis of the site's geomorphological context and from radiocarbon analyses of soil caliches. In rebuttal, arguments in defence of the original age assignment have been presented as well as an amino acid recemization analysis on the Yuha skeleton indicating an age of 23,600 +/- 2,600 yr BP. The tandem accelerator mass spectrometer at the University of Arizona has now been used to measure the ratio of 14C/13C in several organic and inorganic fractions of post-cranial bone from the Yuha H. sapiens sapiens skeleton. Isotope ratios from six chemical fractions all yielded radiocarbon ages for the skeleton of less than 4,000 yr BP. These results indicate that the Yuha skeleton is of Holocene age, in agreement with the cultural context of the burial, and in disagreement with the previously assigned Pleistocene age of 19,000-23,000 yr.

Animals↗
PubMedDate not supplied

Albumin impregnated vascular grafts: albumin resorption and tissue reactions.

This study aimed to determine the kinetics of albumin resorption from and the healing of two types of albumin impregnated Vasculour II (Bard Cardiovascular) Dacron grafts (ACG-A and ACG-B) using whole blood preclotted Vasculour II Dacron grafts (without albumin) as controls (PCC). Prostheses measuring 4 mm ID x 50 mm length were implanted in the aortoiliac position in 24 dogs (ACG-A n = 12, ACG-B n = 24, PCC n = 12) and explanted after 1, 2 4, and 6 months. Platelet count, platelet aggregometry to 10(-5) M ADP, prothrombin time (PT), and partial thromboplastin time (PTT) were determined preoperatively and at explantation. Sections of the explanted grafts were assayed for human albumin by immunohistochemical techniques utilizing a rabbit polyclonal mono-specific antibody for human albumin followed by the addition of a biotinylated goat anti-rabbit IgG. Immunoperoxidase staining was then performed using Avidin D horse-radish peroxidase. Histology of the grafts (light microscopy, scanning electron microscopy, and transmission electron microscopy) as well as percent thrombus free surface area (TFSA) by computerized planimetry were also determined. Seven of 48 grafts were occluded (85.4% patency) with no difference among the three groups. Platelet aggregometry was not predictive of graft patency. No change in PT or PTT occurred nor was there any difference among the three groups. Retained albumin was detected in every one-month explant but not beyond that time, with the sensitivity for detecting human albumin in this assay being 20 mg albumin per gram of Dacron. All ACG explants at one month revealed inner capsular fibrin coagula not present in PCC specimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Albumins↗