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Biomedical subjects

H L Bank

Publications and source records attributed to H L Bank.

At least 37 records · Page 2Linked to original sources
PubMed1986

Analog enhancement of videomicroscope images.

A simple, inexpensive technique for enhancing the contrast and resolution of videomicroscope images has been developed. The system has manual controls for gain and pedestal (black level) which permit expansion of low contrast images to the full white-to-black video range. Analog delay-line based circuits are used to sharpen the edges and enhance fine details in the image. These circuits also produce an effective increase in the information content of the image by selectively amplifying low amplitude, high frequency components of the video signal. When live, unstained cells were examined at high magnifications, cytoplasmic structures which were only faintly visible in the unenhanced image became clear. The images of fluorescent objects appear in pseudo-relief, which improves visibility even in the presence of background fluorescence. The system enhances images by performing signal processing functions that otherwise require expensive digital image processing equipment.

Animals↗
PubMed1984

Freeze-fracture and lead ion tracer evidence for a paracellular fluid secretory pathway in rat parotid glands.

The morphology and permeability of tight junctions of the three major epithelial constituents of rat parotid gland-acinus, intercalated duct, and striated duct-have been examined ultrastructurally. Acinar and intercalated duct junctions (including those surrounding intercellular canaliculi) averaged two to three sealing strands, whereas striated duct junctions had five to eight sealing strands. When the permeability of the junctional complex was probed by means of a recently devised lead ion tracer technique, acinar junctions were found to be very permeable, intercalated duct junctions were somewhat permeable, and striated duct junctions were essentially impermeable to the tracer. Thus, by both morphological and tracer-permeability criteria, acinar tight junctions appear to be "leaky." These data provide strong evidence that, in rat parotid glands, a potential paracellular secretory pathway exists in the acinar region for the transepithelial passage of fluid.

Animals↗
PubMed1984

X-ray microanalysis: identification and quantification of elements in normal and pathologically altered cells.

It is apparent that advanced technology in X-ray microanalysis is rapidly becoming applicable to experimental cellular pathology. Additionally, it has already proven to be of significant value in diagnostic human pathology and clinical research, especially in the areas of environmental toxicology and forensic pathology. Like routine electron microscopy, X-ray microanalysis will soon be a necessary technology for any major medical center practicing 'state-of-the-art' medicine.

Calcinosis↗
PubMed1983

A high yield method for isolating rat islets of Langerhans using differential sensitivity to freezing.

Conventional methods of isolating islets of Langerhans rely upon the differential sensitivity of the pancreatic acinar tissue vs islets to enzymatic dissociation by crude collagenase, however, the yield of intact islets obtainable with this technique is quite low. Higher yields of islets can be obtained with pharmacological or surgical methods which either destroy acinar cells or cause them to release their zymogen granules. However, because of the requirement to pretreat the donor, these methods cannot be scaled-up for potential clinical use. To overcome the limitations of the conventional isolation procedures, we exploited the differential sensitivity of acinar cells and islet cells to freezing damage. Using this approach we are able to isolate greater than 2500 islets from the pancreas of a single rat. Basically, we rapidly mince pancreatic tissue, subject the tissue to a short collagenase digestion, briefly freeze the tissue at -30 degrees C in the presence of glycerol, and immediately thaw it. Subsequent enzyme treatment digests the residual acinar tissue, collagen, DNA, and proteins. Preliminary results indicate that the islets are morphologically indistinguishable from islets isolated using conventional digestion techniques.

Animals↗
PubMed1983

Scanning electron microscopy of Dalkon Shield tails.

Scanning electron micrographs of Dalkon Shield tails removed from asymptomatic patients show a variety of microbes and debris throughout their entire length. Apparently, even in undamaged tails, bacterial flora thrive in the protein-rich environment within the multifilament tail. The presence of microbes in the portion of the tail beyond the double knot indicates that an alternative mechanism of microbial transport can occur. Since transient endometritis often occurs immediately after insertion of intrauterine devices, microbes may come in contact with both exposed ends of the multifilament tail and be drawn into the tail by capillary action from the uterine environment down the tail toward the double knot as well as upward from the vagina. Such microorganisms could serve as an inoculum for infection.

Disease Reservoirs↗
PubMed1983

Perturbations of granulocyte counts induced by procedural, chemical and physiological events occurring during filtration leukapheresis in rats.

During filtration leukapheresis a factor(s) is produced, released or extracted into rat blood which causes a transient granulocytosis in pheresed animals and in recipients of homologous plasma from these animals. To identify which factors contribute to this granulocytosis, the procedural steps involved in filtration leukapheresis as well as a number of chemical agents which are potentially extracted from of produced by the procedure, were tested for their ability to stimulate granulocytosis. Procedural steps tested included the depth of anesthesia, effect of the anticoagulant and possible interactions of blood cells with the plastic tubing in the system (sham-pheresis). Chemical agents tested included common mediators of inflammation and proteinases released by polymorphonuclear leukocytes (PMNs), extracts of nylon fibers and Tygon tubing, nylon monomers and solvents used in the manufacture of nylon, oxidized and decomplemented plasma and lysates of PMNs or microorganisms. Our findings demonstrate that several of these agents contribute to the granulocytosis seen during filtration leukapheresis of rats.

Anesthetics↗
PubMed1981

Preparation of fingernails for trace element analysis.

There are substantial differences in the reported elemental composition of human nails. Most investigators have used extensive washing procedures to minimize environmental contamination, however, such washing poses the risk of extraction of elements bound to the nail matrix. To determine if a portion of this variability could be accounted for by the "washing solutions" used by different investigators, nails were washed in nine solvents previously used for cleaning nails and their residual elemental composition measured by atomic absorption spectroscopy or energy dispersion analysis. In general, treatment with organic solvents resulted in less elemental loss than did treatment with aqueous detergents, while aqueous acids caused the greatest loss. Organic solvents more readily extracted iron and magnesium than calcium, copper and zinc. Virtually all of the magnesium was extracted by distilled water or aqueous detergents.

Calcium↗
PubMed1981

Structure of the tight junctions of the human eccrine sweat gland.

The human eccrine sweat gland contains two anatomically and functionally discrete segments: the secretory coil, which produces an isotonic or slightly hypertonic precursor fluid, and the coiled duct, which reabsorbs Na+ and Cl- to yield a hypotonic sweat. We examined the freeze-fracture morphology of tight junctions from isolated secretory coil and coiled duct segments to assess indirectly the contribution of paracellular ion transport in secretion and resorption in the sweat gland. In the secretory coil, tight junctions of the intercellular canaliculus and main lumen consisted of approximately 9 and 6, closely spaced, parallel or anastomosing elements, respectively. Tight junctions of the coiled duct were similar in appearance to those at the main lumen of the secretory coil. In both the secretory coil and coiled duct, and average of 2 to 3, widely spaced junctional elements were usually observed basolateral to the closely spaced junctional elements in the region corresponding to the location of the zonula adherens in Epon sections. The complexity of the tight junctions of the secretory coil exceeded what we expected for an epithelium secreting an isosmotic fluid. The elaborate tight junctions of the coiled duct support other evidence for an intermediate to high transepithelial resistance.

Adolescent↗
PubMed1980

Kallikrein content of rat pancreatic acinar cells or islets by direct radioimmunoassay.

Recent reports have suggested that kallikreins may enzymatically convert proinsulin to insulin. The quantity of rat pancreatic kallikrein in isolated Islets of Langerhans, acinar cells and in whole pancreatic extracts was measured by direct radioimmunoassay and bioassay. Immunoreactive kallikrein content in acinar cells was 813 +/- 111 ng/mg protein (mean +/- S.E.M.). In whole pancreatic homogenates, it was 1303 +/- 213 ng/mg protein. Appreciable quantities of the enzyme were not detected in islets. Kallikrein activity as measured with a rat uterine bioassay had similar distribution. Because of the localization of kallikrein, it is unlikely that the enzyme is involved in the in vivo conversion of proinsulin to insulin.

Animals↗
PubMed1980

Cryogenic preservation of rat polymorphonuclear leukocytes.

Rat polymorphonuclear leukocytes (PMNs) were frozen to --196 degrees C, thawed, and tested for functional viability using a variety of criteria, which included: qualitative and quantitative nitroblue tetrazolium assays, fluorometric membrane integrity assays, chemotactic assays, and bactericidal assay. Using these criteria, the survival of rat PMNs obtained from a glycogen-induced peritoneal wash averaged approximately 70% after thawing. The survival of PMNs obtained from rat peripheral blood was greater than 95%. Maximal survival for cryopreservation of these cells frozen in the presence of 10% dimethyl sulfoxide and 5% hydroxyethyl starch was obtained when the cells were cooled at approximately 10 degrees C/min.

Animals↗
PubMed1979

Cryogenic preservation of isolated rat Islets of Langerhans: effect of cooling and warming rates.

Isolated rat Islets of Langerhans have been frozen to and stored at -196 degrees. After thawing, these islets were capable of secreting near normal levels of insulin in response to graded glucose challenge. Maximal retention of functional viability as measured by the ability of the islets to secrete insulin in response to a glucose challenge was obtained after freezing islets at a cooling rate of approximately 75 degrees per minute in the presence of 1.0 mol/1 dimethyl sulfoxol followed by warming at rates of greater than 3.5 degrees/minute. The critical freezing parameters include the time and temperature of exposure to dimethyl sulfoxide, the rate of cooling, the temperature of the post-thaw dilution from the freezing medium and the presence of serum in the dilution medium.

Animals↗
PubMed1979

X-ray microanalysis of pyroantimonate-precipitable cations.

Modifications of the Komnick potassium (pyro)antimonate precipitation method have been widely used for the subcellular localization of a variety of cations. The identity of cations precipitated with this method has often been controversial, and it is therefore important to establish definitive criteria for identifying precipitated cations in situ. In the present study, we have precipitated antimonate salts in vitro and examined the salts both in crystalline powder form and after embedment in Epon, using energy-dispersive X-ray microanalysis, in an attempt to identify biologically important antimonate-precipitable cations. We have found that the cations sodium, magnesium, and calcium, if present in physiological concentrations, will precipitate antimonate under "standard" conditions (2.5% antimonate, pH 7.2 - 7.4, in the presence of 1% OsO4). Characteristic X-ray emissions were observed for sodium and magnesium, as well as for lead similarly precipitated, but Lalpha and Lbeta emission peaks from antimony interfered with calcium identification and necessitated complex computerized deconvolution or peak stripping to determine the presence of a calcium peak. Precipitates of sodium did not contain appreciable potassium, whereas variable amounts of potassium were present in precipitates of calcium and lead, depending upon the extent of washing prior to dehydration. Sizeable potassium peaks were consistently present in even well washed magnesium precipitates. X-ray spectra of standardized precipitates were found useful as an aid in interpreting the more complicated spectra obtained from tissue samples.

Animals↗