Study on the prevention of surface-induced platelet activation by albumin coating

To understand how albumin on the surface inhibits surface-induced platelet activation, we adsorbed albumin on dimethyldichlorosilane-coated glass (DDS-glass) and modified the adsorbed albumin by three different methods. The adsorbed albumin was crosslinked with glutaraldehyde, dried and rehydrated, or digested with trypsin. Surface albumin concentration did not change by crosslinking; however, it decreased by about 15% by a simple dry-and-rehydration process. Trypsin digestion reduced the surface albumin concentration by 50%. Platelets were found to adhere and activate on albumin coated DDS-glass, if the adsorbed albumin was modified. The extent of platelet activation was quantified with two numeric parameters, the spread area and circularity. Fibrinogen adsorption to the dried or digested albumin layer resulted in enhancement of platelet activation, while adsorption of more albumin inhibited platelet activation. The results suggest that albumin can inhibit platelet activation as long as it covers the surface completely and remains flexible on the surface. This study indicates that steric repulsion is one of the mechanisms of surface passivation by albumin.

Amorphic Diamond Films Produced by Laser Ablation

Four types of diamond films have been shown to be stable and free from hydrogen: crystalline diamond, amorphic diamond, i-C and defected graphite. Each is significantly harder than other forms of carbon, but only now are quantitative values of hardness being reported. In this work nanoindentation techniques were used on these highly elastic films and linear ranges of plastic response were identified. Values of hardness were extracted from the on-load data for amorphic diamond and crystalline diamond that could not be distinguished from the hardness of naturally occurring diamond. This seems to explain why thin layers of amorphic diamond have been so effective in protecting substrates from the erosive impacts of particles and droplets reported in previous studies.

Refinement of the localization of human butyrylcholinesterase to chromosome 3q26.1-q26.2 using a PCR-derived probe

The gene for butyrylcholinesterase (EC 3.1.1.8) has been previously localized to three sites in the human genome, at 3q21, 3q26, and 16q21. In situ hybridization using a PCR-derived probe including the active site region gives a single hybridization signal and refines the localization to 3q26.1-q26.2.

Genomic structure of human lysosomal glycosylasparaginase

The gene structure of the human lysosomal enzyme glycosylasparaginase was determined. The gene spans 13 kb and consists of 9 exons. Both 5' and 3' untranslated regions of the gene are uninterrupted by introns. A number of transcriptional elements were identified in the 5' upstream sequence that includes two putative CAAT boxes followed by TATA-like sequences together with two AP-2 binding sites and one for Spl. A 100 bp CpG island and several ETF binding sites were also found. Additional AP-2 and Sp1 binding sites are present in the first intron. Two polyadenylation sites are present and appear to be functional. The major known glycosylasparaginase gene defect G488----C, which causes the lysosomal storage disease aspartylglycosaminuria (AGU) in Finland, is located in exon 4. Exon 5 encodes the post-translational cleavage site for the formation of the mature alpha/beta subunits of the enzyme as well as a recently proposed active site threonine, Thr206.

Differential activation of potato 3-hydroxy-3-methylglutaryl coenzyme A reductase genes by wounding and pathogen challenge

Potato genes encoding 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) were expressed in response to pathogen, elicitor, and wounding. HMGR catalyzes the rate-limiting step in isoprenoid biosynthesis leading to accumulation of phytoalexins and steroid glycoalkaloids. Wounding caused increases in HMGR mRNA levels. A rapid and transient peak occurred 30 minutes after wounding, followed by a slower peak at 14 hours; both were correlated with increased enzyme activity. Induction of HMGR mRNA by the soft rot pathogen Erwinia carotovora subsp carotovora or arachidonic acid began 8 hours after challenge and continued through 22 hours. Potato HMGR is encoded by a gene family. An HMGR gene-specific probe was used to demonstrate that one isogene of the HMGR family is pathogen activated and is distinct from isogene(s) that are wound activated. This provides evidence that defense-related increases in HMGR activity are due to mRNA level increases and that HMGR isogenes are activated differentially by wounding or pathogen challenge.

The minimum surface fibrinogen concentration necessary for platelet activation on dimethyldichlorosilane-coated glass

Albumin and fibrinogen were competitively adsorbed onto dimethyldichlorosilane-coated glass (DDS-glass) and platelet activation was examined as a function of the surface fibrinogen concentration. The weight ratio of albumin to fibrinogen in the adsorption solution was varied from 10 to 700. Platelet activation was quantitated by the area and circularity of spread platelets. When the DDS-glass was coated with albumin alone, platelets were only contact adherent and could not spread at all. After competitive adsorption of fibrinogen and albumin, however, platelets were able to spread on the surface. Platelet activation increased linearly as the surface fibrinogen concentration increased up to 0.02 micrograms/cm2. Platelets were able to activate fully if the surface fibrinogen concentration was 0.02 micrograms/cm2 or higher, even though the surface was dominated by albumin. It appears that platelets can activate fully as long as only a small fraction (2-15%) of the surface is covered with tightly bound fibrinogen.

Demographic and socioeconomic characteristics of Korean Americans in the United States in 1980

"Based on the analysis of 1980 [U.S. Census] Public-Use Microdata Samples, this article demonstrates that the Korean immigrant stream, particularly men, has been very selective even before the 1965 reform.... Despite the educational superiority and somewhat positive occupational position, Korean men in the U.S. are seriously disadvantaged in income regardless of nativity status. Korean Americans are not as successful as whites in translating their education into occupation and income; they are better educated for the same job, but experience a lower income return to the same education and the same occupation."

Increase in glucose-stimulated insulin release and insulin biosynthesis in isolated pancreatic islets from D-galactosamine-treated rats

Insulin secretion in response to glucose, glucose-stimulated insulin biosynthesis and insulin content was studied in pancreatic islets freshly isolated from male Wistar rats (150-200 g) with galactosamine-induced hepatitis. Animals were sacrificed by decapitation 3, 6, 12 and 24 hours after a single intraperitoneal injection of 500 mg/kg of galactosamine. Isolated islets prepared by collagenase method were perifused in Swim's medium with 20 mM glucose at 37 degrees C up to 30 minutes. Samples were taken at 2-10 min intervals for insulin assay. Insulin biosynthesis was assessed by the incorporation of [3H]-leucine into immunoprecipitable products (insulin and proinsulin) in pancreatic islets after 120 min incubation with 20 mM glucose. Glucose-stimulated insulin secretion was significantly increased at 6, 12 and 24 hours following the administration of galactosamine compared to control. The rate of insulin biosynthesis was stimulated to 170, 138 and 185% of control level 3, 6 and 12 hours after galactosamine-treatment, respectively. Significant increase in insulin content of islets was found 24 hours after galactosamine treatment, following the increased insulin biosynthesis. The present results indicate that pancreatic B cell function is activated in early stage of acute liver injury.

Suicide by captopril overdose

We report a case of a 75 year-old male who committed suicide by taking an overdose of captopril. He took approximately ninety 12.5 mg captopril tablets. The postmortem plasma concentration of captopril was 60.4 mg/L. A review of the medical literature revealed five cases of captopril overdose all from unsuccessful suicide attempts. To our knowledge, this is the first case report of fatal captopril overdose with the measurement of plasma concentration of the drug.

Morphological characterization of surface-induced platelet activation

Morphological changes of platelets activated on glass and dimethyldichlorosilane-treated glass were investigated using video microscopy. The platelet morphological changes were quantified by measuring the area and circularity of spreading platelets. In addition, re-organization of cytoskeletal structures of spread platelets was examined. The effects of precoated albumin and fibrinogen on the platelet spreading kinetics were examined as a function of surface protein concentrations. Results showed that platelet shape changes were very sensitive to the surface concentration of precoated proteins. In general, platelets on fibrinogen-precoated surfaces spread fully to a circular shape and developed an extensive inner filamentous zone. In the presence of albumin on the surface, however, platelets could not spread fully and the development of the inner filamentous zone was very poor. For both albumin and fibrinogen, the maximum effects of precoated proteins on platelet shape changes were observed when the surface protein concentration reached the monolayer concentration.

A multistate model for coronary heart disease--an application to different prevention strategies

"The discrete-time stochastic model presented in this paper pays attention [to] the association between physiological risk factors and [coronary heart disease] morbidity as well as mortality trends. Transition probabilities are modeled as a polychotomous logistic function of risk factors. A series of separate simple logistic regression analyses...are performed as a replacement for estimating polychotomous logistic regression parameters. Data from the Finnish North Karelia Project is used to test the model." (SUMMARY IN KOR)

Immunophenotypic spectrum of plasma cell leukemia

Four cases of plasma cell leukemia (PCL) are reported that illustrate the variable immunotype of this disorder in contrast with the immunologic profile described for normal B-cell maturation and typical multiple myeloma (MM). Mature B-lymphocytes express B1 antigen (Ag) and surface immunoglobulin (SIg) whereas maturation to the plasma cell stage is accompanied by loss of these immunologic markers and expression of T10 Ag, plasma cell Ag (PCA), and cytoplasmic immunoglobulin (CIg). Plasma cells from patients with MM have previously been found to express the immunophenotype of normal plasma cells. In contrast, none of the four cases reported here express an immunologic profile typical for specific B-cell differentiation stages. Only one of four cases was strongly positive for PCA but additionally expressed B1 Ag and SIg. Of the remaining three cases, all expressed T10 Ag and CIg; two cases also expressed SIg, weak PCA, and B1 Ag. All four cases were monoclonal for lambda light chains and negative for common ALL Ag (CALLA). The variable expression of mature B-cell markers and plasma cell markers demonstrates the immunophenotypic spectrum of PCL; the prognostic significance of this heterogeneity needs to be more closely examined.

CHAPS solubilization of a G-protein sensitive 5-HT1A receptor from bovine hippocampus

The binding of [3H] 8-OH-DPAT to membrane-bound 5-HT1A receptors from bovine hippocampus was saturable and corresponded to a single high-affinity state. Solubilization of the bovine hippocampal membranes with 10 mM CHAPS containing 200 mM NaCl, renders a preparation which binds [3H] 8-OH-DPAT with high-affinity (Kd = 1.9 nM) and is guanine nucleotide sensitive and ketanserin insensitive. 50% of [3H] 8-OH-DPAT binding activity is solubilized. The presence of GMP-P(NH)P promotes a low-affinity (Kd = 9.6 nM) state which is characteristic of receptors coupled to G-proteins. GMP-P(NH)P markedly accelerates the dissociation [3H] 8-OH-DPAT from solubilized membranes while having negligible effects on association. Thus, the agonist can activate the terniary complex rather than to promote its formation. 8-OH DPAT, WB 4101 and 5-carboxamidotryptamine dose responsively inhibit soluble [3H] 8-OH-DPAT binding with IC(50) values of 16.1, 15.6 and 1.3 nM, respectively. The CHAPS solubilized membrane preparation retains many of the [3H] 8-OH-DPAT binding characteristics of the membrane bound form.

Simulation of a population-based model of coronary heart disease morbidity and mortality

"The main objective of this study is to develop a modelling strategy useful to examine and predict major trends in coronary heart disease. Once we develop a model which can mimic population changes over time, then the models can be extended to provide information on intervention effects by changing the risk factors." The model is illustrated using data for North Karelia, Finland, for the period 1972-1978. (SUMMARY IN KOR)

Mechanisms of mucoadhesion of poly(acrylic acid) hydrogels

It has been proposed that mucoadhesives which adhere to the gastric mucus layer may be used to prolong gastric retention time of oral dosage forms. Preliminary studies, using acrylic hydrogels, have established that the density of carboxyl groups on the polymer chain is important for mucoadhesion. To understand the role(s) of the carboxyl groups in mucoadhesion, acrylic acid-acrylamide random copolymers [P(AA-co-AM)] were synthesized, and the adhesion strength of the cross-linked polymers to the gastric mucus layer was examined as a function of the pH, initial concentration of the cross-linking agent, degree of swelling, and carboxyl-group density. From the study on mucoadhesion of various P(AA-co-AM), it was found that at least 80% of the vinyl groups of the polymer must possess carboxyl groups in the protonated form. The dependence of mucoadhesion on pH and carboxyl-group density suggests that mucoadhesion occurs through hydrogen bonding. In addition, the density of the cross-linking agent significantly affects mucoadhesion. As the density of the cross-linking agent is lowered, the mucoadhesive strength increases, although the density of carboxyl groups in the test surface area is reduced. It is concluded that for mucoadhesion to occur, polymers must have functional groups that are able to form hydrogen bonds above the critical concentration (80% for vinyl polymers), and the polymer chains should be flexible enough to form as many hydrogen bonds as possible.

Bacterial peptidoglycan induces in vitro rheumatoid factor production by lymphocytes of healthy subjects

The present studies were carried out to further characterize the polyclonal B cell activating properties of bacterial peptidoglycan (PG) and to determine if this ubiquitous agent induces in vitro IgM rheumatoid factor (RF) production by lymphocytes from healthy volunteers. Peripheral blood mononuclear cells (PBMC) were cultured in the presence of peptidoglycan, pokeweed mitogen (PWM), a standard polyclonal B cell activator, or additional culture medium. Supernatants were harvested on days 7-8 for determination of total IgM, total IgG, and IgM RF by an enzyme-linked immunosorbent assay (ELISA). PG and PWM induced comparable amounts of total IgM production but PG was a less potent stimulant of total IgG production. PG induced in vitro IgM-RF production in 9/33 experiments, a frequency of response of less than that observed in corresponding PWM stimulated cultures (22/33 experiments). PG-induced IgM-RF production depended upon active protein synthesis and did not correlate with the magnitude of PG-induced total IgM production. The latter finding suggests that PG-induced IgM-RF may not merely reflect polyclonal B cell activation. These results add to a growing list of PG's functional properties and provide further impetus for considering this ubiquitous agent as a potential stimulant for in vivo RF production.

Bioadhesive polymers as platforms for oral controlled drug delivery II: synthesis and evaluation of some swelling, water-insoluble bioadhesive polymers

A series of cross-linked, swellable polymers was sythesized from monomers such as acrylic acid, methacrylic acid, and others with various cross-linking agents to produce a range of polymers differing in charge densities and hydrophobicity. The densities, rate, and extent of hydration of the polymers were determined. An increase in the number of hydrophobic groups in the polymer structure reduced hydration whereas the density of the polymer was unaffected. A sensitive in vitro method for measuring adhesion of polymer to tissue from the rabbit stomach was developed. Polymers of acrylic acid loosely cross-linked (0.3%, w/w) with three different agents, divinyl glycol, 2,5-dimethyl-1,5-hexadiene, and divinylbenzene, showed the same degree of bioadhesion while poly(methacrylic acid-divinylbenzene) showed reduced bioadhesion. The small percent of cross-linking agent, irrespective of physicochemical properties, did not contribute substantially to bioadhesion, whereas the starting monomer had a large effect. The effect of pH on the bioadhesion of poly(acrylic acid-divinyl glycol) was studied at constant temperature, ionic strength, and osmolality. The polymer showed maximum adhesion at pH 5 and 6 and a minimum at pH 7. Gastrointestinal transit studies of cross-linked polymers in rats were studied. Poly(acrylic acid-divinyl glycol) and poly(methacrylic acid-divinylbenzene) were shown to have substantially longer GI transit times than the control, Amberlite 200 resin beads. The delay in transit time was due to bioadhesion of the polymer to the mucin-epithelial cell surface which was clearly observable on animal autopsy. The acrylic acid polymer showed a longer GI transit time than the methacrylic acid polymer, and this in vivo GI transit result is consistent with in vitro bioadhesion test results.

Antibodies to peptidoglycan in patients with spondylarthritis: a clue to disease aetiology?

Although the aetiology of the spondylarthritic diseases, ankylosing spondylitis and Reiter's syndrome, is obscure, a clue to the pathogenesis might be an animal model, adjuvant arthritis. Rats with this disease develop a spectrum of pathology with marked similarity to the spondylarthritides. Since peptidoglycan, a major cell wall component of most bacteria is causally implicated in adjuvant arthritis, we sought evidence that peptidoglycan exposure accompanies both Reiter's syndrome and ankylosing spondylitis. Antibodies to the D-Ala-D-Ala moiety of peptidoglycan were measured by a sensitive and specific ELISA. Antibodies were elevated significantly in patients with ankylosing spondylitis or Reiter's syndrome, but not in patients with rheumatoid arthritis or degenerative joint disease in comparison with normal controls. The findings should be considered preliminary, since only a minority of patients had increased antibody titres. However, the findings are compatible with the hypothesis that peptidoglycan is causally related to spondylarthritis. Antibodies to other moieties in the peptidoglycan molecule might be a more sensitive test for significant exposure.

Detection of soluble peptidoglycan in urine after penicillin administration

A unique enzyme-linked immunosorbent assay was developed to detect soluble peptidoglycans in biological fluids. It makes use of the similar affinities of vancomycin and purified rabbit antibodies to peptidoglycan precursor sequences found in soluble peptidoglycans. This assay has been used to detect as little as 500 pg of soluble peptidoglycan per ml of serum and 5 pg/ml of urine. Studies of normal individuals and Staphylococcus aureus-infected patients revealed only a few sera with detectable levels of soluble peptidoglycans. Studies of normal volunteers who were given a single oral dose of 250 mg of penicillin VK showed that about half had detectable levels of soluble peptidoglycans in their urine up to 6 h after ingestion. This suggests that soluble peptidoglycans can be released by indigenous bacteria in detectable amounts. In one volunteer, a detectable level of soluble peptidoglycan in the urine at 6 h decreased to an undetectable level at 12 h. Such an ephemeral appearance of soluble peptidoglycan in the urine could account for the small number of human sera that had detectable levels of soluble peptidoglycan.