Showing papers by "University of Louisville published in 1989"

Hydrocarbon Degradation in Soils and Methods for Soil Biotreatment

Abstract: The cleanup of soils and groundwater contaminated with hydrocarbons is of particular importance in minimizing the environmental impact of petroleum and petroleum products and in preventing contamination of potable water supplies. Consequently, there is a growing industry involved in the treatment of contaminated topsoils, subsoils, and groundwater. The biotreatment methodologies employed for decontamination are designed to enhance in situ degradation by the supply of oxygen, inorganic nutrients, and/or microbial inocula to the contaminated zone. This review considers the fate and effects of hydrocarbon contaminants in terrestrial environments, with particular reference to the factors that limit biodegradation rates. The potential efficiencies, advantages, and disadvantages of biotreatment techniques are discussed and the future research directions necessary for process development are considered.

Characteristics and distribution of receptors for [D-TRP6]-luteinizing hormone-releasing hormone, somatostatin, epidermal growth factor, and sex steroids in 500 biopsy samples of human breast cancer.

Abstract: Binding capacities and apparent dissociation constants of receptors for [D-Trp6]-luteinizing hormone-releasing hormone [( D-Trp6]-LH-RH), somatostatin (SS-14), epidermal growth factor (EGF), and estrogen and progesterone were determined in 500 breast cancer specimens using multipoint assays. Specific binding sites greater than 10 fmol/mg cytosol protein for estrogen were found in 408 carcinomas (81.6%), and for progesterone in 340 specimens (68%). High affinity EGF receptors were present in membrane preparations from 335 samples (67%). In 260 of 500 samples (52%), two classes of [D-Trp6]-LH-RH membrane receptor sites were also detected, one class showing high affinity and low capacity, and the other class showing low affinity and high capacity; 178 biopsy samples (35.6%) exhibited binding sites for SS-14. Statistically significant inverse correlations were found between the binding capacities of estrogen and EGF receptors as well as between Bmax of progesterone and EGF receptors. Significant positive correlations were demonstrated between binding capacities of estrogen and progesterone and between Bmax of high affinity and low affinity binding sites of [D-Trp6]-LH-RH receptors. However, no correlation was found between the dissociation constants of different receptor sites in human breast cancer specimens. These results demonstrate that numerous human breast cancers, in addition to receptors for estrogen and progesterone, also show binding sites for EGF, [D-Trp6]-LH-RH and SS-14. The methods described herein permit a routine quantification of receptor sites for [D-Trp6]-LH-RH, SS-14, and EGF in membrane preparations of biopsy samples of breast cancer and can be used in conjunction with the determination of estrogen and progesterone receptors in nuclear-cytosolic extracts. The simultaneous measurements using a microanalytic approach allow the determination of peptide and steroid hormone receptors that might be involved in the response mechanisms of human breast cancer. It should be possible to correlate the levels of these receptors with clinical parameters to better identify endocrine-responsive neoplasms. This approach might be useful to guide a rational hormonal therapy in women with breast cancer.

Psychological symptoms in older adults following natural disaster: nature, timing, duration, and course.

Abstract: Using a prospective design with five follow-up intervals, the study addressed questions regarding the timing of onset, duration, course, and nature of psychological reaction to natural disaster. As participants in a statewide panel study, more than 200 older adults were interviewed both before and after two distinct floods occurred in southeastern Kentucky in 1981 and 1984. Exposure to these incidents, which differed in overall intensity, was assessed at both the individual and community levels. Personal loss was associated with short-term increases in negative affect, limited to one year postflood. Longer-term effects were more dependent on the level of community destruction. Exposure to high levels of community destruction was related to decreased positive affect up to two years postdisaster, whereas exposure to high levels of both community destruction and personal loss was predictive of increased negative affect for two years.

Inhibition of purified collagenase from alkali-burned rabbit corneas.

Abstract: The inhibitory potency of four classes of compounds that inhibit corneal ulceration (thiols, tetracyclines, sodium citrate and sodium ascorbate) was assessed with collagenase purified from culture medium of alkali-burned rabbit corneas. The most potent inhibitor, a /3-mercaptomethyl tripeptide HSCH2(Z)L)CHICH2CH(CH3)2]CO-Phe-Ala-NH2, exhibited 50% inhibition (IC50) at -1 0 nM using the synthetic metalloproteinase substrate Dnp-Pro-Leu-Gly-Leu-Trp-Ala-D-Arg-NH2. The inhibitor was somewhat less potent with type I collagen as substrate (IC50 between 1 and 3 nM), possibly because autooxidation of the essential —SH moiety of the inhibitor occurred during the longer time required for assay with the natural substrate. An N-carboxyalkyl tripeptide, CH3(CH2)2(DZ,)CH(COOH)-Leu-Phe-Ala-NH2, was less potent (IC50 = 25 nM) than the thiol peptide. N-acetylcysteine, which is used to treat corneal ulceration, gave IC50 values of 2.7 mM and >10 mM with the synthetic and natural substrates, respectively. The IC50 values for the tetracyclines using the synthetic substrate were 15, 190 and 350 MM for doxycycline, minocycline and tetracycline, respectively. Inhibition by sodium citrate, but not the tetracyclines, could be reversed by excess Ca 2+ . Sodium ascorbate did not inhibit collagenase-mediated hydrolysis of either collagen or the synthetic substrate, thus indicating that the mechanism by which this agent inhibits corneal ulceration is not related to inhibition of collagen degradation by collagenase. Invest Ophthalmol Vis Sci 30:1569-1575,1989

Neighborhood Environmental Satisfaction, Victimization, and Social Participation as Determinants of Perceived Neighborhood Safety

Abstract: This research examines the effect of overall neighborhood satisfac-tion, victimization, and social participation on perceived neighborhood safety. It systematically tests the relative importance of...

Restriction fragment length polymorphisms within proximal 15q and their use in molecular cytogenetics and the Prader-Willi syndrome.

Abstract: Restriction fragment length polymorphisms (RFLPs) are described in detail for 6 DNA probes (D15S9-13, D15S18) that localize to the proximal long arm of human chromosome 15 (15q11-15q13: this report and Tantravahi et al., Am. J. Med. Genet. 33:78-87. Multiple RFLPs are detected by the probe that identifies locus D15S13, and these RFLPs are shown by genomic mapping to result from a nearby insertion or deletion of 1.8 kilobases (kb) of DNA. This set of RFLPs detected by proximal 15q probes can be used for studies on the Prader-Willi syndrome (PWS) and on mentally retarded individuals with a supernumerary inv dup(15) chromosome. Five of the polymorphic loci (D15S9-13) map to the region implicated in the cause of the PWS (15q11.2-15q12). Each of 4 families tested with these probes, as well as an additional "PWS-like" patient, was informative by RFLP analysis. The two PWS deletions studied, which occurred de novo, were inherited from the chromosome 15 provided by the father. By contrast, the 2 inv dup(15) chromosomes analyzed were of maternal origin. The use of RFLPs can also simplify the molecular determination of copy number in chromosomal aneuploidy, as exemplified by analysis of individuals with the PWS and a deletion, patients with an inv dup(15), and one patient with a more complex rearrangement involving chromosome 15. Our studies demonstrate the application of DNA probes for both molecular cytogenetic studies on this chromosome region and the development of diagnostic molecular markers to aid early clinical diagnosis of the PWS.

Pelvic Fracture Hemorrhage: Priorities in Management

Abstract: • Hemorrhage remains the leading cause of mortality in patients with severe pelvic fractures. To evaluate diagnostic and treatment priorities for this problem, we retrospectively reviewed 245 consecutive patients admitted to our institution with pelvic fractures. Supraumbilical diagnostic peritoneal lavage (DPL) was grossly positive in 27 patients, and eight (30%) of these had life-threatening intra-abdominal hemorrhage identified at laparotomy. No patient with a positive DPL by count alone had life-threatening intra-abdominal hemorrhage. Pelvic fracture stabilization with early external pelvic fixation was associated with less requirement for blood transfusion (10±1 U) than with the pneumatic antishock garment (17±3 U). Nine patients with pelvic arterial injuries underwent angiographic embolization, and eight patients died (89%). We conclude that pelvic angiography should be performed before laparotomy in hemodynamically unstable patients with pelvic fracture, unless the DPL is grossly positive. ( Arch Surg 1989;124:422-424)

Tooth transpositions--a review of the literature and treatment considerations.

Abstract: This paper defines tooth transposition and discusses its history, incidence and possible etiology. An interesting parallel is drawn between tooth transposition and other dental anomalies (number, size, shape and location of teeth). Treatment options are discussed in terms of the age at which the transposition is discovered, as well as in terms of severity and completeness of the anomaly. While a logical and relatively predictable treatment solution should normally be considered, in some selected cases it may be prudent to venture into more complex treatment solutions.

OH substitution in garnets: X-ray and neutron diffraction, infrared, and geometric-modeling studies

Abstract: Tetrahedral-site occupations were determined for three titanian andradites (San Benito County, California) and a synthetic deuterated hibschite by using X-ray single-crystal and neutron powder data, respectively. Site refinements reveal the presence of tetrahedral vacancies (4-14%) in all three andradites. Infrared absorption spectra measured for the same material used in the X-ray analysis indicate structurally bound water (as OH^-) in amounts of 0.8 to 5. 7 wt% OH, which is in good agreement with water contents derived from the refinements. These data confirm that the tetrahedral site is not fully occupied and that charge balance can be achieved by the substitution (O_4H_4)^(4-) = (SiO_4)^(4-). The proton position could not be determined because of the small amount of H present. Diffraction maxima in the neutron profile for hibschite exhibited small, well-defined shoulders related to chemical inhomogeneity. The data were fit using multiphase Rietveld techniques assuming four phases with slightly different Si/D ratios. Structural parameters [ɑ= 12.0105(3) A; O(x,y,z) = 0.03561(14), 0.04653(12), 0.64957(12); d site= 0.767(6) Si] refined for the major phase [62(3)% mole fraction) were consistent with X-ray refinements of natural hydrogrossulars. The deuterium atom [0.0965(5), 0.0520(4), 0.6600(5)] was located (ΔF map) outside the tetrahedral volume near the position reported for the Si-free end-member. A significant improvement in R factor was obtained after refinement of a split-atom model to describe the oxygen positional disorder. The short O-D distance [0.744(6)] calculated for the ordered (average) structure can be interpreted within the context of this model. Distance-least-squares (DLS-76) calculations were used to simulate the effect of the (O_4H_4)^(4-) = (SiO_4)^(4-) substitution on the grossular structure. If the tetrahedral d-O distance, calculated from vacancy concentration, is weighted heavily in the geometric refinement, structural variations in the hydrogrossular series [Ca_3Al_2(SiO_4)_(3-)Ca_3Al_2(O-4H_4)_3] can be predicted. Application of DLS to other garnet structures suggests that mantle garnets (rich in pyrope component) may contain only very limited amounts of water.

Acquisition of Route Network Knowledge by Males and Females

Abstract: Male and female subjects were tested for spatial ability and were shown slides depicting pairs of intersecting suburban routes. They saw each route either one or three times. Pairs of test slides were then presented, and measures were taken of the judged angle and direct distance between the two scenes as well as of the time taken to make the judgment. In addition, subjects made judgments of the travel distances and placed target locations on a sketch map of the route network. The crucial comparison was between those judgments made across routes and those made within routes. Because these did not differ, it appeared that network knowledge had been acquired during original learning. Males were more accurate than females in angular judgment and in travel distance estimation. Further analysis of the angular estimates, using circular statistics, illustrated a tendency for females to underestimate the wider angles. The correlations between the various measures of spatial ability were low, suggesting t...

An experimental field study of anther-smut disease of Silene alba caused by Ustilago violacea: genotypic variation and disease incidence.

Abstract: Twenty cloned genotypes of Silene alba differed greatly (0-100%) in the percentage of flowering plants that became diseased by the anther-smut fungus Ustilago violacea following natural spore dispersal in a two-year field experiment. Male genotypes with the highest percentage of disease had high rates of flower production; this trait may increase the probability of spore deposition on flowers, a common site of infection. Because of this relationship, male genotypes with the highest percentage of disease also produced the most healthy flowers in the two-year period. Flowering early in the season was also a predictor of high disease levels for male genotypes in the first year. Variation among female genotypes in disease levels was not correlated with either flower production or phenology, suggesting that the sexes differ in their interaction with the pathogen. Plants of both sexes that remained nonreproductive the first year but flowered the second year could become diseased due to infection of vegetative tissue. Disease levels of the genotypes following natural spore dispersal were not correlated with disease levels of the genotypes following inoculation of vegetative tissue. This discrepancy points out that the methodology used to investigate genetic variation in disease resistance may affect the results obtained.

Transcranial magnetic motor evoked potentials (tcMMEP) for functional monitoring of motor pathways during scoliosis surgery.

Abstract: Transcranial magnetic motor evoked potentials (tcMMEP) were used to assess the functional integrity of the descending motor pathways. The tcMMEP, recorded bilaterally from anterior tibialis muscles, were evoked by an electric current induced in the motor cortex by a high-intensity transient magnetic field applied to the scalp surface. Potentials were recorded from ten of 12 volunteer subjects and preoperatively in 11 of 11 scoliotic patients. Group mean latency in the volunteers (32.0 +/- 2.1 msec) did not differ from that of the scoliotics (28.6 +/- 5.0 msec), but values in the latter group were more variable. During nitrous oxide-narcotic anesthesia, tcMMEP with reproducible latencies were obtained in 9 of 11 (82%) cases. A small, but statistically significant, increase in latency occurred during anesthesia. Compared with preoperative values (523 +/- 490 microV), individual tcMMEP amplitudes were significantly decreased intraoperatively (163 +/- 153 microV). Although the absolute amplitudes varied widely, the minimum recorded value was over 20 microV. Thus, intraoperative tcMMEP waveforms were readily discriminable from background electrical noise. These results demonstrate the technical feasibility of intraoperative tcMMEP monitoring. Combined somatosensory evoked potential and tcMMEP monitoring may provide a more complete picture of spinal cord function, intraoperatively.

Children's Behavioral Inhibition Over Age and Across Situations: Genetic Similarity for α Trait During Change

Abstract: Ratings of behaviors pertaining to inhibition were observed for 130 twins participating in a longitudinal study. Ratings were available for four ages (12, 18, 24, and 30 months) and from three sources at each age: direct observations obtained in a laboratory setting, direct observations obtained in conjunction with infant mental testing, and a temperament measure from a questionnaire completed by parents. For the individual twins, the age-to-age correlations were in the moderate range (.26 to .64). The situation-to-situation correlations were generally in the same range (.17 to .64). When the twins were recombined into twin pairs, within-pair (intraclass) correlations indicated that monozygotic (MZ) twins were more concordant than dizygotic (DZ) twins for each of the behaviors at each of the ages. Also, the MZ twins were more concordant for the direction and degree of behavioral change from age to age or from situation to situation. These data provide additional evidence for the biological influence on behavioral inhibition, a characteristic that has been studied in temperament and personality research. The results suggest that the trait of behavioral inhibition and a change in the trait are genetically conditioned. In addition, it is suggested that the concept of trait be expanded to include the person-centered biological regulation of change.

Hypoperfusion of the intestinal microcirculation without decreased cardiac output during live Escherichia coli sepsis in rats.

Abstract: In order to determine the intestinal microvascular responses to normotensive, high cardiac output (CO) bacteremia, we measured vascular diameters and blood flow at different levels of the intestinal microcirculation during live E. coli bacteremia in male Sprague-Dawley rats (n = 16). Precollicular brainstem transection was used to allow study free of drug anesthesia. The microcirculation of a loop of small intestine (with intact neurovascular connections) was observed by in vivo video microscopy and optical Doppler velocimetry at a magnification of x1,500. Intraluminal microvessel diameters and red cell velocity were measured in successive branches until the vessel entered a villus. CO was measured by transpulmonary thermodilution. Intravenous infusion of 1 x 10(9) live E. coli caused a 20% increase in CO at 50 min and a 14% decrease in systemic vascular resistance. However, microvascular blood flow to the small intestine decreased by 27% at 1 hr and by 56% at 2 hr. Progressive arteriolar constriction (25-50%, P less than .05) occurred at all levels of the intestinal microcirculation. These data indicate that intestinal hypoperfusion caused by arteriolar constriction occurs during high CO bacteremia. This hypoperfusion could contribute to mucosal injury and intestinal mucosal barrier dysfunction during sepsis.

The effect of aging on glutathione and cysteine levels in different regions of the mouse brain.

Abstract: A general glutathione (GSH) deficiency occurs in many tissues of the aging mouse. However, there is no information on GSH in the aging brain even though it has been involved in a number of neurobiologic reactions. To this end, C57BL/6 mice, 3-31 months old, representing the growth, maturation, and aging periods of the life-span were studied. Brain cortex, hippocampus, and stem samples were dissected, processed, and analyzed specifically for reduced and oxidized glutathione (GSH, GSSG) and cyst(e)ine using high performance liquid chromatography with dual electrochemical detection. The GSH content of each brain region varied in the order brain cortex > brain hippocampus > brainstem. However, the GSH profiles of all regions were the same through the life-span, namely, high values during growth dropping to a maturation plateau and then decreasing 30% during aging. In contrast to GSH, the order of cysteine levels was brain cortex c brain hippocampus e brainstem and no life-span changes occurred in any region. In addition, the brain GSSG and cystine contents of all regions were very low and did not change during the life-span. Thus, the GSH loss was not accountable by oxidation to GSSG or degradation to cyst(e)ine. Altogether these results demonstrated a GSH deficiency in brain tissues of aging mice like that found previously in other tissues. These findings suggest an increased susceptibility of the aging brain to oxidative damage. (P.S.E.B.M. 1989, Vol 1901

Pancreastatin, a presumed product of chromogranin-A (secretory protein-I) processing, inhibits secretion from porcine parathyroid cells in culture.

Abstract: Chromogranin-A, also referred to as secretory protein-I, is a 50K protein found in and secreted by endocrine cells, in which it is costored with the native hormone. Porcine chromogranin-A contains a sequence identical to pancreastatin, a 49-amino acid, C-terminally amidated peptide that has been isolated from porcine pancreas, suggesting that chromogranin- A is the precursor of pancreastatin. Pancreastatin has been found to be a potent inhibitor of glucose-stimulated insulin release. As it is possible that pancreastatin inhibits secretion from other chromogranin-A-containing tissues in which it may be formed, we tested its action on dispersed porcine parathyroid cells in culture. Secretion of chromogranin-A and PTH was up to 6-fold greater at 0.5 mM Ca 2+ than at 3.0 mM Ca 2+ . Pancreas-

Antiphospholipid Antibodies and Reproduction

Abstract: Antiphospholipid antibodies (APAs) may be identified in the laboratory by using either coagulation studies or solid-phase immunologic assays (ELISA; RIA). These methodologies do not necessarily evaluate the same antibody; consequently, it is appropriate to screen a patient's plasma by utilizing both assays. APAs have been associated with a variety of obstetrical complications including recurrent spontaneous abortion, intrauterine fetal death, early onset preeclampsia, deep vein thrombosis, and postpartum serositis syndrome. The Kaolin Clotting Time appears to be the most sensitive coagulation test for identifying the lupus anticoagulant. However, preliminary studies would suggest the presence of anticardiolipin antibodies as detected by solid-phase assays are more sensitive and predictive of the clinical course. Although there are no prospective trials to analyze treatment of patients with APA, preliminary data suggest the use of prednisone in combination with aspirin significantly improves the probability of delivery of a viable infant. In addition, heparin, intravenous gammaglobulin, and exchange plasmapheresis have all been tried with varying degrees of success in individual patients in small series.

Induction of Microsomal NADPH-Cytochrome P-450 Reductase and Cytochrome P-450IVA1 (P-450LAω) by Dehydroepiandrosterone in Rats: A Possible Peroxisomal Proliferator

Abstract: Dehydroepiandrosterone (DHEA) is a naturally occurring C19-steroid that is found in the peripheral circulation of mammals, including humans. The feeding of DHEA to rodents has been shown to inhibit chemical carcinogenesis in colon, liver, and lung. Therefore, the effect of DHEA on hepatic enzyme activities that are associated with carcinogen metabolism was assessed. Microsomal NADPH-cytochrome P-450 reductase activity and the content of cytochrome b5 were induced 1.8- and 1.4-fold, respectively, upon feeding male Sprague-Dawley rats a synthetic diet containing 0.45% DHEA (w/w). No significant changes in total content of microsomal cytochrome P-450 or the activities of microsomal NADH-cytochrome b5 reductase and cytosolic or microsomal NAD(P)H-quinone oxidoreductase were noted at day 7 of feeding. Cytosolic glutathione S-transferase activity was decreased to 68% of control activity. Administration of DHEA p.o. or by i.p. injection for 5 days led to the same extent of induction of NADPH-cytochrome P-450 reductase activity. Maximal induction of this flavoprotein reductase was noted between days 3 and 4 of feeding or at a dose of 80-120 mg/kg i.p. A small but statistically significant increase in total microsomal cytochrome P-450 was observed after DHEA administration i.p. Rats fed DHEA had a slower growth rate compared with rats fed control diet, whereas rats treated with DHEA i.p. had growth rates identical to those of controls. The liver weights of rats given DHEA by p.o. or i.p. routes were increased significantly compared to those of control rats. Pair feeding of rats with DHA-containing or control diets served to demonstrate that the levels of induction of hepatic microsomal NADPH-cytochrome P-450 reductase and at least one form of cytochrome P450 (P-450IVA1) were the same as those seen in livers of rats fed DHEA ad libitum. This finding suggested that the induction of the flavoprotein and at least one form of the cytochrome was not due to caloric restriction. The increase in NADPH-cytochrome P-450 reductase content of liver microsomes prepared from rats either fed or treated i.p. with DHEA was also observed by Western blotting techniques. DHEA did not appear to induce any of the major forms of rat liver microsomal cytochrome P-450 that are normally increased by either phenobarbital, beta-naphthoflavone, or dexamethasone pretreatment of rats in vivo. However, the measurement of androstenedione and testosterone metabolism in vitro showed pronounced decreases in the 16 alpha-hydroxylase activities of liver microsomes following DHEA feeding.(ABSTRACT TRUNCATED AT 400 WORDS)

Variation in benthic diatom (Bacillariophyceae) immigration with habitat characteristics and cell morphology

Abstract: We studied the hypothesis that diatom immigration abilities are related to their fitness for colonizing stream substrates. Diatom abundances on artificial substrates exposed for 24 h (the measure of immigration rate) and abundances of stream plankton were determined in six habitats. Diatom immigration varied among habitats from 50–2500 cells·cm−2·d−1. Immigration rates decreased 10-fold with increases in current from 10 to 30 cm·s−1 but changed little during a 40-d summer period. Immigration abilities of diatom taxa were characterized as ratios of either their abundances or relative abundances in immigration assemblages versus in the plankton. Immigration abilities varied over 100-fold among different species. Immigration of some species could be characterized as slower than others in different streams; however, variation in immigration abilities of other species among streams indicated that environment also affected immigration. Diurnal variation in abundance and species composition of the immigration pool (stream plankton) can be important in assessing immigration abilities. Immigration ability may affect benthic diatom fitness. Monoraphid diatoms had a lower probability of immigrating from the plankton than araphid diatoms.

Purification and characterization of an altered topoisomerase II from a drug-resistant Chinese hamster ovary cell line.

Abstract: The cytotoxicity and DNA damage induced by the epipodophyllotoxins and several intercalating agents appear to be mediated by DNA topoisomerase II. We have purified topoisomerase II to homogeneity both from an epipodophyllotoxin-resistant Chinese hamster ovary cell line, VpmR-5, and from the wild-type parental cell line. Immunoblots demonstrate similar topoisomerase II content in these two cell lines. The purified enzymes are dissimilar in that DNA cleavage by VpmR-5 topoisomerase II is not stimulated by VP-16 or m-AMSA. Furthermore, the VpmR-5 enzyme is unstable at 37 degrees C. Thus, the drug resistance of VpmR-5 cells appears to result from the presence of an altered topoisomerase II in these cells. Purified topoisomerase II from VPMR-5 and wild-type cells has the same monomeric molecular mass as well as equivalent catalytic activity with respect to decatenation of kinetoplast DNA. Etoposide (VP-16) inhibits the activity of both enzymes. Noncovalent DNA-enzyme complex formation, assayed by nitrocellulose filter binding, is also similar, as is protection from salt dissociation of this complex by ATP and VP-16. The data suggest a model in which the drug-resistant cell line, VpmR-5, has religation activity which is less affected by drug than that of the wild-type cells. Drug effect on DNA religation and catalytic activity are dissociated mechanistically. In addition, under certain circumstances, the "cleavable complex" observed following denaturation of a drug-stabilized DNA-enzyme complex may not adequately reflect the nature of the antecedent lesion.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction of calcium with porcine adrenal chromogranin A (secretory protein-I) and chromogranin B (secretogranin I)

Abstract: Secretory granules of endocrine cells contain one or more of the acidic secretory proteins chromogranin A (secretory protein-I), chromogranin B (secretogranin I), and secretogranin II (chromogranin C). It has been proposed that these proteins play a role in the packaging of secretory products. In the present study, lysates of purified porcine adrenal chromaffin granules containing chromogranins A and B and a putative chromogranin B fragment bound calcium and formed aggregates in the presence of 10-20 mM calcium at pH 5-6 and at 100 mM or less KCl, NaCl, or norepinephrine. The precipitates contained virtually all of the chromogranin B and the chromogranin B fragment and about one-third of the chromogranin A. The aggregates did not form or were dissociated at the pH and salt concentration of the extracellular fluid. Calcium precipitated purified chromogranin A and chromogranin B from pure solution to the same extent as from the granule lysates. Parathormone, added to the lysates, was incorporated in the precipitates, whereas the acidic secretory protein ovalbumin and norepinephrine were not. These findings suggest that secretory protein-I and secretogranin can exist in situ as aggregates that may include selected secretory products.

Substratum conditioning and diatom colonization in different current regimes1

Abstract: Short-term (3 day) diatom colonization of clean ceramic tiles and tiles conditioned with a thin, nonalgal biofilm was examined in fast- and slow-current outdoor experimental stream channels to assess effects of organic conditioning and current regime on diatom colonization. Colonization rates onto unconditioned tiles were 10 times lower in fast current that in slow. Substratum conditioning reduced the effects of current because organic conditioning of tiles significantly enhanced colonization in fast current, but not in slow current. Two diatom taxa (Nitzschia acicularis W. Sm. and Synedra radians Kutz) colonized unconditioned tiles more rapidly than conditioned tiles in slow current, suggesting the existence of negative interactions between these diatoms and bacteria and/or organics in conditioning films.