Is Hypertension Diagnostic Testing and Diagnosis Associated With Psychological Distress?

BACKGROUND

Psychological impacts of hypertension diagnostic testing and new hypertension diagnoses are unclear.

METHODS

BP-CHECK was a randomized diagnostic study conducted in 2017-2019 in an integrated healthcare system. Participants with no hypertension diagnosis or medications and elevated blood pressure (BP) were randomized to one of three diagnostic regimens: (i) Clinic, (ii) Home, or (iii) Kiosk. Participants completed questionnaires at baseline, after completion of the diagnostic regimens, and at 6 months. Outcomes included changes from baseline in health-related quality of life (HRQOL), BP-related worry, and thoughts about having a stroke or heart attack.

RESULTS

Participants (n = 482) were mostly over age 50 (77.0%), and White race (80.3%). HRQOL did not significantly change from baseline to 3 weeks or 6 months. Among all participants, BP-related worry and concerns about having a heart attack or stroke increased significantly from baseline to 3 weeks, with heart attack and stroke concerns significantly higher in the Kiosk compared Clinic and Home groups. At 6 months, thoughts about having a heart attack or stroke returned to baseline overall and in the Kiosk group, however BP-related worry was significantly higher among those with, compared to those without, a new hypertension diagnosis.

CONCLUSIONS

The hypertension diagnostic process did not lead to short-term or intermediate-term changes in self-reported HRQOL. However, BP-related worry increased short-term and persisted at 6 months among individuals with a new hypertension diagnosis. Results warrant validation in more representative populations and additional exploration of the impacts of this worry on psychological well-being and hypertension control.

CLINICALTRIALS.GOV IDENTIFIER

NCT03130257.

Endogenous Cushings syndrome is associated with impaired myocardial work efficiency

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): German Ministry of Research and Education within the Comprehensive Heart Failure Center, Würzburg

OnBehalf

STAAB Cohort Study and CV-CORT-EX Study

Background

Endogenous Cushing’s syndrome (CS) is associated with increased cardiovascular morbidity and mortality. Long-term remission (LTR) after successful treatment is considered to positively affect the cardiovascular system including the heart. Left ventricular (LV) myocardial work (MyW) based on pressure-strain loops is a novel tool to non-invasively assess LV performance and is considered less load-dependent than LV ejection fraction (LVEF) and global longitudinal strain (GLS). We analyzed LV function in patients with overt CS and CS in LTR in comparison to healthy individuals derived from a local population-based cohort.

Methods/Results: In a cross-sectional analysis, we compared n = 31 comprehensively characterized patients with overt CS (mean age 48 ± 12 years, 71% women) and 49 patients with CS in LTR (53 ± 12 years, 77% women) with a control group who underwent transthoracic echocardiography. As control group, we analyzed a population-based sample of apparently healthy individuals (in sinus rhythm, free from CV risk factors, and no significant valve disease) from a population-based cohort: n = 439, 49 ± 11 years, 56% women. MyW assessment was performed off-line using EchoPAC (GE, version 202).

Systolic and diastolic blood pressure, HbA1c, and body mass index were significantly higher in patients with either overt CS or CS in LTR when compared to healthy participants (without significant differences between both patient groups). LVEF was equal between all three groups, but GLS was significantly lower in healthy participants and tended to be lower in LTR when compared to patients with CS. Global work index was equal between all three groups, but global wasted work was significantly higher in CS patients when compared to healthy participants, resulting in lower global work efficiency (Table).

Conclusion

In contrast to LVEF as established parameter of cardiac function, myocardial work analysis revealed functional alterations in patients with current and previous cortisol excess when compared to healthy individuals derived from a population-based sample. CS patients´ hearts appear to perform larger amounts of wasted work even during long-term remission. Abstract Figure.

pH sensing through a single optical fibre using SERS and CMOS SPAD line arrays

Full exploitation of fibre Raman probes has been limited by the obstruction of weak Raman signals by background fluorescence of the sample and the intrinsic Raman signal of the delivery fibre. Here we utilised functionalised gold nanoshells (NS) to take advantage of the surface-enhanced Raman spectroscopy (SERS) effect to enhance the pH responsive spectrum of 4-mercaptobenzoic acid (MBA). However, the fibre background is still dominant. Using the photon arrival time-resolving capability of a CMOS single-photon avalanche diode (SPAD) based line sensor, we recover the SERS spectrum without a fibre background in a 10 s measurement. In this manner, pH sensing through a multimode fibre at a low excitation power that is safe for future in vivo applications, with short acquisition times (10 or 60 s), is demonstrated. A measurement precision of ± 0.07 pH units is thus achieved.

Time-resolved spectroscopy at 19,000 lines per second using a CMOS SPAD line array enables advanced biophotonics applications

A SPAD-based line sensor fabricated in 130 nm CMOS technology capable of acquiring time-resolved fluorescence spectra (TRFS) in 8.3 milliseconds is presented. To the best of our knowledge, this is the fastest time correlated single photon counting (TCSPC) TRFS acquisition reported to date. The line sensor is an upgrade to our prior work and incorporates: i) parallelized interface from sensor to surrounding circuitry enabling high line rate to the PC (19,000 lines/s) and ii) novel time-gating architecture where detected photons in the OFF region are rejected digitally after the output stage of the SPAD. The time-gating architecture was chosen to avoid electrical transients on the SPAD high voltage supplies when gating is achieved by excess bias modulation. The time-gate has an adjustable location and time window width allowing the user to focus on time-events of interest. On-chip integrated center-of-mass (CMM) calculations provide efficient acquisition of photon arrivals and direct lifetime estimation of fluorescence decays. Furthermore, any of the SPC, TCSPC and on-chip CMM modes can be used in conjunction with the time-gating. The higher readout rate and versatile architecture greatly empower the user and will allow widespread applications across many techniques and disciplines. Here we focused on 3 examples of TRFS and time-gated Raman spectroscopy: i) kinetics of chlorophyll A fluorescence from an intact leaf; ii) kinetics of a thrombin biosensor FRET probe from quenched to fluorescence states; iii) ex vivo mouse lung tissue autofluorescence TRFS; iv) time-gated Raman spectroscopy of toluene at 3056 cm^-1 peak. To the best of our knowledge, we detect spectrally for the first time the fast rise in fluorescence lifetime of chlorophyll A in a measurement over single fluorescent transient.

The effects of different antioxidants on the activity of cerebrocortical MnSOD and Na,K-ATPase from post mortem Alzheimer's disease and age-matched normal brains

Among the markers and targets of the early phase of Alzheimer's disease (AD) pathogenesis MnSOD (mitochondrial dysfunction) and Na-pump (disturbances in function/regulation) are often highlighted. This paper focused on comparison of the effects of three antioxidants on the activity of cerebrocortical MnSOD and Na,K-ATPase from post mortem Alzheimer's disease and age-matched normal brains. Antioxidant compounds with different origins: natural glutathione, synthetic UPF peptides (glutathione analogues) and phytoestrogen genistein were investigated. Firstly, MnSOD and Na,K-ATPase activities were found to be decreased in the post mortem AD brains compared with age-matched controls. Secondly, GSH had no effect on MnSOD activity, but decreased Na,K-ATPase activity both in the control and AD brains. Thirdly, UPF1 and UPF17 increased MnSOD activity, and UPF17 suppressed Na,K-ATPase activity. Further studies are needed to clarify, if the inhibitory effect of UPF17 on Na,K-ATPase could abolish the beneficial effect gained from MnSOD activation. Both the antioxidative potential of genistein and its potency to up-regulate Na,K-ATPase activity make it an attractive candidate substance to suppress the early phase of the pathogenesis of AD.

A hypothesis to explain how LaeA specifically regulates certain secondary metabolite biosynthesis gene clusters

Biosynthesis of mycotoxins involves transcriptional co-regulation of sets of clustered genes. We hypothesise that specific control of transcription of genes in these clusters by LaeA, a global regulator of secondary metabolite production and development in many filamentous fungi, results from its interaction with a Cys6Zn2 DNA-binding protein unique to the gene cluster.

Increased sensitivity of Aspergillus flavus and Aspergillus parasiticus aflatoxin biosynthesis polyketide synthase mutants to UVB light

One strategy to reduce aflatoxin contamination of maize and cottonseed is to introduce spores of non-aflatoxigenic strains as competitors. Using isogenic mutants we show that, upon 5 or 20 min exposure to 302 nm (UVB) light, the viability of conidia of Aspergillus flavus and Aspergillus parasiticus mutants lacking the ability to accumulate any aflatoxin precursor metabolite is reduced five-fold compared to that of aflatoxin-producing strains or pigmented mutants that accumulate aflatoxin precursors. This result suggests that the long-term viability of introduced non-aflatoxigenic competitor strains may be lower than that of natural aflatoxin-producing isolates when exposed to sunlight.

Secondary metabolite profiling, growth profiles and other tools for species recognition and important Aspergillus mycotoxins

Species in the genus Aspergillus have been classified primarily based on morphological features. Sequencing of house-hold genes has also been used in Aspergillus taxonomy and phylogeny, while extrolites and physiological features have been used less frequently. Three independent ways of classifying and identifying aspergilli appear to be applicable: Morphology combined with physiology and nutritional features, secondary metabolite profiling and DNA sequencing. These three ways of identifying Aspergillus species often point to the same species. This consensus approach can be used initially, but if consensus is achieved it is recommended to combine at least two of these independent ways of characterising aspergilli in a polyphasic taxonomy. The chemical combination of secondary metabolites and DNA sequence features has not been explored in taxonomy yet, however. Examples of these different taxonomic approaches will be given for Aspergillus section Nigri.

Biodiversity of Aspergillus species in some important agricultural products

The genus Aspergillus is one of the most important filamentous fungal genera. Aspergillus species are used in the fermentation industry, but they are also responsible of various plant and food secondary rot, with the consequence of possible accumulation of mycotoxins. The aflatoxin producing A. flavus and A. parasiticus, and ochratoxinogenic A. niger, A. ochraceus and A. carbonarius species are frequently encountered in agricultural products. Studies on the biodiversity of toxigenic Aspergillus species is useful to clarify molecular, ecological and biochemical characteristics of the different species in relation to their different adaptation to environmental and geographical conditions, and to their potential toxigenicity. Here we analyzed the biodiversity of ochratoxin producing species occurring on two important crops: grapes and coffee, and the genetic diversity of A. flavus populations occurring in agricultural fields. Altogether nine different black Aspergillus species can be found on grapes which are often difficult to identify with classical methods. The polyphasic approach used in our studies led to the identification of three new species occurring on grapes: A. brasiliensis, A. ibericus, and A. uvarum. Similar studies on the Aspergillus species occurring on coffee beans have evidenced in the last five years that A. carbonarius is an important source of ochratoxin A in coffee. Four new species within the black aspergilli were also identified in coffee beans: A. sclerotioniger, A. lacticoffeatus, A. sclerotiicarbonarius, and A. aculeatinus. The genetic diversity within A. flavus populations has been widely studied in relation to their potential aflatoxigenicity and morphological variants L- and S-strains. Within A. flavus and other Aspergillus species capable of aflatoxin production, considerable diversity is found. We summarise the main recent achievements in the diversity of the aflatoxin gene cluster in A. flavus populations, A. parasiticus and the non-toxigenic A. oryzae. Studies are needed in order to characterise the aflatoxin biosynthetic genes in the new related taxa A. minisclerotigenes and A. arachidicola.

Pluraflavins, potent antitumor antibiotics from Saccharothrix sp. DSM 12931

The new pluramycin-type antibiotics pluraflavin A, C43H54N2O14, pluraflavin B, C43H56N2O15, and pluraflavin E, C36H41NO14 were isolated from cultures of the Saccharothrix species DSM 12931. The structures of the novel compounds were elucidated with the aid of 2D NMR and mass spectrometric investigations. The characteristic structural element of pluraflavins A and B is an additional 4-epi-vancosamine unit at position 13 of the anthraquinone-gamma-pyrone ring system. Pluraflavin E has a carboxyl group in this position. Pluraflavin A has a reactive dimethyl epoxide side chain at position 2 of the anthraquinone-gamma-pyrone aglycon, which may explain the high activity of the antibiotic. The outstanding biological characteristic of pluraflavin A is its powerful, organ-dependent cytostatic action: the IC50 in the colon carcinoma proliferation assay is in the subnanomolar range.

Selective cyclo-oxygenase-2 inhibitors aggravate ischaemia-reperfusion injury in the rat stomach

1. Effects of indomethacin, the selective cyclo-oxygenase (COX)-2 inhibitors NS-398 and DFU, and dexamethasone on gastric damage induced by 30 min ischaemia followed by 60 min reperfusion (I-R) were investigated in rats. Modulation of gastric levels of COX-1 and COX-2 mRNA by I-R was evaluated using Northern blot and reverse transcription-polymerase chain reaction. 2. I-R-induced gastric damage was dose-dependently aggravated by administration of indomethacin (1 - 10 mg kg(-1)), NS-398 (0.4 - 4 mg kg(-1)) or DFU (0.02 - 2 mg kg(-1)) as assessed macroscopically and histologically. 3. Likewise, administration of dexamethasone (1 mg kg(-1)) significantly increased I-R damage. 4. Low doses of 16, 16-dimethyl-prostaglandin(PG)E(2), that did not protect against ethanol-induced mucosal damage, reversed the effects of the selective COX-2 inhibitors, indomethacin and dexamethasone. 5. I-R had no effect on gastric COX-1 mRNA levels but increased COX-2 mRNA levels in a time-dependent manner. Dexamethasone inhibited the I-R-induced expression of COX-2 mRNA. 6. I-R was not associated with a measurable increase in gastric mucosal formation of 6-keto-PGF(1alpha) and PGE(2). PG formation was substantially inhibited by indomethacin (10 mg kg(-1)) but was not significantly reduced by NS-398 (4 mg kg(-1)), DFU (2 mg kg(-1)) or dexamethasone (1 mg kg(-1)). 7. The findings indicate that selective COX-2 inhibitors and dexamethasone markedly enhance gastric damage induced by I-R. Thus, whereas COX-2 has no essential role in the maintenance of gastric mucosal integrity under basal conditions, COX-2 is rapidly induced in a pro-ulcerogenic setting and contributes to mucosal defence by minimizing injury. This suggests that in certain situations selective COX-2 inhibitors may have gastrotoxic effects.

Peptidergic and cholinergic neurons and mediators in peptone-induced gastroprotection: role of cyclooxygenase-2

This study investigates the neural pathways, mediators, and cyclooxygenase isoenzymes involved in the gastroprotection conferred by peptone in rats. Intragastric perfusion with 8% peptone protected against gross and histological damage induced by subsequent perfusion with 50% ethanol. The gastroprotective effect of peptone was near maximally inhibited by gastrin immunoneutralization, inactivation of capsaicin-sensitive afferent neurons, calcitonin gene-related peptide (CGRP) immunoneutralization, blockade of gastrin receptors, CGRP, bombesin/gastrin-releasing peptide (GRP), or somatostatin receptors, and by the nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine methyl ester and was partially (46%) counteracted by atropine. Indomethacin and the selective cyclooxygenase-2 inhibitors NS-398 and L-745,337 dose dependently (50% inhibitory dose, 4.2, 0.8, and 1.5 mg/kg, respectively) attenuated the peptone-induced protection. Dexamethasone was ineffective. These results indicate that protective effects of peptone involve endogenous gastrin and possibly somatostatin and are mediated by capsaicin-sensitive afferent, cholinergic, and bombesin/GRP neurons. CGRP, NO, and prostaglandins participate as essential mediators. The study provides evidence that prostaglandins derived from a constitutive cyclooxygenase-2 contribute to mucosal defense in the presence of ulcerogens and thus participate in homeostatic functions of the stomach.

Selective cyclo-oxygenase-2 inhibitors and their influence on the protective effect of a mild irritant in the rat stomach

1. The effects of the non-selective cyclo-oxygenase (COX) inhibitor indomethacin and the selective COX-2 inhibitors, N-[2-(cyclohexyloxy)-4-nitrophenyl] methanesulphonamide (NS-398), 5-methanesulphonamido-6-(2,4-difluorothio-phenyl)-1-indan one (L-745,337) and 5,5-dimethyl-3-(3-fluorophenyl)-4-(4-methylsulphonyl) phenyl-2(5H)-furanone (DFU), on the protection induced by the mild irritant 20% ethanol were investigated in the rat stomach. 2. Instillation of 20% ethanol (1 ml, p.o.) effectively protected against gastric mucosal injury induced by subsequent instillation of 70% or 96% ethanol (1 ml, p.o.). 3. Oral administration of indomethacin (1.25-20 mg kg[-1]) dose-dependently counteracted the protective effect of 20% ethanol (ID50: 3.5 mg kg[-1]). 4. Likewise, NS-398 (0.1-1 mg kg[-1]), L-745,337 (0.2-2 mg kg[-1]) and DFU (0.02-0.2 mg kg[-1]) inhibited the protective effect of 20% ethanol in a dose-dependent manner with ID50 values of 0.3 mg kg(-1), 0.4 mg kg(-1) and 0.06 mg kg(-1), respectively. 5. Inhibition of mild irritant-induced protection was also found when NS-398 (1 mg kg[-1]) was administered s.c. or when 96% ethanol was used to damage the mucosa. 6. Pretreatment with 16,16-dimethyl-prostaglandin (PG)E2 at 4 ng kg(-1), a dose that did not protect against ethanol (70%)-induced mucosal damage when given alone, completely reversed the effect of the selective COX-2 inhibitors on the mild irritant-induced protection. 7. Pretreatment with dexamethasone (3 mg kg(-1), 24 and 2 h before instillation of 20% ethanol) did not affect the protective activity of the mild irritant, indicating that enzyme induction is not involved. 8. Indomethacin (20 mg kg(-1), p.o.) did not prevent the protection conferred by sodium salicylate (100 mg kg[-1]), dimercaprol (30 microg kg[-1]), iodoacetamide (50 mg kg[-1]) and lithium (20 mg kg[-1]). Likewise, the protective effect of these agents was not counteracted by NS-398 (1 mg kg(-1), p.o.). 9. Whereas indomethacin (20 mg kg(-1), p.o.) near-maximally inhibited gastric mucosal formation of PGE2, 6-keto-PGF1alpha and thromboxane (TX) B2 as well as platelet TXB2 release, the selective COX-2 inhibitors were ineffective. 10. The findings show that selective COX-2 inhibitors, although lacking in ulcerogenic activity, prevent the protection conferred by a mild irritant. Prostaglandis generated by a constitutive COX-2 could thus contribute to physiological functions involved in gastric homeostasis, although at present a non-COX-2-related mechanism underlying the effect of the selective COX-2 inhibitors tested on mild irritant-induced protection cannot be completely excluded.

Back pain in primary care. Patient characteristics, content of initial visit, and short-term outcomes

STUDY DESIGN

Prospective study of patients making primary care visits for back pain.

OBJECTIVE

To examine the content of primary care visits for back pain in patients with little interference of pain with activities at the visit and 1 month later; high interference of pain with activities at the visit but not 1 month later; and high interference of pain with activities, both at the visit and 1 month later.

SUMMARY OF BACKGROUND DATA

Advice about resumption of activities may be therapeutic for patients with back pain, but little is known about the extent to which primary care providers assess and respond to limitation of activities in patients.

METHODS

Audiotapes of primary care visits for back pain were coded for content. Patients indicated their goals for the visit and completed measures of pain and the pain's interference with activities, just before the visit and 1 month later.

RESULTS

In most visits, providers did not assess functional limitations related to pain and did not discuss how to resume normal activities, although this was a highly rated goal for most patients. Providers did not appear to assess or respond to patients differently according to how much pain interfered with their activities. However, in patients with high interference of pain with activities, there was more discussion of limitation of activities and how to return to usual activities among those who improved than there was among those who did not improve during the next month.

CONCLUSIONS

Although back pain frequently is associated with limitation of activity, pain's interference with activities is assessed inconsistently in primary care visits.

Flow cytometric analysis of Eimeria tenella sporozoite populations exposed to salinomycin sodium in vitro: a comparative study using light and electron microscopy and an in vitro sporozoite invasion-inhibition test

Eimeria tenella sporozoites exposed to 100, 70, 60 and 50 micrograms salinomycin sodium (SAL)/ml medium 199 at 41 degrees C and then stained with propidium iodide/fluorescein diacetate were analysed by means of flow cytometry (FCM). After 20 min exposure, they showed dose-dependent alterations in their size and shape, i.e. ballooning of most cells, and enhanced intracellular esterase activity as compared with untreated controls. After longer exposure periods (40 and 70 min), inflated cells gradually changed into shrivelled or crumpled, nonviable ones, thereby showing a gradual decrease in esterase activity and a gradual loss of membrane integrity (RFA+). As compared with untreated controls, sporozoites treated with 10 micrograms SAL/ml showed negligible RFA+ values (0.4%-2%), whereas those exposed to 1 and 0.1 microgram SAL ml and to the solvent dimethylsulfoxide (DMSO, 1%) did not, even after 70 min exposure. Slight to severe structural changes manifesting as an extremely wavy surface (1 microgram SAL/ml), vacuolization of the cytoplasm, distension or destruction of the mitochondrion and rupture of cell membranes (10 micrograms SAL/ml) were seen not only at higher SAL concentrations but also (rarely) at lower ones. The ability of sporozoites to invade primary chick-kidney cells was significantly inhibited by 70, 60 and 50 micrograms SAL/ml. In general, there were close relationships between findings obtained using FCM, electron microscopy and an invasion-inhibition test. The results indicate that FCM is a reliable and sensitive technique for characterizing the parasiticidal effects on and the possible mode of action of drugs in free coccidian sporozoites.

Effect on aflatoxin production of competition between wild-type and mutant strains of Aspergillus parasiticus

Co-cultivation of a strain of Aspergillus parasiticus, capable of making aflatoxins, with blocked mutant strains, capable of producing none or only a low level of aflatoxins, reduced the net yield of aflatoxins more than that expected based on spore recovery. Yields of aflatoxins were 8-fold less for a norsolorinic acid-producing strain, 14-fold less for an averantin-producing strain, 6-fold less for an averufin-producing strain, and 21-fold less for a versicolorin A-producing strain when co-cultured in equal amounts with a wild-type strain of Aspergillus parasiticus. Even when the wild-type strain was initially present in 100-fold excess, with two of the mutant strains, reduced aflatoxin production was still observed.

Effect of phytate on aflatoxin formation by Aspergillus parasiticus grown on different grains

Aflatoxin production by Aspergillus parasiticus on corn, soybean, and cottonseed in the absence or presence of added sodium phytate was examined. No variation in aflatoxin concentrations was found in raw, chemically sterilized, or autoclaved soybeans whereas a five-fold reduction in total aflatoxins was found in cottonseed after addition of 330 micrograms sodium phytate to 10 g of autoclaved material. However, phytate did not affect aflatoxin production on non-sterile cottonseeds, although in corn a slight inhibition was found. Extraction of raw soybeans with hexane allowed production of 20-fold more aflatoxins, but levels were still lower than those found on rice or corn. Part of this relative inhibition in soybeans may arise from a heat-unstable, polar solvent-soluble, dialyzable factor present in soybeans. Our results support the conclusion that phytate is not the factor in soy responsible for its relative resistance to aflatoxin formation.

Biosynthetic relationship among aflatoxins B1, B2, M1, and M2

Aflatoxins are a family of toxic, acetate-derived decaketides that arise biosynthetically through polyhydroxyanthraquinone intermediates. Most studies have assumed that aflatoxin B1 is the biosynthetic precursor of the other aflatoxins. We used a strain of Aspergillus flavus which accumulates aflatoxin B2 to investigate the later stages of aflatoxin biosynthesis. This strain produced aflatoxins B2 and M2 but no detectable aflatoxin B1 when grown over 12 days in a low-salt, defined growth medium containing asparagine. Addition of dichlorvos to this growth medium inhibited aflatoxin production with concomitant accumulation of versiconal hemiacetal acetate. When mycelial pellets were grown for 24, 48, and 72 h in growth medium and then transferred to a replacement medium, only aflatoxin B2 and M2 were recovered after 96 h of incubation. Addition of sterigmatocystin to the replacement medium led to the recovery of higher levels of aflatoxins B2 and M2 than were detected in control cultures, as well as to the formation of aflatoxins B1 and M1 and O-methylsterigmatocystin. These results support the hypothesis that aflatoxins B1 and B2 can arise independently via a branched pathway.

Effect of phytate on aflatoxin formation by Aspergillus parasiticus and Aspergillus flavus in synthetic media

The effect of phytate on the production of aflatoxins by Aspergillus parasiticus and Aspergillus flavus grown on synthetic media was examined. In the absence of pH control (initial pH 4.5-6.5) for A. parasiticus, phytate (14.3 mM) caused a six-fold decrease in aflatoxins in the medium and a ten-fold decrease in those retained by the mycelia. When the initial pH of the medium was adjusted to 4.5 no effect on aflatoxin production was observed. With A. flavus or A. parasiticus grown on media with a higher initial pH value (6 to 7), the presence of phytate in the media caused an increase in aflatoxin production. These results are inconsistent with previous studies which indicated that phytate depresses aflatoxin production by rendering zinc, a necessary co-factor for aflatoxin biosynthesis, unavailable to the mold.

Osmotic concentration of polypeptides from hemofiltrate of uremic patients

Hemofiltrate from uremic patients was concentrated 15- to 40-fold by osmotic removal of water across a reverse osmosis membrane which retains salts and proteins. Salts and low molecular weight components were removed from the concentrate by partial dialysis using a highly impermeable cellulose membrane. Following this desalting step, 100- to 500-fold concentration could be achieved by evaporation at low pressure. The concentrate was fractionated on Sephadex G15 columns. Fractions were tested for their toxicity to human cells in culture. Fractions containing components with molecular weights greater than 700 daltons inhibited 3H-thymidine incorporation into the DNA of HeLa and skin fibroblast cells more than did low molecular weight peptides and an iso-osmolar control. Components eluting in the molecular weight range of angiotensin I and vitamin B-12 were most inhibitory. These studies show that hemofiltrate from uremic patients is a readily available source of toxic polypeptides. The osmotic concentration and gel chromatographic procedures described should make available large amounts of these molecules for further studies.

Isolation and characterization of acylneuraminate cytidylyltransferase from frog liver

Frog liver (Rana esculenta) is a rich source of acylneuraminate cytidylyltransferase. The soluble enzyme was purified 250-fold almost to purity with 25% yield and a specific activity of 9 mkat/kg protein (0.54 U/mg protein) using DEAE Sephadex and Sepharose 6B chromatography, followed by preparative polyacrylamide gel electrophoresis. The molecular weight of the cytidylyltransferase was determined to be 163 000 with the aid of Sepharose 6B chromatography and gel electrophoresis, with or without dodecyl sulphate or urea. No subunits were found. The isoelectric point of the enzyme is at pH 6. Optimum reaction rate was observed at pH 9, 37 degrees C, 50mM Mg2 or Ca2 and ImM mercaptoethanol. The Km values for N-acetylneuraminic acid, N-glycoloylneuraminic acid and CTP are 1.6mM, 2.3 mM and 0.6mM, respectively. O-Acetylated sialic acids are inactive with the cytidylyltransferase from frog liver. Enzyme activity can be inhibited by SH reagents and CMP (Ki = 0.5mM).

A comparative study of proteoglycans from bovine lung, trachea, tracheal mucosa, and aorta

Proteoglycans were isolated from bovine lung, trachea, tracheal mucosa, and aorta by dissociative extraction with 4M guanidinium hydrochloride. Fractionation of these tissue extracts by cesium chloride density centrifugation and gel chromatography allowed the isolation from each extract of a high molecular weight fraction consisting mainly of proteochondroitin sulfate and hyaluronic acid.

Mammalian cell culture mutagenicity and carcinogenicity testing of dimethyl sulfoxide extracts of flame retardant-treated cotton fabrics

Dimethyl sulfoxide extracts of flame retardant-treated cotton fabrics were tested for ability to mutate and transform mammalian cells in culture. Fabrics were treated with tetrakis(hydroxymethyl)phosphonium chloride (THPC) and tetrakis(hydroxymethyl)-phosphonium sulfate (THPS). Extracts were prepared at the precondensate stage of flame retardant processing and after ammonia neutralization (THPOH-NH3). Unconcentrated or 10-fold concentrated extracts were tested as 0.5 or 1% solutions in cell culture medium. All extracts were mutagenic to V79 hamster lung cells (conversion to ouabain resistance) with or without addition of rat liver microsomes (S9). Up to 84 mutant colonies per 10(6) surviving cells were found with THPS fabric extracts, whereas up to 113 were obtained with THPC fabric extracts. Extracts were also able to transform mammalian cells, as shown in two different assays. Transformation of BHK cells, as measured by colony formation in soft agar, increased more than 20-fold with THPC extracts, but less than 2-fold with THPS extracts. Both the THPC and THPS extracts induced 3T3 cell transformation with linear dose-response. The number of foci of transformed cells per 10(5) survivors was 10--100 times that in the solvent control. Greater numbers of transformed foci were obtained after treatment at the highest doses tested than after treatment with the positive control compounds, benzo[a]pyrene and N-methyl-N-nitro-N-nitrosoguanidine.

Separation of six DNA bases by ion pair--reversed phase high pressure liquid chromatography

An ion pair-reversed phase chromatography system is described which separates six of the bases normally found in prokaryotic and/or eukaryotic DNA from each other and from uracil, the characteristic base found in RNA. The effect of varying pH and the percentage of methanol in the column buffer is described. The addition of the ion-pairing reagent heptane sulfonate was shown to be necessary to achieve separation of all of these bases.

Effect of low density lipoprotein on proteoglycan synthesis by aorta cells in culture

Increasing the content of human serum low density lipoprotein in the growth medium led to greater incorporation of 35S-sulfate into proteoglycan (mostly into dermatan sulfate) by primary aorta cells but did not affect similar incorporation by fibroblast cells. These results suggest a mechanism which can explain the increased deposition of lipid in aorta due to hyperlipidemia.

Changes in macromolecular synthesis in Xanthomonas oryzae infected with bacteriophage XP-12

Phage XP-12, which has complete substitution of the cytosine residues in its DNA with 5-methylcytosine residues, was shown to inhibit incorporation of uracil into host DNA and RNA during the latent period. This apparent inhibition of host macromolecular synthesis was not accompanied by extensive degradation of the host chromosome. Phage DNA synthesis in infected cells occurred at a faster rate than host DNA synthesis in analogous uninfected cells. However, phage DNA synthesis could not be accurately monitored by incorporation of [methyl-3H]thymidine into DNA because, soon after infection, there was a marked inhibition of utilization of exogenous thymidine for DNA synthesis. Phage infection conferred upon a thymine auxotrophic host the ability to synthesize thymine nucleotides for phage DNA synthesis. It is suggested that a phage-induced thymidylate synthetase activity is partially responsible for the inhibition of thymidine incorporation.

Unusual properties of the DNA from Xanthomonas phage XP-12 in which 5-methylcytosine completely replaces cytosine

Xanthomonas phage XP-12 contains 5-methylcytosine completely replacing cytosine. This substitution confers several unusual properties upon XP-12 DNA. The buoyant density of XP-12 DNA in CsCl gradients is 1.710 g/cm-3, 0.16 g/cm-3 lower than that expected for a normal DNA with the same percentage of adenine plus thymine. The melting temperature for XP-12 DNA in 0.012 M Na+ is the highest reported for any naturally occurring DNA, 83.2 degrees C, 6.1 degrees C higher than that of normal DNAs with the same percentage of adenine plus thymine. Unlike the minor amounts of 5-methylcytosine found in most plant and animal DNAs, the 5-methylcytosine residues of XP-12 derive their methyl group from the 3-carbon of serine instead of from the thiomethyl carbon of methionine. .