Regulatory aspects of alkali tolerance induction in Escherichia coli

Escherichia coli shifted from external pH (pH(O)) 7.0 to pH(O) 8.5-9.5 rapidly becomes tolerant to pH(O) 10.0-11.5, induction of tolerance (alkali habituation) being dependent on periplasmic or external alkalinization with either NaOH or KOH. Induction needs protein synthesis and makes organisms resistant to DNA damage by alkali and better able to repair any damage that occurs. Induction of tolerance was reduced by glucose (not reversed by cAMP) and by amiloride, was dependent on DNA gyrase and was abolished by fur and himA lesions (the latter suggests IHF involvement). Tolerance induction was not prevented by L-leucine, FeCl3 or FeSO4 nor by hns or relA mutations. Habituation probably involves attachment of IHF upstream of the promoter leading to DNA bending which switches on transcription. Habituation is aberrant in nhaA mutants, so ability to resist alkali damage may only arise if NhaA is induced, with extrusion of Na+ by this antiporter during alkali challenge. In accord with one tolerance component involving NhaA induction, beta-galactosidase formation from nhaA-lacZ fusions at pH(O) 9.0 was inhibited by glucose and amiloride.

Implication of sensory neurons in the diverse mechanisms of adaptive cytoprotection in the rat stomach

Adaptive cytoprotection is mediated by diverse mediators and mechanisms. We investigated the implication of capsaicin-sensitive afferent neurons in the adaptive cytoprotection in the rat stomach, taking special notice of nitric oxide, prostaglandins and luminal dilution. Sensory deafferentation abolished the protective effect of capsaicin against 0.6 N HCl-induced gastric injury but not the indomethacin-resistant or NG-nitro-L-arginine-resistant adaptive cytoprotection conferred by 0.1 N NaOH. Nor did it attenuate the protection by 0.35 N HCl which accompanied luminal dilution. These findings suggest that certain mild irritants do not require sensory neurons to provide nitric oxide- and prostaglandins-mediated adaptive cytoprotection and, furthermore, that capsaicin-sensitive afferent neurons are not crucial, either, so long as there is a contribution of luminal dilution in the adaptive cytoprotection.

Exposure to autoclaving or sodium hydroxide extends the dose-response curve of the 263K strain of scrapie agent in hamsters

An analysis was made of incubation period data from experiments in which samples of brain-tissue infected with the 263K strain of scrapie agent were injected intracerebrally into hamsters following exposure of the tissue to autoclaving or sodium hydroxide. Where there was survival of infectivity, this often produced extended mean incubation periods compared with the maximal incubation periods in controls injected with untreated agent. These results confirmed that, after chemical or physical treatment, infectivity titre should not be calculated by comparing the incubation period from a single dilution-group against a standard dose-response curve for untreated agent.

Decreased heterogeneity of CS histone variants after hydrolysis of the ADP-ribose moiety

Sea urchin CS histone variants are electrophoretically heterogeneous when analyzed in two dimensional polyacrylamide gels (2D-PAGE). Previous results suggested that this heterogeneity is due to the poly (ADP-ribosylation) of these proteins. Consequently, native CS histone variants were subjected to different treatments to remove the ADP-ribose moiety. The incubation in 1 M hydroxylamine was not effective in eliminating the polymers of ADP-ribose from CS variants, and the treatment with sodium hydroxide was deleterious to the proteins. In contrast, the ADP-ribose moiety was successfully removed from the CS variants by incubation with phosphodiesterase (PDE). To eliminate contamination of CS histone variants with PDE extract, the enzyme was covalently bound to Sepharose 4B prior to its utilization. Treatment of native CS histone variants with this immobilized phosphodiesterase removed around 85% of the total ADP-ribose moiety from these proteins. After S-PDE treatment the complex electrophoretic pattern of CS histone variants in 2-D PAGE decreases to five major fractions. From these results we conclude that the electrophoretic heterogeneity of native CS histone variants is mainly due to the extent to which five main CS histone variants are poly(ADP)-ribosylated).

Modulation of the resorptive activity of rat osteoclasts by small changes in extracellular pH near the physiological range

We investigated the effect of small shifts in extracellular pH on the resorptive activity of rat osteoclasts in vitro. Osteoclast-containing mixed bone cell populations disaggregated from neonatal rat long bones were cultured for 26 h at low density on bovine bone disks in HCO-3/CO2-buffered medium modified by the addition of small amounts of protons as HCl (2.5-15.0 mEq/L) or hydroxyl ions as NaOH (2.5-10.0 mEq/L). Little or no bone resorption occurred when ambient pH was above about 7.30; at pH 7.00, osteoclasts exhibited near-maximal activity. The greatest changes were associated with a pH difference of as little as 0.10 unit, between pH 7.25 and pH 7.15. Over this narrow range, the average number of resorption pits formed on each bone wafer increased sixfold. The steep sigmoidal pH response curve indicates that very slight alterations in ambient hydrogen ion concentration can effectively "switch on" or "switch off" rat osteoclasts in vitro.

Capillary electrophoresis and electrochemical detection of underivatized oligo- and polysaccharides with surfactant-controlled electroosmotic flow

Complex polysaccharide mixtures were analyzed directly without derivatization by capillary zone electrophoresis in strongly alkaline solutions and electrochemical detection at a Cu electrode. The positively charged surfactant cetyltrimethylammonium bromide was included in the electrophoresis medium in order to reverse the electroosmotic flow and permit elution to be in order of increasing polysaccharide size. Carbohydrate samples analyzed by this approach included linear maltoses, enzymatically hydrolyzed starch, and commercially available dextrans of up to an average molecular weight of 18,300. Detection by constant-potential oxidation at a Cu electrode was very sensitive, with detection limits for individual carbohydrates generally below the femtomole level.

Determination of beta 2-agonists in hair by gas chromatography/mass spectrometry

A method is described for the determination of the beta 2-agonists clenbuterol and salbutamol in hair. The method involves washing hair in sodium dodecyl hydrogensulphate solution, chemical digestion of the hair matrix in alkaline medium, solid-phase extraction, derivatization with methylboronic acid and analysis by gas chromatography/electron impact mass spectrometry in either the selected-ion monitoring or the scan mode. the effects of chemical digestion and of extraction on the recovery of the analytes were evaluated. Derivatization with methyl-boronic acid was compared with trimethylsilylation for GC/MS analysis of hair extracts, and was found to give mass spectra which showed more structural information with less chemical noise and better sensitivity. The proposed method was tested on real hair samples obtained from guinea pigs treated with growth-promoting doses of clenbuterol and salbutamol. Both compounds could be detected in hair of treated animals.

Effect of cassavar cultivar, age and pretreatment processes of cellulase and xylanase production from cassava waste by Trichoderma harzianum

Cassava wastes--the peel and the root fibre were taken through various pretreatment procedures before being subjected to solid state fermentation with Trichoderma harzianum. Most of the pretreatment processes increased the cellulose and hemicellulose content of the cassava peel and fibre by as high as 155% while sulfuric acid treatment resulted in 25.3% loss in the peel hemicellulose. The best pretreatment found to be 1% NaOH at 120 degrees C gave the highest production of the Cx, the Cl and xylanase enzymes with the cassava root fibre. Xylanase and cellulase production with the exception of the Cx was found to be affected by age while an improved cassava variety TMS(2) 1425 peel and fibre rated highest in terms of production of the enzymes. Percentage hydrolysis within range of 56.52-67.64% were recorded for the enzymes on sorghum grains.

A neutrophil chemoattractant is released from cellular and extracellular components of the alkali-degraded cornea and blood

PURPOSE

A tripeptide chemoattractant(s) for neutrophils has been shown to release from alkali-degraded cornea. This study is designed to determine the source of the chemoattractant(s).

METHODS

Whole corneas were degraded in 1 N NaOH for 10 minutes, 30 minutes, 1 hour, 4, 8, 24, and 48 hours to determine an optimal duration of alkali exposure for production of the chemoattractant. Whole cornea, cornea minus epithelium, cornea minus endothelium, and stroma alone were degraded in 1 N NaOH for 4 hours to determine the relative contribution of each corneal layer. In a separate experiment, epithelium alone, endothelium alone, cultured keratocytes alone, or bovine corneal collagen were treated separately in 1 N NaOH for 4 hours. Finally, human plasma, platelets, polymorphonuclear leukocytes (PMNL), and red blood cells were treated separately in 1 N NaOH for 4 hours to determine if a similar chemoattractant was released from alkali-treated noncorneal tissue. Neutralized suspensions of all samples were ultrafiltered and dialyzed. The chemotactic potential of each sample was determined in the polarization assay.

RESULTS

Activation of the PMNL polarization response increased with the duration of exposure of corneal tissue to alkali, peaking at 6 hours. Release of the chemoattractant from alkali-degraded corneal tissue showed a significant decrease when the epithelium was removed from the stroma. All tissue layers showed a PMNL polarization response when treated with alkali. The response decreased from epithelium > endothelium > cultured keratocytes > collagen. Alkali degradation of human blood components, including plasma, showed significant polarization responses ranked in the following order: plasma > PMNL > tendon collagen > platelets = red blood cells.

CONCLUSIONS

This study demonstrates that the tripeptide chemoattractant(s) is released from all layers of the cornea after alkali injury. The substance released from blood components is of similar size and biologic activity as that found in the cornea, but its exact molecular composition is yet to be determined. Timed response of alkali degradation determined the optimal conditions for generation of the chemoattractant(s) including clinically relevant time intervals.

Steam explosion of woody hemp chènevotte

This paper concerns the morphology of hemp woody core cells, investigated by optical and scanning electron microscopy, and the chemical analysis of the hemp cells. Steam explosion was investigated as a pre-treatment step for woody hemp 'chènevotte', with the aim of optimizing the separation and delignification of woody fibres. In this study, we report the results of five experiments performed on 'chènevotte' samples impregnated in acid solution (0.1% w/w H2SO4) and steamed at 200, 210, 220, 230 and 240 degrees C for 180 s. The effect of process temperatures on the woody hemp core after acidic impregnation was followed by optical and scanning electron microscopy, by assessment of the chemical composition, and by evolution of the average degree of polymerization (DPv) values of the purified wood fibres. We found that treatment at 200 and 210 degrees C led to samples that were difficult to delignigy because the destructuring and disintegration of lignocellulosic materials were insufficient. A temperature of the order of 220-230 degrees C is required to obtain well-separated fibres. However, at a temperature of 240 degrees C, degradation and fibre damage were noted.

Effect of alkali treatments on the nutritive value of common bean (Phaseolus vulgaris)

The effect of alkali treatments of common bean seeds with red seed coat on the stability of antinutritional factors such as tannins, phytates and trypsim inhibitors, vitamins such as niacin and riboflavin and on protein quality has been studied. The samples were processed by soaking and pressure cooking in alkalies such as sodium hydroxide, sodium carbonate and sodium bicarbonate. At low temperature sodium carbonate and at high temperature sodium bicarbonate were found to be most effective in the extraction of tannins. At both low and high temperatures sodium carbonate was found to be more efficient in destruction of phytates. In the case of trypsin inhibitors, extraction at both low and high temperatures with sodium bicarbonate was most effective. Sodium hydroxide treatment was found to be better as far as the retention of niacin and riboflavin was considered.

Factors affecting the concentration of compound A resulting from the degradation of sevoflurane by soda lime and Baralyme in a standard anesthetic circuit

Carbon dioxide absorbents, such as soda lime and Baralyme brand absorbent, convert sevoflurane to CF2 = C(CF3)OCH2F, a vinyl ether called "Compound A," whose toxicity raises concerns regarding the safety of sevoflurane in rebreathing circuits. Because an increased inflow rate to an anesthetic circuit decreases rebreathing, we assumed that an increased rate would proportionately decrease the concentration of Compound A. In the present report, we measured the Compound A concentration resulting from the action of wet (standard) soda lime and wet (standard) Baralyme on 2% sevoflurane in a model anesthetic circuit, using inflow rates (0.5, 1.0, 2.0, 4.0, and 6.0 L/min), ventilations (5 and 10 L/min), and carbon dioxide production/removal (200 and 400 mL/min) found in clinical practice. An increase in inflow rate decreased Compound A concentration to lower levels as inflow rate approached minute ventilation. At lower inflow rates, increasing duration of sevoflurane inflow increased the concentration of Compound A, a finding consistent with a progressive increase in absorbent temperature from absorption of carbon dioxide and consequently greater sevoflurane degradation. There was no material difference between Baralyme and soda lime in the concentrations of Compound A produced at a particular inflow rate. An increase in ventilation increased the concentration of Compound A, having a much greater effect at high rather than low inflow rates. An increase in amount of carbon dioxide absorbed also increased the concentration of Compound A. We conclude that inflow rate, ventilation, and carbon dioxide production are major determinants of the concentration of Compound A.

The three-dimensional organization of the smooth musculature in the ampulla of the human fallopian tube: a new morpho-functional model

The three-dimensional organization of the smooth musculature around the human ampulla is revealed by means of scanning electron microscopy after NaOH maceration and ultrasonic microdissection of the interstitial connective tissue. The muscular wall of the ampulla appears as a continuous network of randomly anastomosed smooth muscle cell bundles that showed a multidirectional arrangement. The smooth muscle cell bundles modify their orientation along their course, intertwine repeatedly with each other and dichotomize, generating new bundles with a different orientation from that at the origin. These results demonstrate that the myosalpinx of the human ampulla is not organized into clear cut longitudinally, circularly or spirally arranged layers, as suggested in previous light microscopy studies. In contrast, the presence of a network of multidirectional smooth muscle cell bundles revealed in this study suggests that there is no morphological evidence for unidirectional peristalsis, and that the musculature is probably structurally designed to stir rather than push the tubal contents. These morphological findings better explain the random pattern of propagation of the contraction waves and the electrical impulses through the smooth musculature of the human ampulla, as postulated in early experimental physiological studies. Further, they suggest a specific function for the ampullar musculature which may not be only strictly related to tubal content transport.

Influence of roasting or sodium hydroxide treatment of barley on digestion in lactating cows

Three cannulated, lactating cows were used in a 3 x 3 Latin square design to determine the effect of roasting or NaOH treatment of barley on ruminal fermentation and site and extent of digestion of nutrients. Experimental treatments were rolled barley, roasted (exit temperature, 135 degrees C) and rolled barley, and treated with 4% NaOH and 220 L of H2O/tonne of barley. Diets also consisted of grass silage and soybean meal. Treatment with NaOH reduced concentrations of several AA, starch, and NDF in the barley. Starch digestibility in the rumen was lower for barley that was treated with NaOH but was unaffected for roasted barley. Digestibilities of N and starch in the small intestine were reduced for barley treated with NaOH, but values for rolled and roasted barley were similar. Apparent total tract digestibility of starch was reduced for the NaOH treated barley. Treatment of barley with NaOH tended to have a detrimental effect on feed intake, digestibility, and milk production. Roasting of barley did not appear to affect the site or extent of carbohydrate digestion, but roasting protected N from ruminal degradation. The protective effect on the carbohydrate fraction would be expected to be greater if the grain were cooled prior to rolling so that the protein matrix of the starch granule remained intact.

Localization of the start sites of lagging-strand replication of rolling-circle plasmids from gram-positive bacteria

A number of small, multicopy plasmids from Gram-positive bacteria replicate by an asymmetric rolling-circle mechanism. Previous studies with several of these plasmids have identified a palindromic sequence, SSOA, that acts as the single-strand origin (SSO) for the replication of the lagging-strand DNA. Although not all the SSOA sequences share DNA sequence homology, they are structurally very similar. We have used an in vitro system to study the lagging-strand replication of several plasmids from Gram-positive bacteria using the SSOA sequences of pT181, pE194 and pSN2 as representative of three different groups of Staphylococcus aureus plasmids. In addition, we have investigated the lagging-strand replication of the pUB110 plasmid that contains an alternative single-strand origin, SSOU. Our results confirm that RNA polymerase is involved in lagging-strand synthesis from both SSOA and SSOU-type lagging-strand origins. Interestingly, while initiation of lagging-strand DNA synthesis of pUB110 occurred predominantly at a single position within SSOU, replication of pT181, pSN2 and pE194 plasmids initiated at multiple positions from SSOA.

Digestibility of alkali-treated wheat straw measured in vitro or in vivo using Holstein heifers

Three experiments were conducted to determine the effect of different alkali solutions on in vitro degradation and in vivo digestibility of wheat straw. In Exp. 1, ground wheat straw was treated with 15 different alkali solutions grouped as NaOH, NH4OH, urea, and Ca(OH)2. The greatest (P < .05) 48-h in vitro NDF degradability was obtained with 5% NaOH and the combination of 2.5% NaOH + 2.5% Ca(OH)2. In Exp. 2, chopped wheat straw was treated with one of the following: 1) untreated; 2) 2.5% NaOH; 3) 5% NaOH; 4) 2.5% Ca(OH)2 + 2.5% NaOH; or 5) 5% Ca(OH)2. Five Holstein heifers were fed diets that contained 60% straw, 20% alfalfa hay, and 20% concentrate mix (DM basis) fed as total mixed rations in a 5 x 5 Latin square design. The greatest in vivo NDF digestibility (P < .05) was obtained with the NaOH and NaOH+Ca(OH)2 treatments. The 5% Ca(OH)2 treatment had higher fiber digestibility than the control and was equivalent to the 2.5% NaOH and 2.5% NaOH+Ca(OH)2 treatments. Rate of passage of straw was not affected by chemical treatment, whereas rate of passage of dietary alfalfa hay increased with NaOH. In Exp. 3, wheat straw ground through a 2-mm screen was treated with one of the following chemicals: 1) untreated (control); 2) 5% NaOH; 3) 5% NH4OH; 4) urea supplying N equivalent to 5% NH4OH; and 5) 5% Ca(OH)2 (all on DM basis).(ABSTRACT TRUNCATED AT 250 WORDS)

Thiol ester-linked p-coumaric acid as a new photoactive prosthetic group in a protein with rhodopsin-like photochemistry

A number of Eubacteria contain a photoactive yellow protein which has a photosensory function in negative phototaxis. It has been proposed that the cofactor responsible for the intense yellow color of this protein is retinal [McRee, D. E., et al. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 6533-6537]. This would make it the first eubacterial rhodopsin. Here we report the chemical structure of this chromophoric group to be p-coumaric acid, which is covalently bound to a unique cysteine in the apoprotein via a thiol ester bond, and thus not retinal. This makes PYP the first example of a protein containing p-coumaric acid, a metabolite previously found only in plants, as a prosthetic group and establishes the photoactive yellow proteins as a new type of photochemically active receptor molecule.

Cell culture and PCR determination of poliovirus inactivation by disinfectants

Inactivation of poliovirus type 1 by 1 N HCl, 1 N NaOH, 0.5 and 1.0 mg of free chlorine per liter, and UV light was compared by using cell culture and seminested PCR (30 cycles of reverse transcriptase-PCR plus 30 cycles of seminested PCR). A minimum contact time of 45 min with HCl, 3 min with NaOH, 3 and 6 min with 1.0 and 0.5 mg of free chlorine per liter, respectively, was required to render 1.64 x 10(2) PFU of poliovirus type 1 per ml undetectable by seminested PCR. In cell culture, a minimum contact time of 5 min to HCl, 30 s to NaOH, and 1 min to either chlorine concentration was required to render the viruses undetectable by the plaque assay method. No correlation was observed between results by PCR and cell culture when viruses were exposed to UV light. These data suggest that inactivated virus with intact nucleic acid sequences can be detected by PCR.

Influence of the method of purification on some solution properties of welan gum

The origin and some consequences of the presence of aggregates and impurities (deriving from the fermentation procedure) on the solution properties of welan gum have been studied. For this purpose, a method of purification was developed for a fermentation welan broth. It was verified that this method is ineffective for the dissociation of aggregates in the commercial product. This demonstrates the irreversible nature of the intermolecular interactions of welan samples isolated by precipitation in the presence of impurities. The purified products were characterized (Mw, [eta], kH) and the results were compared to those obtained from commercial samples of welan. The influence of the method of purification on the rheological properties was analysed.

[Function of the upper esophageal sphincter after denervation of recurrent laryngeal nerves and intramural nerves of the cervical esophagus in dogs]

The upper esophageal sphincter prevents reflux into the pharynx. If it functions improperly, aspiration pneumonia can result. We studied the functioning of the sphincter in unanesthetized dogs after denervation under anesthesia of the recurrent laryngeal nerves. The pressure of the sphincter at rest was measured by manometry with a transducer that measured pressure around the tip of a catheter. Then the pressure in response to inflation of a balloon to the diameter of 1.5, 2.0 and 2.5 cm at 5 and 10 cm aboral to the sphincter was measured. Next, the pressure during perfusion of 0.1 N HCl or NaOH 10 cm aboral to the sphincter was measured. These studies were done first in 10 dogs that had undergone only gastrostomy for measurements (controls). Measurements were repeated after the left recurrent laryngeal nerve in the controls was cut (L group), after the right recurrent laryngeal nerve in the L group was cut (B group), and after transection of the esophagus 7 cm aboral to the sphincter in the B group (T group). The differences in the pressure at rest were not significant. In each group, balloon inflation to any diameter tested and at either position made the pressure rise above that at rest. This pressure in the L, B, and T groups, however, was significantly lower than in the controls. When the balloon was inflated to 2.5 cm when it was 10 cm aboral to the sphincter, the pressure in the T group was significantly lower than in the B group. When HCl or NaOH were perfused, the pressure increased gradually in the controls, but not in the other groups. In conclusion, although recurrent laryngeal nerves did not affect the function of the sphincter at rest, they were the afferent routes of the contraction by the sphincter as a reflex following distension or chemical stimulation of the esophagus. The intramural nerve network of the cervical esophagus may be another reflex route of contraction of the upper esophageal sphincter.

Chemical ablation of the gallbladder: evaluation of multiple agents in vitro

PURPOSE

To find a more effective chemical regimen for transcatheter ablation of the gallbladder in an in vitro model.

MATERIALS AND METHODS

Sectioned and whole pig gallbladders were exposed in vitro to 12 different chemical solutions at varying conditions of exposure time, pH, and temperature.

RESULTS

In the in vitro studies, 0.1 N and 1.0 N solutions of sodium hydroxide in water or ethanol and 3% hydrogen peroxide were the most effective sclerosant agents. Ethanol and hydrochloric acid failed to completely eliminate the epithelium from the gallbladder sections. Increasing exposure time from 10 to 20 minutes or increasing the temperature of the solutions from 37 degrees C to 50 degrees C did not alter these results. Sequential 15-minute exposures to 0.1 N sodium hydroxide in ethanol followed by peroxide completely eliminated the epithelium from whole gallbladders in vitro.

CONCLUSION

Alkaline solutions and hydrogen peroxide are more effective than ethanol alone, acids, or detergents in eliminating gallbladder epithelium in this model. Further evaluation of these agents in vivo is merited.

Decontamination studies with the agents of bovine spongiform encephalopathy and scrapie

Macerates of bovine brain infected with bovine spongiform encephalopathy (BSE) agent, and rodent brain infected with the 263K or ME7 strains of scrapie agent, were subjected to porous-load autoclaving at temperatures between 134 and 138 degrees C for < or = 60 min. Bioassay in rodents showed that none of the regimens produced complete inactivation. Homogenates of BSE-infected bovine brain were exposed for < or = 120 min to solutions of sodium hypochlorite or sodium dichloroisocyanurate containing < or = 16,500 ppm available chlorine. There was no detectable survival of infectivity after the hypochlorite treatments but none of the dichloroisocyanurate solutions produced complete inactivation. Homogenates of BSE-infected bovine brain, and rodent brain infected with the 263K and ME7 strains of scrapie agent, were exposed for < or = 120 min to 1M or 2M sodium hydroxide but no procedure produced complete inactivation of all agents tested.