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PubMed1991

Elemental composition of pyroantimonate precipitates analysed by electron spectroscopic imaging (ESI) and electron energy-loss spectroscopy (EELS) in vitellogenic ovarian follicles of Drosophila.

Ca2+ was precipitated with potassium antimonate in vitellogenic follicles of the fruit fly Drosophila melanogaster and the distribution of the precipitates formed was studied by electron microscopy. The microvilli of the oolemma in mid- and late vitellogenic follicles were lined with precipitates. The chemical composition of the precipitates was analysed by electron spectroscopic imaging (ESI). The images produced by inelastically scattered electrons at specific ionization edges were compared, and the non-specific background signals were subtracted by an image processing system. The presence of Ca2+, antimony and oxygen in the precipitates formed could be demonstrated. The elemental composition of the precipitates and of yolk spheres was also analysed by electron energy-loss spectroscopy (EELS). With respect to the precipitates, signals at the calcium L2,3-edge, the oxygen K-edge and the antimony M4,5-edge were recorded without deconvolution and background subtraction. The yolk spheres, which were free of precipitates, gave the characteristic signal of the nitrogen K-edge. The applied techniques combine good ultrastructural resolution with the possibility of analysing the elemental composition of histochemical reaction products and cellular structures.

Animals↗

PubMed1986

Evidence that an extract of Staphylococcus capitis can precipitate human serum HDL2.

The high density lipoprotein (HDL) fraction involved in the precipitation with Staphylococcus capitis can be quantitated by single radial diffusion in agar containing an extract of the bacteria. Both whole serum and purified HDL produce a precipitation ring with bacterial extract. When dilutions of serum are tested, the squared radius of the precipitation ring plotted against serum concentration gives a linear relationship. Cumulative density flotation of HDL, followed by quantitative analysis of precipitating activity and apo A, indicates that the precipitating activity is present in the less dense fraction of serum HDL (i.e. HDL2). This suggestion is supported by the finding that the precipitating activity correlates positively with HDL2 (but not with HDL3) in human sera. Precipitating activity was higher in sera from women than from men, in accordance with the sex difference in serum HDL. The results raise the question whether precipitation with an extract of S. capitis might serve as a simple, direct method to assess serum HDL2 levels.

Chemical Precipitation↗

PubMed2004

Lead precipitation by Vibrio harveyi: evidence for novel quorum-sensing interactions.

Three pleiotropic, quorum sensing-defective Vibrio harveyi mutants were observed to precipitate soluble Pb2+ as an insoluble compound. The compound was purified and subjected to X-ray diffraction and elemental analyses. These assays identified the precipitated compound as Pb9(PO4)6, an unusual and complex lead phosphate salt that is produced synthetically at temperatures of ca. 200 degrees C. Regulation of the precipitation phenotype was also examined. Introduction of a luxO::kan allele into one of the mutants abolished lead precipitation, indicating that the well-characterized autoinducer 1 (AI1)-AI2 quorum-sensing system can block lead precipitation in dense cell populations. Interestingly, the V. harveyi D1 mutant, a strain defective for secretion of both AI1 and AI2, was shown to be an effective trans inhibitor of lead precipitation. This suggests that a previously undescribed V. harveyi autoinducer, referred to as AI3, can also negatively regulate lead precipitation. Experiments with heterologous bacterial populations demonstrated that many different species are capable of trans regulating the V. harveyi lead precipitation phenotype. Moreover, one of the V. harveyi mutants in this study exhibited little or no response to intercellular signals from other V. harveyi inocula but was quite responsive to some of the heterologous bacteria. Based on these observations, we propose that V. harveyi carries at least one quorum sensor that is specifically dedicated to receiving cross-species communication.

Bacterial Proteins↗

PubMed1982

An improved method for the subcellular localization of calcium using a modification of the antimonate precipitation technique.

A new variation of the antimonate precipitation technique, employing tannic acid in the primary aldehyde-antimonate fixative, is described for use in the subcellular localization of calcium in various tissues. Chelation studies and electron microscopic, X-ray microanalytical studies of antimonate precipitates in etiolated oat tissues indicate that calcium is the major cation localized using the present experimental protocol. Preservation of ultrastructural morphology in these tissues is greatly improved over that observed in tissues fixed with conventional antimonate-aldehyde or antimonate-osmium fixatives. The regularity and reproducibility of tissue precipitate patterns suggests that 1) penetration of the tissue by the fixative, and subsequent precipitation of calcium, is rapid and uniform and 2) ion displacement during sample preparation is negligible. Calcium appears to be immobilized efficiently in situ, with greater than 90% 45Ca retention in radiolabeled tissues prepared for electron microscopy. Quantitative aspects of calcium precipitation by antimonate in 45Ca-labeled CaCl2 solutions were examined over a wide range of calcium concentrations. Precipitation was essentially linear over the expected range of biological concentrations of calcium. Furthermore, the 3:1 antimonate to calcium ratio estimated for test tube precipitates was also established for Sb/Ca in tissue precipitates analyzed using energy dispersive x-ray microanalytical (EDX) techniques. These observations suggest that the present technique is potentially useful in the semiquantitative estimation of tissue calcium levels.

Animals↗

PubMed2005

Enhanced radionuclide immobilization and flow path modifications by dissolution and secondary precipitates.

Caustic radioactive wastes that have leaked at Hanford Site (Richland, WA) induce mineral dissolution and subsequent secondary precipitation that influence the fate and transport of contaminants present in the waste solutions. The effects of secondary mineral precipitates, formed after contacting solids with simulated caustic wastes, on the flow path changes and radionuclide immobilization were investigated by reacting quartz, a mixture of quartz and biotite, and a Hanford sediment (Warden soil: coarse-silty, mixed, superactive, mesic Xeric Haplocambids) with simulated caustic tank waste solution. Continuous Si dissolution and concomitant secondary mineral precipitation were the principal reactions observed in both batch and flow-through tests. Nitrate-cancrinite was the dominant secondary precipitate on mineral surfaces after 3- to 10-d reaction times in batch experiments. X-ray microtomography images of a reacted quartz column revealed that secondary precipitates cemented quartz grains together and modified pore geometry in the center of the column. Along the circumference of the packed column, however, quartz dissolution continuously occurred, suggesting that wastes that leaked from buried tanks in the past likely did not migrate vertically as modeled in risk assessments but rather the pathways likely changed to be dominantly horizontal on precipitation of secondary precipitate phases in the Hanford vadose zone. Based on batch equilibrium sorption results on the reacted sediments, the dominant secondary precipitates (cancrinites) on the mineral surfaces enhanced the sorption capacity of typical Hanford sediment for radionuclides 129I(-I), 79Se(VI), 99Tc(VII), and 90Sr(II), all of which are of major concern at the Hanford Site.

Adsorption↗

PubMed2005

[Responses of three Stipa communities net primary productivity along Northeast China Transect to seasonal distribution of precipitation].

This paper analyzed the annual dynamics of the net primary productivity (NPP) of three Stipa communities along Northeast China Transect, and based on an integral regression model, discussed the responses of the NPP to the seasonal distribution of precipitation, aimed to reveal the effects of precipitation availability on plant NPP. The results indicated that the main factor restricting the annual dynamics of three Stipa communities NPP was the annual fluctuation of the monthly precipitation from November to next August. The precipitation from November to next April had a positive effect on the NPP, while the effect of that from May to July was decreased in different degrees. The seasonal distribution pattern of precipitation was quite similar for test Stipa communities, but S. grandis community had a higher utilization efficiency of precipitation than S. krylovii community, and S. baicalensis community had a much higher utilization efficiency of precipitation. Therefore, the seasonal distribution pattern of precipitation and its different effects on Stipa communities could be the main reasons inducing the zonal distribution of three test Stipa communities.

Biomass↗

PubMed1996

Precipitating factors for delirium in hospitalized elderly persons. Predictive model and interrelationship with baseline vulnerability.

OBJECTIVES: To prospectively develop and validate a predictive model for delirium based on precipitating factors during hospitalization, and to examine the interrelationship of precipitating factors and baseline vulnerability. DESIGN: Two prospective cohort studies, in tandem. SETTING: General medical wards, university teaching hospital. PATIENTS: For the development cohort, 196 patients aged 70 years and older with no delirium at baseline, and for the validation cohort, 312 comparable patients. MAIN OUTCOME MEASURE: New-onset delirium by hospital day 9, defined by the Confusion Assessment Method diagnostic criteria. RESULTS: Delirium developed in 35 patients (18%) in the development cohort. Five independent precipitating factors for delirium were identified; use of physical restraints (adjusted relative risk [RR], 4.4; 95% confidence interval [CI], 2.5 to 7.9), malnutrition (RR, 4.0; 95% CI, 2.2 to 7.4), more than three medications added (RR, 2.9; 95% CI, 1.6 to 5.4), use of bladder catheter (RR, 2.4; 95% CI, 1.2 to 4.7), and any iatrogenic event (RR, 1.9; 95% CI, 1.1 to 3.2). Each precipitating factor preceded the onset of delirium by more than 24 hours. A risk stratification system was developed by adding 1 point for each factor present. Rates of delirium for low-risk (0 points), intermediate-risk (1 to 2 points), and high-risk groups (> or equal to 3 points) were 3%, 20%, and 59%, respectively (P < .001). The corresponding rates in the validation cohort, in which 47 patients (15%) developed delirium, were 4%, 20%, and 35%, respectively (P < .001). When precipitating and baseline factors were analyzed in cross-stratified format, delirium rates increased progressively from low-risk to high-risk groups in all directions (double-gradient phenomenon). The contributions of baseline and precipitating factors were documented to be independent and statistically significant. CONCLUSIONS: A simple predictive model based on the presence of five precipitating factors can be used to identify elderly medical patients at high risk for delirium. Precipitating and baseline vulnerability factors are highly interrelated and contribute to delirium in independent substantive, and cumulative ways.

Aged↗

PubMed1982

Digitonide precipitable sterols: a reevaluation with special attention to lanosterol.

The ability of digitonin to precipitate lanosterol from prepared mixtures and biological sources was evaluated. Commercially available lanosterol was determined to be composed of about 60% lanosterol and 40% dihydrolanosterol. Both sterols were only partially precipitated by digitonin under all conditions examined. The presence of cholesterol increased the precipitation of lanosterol, but never to completion. About 40% of the lanosterols from saponified sheep's-wool fat was not precipitated by digitonin. Also 14C-labeled lanosterol recovered from rat brain following intracerebral injection of 2-[14C]mevalonate was only 70% precipitated by digitonin. Steric hinderance by the methyl groups at carbon -4 is suggested to explain the poor precipitability of this sterol. In conclusion, lanosterol can not be considered to be a digitonide-precipitable sterol equivalent to cholesterol. Caution should be exercised in situations where digitonin-precipitable sterols are being prepared from sources containing significant concentrations of lanosterol (i.e., mass and/or radiolabel).

Animals↗

PubMed1984

Immunochemical studies on the binding properties of Brucella abortus lipopolysaccharides to bovine precipitating antibodies.

The binding properties of Brucella abortus smooth lipopolysaccharides (LPS) to the precipitating antibodies in the serum of a B. abortus S2308 infected cow were studied by quantitative precipitin and precipitin-inhibition assays. Crude B. abortus lipopolysaccharides (cLPS) and chemical modification products of strains 1119.3, 19 and 2308 (virulent) were used for this study. In the quantitative precipitin assay, 13 micrograms of cLPS precipitated about 4.0-5.2 micrograms nitrogen of precipitating antibodies in 10 microliter of serum. After alkaline treatment (0.125 N NaOH at 56 degrees C for 1 hr), the alkali-treated lipopolysaccharides (aLPS) from S19 and S1119.3 maintained the maximum precipitability, but the precipitation profile was changed from a sigmoidal to a bell-shaped curve, and aLPS from S2308 was reduced to about 40% of its reactivity. These results indicate that some of the antigenic determinants blocked by other molecules were reshielded by alkaline treatment, and possibly that structural differences exist between virulent (S2308) and nonvirulent (S19 and S1119.3) strains. Among the monosaccharides and glycosides tested for inhibition of precipitation, methyl alpha-D-mannose was most active and about 3.3 times as active as D-mannopyranose (DMan) and only 1/200 as active as acid hapten or the carbohydrate moiety of cLPS prepared from S1119.3 (expressed as a monosaccharide of mol. wt 200) implying that the carbohydrate determinants of this antigen are probably related to a DMan alpha 1----linked compound. The precipitability of the antibodies in this serum was greatly reduced after absorption with cLPS and the precipitin reaction was completely inhibited by the carbohydrate moiety of LPS (O-antigen) S1119.3 demonstrating that the common antigenic determinants (hapten) of B. abortus LPS reacting with these precipitating antibodies are in the region of the carbohydrate moiety of the LPS.

Animals↗

PubMed2004

Prevalence of delirium in a geriatric convalescence hospitalization unit: patient's clinical characteristics and risk precipitating factor analysis.

The aim was to evaluate the prevalence of delirium among patients discharged from an acute care hospital and admitted to a geriatric convalescence unit (GCU), and to analyze patient's characteristics and risk precipitating factors. Sixty-eight patients were analyzed during a 2-week period. The confusion assessment method (CAM) was used to detect delirium. The precipitating factors evaluated were: major surgery-intensive care unit(ICU) stay, pulmonary and heart failure, acute infections, metabolic disorders/anemia,psychoactive medications, other drugs, severe pain, changing environmental influences and others. According to CAM, fifteen patients presented delirium (22%), and in 14 of them(93.3 %) the delirium was developed before admission at GCU. The precipitating factors in the studied population were the following: changing environmental influences in 66 patients(97%) (15 with delirium and 51 without delirium); other drugs 56 (82.3 %) (11 vs. 45);others 56 (82.3%) (9 vs. 24); psychoactive medications 50 (73.5%) (12 vs. 38); acute infections 48 (70.5 %) (13 vs. 35); metabolic disorders/anemia 40 (58.8 %) (9 vs. 31); major surgery-ICU stay 28 (41 .1%) (8 vs. 20); severe pain 26 (38.2%) (6 vs. 20); pulmonary and heart failure 22 (32.3%) (5 vs. 17). The univariant analysis showed that, none of the precipitating factors studied was significantly related to delirium. Seventy-two patients (91.1%) had simultaneously >3 precipitating factors. There were 16 patients with >6 precipitating factors, 7 of 15 with delirium and 9 of the 53 without delirium (46.6 % vs 16.9 %) (p < 0.05). The prevalence of delirium has been 22 %. Most of the patients had developed delirium before the admission at GCU. A high proportion of patients had >3 precipitating factors. In the study the presence of > 6 precipitating factors simultaneously has been significantly related to delirium.

Aged↗

PubMed2006

Calcium sulfate precipitation in the presence of water-soluble polymers.

The effect of four different polymers on the precipitation of calcium sulfate was investigated in the present work. The degree of inhibition was estimated from measurements of the calcium ion activity and from specific solution conductivity measurements in the supersaturated solutions during the course of the precipitation process. The effects of polyacrylic acid (PAA, three different polymers with average molecular weight 2000, 50,000, and 240,000, respectively) and of a co-polymer of PAA with polystyrene sulfonic acid (PSA, average molecular weight<20,000) were investigated with respect to their effect on the kinetics of spontaneous precipitation of calcium sulfate salts. The results of the kinetics experiments suggested that the spontaneous precipitation from supersaturated calcium sulfate solutions at 25 degrees C yielded exclusively calcium sulfate dihydrate (gypsum) both in the absence and in the presence of the polymeric additives. The induction times, preceding the formation of the solid increased in all cases in the presence of the polymeric additives. Polymer concentrations as low as 2.0 ppm increased induction time from practically zero to 10 min. The rates of precipitation were reduced according to the solutions content in the polymers added and precipitation was completely suppressed in the presence of 6.0 ppm of the polymers tested, depending on their molecular weight. The lower the molecular weight of PAA, the more efficient was the threshold inhibition and the stronger the reduction of the rates of spontaneous precipitation. PSA yielded the poorest inhibition efficiency in comparison with the PAA, possibly because of the relatively lower affinity of the sulfonate groups for the calcium ions of the surface of the solid forming. The kinetics results analysis assuming Langmuir-type adsorption of the polymeric molecules on the growing supercritical gypsum nuclei showed different affinity for the polymers tested in agreement with the respective inhibition efficiency, in the order: PAA1>PAA2>PSA>PAA3. The presence of the polymers in the supersaturated solutions resulted in modification of the precipitated gypsum crystals morphology.

Journal Article↗

PubMed2003

Optimization of protein precipitation based upon effectiveness of protein removal and ionization effect in liquid chromatography-tandem mass spectrometry.

Four categories of protein precipitation techniques (organic solvent, acid, salt and metal ion) were tested in plasma using spectrophotometry to assess protein removal efficiency across a range of volumes, species and lots. Acetonitrile, trichloroacetic acid (TCA) and zinc sulfate were found to be optimal at removing protein in their categories (>96, 92 and 91% protein precipitation efficiency at a 2:1 ratio of precipitant to plasma, respectively). A post-column infusion LC-MS/MS system was used to assess ionization effect of a protein-bound drug caused by the endogenous components remaining after using various protein precipitants. The extent of ionization effect varied with mobile phase (-20 to 93%), protein precipitant (0.3-86%), but only slightly with species (86-93%). The optimal bioanalytical methodologies for removal of plasma proteins and minimal ionization effect for the probe molecule in positive ion turboionspray LC-MS/MS involve the use of TCA for precipitation with mobile phases consisting of either pure organic solvents (methanol:water or acetonitrile:water) or precipitation with all of the mass spectrometer compatible precipitants evaluated with a methanol:aqueous 0.1% formic acid mobile phase.

Animals↗

PubMed1997

Changes in arrangement and in conformation of molecular components of peripheral T-cell antigen receptor complex after ligand binding: analyses by co-precipitation profiles.

Amounts of co-precipitating CD3 components by anti-T-cell receptor (TCR)V beta or anti-CD4/8 monoclonal antibodies were compared between non-stimulated and stimulated splenic T cells. The amounts of co-precipitating CD3 delta, epsilon and gamma chains with TCR alpha beta and with CD4/8 were not significantly changed after TCR ligation. The apparent amount of CD3 zeta chain co-precipitated with TCR alpha beta increased up to threefold, while the actual amount of co-precipitating CD3 zeta with TCR alpha beta and the total amount of specifically precipitated CD3 zeta are not changed after cross linking of TCR. The apparent amount of CD3 zeta chain co-precipitated with CD4/8 also increased. Unlike co-precipitation with TCR alpha beta, the actual amount of CD3 zeta co-precipitated with CD4/8 increased significantly. This observation suggests a conformational change as well as the relocation of CD3 zeta molecules within the TCR complex after the signal delivery. After TCR ligation, CD3 zeta chains relocate to the vicinity of either CD4 or CD8 molecules. In addition, when cross linking and binding signals are compared, CD3 chains undergo two distinct phases of conformational change. The responses, while the later conformational change caused by the cross linking of TCR does not induce but enhances the proliferative response.

Animals↗

PubMed1991

Differential emotional precipitation of migraine and tension-type headache attacks.

The frequency of precipitation of headache attacks by individual emotional states as well as the awareness of vulnerability to particular emotional precipitants were investigated in 90 consecutive patients with tension-type headache and 50 consecutive migraine subjects at an Outpatient Headache Clinic. There was differential emotional precipitation in tension-type headache and migraine, with patients with tension-type headache reacting more selectively to negative emotional arousal (anger, anxiety) and reporting a graded frequency of attack precipitation by individual emotional states. Migraine subjects reported a more uniform distribution of attacks among different emotional precipitants. The two groups also showed a differential awareness of vulnerability to individual emotional precipitants. A cognitive process screening the emotional precipitants of tension-type headache and migraine attacks is proposed, based on different cognitive schemata functioning either over-effectively or defectively. The significance of cognitive mediation of the precipitation of attacks is further emphasized for a comprehensive management of both tension-type headache and migraine.

Adult↗

PubMed2003

Migraine and tension-type headache in Croatia: a population-based survey of precipitating factors.

The careful monitoring of the trigger factors of headache could be an important step in treatment, because their avoidance may lessen the frequency and severity of attacks. Furthermore, they may provide a clue to the aetiology of headache. The aim of the present study was to estimate the prevalence of tension-type headache (TTH) and to establish the frequency of precipitating factors in subjects with migraine and TTH in the adult population of Bakar, County of the Coast and Gorski Kotar, Croatia. Another important purpose of the study was to examine the relationship of the precipitating factors with migraine and TTH, and with migraine subtypes: migraine with aura (MA) and migraine without aura (MO). We performed a population-based survey using a 'face-to-face door-to-door' interview method. The surveyed population consisted of 5173 residents aged between 15 and 65 years. The 3794 participants (73.3%) were screened for headache history according to the International Headache Society (IHS) criteria. Headache screen-positive responders, 2475 (65.2%), were interviewed by trained medical students with a structured detailed interview focused on the precipitating factors. The following precipitating factors in lifetime migraineurs and tension-type headachers have been assessed: stress, sleep disturbances, eating habits, menstrual cycle, oral contraceptives, food items, afferent stimulation, changes in weather conditions and temperature, frequent travelling and physical activity. A total of 720 lifetime migraineurs and 1319 tension-type headachers have been identified. The most common precipitants for both migraine and TTH were stress and frequent travelling. Stress (odds ratio (OR) 1.4, 95% confidence interval (CI) 1.17, 1.69) was associated with migraine, whereas physical activity (OR 0.72, 95% CI 0.59, 0.87) was related to TTH. Considering MA and MO, frequent travelling (OR 2.2, 95% CI 1.59, 2.99), food items (OR 2.2, 95% CI 1.35, 3.51) and changes in weather conditions and temperature (OR 1.75, 95% CI 1.27, 2.41) exhibited a significant positive association with MA. The present study demonstrated that precipitant-dependent attacks are frequent among both migraineurs and tension-type headachers. Lifetime migraineurs experienced headache attacks preceded by triggering factors more frequently than tension-type headachers. MA was more frequently associated with precipitating factors than MO. We suggest that some triggering factors may contribute to the higher occurrence of precipitant-dependent headache attacks in susceptible individuals.

Adolescent↗

PubMed2001

Precipitating and aggravating factors of migraine versus tension-type headache.

OBJECTIVE: We conducted the present study to determine whether there are headache precipitating and aggravating factors that differentiate migraine from tension-type headache and headache precipitating and aggravating factors that differentiate tension-type headache from migraine. METHODS: We interviewed 38 patients with migraine and 17 patients with tension-type headache (diagnosed using International Headache Society criteria) by telephone, using a questionnaire. The questionnaire inquired about the following precipitating and aggravating headache factors: (1) physical activity, (2) straining, (3) bending over, (4) stress/tension, (5) coughing/sneezing, (6) fatigue, (7) reading, (8) driving, (9) lack of sleep, (10) specific foods/drinks, (11) alcohol, (12) not eating on time, (13) smoke, (14) smell, (15) light, (16) noise, (17) menstruation, and (18) weather. RESULTS: The most common precipitating factors acknowledged by both groups of patients were stress/tension, not eating on time, fatigue, and lack of sleep. Weather, smell, smoke, and light were the precipitating factors that differentiated migraine from tension-type headache. Excluding those factors that are part of the International Headache Society migraine diagnosis, the aggravating factors were straining, bending over, and smell. We found no precipitating or aggravating factors differentiating tension-type headache from migraine. CONCLUSION: Apparently there are precipitating and aggravating factors differentiating migraine from tension-type headache but not vice versa. It is interesting that three of the migraine-specific precipitating factors (ie, weather, smell, and smoke) involve the nose/sinus system, suggesting a greater significance of this system in headache than is generally considered.

Eating↗

PubMed2006

Critique of "Precipitation in light extinction reconstruction" by P.A. Ryan.

The goal of the Regional Haze Rule (RHR) is to return visibility in class I areas (CIAs) to natural levels, excluding weather-related events, by 2064. Whereas visibility, the seeing of scenic vistas, is a near instantaneous and sight-path-dependent phenomenon, reasonable progress toward the RHR goal is assessed by tracking the incremental changes in 5-yr average visibility. Visibility is assessed using a haze metric estimated from 24-hr average aerosol measurements that are made at one location representative of the CIA. It is assumed that, over the 5-yr average, the aerosol loadings and relative humidity along all of the site paths are the same and can be estimated from the 24-hr measurements. It is further assumed that any time a site path may be obscured by weather (e.g., clouds and precipitation), there are other site paths within the CIA that are not. Therefore, when calculating the haze metric, sampling days are not filtered for weather conditions. This assumption was tested by examining precipitation data from multiple monitors for four CIAs. It is shown that, in general, precipitation did not concurrently occur at all monitors for a CIA, and precipitation typically occurred 3-8 hr or less in a day. In a recent paper in this journal, Ryan asserts that the haze metric should include contributions from precipitation and conducted a quantitative assessment incorrectly based on the assumption that the Optec NGN-2 nephelometer measurements include the effects of precipitation. However, these instruments are programmed to shut down during rain events, and any data logged are in error. He further assumes that precipitation occurs as often on the haziest days as the clearest days and that precipitation light scattering (bprecip) is independent of geographic location and applied an average bprecip derived for Great Smoky Mountains to diverse locations including the Grand Canyon. Both of these assumptions are shown to be in error.

Air Pollutants↗

PubMed1953

Immunochemical studies of antitoxin produced in normal and allergic individuals hyperimmunized with diphtheria toxoid. III. Studies of the passive Arthus reaction in guinea pigs using human precipitating and nonprecipitating diphtheria antitoxin.

The Arthus reaction was studied in guinea pigs passively immunized with human diphtheria antitoxin. Diphtheria toxoid was given intradermally 24 hours following the intravenous administration of antitoxin and the subsequent reactions were graded and measured. The intensity of Arthus reactions was dependent upon the relative amounts of precipitating antitoxin and toxoid used. Severe lesions were caused by intravenous sensitization with 0.48 mg. precipitating antitoxin N and intradermal challenge with 0.05 or 0.17 toxoid N. Reactions of lesser intensity were caused by smaller amounts of antitoxin and toxoid. The nature of the antibody used for sensitization was of importance in the severity of Arthus reactions. In contrast to the behavior of precipitating antitoxin, amounts of non-precipitating antitoxin equivalent to 0.48 mg. N did not cause severe Arthus reactions when 0.05 or 0.17 mg. toxoid N was given intradermally. Precipitating antitoxic whole serum is altered by heating at 56 degrees C. for 5 hours so that its precipitability is lost without any appreciable loss of antitoxic strength. This modified antitoxin produced Arthus reactions of only intermediate severity in guinea pigs sensitized with 0.48 mg. antitoxin N. When fractions of precipitating antitoxic serum were obtained using a cold ethanol technique described by Deutsch (16), a mixture of the purified gamma(2)-globulin and the crude albumin fraction heated together at 56 degrees C. for 5 hours behaved similarly to whole serum. However, gamma(2)-globulin alone was not affected by the heating procedure, remained precipitable by toxoid, and was able to cause a severe Arthus reaction following sensitization with 0.48 mg. antitoxin N.

Administration, Intravenous↗