OP0177 IMMUNOGENICITY INDUCED BY TWO AND THREE DOSES OF THE BNT162B2 mRNA VACCINE IN PATIENTS WITH AUTOIMMUNE INFLAMMATORY RHEUMATIC DISEASES AND IMMUNOCOMPETENT CONTROLS: A LONGITUDINAL MULTI-CENTER STUDY

Background

Data on the kinetics of the immune response to SARS-CoV-2 vaccination in patients with autoimmune inflammatory rheumatic diseases (AIIRD) are limited.

Objectives

To evaluate the kinetics of the immune response induced by two and three doses of the BNT162b2 mRNA vaccine in adult patients with AIIRD and immunocompetent controls.

Methods

A prospective multicenter study investigated the antibody response to the BNT162b2 vaccine by serial measurement of serum anti-SARS-CoV-2 S1/S2 IgG titers at the following time points: 2-6 weeks (AIIRD n=720, controls n=122) and six months (AIIRD n=628, controls=116) after the second vaccine dose, and 2-6 weeks after the third vaccine dose (AIIRD n=169, controls n=45). A seropositive response was defined as a detectable anti-S1/S2 IgG titer ≥ 15 BAU/ml. T-cell immune response was evaluated in a sample of patients (n=28) and controls (n=9) by intracellular staining of S-stimulated CD4+ T-cells for TNFα and IFNγ production.

Results

The two-dose vaccine regimen induced a higher humoral response in controls compared to patients, as reflected by the post-vaccination seropositivity rates of 100% vs 84.72%, p<0.0001, and 96.55% vs 74.26%, p<0.0001 at 2-to-6 weeks and at 6 months, respectively. The decline of S1/S2 IgG titers within six months was similar in controls and patients. Following the 3rd vaccine, the seropositivity rate increased to 80.47% and 100% in AIIRD and control groups, p=0.0028, with a significantly higher increase of S1/S2 IgG titers in controls compared with AIIRD patients, 284.09±76.58 vs 219.39±151.55 BAU/ml, p=0.0016. At all-time points, S1/S2 IgG titers were significantly lower in AIIRD patients compared with controls (Figure 1).

We further investigated the impact of therapies on the vaccine‘s immunogenicity (Figure 1). Glucocorticoids (GC) were associated with a significantly lower seropositivity rate and lower S1/S2 IgG titers compared to controls at all time points. Monotherapy with methotrexate (MTX) was associated with a comparable to controls humoral response at all time points. Anti-cytokine biologics (TNFi, IL6i, IL17i) were associated with an initial high seropositivity rate, similar to controls, followed by a steeper decline at 6 months, 79.82% vs 96.55%, p=0.0001, and restoration of seropositivity after the 3rd vaccine dose in all patients. JAKi were associated with a mildly decreased seropositivity rate after the 2nd vaccine dose and similar to controls response after the 3rd vaccine dose. Abatacept was associated with a reduced immunogenicity after the 2nd vaccine dose, but was restored to 100% seropositivity after the 3rd vaccine dose. Rituximab (RTX) significantly blunted the humoral response at all time points, with a seropositivity rate of 42% after the 2nd vaccine dose, 29% at 6 months, and with increase to 40% after the 3rd vaccine dose. A third of the RTX-treated patients who were seronegative after two vaccine doses, seroconverted after the 3rd dose. The multivariate model for predicting the seropositive response to vaccination found that higher S1/S2 IgG titers after the 2nd vaccine dose was associated with a higher seropositivity rate following the 3rd vaccine dose, OR 1.026 (1.008-1.045), p=0.0027, and that treatment with RTX was associated with a 14.3-fold risk for a negative humoral response, p≤0.0001. Cellular immune response, evaluated mainly in RTX treated patients, was preserved prior to and after the 3rd vaccine dose and was similar to controls.

Conclusion

Over a six-month period, the two dose BNTb262 vaccination was associated with a similar extent of waning of the humoral immune response in AIIRD patients and controls. The 3rd vaccine dose restored the response in all controls and in patients treated with MTX monotherapy, anti-cytokine biologics, abatacept, and JAKi. Treatment with GC and RTX was associated with an impaired humoral response at all time points.

Acknowledgements

We would like to thank the statistician Mr Yishai Friedlander and Mr Yoram Neufeld for their valuable assistance.

Disclosure of Interests

None declared

Process evaluation of five tailored programs to improve the implementation of evidence-based recommendations for chronic conditions in primary care

Background

Although there is evidence that tailored implementation strategies can be effective, there is little evidence on which methods of tailoring improve the effect. We designed and evaluated five tailored programs (TPs) each consisting of various strategies. The aim of this study was to examine (a) how determinants of practice prioritized in the design phase of the TPs were perceived by health care professionals who had been exposed to the TPs and whether they suggested other important determinants of practice and (b) how professionals used the offered strategies and whether they suggested other strategies that might have been more effective.

Methods

We conducted a mixed-method process evaluation linked to five cluster-randomized trials carried out in five European countries to implement recommendations for five chronic conditions in primary care settings. The five TPs used a total of 28 strategies which aimed to address 38 determinants of practice. Interviews of professionals in the intervention groups and a survey of professionals in the intervention and control groups were performed. Data collection was conducted by each research team in the respective national language. The interview data were first analyzed inductively by each research team, and subsequently, a meta-synthesis was conducted. The survey was analyzed descriptively.

Results

We conducted 71 interviews; 125 professionals completed the survey. The survey showed that 76 % (n = 29) of targeted determinants of practice were perceived as relevant and 95 % (n = 36) as being modified by the implementation interventions by 66 to 100 % of professionals. On average, 47 % of professionals reported using the strategies and 51 % considered them helpful, albeit with substantial variance between countries and strategies. In the interviews, 89 determinants of practice were identified, of which 70 % (n = 62) had been identified and 45 % (n = 40) had been prioritized in the design phase. The interviewees suggested 65 additional strategies, of which 54 % (n = 35) had been identified and 20 % (n = 13) had been prioritized, but not selected in the final programs.

Conclusions

This study largely confirmed the perceived relevance of the targeted determinants of practice. This contrasts with the fact that no impact of the trials on the implementation of the recommendations could be observed. The findings suggest that better methods for prioritization of determinants and strategies are needed.

Trial registration

Each of the five trials was registered separately in recognized trial registries. Details are given in the respective trial outcome papers.

Electronic supplementary material

The online version of this article (doi:10.1186/s13012-016-0473-8) contains supplementary material, which is available to authorized users.

Comparison of indirect CsI/a:Si and direct a: SE digital radiography: An assessment of contrast and detail visualization

Purpose: To assess and quantify the image quality at two dose levels for an amorphous Silicon (a:Si) Cesium Iodide (CsI) flat panel system compared with a direct amorphous Selenium (a:Se) digital radiography system.

Material and Methods: A contrast detectability test was performed employing the CDRAD-phantom at mAs-values leading to approximately equal phantom entrance doses of 41.4, 57.9, 75.1 and 120.8 µGy for the a:Se and 39.9, 58.4, 75.6 and 117.9 µGy for the CsI system. Images were presented to 4 independent observers. For quantitative comparison, the image quality figure (IQF) was calculated. Statistical analysis was performed using Pearson's correlation and the Wilcoxon test. A ROC-analysis was performed employing the TRG-phantom in a high- and a low-dose setting leading to entrance doses of 126.2 and 35 µGy for the direct, and 125.9 and 34.4 µGy for the indirect system. Statistical significance was evaluated using the Wilcoxon test

Results: The flat panel a:Si digital system provided superior results compared with the a:Se drum digital system with respect to low-dose settings for CDRAD-phantom and ROC-analysis, ensuring a better image quality with respect to contrast and detail detectability. Higher-dose settings provided similar results for both systems.

Conclusion: Image quality of a:Si flat panel digital radiography proved to be superior to a:Se drum digital radiography using low-dose settings. If the primary target is dose reduction indirect flat panel technology should be used.

[Challenges and potentials of primary care in a multicultural society]

The greatest proportion of basic health care for patients with a migrational background living in Germany is provided by general practitioners. There is evidence that patients with a migrational background see a general practitioner as a gate keeper in case of physical or mental complaints even more frequently than the native German population. In contrast, the impact of migration-specific tasks in general practice appears to be relatively low in the medical and public discourse. This article analyzes the current situation of medical care for migrant patients in general practice and shows its potential to offer low-threshold high quality health care services to migrant patients and the whole population. In addition, an overview on migration-specific issues in research, teaching, and continuous medical education of general practitioners is provided. Finally, the implications of these findings for future research questions on migration-sensitive interventions are discussed.

[Health screening and vaccination status--results from a patient survey in German general practices]

The vaccination status of German adults needs improvement. Low participation is also known in health screening programmes like the "Check up 35" which is offered every two years for adults aged 35 or above. However, the number of participants in health screening increases with age whereas vaccination status decreases. Within a study about patients' attitudes towards prevention in primary care, we investigated the knowledge about the vaccination status. Therefore, an anonymous survey was conducted among 333 patients from five general practices in 2007. 76% of the potential participants in health screening declared that they utilise it at least infrequently. In contrast to those who participate frequently in health screening (67%), those who participate infrequently (38%) or never (33%) but declare that their vaccination status is complete are significantly rare. Due to the results of our study it has to be discussed whether the health screening "Check up 35" should be regularly accompanied with vaccination counselling.

BCG priming of dendritic cells enhances T regulatory and Th1 function and suppresses allergen-induced Th2 function in vitro and in vivo

BACKGROUND

The inverse correlation of mycobacterial infection with asthma prevalence and the inhibitory effects of vaccination with Bacille Calmette-Guérin (BCG) on airway hyperreactivity in asthma models suggest modulation of dendritic cell (DC) and T cell functions by mycobacterial compounds.

METHODS

To delineate these immunological effects, the immunogenicity of BCG Copenhagen, BCG Chicago and BCG Pasteur was compared in a mouse model. Bone marrow-derived dendritic cells (BMDCs) from BALB/c mice were stimulated with ovalbumin (OVA) with or without BCG. BMDCs were phenotypically characterized by flow cytometry, and we used ELISA to measure the cytokine production of BMDCs as well as of co-cultivated allergen-specific T cells in response to OVA-pulsed. Immunomodulatory effects of BCG were studied in a model of allergic airway inflammation by adoptive transfer of allergen-pulsed BMDCs.

RESULTS

Immunomodulation with BCG induced production of IL-10 and IL-12 by BMDCs. Co-cultured allergen-specific T cells produced less IL-5, IL-13 and IFN-gamma but more IL-10. Also the number of FoxP3(+) regulatory T cells was enhanced. Strongest effects were seen with BCG Chicago and BCG Pasteur. In vivo, administration of BCG modulated OVA-pulsed BMDCs then reduced eosinophilic airway inflammation but enhanced infiltration with granulocytes. Airway hyperreactivity and mucus production were reduced and more FoxP3(+) T cells were observed.

CONCLUSION

BCG-induced suppression of Th2-type allergic airway inflammation was associated with enhancement of regulatory T cell function but also of Th1-associated neutrophilic airway inflammation. These findings raise concerns regarding the safety profile of BCG as a potential tool for prevention and therapy of allergic airway disease.

Quantitative proton magnetic resonance spectroscopy of the normal liver and malignant hepatic lesions at 3.0 Tesla

This comparative study of tumour patients and volunteers aimed at differentiating liver parenchyma from neoplastic lesions by using localised (1)H MRS at 3.0 T as an adjunct to MRI. In total 186 single-voxel proton spectra of the liver were acquired at 3.0 T using the body transmit receive coil. Consecutive stacks of breath-hold spectra were acquired in the PRESS technique at a short echo time of 35 ms and a repetition time of 2,000 ms. Processing of the spectra included spectral alignment with the software package SAGE and quantitative processing with LCModel. The resulting metabolite concentrations were presented in arbitrary units relative to the internal water. In general, the spectra showed four main groups of resonances originating from the methyl protons (0.8-1.1 ppm) and methylene protons of the lipids (1.1-1.5 ppm; 2.0-2.2 ppm) as well as the methyl protons of choline-containing compounds (CCC) at 3.2 ppm. Overall, the CCC and lipid values in malignant liver tumours showed no significant differences to liver parenchyma. On average, total lipid measurements in normal liver parenchyma increased with age, while those of the CCC did not show pertinent changes. Significant differences between the contents of CCC in malignant liver tumours and normal liver parenchyma were not observed, because in patients and volunteers normal liver tissue showed a large variability in the content of CCC.

MR-guided interstitial laser thermotherapy of colorectal liver metastases: efficiency, safety and patient survival

PURPOSE

Evaluation of MR-guided interstitial laser thermotherapy (ILT) of colorectal liver metastases under consideration of efficacy, safety and patient survival.

MATERIALS AND METHODS

Sixty-six inoperable patients with a total of 117 colorectal liver metastases were treated with MR-guided laser therapy in 96 sessions. 40.9% of patients presented metastases from rectum carcinoma, 30.3% from sigmoid carcinoma and 28.8% from colon carcinoma. Inclusion criteria were < or =5 metastases < or =5 cm in greatest diameter and no extrahepatic tumor spread. Internally water-cooled 9F power-laser-applicators were placed under CT-fluoroscopy. For MR-guided ILT, a 1064 nm Nd-YAG-lasers with a beam divider with multi applicator technique was used. The energy applied was 10 watt per centimeter diffusor length, with the diffusor length ranging from 20 to 40 mm. The mean duration of the energy application was 23 minutes (range: 15 - 37 minutes). The endpoint of the laser ablation was defined as the absence of hyperintense tumor tissue in the continuously monitored T2-w fat saturated gradient-echo sequences. Follow-up included contrast-enhanced MRI using T1- and T2-weighted spin-echo and gradient-echo sequences every three months after treatment. Survival times were calculated using the Kaplan-Meier method.

RESULTS

The median follow-up was 8.7 months (mean 11.8; standard deviation 9.9; range 1 to 36). The overall median progression free survival was 6.1 months (range, 0.3 to 27+ months). Median survival was 23 months (95% CI, 17-29 months). The rate of major complications was 2.1% (n = 2) and peri-procedural mortality (30 days) was 3% (n = 2). After 3, 6, 9, and 12 months, local tumor control was 98.3%, 91.4%, 76.1%, and 69.4%, respectively. In no patient metastatic deposits along the catheter access route were found.

CONCLUSIONS

In patients with colorectal liver metastases, interstitial laser thermotherapy is an effective and safe therapeutic option and therefore suitable not only in palliative situations.

Colon dissection: a new three-dimensional reconstruction tool for computed tomography colonography

PURPOSE

To improve the sensitivity of computed tomography (CT) colonography in the detection of polyps by comparing the 3D reconstruction tool "colon dissection" and endoluminal view (virtual colonoscopy) with axial 2D reconstructions.

MATERIAL AND METHODS

Forty-eight patients (22 M, 26 F, mean age 57 +/- 21) were studied after intra-anal air insufflation in the supine and prone positions using a 16-slice helical CT (16 x 0.625 mm, pitch 1.7; detector rotation time 0.5 s; 160 mAs und 120 kV) and conventional colonoscopy. Two radiologists blinded to the results of the conventional colonoscopy analyzed the 3D reconstruction in virtual-endoscopy mode, in colon-dissection mode, and axial 2D slices.

RESULTS

Conventional colonoscopy revealed a total of 35 polyps in 15 patients; 33 polyps were disclosed by CT methods. Sensitivity and specificity for detecting colon polyps were 94% and 94%, respectively, when using the "colon dissection", 89% and 94% when using "virtual endoscopy", and 62% and 100% when using axial 2D reconstruction. Sensitivity in relation to the diameter of colon polyps with "colon dissection", "virtual colonoscopy", and axial 2D-slices was: polyps with a diameter >5.0 mm, 100%, 100%, and 71%, respectively; polyps with a diameter of between 3 and 4.9 mm, 92%, 85%, and 46%; and polyps with a diameter < 3 mm, 89%, 78%, and 56%. The difference between "virtual endoscopy" and "colon dissection" in diagnosing polyps up to 4.9 mm in diameter was statistically significant.

CONCLUSION

3D reconstruction software "colon dissection" improves sensitivity of CT colonography compared with the endoluminal view.

Effect of dose on image quality in a detector-based dual-exposure, dual-energy system for chest radiography

PURPOSE

To assess the image quality of subtracted soft tissue and bone images of a CsI-detector-based dual-energy system for chest radiography at varying dose levels.

MATERIAL AND METHODS

We evaluated a CsI-detector-based, dual-exposure, dual-energy prototype system; 126 patients were categorized into groups of small, medium, and large. Fixed values were applied for mAs and mA. The patients were randomized into two groups with intended higher and lower speed pairs of approximately 400/1000 (high and low energy shot) and 200/500, respectively. True speed equivalents were calculated retrospectively using the detector dose. Image quality was evaluated by two highly experienced radiologists in consensus applying a rating scale of 1 to 5 for quality indicators such as image noise, residual bone structures, motion artifacts, and others.

RESULTS

Significantly decreased noise and a significant improvement for display of bone details in the bone image were noted with the higher dose, whereas a significant increase in motion artifacts reduced image quality at the higher dose.

CONCLUSION

Radiation dose did not significantly influence the perception of dual-energy image quality. Dual-energy subtraction, as described, has the potential to become a future routine application in chest radiography.

Comparison of indirect CsI/a:Si and direct a:Se digital radiography. An assessment of contrast and detail visualization

PURPOSE

To assess and quantify the image quality at two dose levels for an amorphous Silicon (a:Si) Cesium Iodide (CsI) flat panel system compared with a direct amorphous Selenium (a:Se) digital radiography system.

MATERIAL AND METHODS

A contrast detectability test was performed employing the CDRAD-phantom at mAs-values leading to approximately equal phantom entrance doses of 41.4, 57.9, 75.1 and 120.8 micro Gy for the a:Se and 39.9, 58.4, 75.6 and 117.9 micro Gy for the CsI system. Images were presented to 4 independent observers. For quantitative comparison, the image quality figure (IQF) was calculated. Statistical analysis was performed using Pearson's correlation and the Wilcoxon test. A ROC-analysis was performed employing the TRG-phantom in a high- and a low-dose setting leading to entrance doses of 126.2 and 35 micro Gy for the direct, and 125.9 and 34.4 micro Gy for the indirect system. Statistical significance was evaluated using the Wilcoxon test.

RESULTS

The flat panel a:Si digital system provided superior results compared with the a:Se drum digital system with respect to low-dose settings for CDRAD-phantom and ROC-analysis, ensuring a better image quality with respect to contrast and detail detectability. Higher-dose settings provided similar results for both systems.

CONCLUSION

Image quality of a:Si flat panel digital radiography proved to be superior to a:Se drum digital radiography using low-dose settings. If the primary target is dose reduction indirect flat panel technology should be used.

GABAergic cells are the major postsynaptic targets of mossy fibers in the rat hippocampus

Dentate granule cells communicate with their postsynaptic targets by three distinct terminal types. These include the large mossy terminals, filopodial extensions of the mossy terminals, and smaller en passant synaptic varicosities. We examined the postsynaptic targets of mossy fibers by combining in vivo intracellular labeling of granule cells, immunocytochemistry, and electron microscopy. Single granule cells formed large, complex "mossy" synapses on 11-15 CA3 pyramidal cells and 7-12 hilar mossy cells. In contrast, GABAergic interneurons, identified with immunostaining for substance P-receptor, parvalbumin, and mGluR1a-receptor, were selectively innervated by very thin (filopodial) extensions of the mossy terminals and by small en passant boutons in both the hilar and CA3 regions. These terminals formed single, often perforated, asymmetric synapses on the cell bodies, dendrites, and spines of GABAergic interneurons. The number of filopodial extensions and small terminals was 10 times larger than the number of mossy terminals. These findings show that in contrast to cortical pyramidal neurons, (1) granule cells developed distinct types of terminals to affect interneurons and pyramidal cells and (2) they innervated more inhibitory than excitatory cells. These findings may explain the physiological observations that increased activity of granule cells suppresses the overall excitability of the CA3 recurrent system and may form the structural basis of the target-dependent regulation of glutamate release in the mossy fiber system.

Excitatory synaptic connections onto rat hippocampal inhibitory cells may involve a single transmitter release site

1. Whole-cell tight-seal records of excitatory postsynaptic currents (EPSCs) were made from inhibitory cells in the CA3 region of thin hippocampal slices. We tested the hypothesis that excitatory synaptic connections made on inhibitory cells involve few transmitter release sites. 2. EPSCs impinging on inhibitory cells had a time to peak of 0.4-3.8 ms and an amplitude of 8-90 pA at a holding potential of -60 mV. They were suppressed by the excitatory amino acid antagonists 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and DL-2-amino-5-phosphonovaleric acid (APV). 3. Addition of tetrodotoxin (TTX) and Co2+ to the external solution reduced the frequency of EPSCs from 0.90 to 0.25 s-1 (n = 24 cells). In the majority of cells EPSC amplitude distributions were not significantly changed. 4. Increasing Ca2+ and reducing Mg2+ in the external solution, in order to enhance the probability of transmitter release, did not change EPSC amplitude distributions. In contrast, amplitude histograms for IPSCs recorded from pyramidal cells were shifted to higher mean values in this solution. 5. EPSCs were elicited in inhibitory cells by electrical stimulation via a glass pipette placed near to pyramidal cells in stratum pyramidale. EPSCs elicited by weak stimuli had similar amplitude distributions to excitatory synaptic events recorded in the presence of TTX and Co2+. 6. These findings suggest excitatory synaptic connections made with CA3 inhibitory cells involve few or possibly just one transmitter release site.

Relative functional buffering capacity in 400-meter runners, long-distance runners and untrained individuals

Buffering is a factor which influences performance in short and middle-term endurance by compensating exercise acidosis. The aim of the study was to establish whether respiration parameters are a relative measure of buffering capacity and to study the influence of buffering on specific performance parameters. Three groups (each of ten subjects) with defined degrees of adaptation [untrained (UT), aerobic-trained (AeT) and elite 400-m runners (AnT) with a best time of 48.47 +/- 0.98 s] were examined in an incremental multi-stage test on the treadmill. Breath-by-breath gas analysis was performed using mass spectrometry and computer routines. Serum lactate concentrations were determined at each exercise level until subjective exhaustion. A value for the relative functional buffering capacity (relFB) was calculated using exercise metabolic parameters. Running speed at the lactate threshold was used as the starting point of buffering. The start of respiratory compensation of acidosis (RCP) was taken as the endpoint of buffering. RCP was determined at the point of decrease in end-tidal CO2 content (CO2-ET). RelFB was given in percent of buffering to running speed at RCP. Group AnT attained the same maximum performance data (maximum running speed, maximum rate of O2 consumption) as group AeT. However, these values were attained in group AnT with a significantly higher relFB (AnT: 31.0 +/- 3.2% vs. AeT: 15.7 +/- 3.9%, P < 0.0001), while a higher lactate threshold indicated a greater oxidative capacity in AeT (AeT: 3.07 +/- 0.26 m.s-1 vs. AnT: 2.68 +/- 0.22 m.s-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Stimulation in vitro by 1,25-dihydroxy-vitamin D3 of intestinal cell calcium uptake and calcium-binding protein

Treatment of duodenal tissue from rats deficient in vitamin D with 1,25-dihydroxy-vitamin D3 [1,25-(OH)2-D3] led to more than a doubling of calcium uptake by the isolated cells and the appearacne in those cells of previously undetectable calcium-binding protein (CaBP). Treatment with the precursor, 25-hydroxy-vitamin D3, was without effect on calcium uptake or CaBP. Cells from vitamin D-replete animals took up three and a half times more calcium than cells from deficient animals. This rapid (90-minute) effect of in vitro treatment with a physiological dose (4.7 X 10(-8)M) of 1,25-(OH)2-D is the first such report and is in accord with the regulatory role of the hormone-like sterol.

Intestinal CaBP: a new quantitive index of vitamin D deficiency in the rat

Rats raised from weaning on regiments adequate in calcium and phosphorus but deficient in vitamin D will have no detectable intestinal calcium-binding proteins (CaBP), whether or not they show other signs of vitamin D deficiency, such as hypocalcemia. When hypocalcemic, vitamin D-deficient animals were treated with 25-hydroxycholecalciferol, a vitamin D metabolite, they showed a dose-dependent increase in plasma calcium and CaBP; both responses can be described by a single linear relationship, which appears to apply whether the metabolite is 25-hydroxycholecalciferol or dihydrotachysterol. Since vitamin D status is only one determinant of plasma calcium, whereas CaBP (or its expression) appears to depend on vitamin D quantitatively, CaBP may be used as an index of vitamin D status, provided calcium intake is controlled.

Regulation of intestinal calcium-binding protein calcium intake in the rat

Analytical gel electrophoresis of the vitamin D-dependent intestinal calcium-binding protein (CaBP) has demonstrated two protein bands (1 and 2) of similar molecular weight and similar specific binding activity. The mucosal concentration of CaBP, measured by a quantitative competitive binding assay, has been shown to vary reproducibly and inversely with calcium intake and the mucosal calcium concentration. These same factors also influence the relationship of bands 1 and 2. When animals on a high-calcium diet were placed on a low-calcium diet, their CaBP increased by 35% in 24 h and by 48% in 48 h and reached a level typical of animals on a low-calcium diet. Measurement of the diurnal variation of CaBP and mucosal calcium in animals allowed access to feed only at night revealed significant, but inverse, oscillations. These observations are interpreted as reflecting a regulation of CaBP by the mucosal calcium concentration, which appears to reflect absorbed calcium in transit.

-Crystallin. The isolation and characterization of distinct macromolecular fractions

alpha-Crystallin was isolated from calf lens periphery by chromatography on DEAE-cellulose and gel filtration. Three distinct populations of macromolecules have been isolated with molecular weights in the ranges approx. 6x10(5)-9x10(5), 0.9x10(6)-4x10(6) and greater than 10x10(6). The concentration of macromolecules at the molecular-weight limits of a population are very low. The members of the different populations do not appear to be in equilibrium with each other. Further, in those molecular-weight fractions investigated, no equilibrium between members of the same population was observed. The population of lowest molecular weight comprises 65-75% of the total material. The amino acid and subunit composition of the different-sized fractions appear very similar, if not identical. The only chemical difference observed between the fractions is the presence of significant amounts of sugar in the higher-molecular-weight fractions. Subunit molecular weights of approx. 19.5x10(3) and 22.5x10(3) were observed for all alpha-crystallin fractions.