[Preparation of oral microspheres carrying V. cholera vaccine and its target's distribution]

To prepare oral biodegradable microspheres carrying V. cholera vaccine, the major outer membrane protein (OMP, MW = 41 kd) as a common antigen of cholera Vibriae was obtained from the classical strain Inaba 569 B, and the OMP was encapsulated in the biodegradable delivery system comprising Poly (DL-Lactide)-Co-Poly(ethylene glycol)microspheres. The average size of the microspheres was less than 5 microns, the amount of OMP encapsulated in microspheres was 15.3%. It was found that microspheres were taken up in Peyer's patches and then distributed in spleen, liver and mesenteric lymph nodes after oral administration.

[Association of Gln223Arg variant in leptin receptor gene with metabolic abnormalities and hypertension in type II diabetes mellitus in Shanghai "Han" population]

OBJECTIVE

To investigate the association of Gln223Arg variant in leptin receptor gene with metabolic abnormalities and hypertension in type II diabetes mellitus.

METHODS

The genotypes of Gln223Arg variant in leptin receptor gene were determined by polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) assay in 359 unrelated subjects of Shanghai "Han" population (including 193 subjects with normal glucose tolerance and 166 type II diabetic patients). The clinical data were also analyzed. The parameters for regional adipose tissue distribution were measured by magnetic resonance imaging (MRI).

RESULTS

Significant difference of genotype frequency of Gln223Arg variant in leptin receptor gene was observed between hypertensive and normotensive type II diabetic male patients (P = 0.008). "A" allele was associated with increased systolic blood pressure (P = 0.0026) and diastolic blood pressure (P = 0.0084) in type II diabetic male patients. Logistic regression analysis showed that this gene variant was an independent risk factor of type II diabetic male patients accompanied with hypertension (P = 0.0031), and it was associated with elevation of systolic blood pressure (P = 0.0054). The odds ratio of hypertension in type II diabetic male patients with "A" allele was 2.825 (95% CI 1.418, 5.627).

CONCLUSION

Gln223Arg variant in leptin receptor gene is associated with hypertension in type II diabetic male patients, especially with elevation of systolic blood pressure.

[Purification and identification of pili of Vibrio cholera O139]

To provide the base of manufacturing V. cholera O139 subunit vaccine, purification and identification methods of V. cholera O139 Toxin-coregulated pili (TCP) were studied. The results showed the optimal expressing condition of TCP was in AKI or CFA medium, at 30 C for 24-36 h with stationary cultivation. The molecular weight of the TCP subunit protein measured by sodium dodecyl sulfate-poly acrylamide gel electrophoresis was about 20.5 kd. By using mouse anti-TCP monoclone antibody and sheep anti-mouse IgG-HRP antibody, the TCP was confirmed by dot blot immunoassay. Rabbit immune serum of TCP purified from O139 strain agglutinated both O139 biotype and El Tor biotype Vibrio cholera strains. These indicate that TCP may be an effective and protective antigen to conduct the preparation of V. cholera vaccine.

Investigation on process parameters involved in preparation of poly-DL-lactide-poly(ethylene glycol) microspheres containing Leptospira Interrogans antigens

Block copolymer, poly-DL-lactide-poly(ethylene glycol) (PELA) with 11.5% of poly(ethylene glycol) (PEG) content was prepared by bulk ring-opening polymerization using stannous chloride as initiator. PELA microspheres with entrapped Leptospira Interrogans antigens, outer membrane protein (OMP) were elaborated by solvent extraction method based on the formation of multiple w/o/w emulsion, and the resulting microspheres were characterized with respect to particle size, OMP entrapment and morphology characteristics. The purpose of the present study is to perform the optimization of preparative parameters for OMP-loaded PELA micropsheres to control particle size and improve the OMP encapsulation efficiency. Of all the parameters investigated, the polymer concentration of organic phase and the external aqueous phase volume play major roles on particle size, while the organic phase volume, internal aqueous phase volume and the addition of surfactant into the internal aqueous phase display considerable effects on OMP loading efficiency. A small volume of internal aqueous phase and intermediate volumes of organic phase and external aqueous phase were favorable to achieve micropsheres with a size of 1-2 microns and high antigen encapsulation efficiency (70-80%). In vitro OMP release profiles from PELA microspheres consist of a small burst release followed by a gradual release phase. The OMP release rate shows some relations with the porous and water-swollen inner structure of the microspheres matrix. The presence of surfactant in microspheres accelerates OMP release, but the OMP entrapment within microspheres shows limited effects on the release profile.

The impact of codon 54 variation in intestinal fatty acid binding protein gene on the pathogenesis of diabetes mellitus in Chinese

OBJECTIVE

To investigate whether or not the intestinal fatty acid binding protein gene (FABP2)-Ala54Thr variation is related to non-insulin dependent diabetes mellitus (NIDDM), obesity, dyslipidemia and glucose stimulated insulin secretion (GSIS) in Chinese.

METHODS

The FABP2-Ala54Thr variation was detected by PCR/Hhal digestion in 231 Chinese subjects (116 with normal glucose tolerance (NGT), 54 with impaired glucose tolerance (IGT) and 61 with NIDDM). Plasma glucose, insulin and C-peptide levels before and after 75 g glucose load as well as fasting lipid profile were determined.

RESULTS

(1) The Ala54 and Thr54 allele frequencies in Chinese were 0.71 and 0.29 respectively; (2) The FABP2-Ala54Thr variation was neither associated with fasting and post-challenged plasma glucose levels nor with NIDDM; (3) This variation was neither associated with fasting lipid profile nor with obesity; (4) The IGT subjects with genotype Thr54(+) (Thr54 homozygotes and heterozygotes) had lower fasting, 2-hour and total C-peptide levels and smaller AUC representing lesser C-peptide secretion after glucose challenge than those with genotype Thr54(-) (Ala54 homozygotes) (P = 0.04, 0.03, 0.01 and 0.01 respectively). The serum insulin levels changed in the same tendency.

CONCLUSIONS

The glucose stimulated insulin secretion (GSIS) reserve of islet beta-cells is more limited in subjects with FABP2-Thr54(+) genotype than in those with FABP2-Thr54(-) genotype. It suggests that FABP2-codon 54 variation might contribute to the insufficient insulin secretion in the development of NIDDM in Chinese.

Urinary cross-linked N-telopeptides of type I collagen and bone metabolic diseases

OBJECTIVE

To evaluate the type I collagen cross-linked N-telopeptide (NTx) levels in human urine as an indicator of bone resorption rate in different ages, sex and in bone metabolic diseases.

METHODS

Urinary NTx was determined by immunoassay in 591 Beijing healthy subjects aged from 0 to 86 years and 379 patients with bone metabolic diseases.

RESULTS

The levels of urinary NTx were significantly higher in children than in adults (P < 0.001) and higher in boys than in girls (P < 0.01) and increased 1.4-2.2 times in postmenopausal females than in men and premenopausal women. Urine NTx had a positive linear correlation with urine HOP/Cr (r = 0.778, P < 0.01) and Ca/Cr ratio (r = 0.320, P < 0.01), and a negative linear correlation with age (r = -0.523, P < 0.01) and lumbar spine BMD (r = -0.426, P < 0.01). The levels of urine NTx increased for 3.6 times in pregnancy, 1.5 times in osteoporosis, 1.9 times in fragility fracture, 3.6 times in chronic renal failure, 2.1 times in rickets and 7.2 times in multiple myeloma compared to age matched controls.

CONCLUSIONS

NTx in urine is a specific and sensitive indicator of bone resorption and is able to distinguish normal premenopause from late osteoporotic patients. NTx could be used as diagnostic information about metabolic bone diseases, and to monitor antiresorptive therapy.

Cell surface expression of MHC molecules in glioma cells infected with herpes simplex virus type-1

9L glioma cells consistently expressed major histocompatibility complex (MHC) class I but not class II molecules. Herpes simplex type-1 virus (HSV-1) infection significantly reduced the expression of MHC I on the cell surface. Recombinant interferons could enhance the cell-surface expression of MHC I but had no effect on MHC II. This enhancement was partially inhibited by HSV-1 infection. HSV-1 mutants with deletions in ICP4, ICP6, ICP27, ICP47 and UL41 genes do not affect the infection induced inhibition, suggest that a different mechanism may be employed in the inhibition of cell-surface expression of MHC molecules.

Immunohistochemical localization of dopamine-beta-hydroxylase in human and monkey eyes

PURPOSE

To investigate the pattern of dopamine-beta-hydroxylase (DBH)-containing fibers in human and monkey eyes.

METHODS

DBH-containing fibers were detected by immunohistochemistry. The primary antibody used recognized DBH, the key enzyme in the conversion of dopamine to noradrenaline.

RESULTS

In the anterior segment, DBH immunoreaction product was found in the peripheral corneal endothelium layer, in both the dilator and sphincter muscles of the iris, as well as in the anterior border layer of the iris. The ciliary muscle and the stroma of the ciliary processes were also zones of concentration. In the posterior segment, staining was seen around blood vessels in the choroid, in the vascular walls of the short posterior ciliary arteries and in the ciliary nerves. The retina was also immunopositive, with specific labeling in cones and rods of photoreceptors, inner and outer plexiform layers and ganglion cell layer. There was no significant difference in the distribution of DBH-related immunoreactivity in human and monkey eyes.

CONCLUSIONS

The localization of DBH-related immunoreactivity is generally consistent with the known physiological roles of noradrenaline. However, an apparently high concentration of the enzyme in the anterior border layer of the iris and in retinal photoreceptors raises questions about the possible role of DBH-containing fibers in these structures.

[Effects of Trp64Arg mutation in the beta 3-adrenergic receptor gene on body fat, plasma glucose level, lipid profile, insulin secretion and action in Chinese]

OBJECTIVE

To ascertain the association of the Trp64Arg mutation in the beta 3-adrenergic receptor (ADRB3) gene with the total body fat and fat distribution, plasma glucose level, lipid profile, insulin secretion and action in Chinese.

METHODS

Genotyping of the Trp64Arg mutation in the ADRB3 gene as well as measurment of clinical variables body mass index(BMI), percent of desirable weight(PDW), area of regional adipose tissue depots, fasting lipid profile, and also, plasma glucose, insulin, C-peptide, free fatty acids levels before and after glucose challenge and blood pressure were performed in 308 Chinese, of whom, 161 were nondiabetics and 147, type 2 diabetic subjects.

RESULTS

(1) The frequency of Arg64 allele of ADRB3 gene in Chinese was similar to that in Japanese but slightly higher than that in Caucasians. (2) No association of any of the clinical varaibles with Trp64Arg mutation was observed in nondiabetics. (3) The Trp64Arg mutation in the ADRB3 gene was associated with BMI(P=0.019), PDW(P=0.001) and waist circumference (P=0.045) in type 2 diabetic subjects. In female diabetic subjects, more significant association with BMI(P=0.001), PDW(P=0.001), waist circumference(P=0.023), and also, association with abdominal and femoral subcutaneous fat area(P=0.032 and P=0.023) were observed. The frequencies of Arg64 allele were 21%, 14% and 4% in female diabetics with obesity, over-weight and normal-weight respectively (P=0.026). Logistic regression analysis showed that BMI was the only independent clinical variable related to the Trp64Arg mutation in the ADRB3 gene (P=0.0027).

CONCLUSION

The Trp64Arg mutation in ADRB3 gene contributes to the variation of total body fat in Chinese type 2 diabetic subjects.

Mini-proinsulin and mini-IGF-I: homologous protein sequences encoding non-homologous structures

Protein minimization highlights essential determinants of structure and function. Minimal models of proinsulin and insulin-like growth factor I contain homologous A and B domains as single-chain analogues. Such models (designated mini-proinsulin and mini-IGF-I) have attracted wide interest due to their native foldability but complete absence of biological activity. The crystal structure of mini-proinsulin, determined as a T3R3 hexamer, is similar to that of the native insulin hexamer. Here, we describe the solution structure of a monomeric mini-proinsulin under physiologic conditions and compare this structure to that of the corresponding two-chain analogue. The two proteins each contain substitutions in the B-chain (HisB10-->Asp and ProB28-->Asp) designed to destabilize self-association by electrostatic repulsion; the proteins differ by the presence or absence of a peptide bond between LysB29 and GlyA1. The structures are essentially identical, resembling in each case the T-state crystallographic protomer. Differences are observed near the site of cross-linking: the adjoining A1-A8 alpha-helix (variable among crystal structures) is less well-ordered in mini-proinsulin than in the two-chain variant. The single-chain analogue is not completely inactive: its affinity for the insulin receptor is 1500-fold lower than that of the two-chain analogue. Moreover, at saturating concentrations mini-proinsulin retains the ability to stimulate lipogenesis in adipocytes (native biological potency). These results suggest that a change in the conformation of insulin, as tethered by the B29-A1 peptide bond, optimizes affinity but is not integral to the mechanism of transmembrane signaling. Surprisingly, the tertiary structure of mini-proinsulin differs from that of mini-IGF-I (main-chain rms deviation 4.5 A) despite strict conservation of non-polar residues in their respective hydrophobic cores (side-chain rms deviation 4.9 A). Three-dimensional profile scores suggest that the two structures each provide acceptable templates for threading of insulin-like sequences. Mini-proinsulin and mini-IGF-I thus provide examples of homologous protein sequences encoding non-homologous structures.

Intracerebral recombinant HSV-1 vector does not reactivate latent HSV-1

Herpes simplex virus type-1 (HSV-1) has been used for gene delivery in the nervous system for the treatment of brain tumors and other neurological diseases. In most protocols, recombinant viruses containing the gene of interest are directly injected into the brain. Since many people harbor latent wild-type HSV-1 virus in sensory ganglia and other regions of the nervous system, there is a potential risk that the injected recombinant virus may reactivate the latent wild-type virus to cause severe encephalitis. The present study used two rat latent infection models to evaluate this risk. Adult rats were infected with wild-type kos by cornea scarification or by intracerebral injection, and after the establishment of latency, the ICP6(-) strain hrR3 was injected intracerebrally. In the control group, the latent virus was reactivated by treatment of cadmium sulfate. Viral shedding from tears was detected by incubation with Vero cells, and the trigeminal ganglia, cortical tissue and the eyes were collected to detect reactivated wild-type virus by RT-PCR. Our results showed that while the reactivated wild-type virus was readily detectable in the cadmium-sulfate-treated animals, intracerebrally infected hrR3 did not reactivate the latent virus in either the corneal model or the cerebral model. These results indicate that intracranial injection of partially defective recombinant virus may bear little risk of reactivating latent wild-type virus harbored in the sensory ganglia or the brain in our animal model.

Elevated nonesterified fatty acid concentrations in severe preeclampsia shift the isoelectric characteristics of plasma albumin

We previously hypothesized that the endothelial cell dysfunction observed in women with preeclampsia might be caused by an imbalance between circulating very low density lipoproteins and a cytoprotective pI 5.6 isoform of albumin, referred to as toxicity preventing albumin (TxPA). An accurate simplified method was developed to quantify TxPA in small volumes of pregnancy plasma by gel electrofocusing. This assay revealed that circulating TxPA concentrations in women with severe preeclampsia were significantly reduced compared to those in normal pregnant women and women with benign transient hypertension of pregnancy. Nonesterified fatty acids (NEFA) and triglycerides were elevated in plasma from women with severe preeclampsia compared to those in plasma from the two control groups. The inverse correlation between TxPA and NEFA values led us to analyze the NEFA bound to plasma albumin. Gas chromatography and mass spectrometry demonstrated no qualitative differences in the specific fatty acids bound to plasma albumin in severe preeclamptic and normal pregnant women. However, the quantity of NEFA bound to albumin was greater in preeclampsia plasma (2.5 mol NEFA/mol albumin) compared to that in normal pregnancy plasma (0.8 mol NEFA/mol albumin), accounting for the acidic pI shift observed in albumin from the former patients. Functional assays demonstrated that human very low density lipoprotein particles were toxic to human umbilical vein endothelial cells in vitro, but this toxicity was prevented by the addition of TxPA albumin to the culture medium.

Comparison of the neuroprotective effects of APV and bcl-2 in glutamate-induced cell death

The neuroprotective effects of the NMDA receptor blocker APV were compared with those of bcl-2 in a glutamate-induced excitotoxic cell death model in cultured rat cortical neurons. Exposure to 100 microM glutamate for 5 h caused approximately 95% of the cultured neurons to die in 24 h. The NMDA-selective antagonist D-(-)-2-amino-5-phosphonopentanoate (APV) protected the neurons effectively when applied prior to or soon after glutamate treatment. However, infection with a viral vector expressing the proto-oncogene bcl-2 strongly protected neurons even if applied as late as 8 h following the glutamate insult. These data provides evidence that APV blocks an early stage of the death cascade in response to elevations of glutamate. By contrast bcl-2 appears to act at a fairly late stage in the cell death process and these results suggest a possible clinical role in treatment of ischemic brain disorders.

Irradiation-induced luminescence enhancement effect of ZnS:Mn(2+) nanoparticles in polymer films

The effects of irradiation-induced luminescence enhancement by ZnS:Mn(2+) nanoparticles in poly(vinyl butyral) films are reported. The luminescence intensity increases several times when fresh samples are irradiated by a 248-nm excimer laser. The decay time also increases with exposure time. The increase in the initial intensity of the slow component of luminescence makes the main contribution to the enhancement effect. A tentative model is proposed in which the efficiency of the energy transfer to Mn(2+) ions increases with exposure. States at interfaces are expected to play an important role in this process.

Investigation into self-pumped and mutually pumped phase conjugation with beams entering the negative c face of doped (K(0.5)Na(0.5))(0.2)(Sr(0.75)Ba(0.25))(0.9)Nb(2)O(6)crystals

We investigated some novel geometries of self-pumped phase conjugation (SPPC) and mutually pumped phase conjugation (MPPC), relying on total internal reflection both from the a face and from corners, with beams entering the negative c face of doped (K(0.5)Na(0.5))(0.2)(Sr(0.75)Ba(0.25))(0.9) Nb(2)O(6) crystals. The different situations for internal light paths and their direct transformation at the same incident wavelength were observed. Similarities and differences between SPPC and MPPC are discussed. The dynamic features of SPPC and MPPC in different situations were also observed. Three or more four-wave-mixing interaction regions were clearly observed inside the phase conjugators. The multistep interaction and its influence on the response rate and conjugation fidelity are analyzed. The large size of the samples seems necessary to ensure an optical path that is long enough for multistep bifurcation. The stability of the light channels is discussed based on the fanning effect.

Mitochondrial tRNA(Leu(UUR)) gene mutation diabetes mellitus in Chinese

OBJECTIVE

To ascertain the prevalence and clinical features of mitochondrial tRNALeu(UUR) gene nucleotide (nt) 3243 A-->G mutation diabetes mellitus in Chinese and to establish the approaches for genetic diagnosis of this subtype of diabetes during routine daily clinical practice.

METHODS

Mitochondrial nt 3243 A-->G mutation was screened among 207 unrelated non-insulin-dependent diabetes mellitus (NIDDM) patients by using polymerase chain reaction (PCR)/Apa I restriction endonuclease digestion. Samples with positive result were confirmed by DNA sequence analysis. Genetic and clinical analysis were carried out in family members of the proband with positive genetic diagnosis.

RESULTS

Positive results were found in two subjects during screening of unrelated NIDDM patients, which account for 2.4%-11.1% of NIDDM subjects with uncommon clinical features (with early age-of-onset, with low body-mass-index and on insulin therapy) or with positive family history of diabetes consistent with or unable to exclude from maternal inheritance. Genetic diagnosis was positive in 10 out of 25 family members in the pedigrees of these two probands.

CONCLUSIONS

Mitochondrial tRNALeu(UUR) gene nt 3242 A-->G mutation should be considered in diabetic patients with the above-mentioned clinical features. The genetic diagnosis in daily clinical practice can be performed with allele specific priming amplification, or PCR/Hae III or Apa I digestion which are technically simple to perform and diagnostically easy to define.

Mapping the functional surface of insulin by design: structure and function of a novel A-chain analogue

Functional surfaces of a protein are often mapped by combination of X-ray crystallography and mutagenesis. Such studies of insulin have yielded paradoxical results, suggesting that the native state is inactive and reorganizes on receptor binding. Of particular interest is the N-terminal alpha-helix of the A-chain. Does this segment function as an alpha-helix or reorganize as recently proposed in a prohormone-convertase complex? To correlate structure and function, we describe a mapping strategy based on protein design. The solution structure of an engineered monomer ([AspB10, LysB28, ProB29]-human insulin) is determined at neutral pH as a template for synthesis of a novel A-chain analogue. Designed by analogy to a protein-folding intermediate, the analogue lacks the A6-A11 disulphide bridge; the cysteine residues are replaced by serine. Its solution structure is remarkable for segmental unfolding of the N-terminal A-chain alpha-helix (A1 to A8) in an otherwise native subdomain. The structure demonstrates that the overall orientation of the A and B chains is consistent with reorganization of the A-chain's N-terminal segment. Nevertheless, the analogue's low biological activity suggests that this segment, a site of clinical mutation causing diabetes mellitus, functions as a preformed recognition alpha-helix.

Influence of the internal photoinduced electric field on the formation of self-pumped phase conjugation in doped (K(0.5)Na(0.5))(0.2)(Sr(0.75)Ba(0.25))(0.9)Nb(2)O(6) crystals

The obvious influence of the internal photoinduced electric field on the formation of self-pumped phase conjugation in doped (K(0.5) Na(0.5))(0.2) (Sr(0.75) Ba(0.25))(0.9) Nb(2)O(6) crystals has been investigated with intermittent and continuous laser beams. An analysis is given that involves the migration of charge carriers driven by the photovoltaic (PV) and the pyroelectric (PY) electric field. Deviation from the optimal state of energy transfer owing to the PV effect and the self-adjusting of holograms owing to the PY field are the two important dominant processes in the self-pumped phase conjugator. The influence of the photoinduced electric field on the conjugation fidelity and the stability of the phase-conjugate output is also observed and analyzed. The bump feature of the two-wave mixing and the oscillating situation of the self-pumped phase conjugator are observed and are explained in view of the photoinduced internal field.

Analysis of the serotype-specific epitopes of avian infectious bronchitis virus strains Ark99 and Mass41

The Ark and Mass serotype-specific epitopes of infectious bronchitis virus were studied by immunofluorescence and immunoprecipitation of mutant and recombinant spike glycoproteins (S protein) expressed in mouse L cells. Serotype-specific monoclonal antibodies could bind to the recombinant proteins of Ark99 and Mass41 expressed from the chimeras in which the N-terminal thirds of the S1 sequences were reciprocally exchanged. Therefore, it appears that the respective serotype-specific epitopes of both strains were localized within the C-terminal two-thirds of the S1 proteins. Deletion and insertion of a five-amino-acid fragment on the S1 proteins of Ark99 and Mass41, altered the serotype-specific epitopes. This result implies that the five-amino-acid insertion on the S1 protein of the Ark serotype was involved in determining the conformation of the protein, probably acting as a spacer. In addition, it appears that an interaction between sequences of the N-terminal third and the remaining portion of the S1 protein determines the tertiary structure of the protein as well as the conformation of the serotype-specific epitope.

Native and non-native structure in a protein-folding intermediate: spectroscopic studies of partially reduced IGF-I and an engineered alanine model

The structure of a metastable folding intermediate of human insulin-like growth factor I (IGF-I) and an engineered model are investigated by circular dichroism and two-dimensional 1H NMR spectroscopy. The intermediate, which contains two of three native disulfide bonds, was trapped by acid quenching and isolated by reverse-phase HPLC. The reduced cysteine residues were mapped to residues 47 and 52 (corresponding to A6-A11 in insulin). In the native state this disulfide bridge anchors an adjoining amphipathic alpha-helix (helix 2; residues 42 to 49) against the hydrophobic core. Comparison of CD and 1H-NMR spectra demonstrates that the acid-quenched intermediate is partially folded and contains elements of native secondary and tertiary structure. Spectra are similar to those of an equilibrium model in which the reduced cysteine residues are replaced by alanine. Complete 1H-NMR sequential assignment of the alanine model has been obtained and demonstrates that removal of the disulfide bond is associated with local unfolding of the adjoining alpha-helix. Native secondary structure (including helices 1 and 3) is otherwise retained and defines a folded subdomain. Long-range nuclear Overhauser effects (NOE) within this subdomain are similar to those of native IGF-I; no non-native NOE is observed. Our results support the hypothesis that folding of the insulin motif is directed by a subset of native structural elements and that these elements form at an early step in the pathway. Formation of helix 2, despite its prominence in the native state, is likely to represent a late step. Hydrophobic collapse of this segment appears to precede helix formation.

[Identification of streptavidin]

In this report, streptavidin (SA) was further identified on the basis of our previous researches in SA isolation and purification. 23.2 mg of SA productivity could be obtained after purification by DEAE-52 column from 1 L of culture supernatant. The spectrum scanning of ultraviolet absorption was congruent with that of the Sigma product. 2 bands appeared on the SDS-PAGE electrophoresis of SA. The molecular weight of SA was 72 881 Dalton with PI 6.0; the averaged biotin-binding activity was 18 micrograms/mg. The results confirmed that the methods of isolation and purification of SA developed by authors were reliable for immunological application.

Color changes in dry-pigmented maxillofacial elastomer resulting from ultraviolet light exposure

Five dry pigments and one maxillofacial elastomer were evaluated for color changes (delta E) resulting from prolonged exposure to two types of ultraviolet light. The elastomer, pigments, and pigmented elastomers were subjected to each ultraviolet light source for 400, 600, and 1800 hours, and delta E color shifts were determined. The unpigmented elastomer underwent minimally perceptible color change after 600 hours of exposure to both types of ultraviolet light. Two pigments underwent substantial color change after 400 hours, whereas the remaining three pigments remained color stable after 1800 hours. It was concluded that for the materials tested, early color changes in a prosthesis may be the result of degradation of certain ultraviolet light-susceptible pigments, whereas longer term color shifts may be caused by color changes within the elastomer.