Stealth polycyanoacrylate nanoparticles as tumor necrosis factor-alpha carriers: pharmacokinetics and anti-tumor effects

The objective of this study was to investigate the pharmacokinetics and in vivo anti-tumor effect of recombinant human tumor necrosis factor-alpha (rHuTNF-alpha) encapsulated in poly(methoxypolyethyleneglycol cyanoacrylate-co-n-hexadecyl cyanoacrylate) (PEG-PHDCA) nanoparticles. Our experimental results showed that PEG-PHDCA nanoparticles could extend the half-life of rHuTNF-alpha to 7.42 h and obviously change the protein biodistribution in tissues, and in particular, increase accumulation of rHuTNF-alpha in tumor. Compared with PHDCA nanoparticles and free rHuTNF-alpha, PEG-PHDCA nanoparticles loaded with rHuTNF-alpha showed higher antitumor potency at the same dose, which might be related to its higher accumulation in tumor tissues and longer plasma circulation time. Therefore, PEG-PHDCA nanoparticles could be an effective carrier for rHuTNF-alpha.

PEGylated recombinant human tumor necrosis factor alpha: pharmacokinetics and anti-tumor effects

The aim of the present work was to investigate and assess the merit of PEGylated recombinant human tumor necrosis factor-alpha (rHuTNF-alpha) following our previous work. The rHuTNF-alpha was modified using activated polyethylene glycol (PEG), N-succinimidyl succinnate monomethoxy polyethylene glycol (SS-PEG). The pharmacokinetics and anti-tumor effect were investigated. The experimental results showed that PEGylated rHuTNF-alpha could obviously alter in vivo behavioral characteristics of rHuTNF-alpha. Among the synthesized PEG-rHuTNF-alphas with different PEG molecules, PEG20000-rHuTNF-alpha demonstrated the longest circulating half-life (24.8 h) which was about 50 times longer than that of rHuTNF-alpha (28.8 min). In addition, there was much more PEG20000-rHuTNF-alpha distributed into tumor tissues than other PEG-rHuTNF-alphas or rHuTNF-alpha with time, and PEG20000-rHuTNF-alpha also showed the highest anti-tumor potency. These results indicated that PEG20000-rHuTNF-alpha was a useful long circulating molecule with selective localization in tumor tissues and enhanced anti-tumor activity of rHuTNF-alpha.

PEGylated polycyanoacrylate nanoparticles as tumor necrosis factor-alpha carriers

The aim of this study was to find an effective carrier for recombinant human tumor necrosis factor-alpha (rHuTNF-alpha). The influence of solvent systems containing poly(methoxy-polyethyleneglycol cyanoacrylate-co-n-hexadecyl cyanoacrylate) (PEGylated PHDCA) on the biological activity of rHuTNF-alpha was investigated. The PEGylated PHDCA nanoparticles loading rHuTNF-alpha were prepared with the double emulsion method. The influence of main experimental factors on the entrapment efficiency was evaluated by the Uniform Design. The physicochemical characteristics and in vitro release of rHuTNF-alpha from the nanoparticles were determined. The results showed that serum albumin such as human serum albumin (HSA) or bovine serum albumin (BSA) could play a protective action on rHuTNF-alpha in the preparation process. At > or =2.0% (w/v) HSA concentration, more than 85% of rHuTNF-alpha activity remained and the role of HSA was not affected by copolymer concentrations from 0.5 to 3.0% (w/v). The entrapment efficiency of the nanoparticles was about 60% and the nanoparticle size was about 150 nm. The nanoparticles were spherical in shape and uniform with the value of the zeta potential about -9 mV. The rHuTNF-alpha release from the nanoparticle showed an initial burst and then continued in a sustained fashion. The results showed that the PEGylated PHDCA nanoparticles could be an effective carrier for rHuTNF-alpha.

Exposure to and actions against passive smoking in non-smoking pregnant women in Guangzhou, China

BACKGROUND

The objective was to describe the extent of passive smoking exposure and preventive actions against passive smoking in non-smoking pregnant women and to analyze factors associated with preventive actions.

METHODS

This was a cross-sectional survey on 1449 never-smoking pregnant women who made their first prenatal visit to the Women and Children's Hospital of Guangzhou, China during 1996-97.

RESULTS

60.2% (95% Confidence Interval 57.7%-62.7%) of the never-smoking pregnant women had a husband who currently smoked. Women with smoking husbands (n=872) were more exposed to ETS than those with non-smoking husbands (n=577) at home (71% vs. 33%), in public places (77% vs. 66%) and at work (60% vs. 50% of working women), and they took less actions against passive smoking in public places. Women with better education and knowledge on smoking and passive smoking had stronger preventive actions.

CONCLUSIONS

Non-smoking pregnant women in China are often exposed to passive smoking and their preventive actions are weak. Passive smoking is an important obstetric and public health problem in developing countries and deserves urgent international attention.

A study of oral health condition in individuals with no oral hygiene and its association with plaque acidogenesis

OBJECTIVE

To study the association of long-term deposited plaque, due to lack of oral hygiene, with acidogenesis of the plaque bacteria.

METHODS

Seventy-seven subjects with poor oral hygiene were selected. Debris index (DI) and calculus index (CI) were recorded. Among them, 16 were DMFS > 8, and comprised the caries active (CA) group; 27 were caries free, and comprised the caries free (CF) group. Plaque fluids in both groups were analyzed for organic acids, phosphate, and inorganic cations by use of capillary electrophoresis, while pH was measured by microelectrodes.

RESULTS

No differences were found on debris index (CF group measured 2.07-0.47, CA group measured 2.01-0.53) or calculus index (CF group measured 2.47-0.50, CA group measured 2.48-0.53) relative to carious status, although there was a positive relationship between DI and CI (r = 0.52, P < 0.001). The main finding in this study was that the quantity of lactic acid produced by sucrose exposure in these individuals with poor oral hygiene was much less (increased no more than 2 times, compared with content at rest) than in a previous report (increased 3 to 5 times, compared with content at rest) on subjects with good oral hygiene habits.

CONCLUSIONS

Long-term deposited plaque due to lack of oral hygiene may have less cariogenic capability, although patients' susceptibility to periodontal disease would increase.

Comparison of methods for analyzing binary data arising from two-sample twin studies

The study of twins is widely used for research into genetic and environmental influences on human outcome measurements. For the study design in which independent samples of monozygotic and dizygotic twins are compared with respect to their similarity on a binary trait, several statistical methods have been proposed. Using a Monte Carlo simulation, we compare the five following procedures: 1) goodness-of-fit method based on the common correlation model, 2) normal approximation of the maximum likelihood estimators of the common correlation coefficients, 3) Ramakrishnan et al. [(1992) Genet Epidemiol 9:273-282] method of odds ratio comparison, 4) generalized estimating equations method of odds ratio estimation, and 5) tetrachoric correlation method. The results show that the goodness-of-fit approach has similar or better performance in both type-one error rates and power than the other methods in all parameter settings. Its advantage with respect to type-one error rates is particularly clear under conditions of small sample sizes, extreme prevalences, or high values of the intraclass correlation coefficients. Therefore, the goodness-of-fit method is recommended for the two-sample twin study design.

Plaque pH and associated parameters in relation to caries

Intensified plaque acidogenicity in caries-prone subjects was reported many years ago, but emerging evidence has suggested that the relationship may not be as strong as once thought. We have now determined a range of acidogenicity variables in subjects having both caries prevalence and incidence data, and have included plaque mineral data in the analysis. pH measurements were made in 20 randomly selected subjects from a high-caries group (mean DMFS = 8. 95) and 20 from a caries-free group of Beijing children aged 12 years participating in a caries prediction study. Subgroups with a 12-month DMFS increment >/=2 or = 0 were also formed from the two groups, respectively. Measurements were made with an iridium oxide electrode inserted between teeth 13/14, 23/24, 34/35 and 44/45, before and every 5 min for 30 min after rinsing with 10% sucrose, and the 4 resulting 'Stephan curves' averaged using a plaque pH analysis program. Supragingival plaque was collected from buccal and lingual smooth surfaces of posterior and upper anterior teeth and its acid extract analysed for Ca, P and F. Caries-free subjects (based on past experience) had a significantly higher maximum plaque pH and pH value after 30 min (reflecting a faster return to resting pH), a lower minimum enamel dissolution capacity of plaque and recorded less time below pH 7.0 than did high-caries subjects. No other differences were significant, including those of the principal acidogenic parameters 'minimum pH attained after a sugar rinse', 'curve area below the critical pH of 5.5' and 'time below the critical pH'. Selection of the caries groups on the basis of both experience and incidence did not reveal significant differences in more parameters. Upper arch plaque was significantly more acidogenic than lower arch plaque, and there was a consistently strong association between upper and lower arch values in individuals. Ca, P and F in the subjects' plaque had little or no influence on the principal acidogenic parameters. Our failure to find a relationship between caries prevalence or activity and these principal acidogenicity parameters may be related to differences between fissure and smooth surface plaque, temporal variations in acidogenicity and/or to use of F toothpaste during the 1-year observation period. These results support the view that factors such as the frequency of acidogenic episodes may be more important in caries progression than the degree of acidogenicity during any one episode.

Bioelectrical impedance analysis (BIA) using bipolar foot electrodes in the assessment of body composition in Type 2 diabetes mellitus

The use of bioelectrical impedance analysis (BIA) for determining human body composition is widely accepted as a safe, rapid, and reliable technique. Although this technique has been validated in normal and obese individuals, only limited studies have been done in special populations. The use of BIA for the measurement of body composition in Type 2 (non-insulin dependent) diabetic patients would be of particular interest for both clinical and investigative studies. The aim of this study was to evaluate the validity of a new bipedal BIA device for the measurement of body composition in a population of individuals with Type 2 diabetes mellitus. The body composition of 48 male and 48 female Type 2 subjects was measured by BIA and dual energy X-ray absorptiometry (DXA). The percentage body fat determined by BIA was significantly correlated with % body fat determined by DXA (r = 0.89, p < 0.0001). Agreement analysis showed that BIA consistently overestimated % fat in female diabetic subjects by approximately 5% and underestimated % fat in male diabetic subjects by approximately 10% of the predicted value obtained with DXA. These differences were statistically significant but probably of minor clinical relevance. We conclude that BIA measurement by TBF 105 is a useful and reliable technique for measuring body composition in subjects with Type 2 diabetes mellitus.

Serum immunoreactive leptin concentrations in a Canadian aboriginal population with high rates of NIDDM

OBJECTIVE

To better understand the relationship between leptin and the anthropometric and physiological variables associated with diabetes, we measured this protein in an isolated Canadian aboriginal population with very high rates of NIDDM.

RESEARCH DESIGN AND METHODS

There were 728 individuals aged 10-79 years who participated in a population-based survey to determine the prevalence of NIDDM and its associated risk factors. Fasting blood samples for glucose, insulin, triglyceride, and leptin were collected; a 75-g oral glucose tolerance test was administered and a second blood sample drawn after 120 min. Height, weight, and waist and hip circumference were determined, and percent body fat was estimated using biological impedance analysis. Fitness level was assessed in a subsample of individuals using a validated submaximal step test. The relationship between serum leptin and the other variables was assessed using Spearman's correlation coefficients and multiple linear regression.

RESULTS

Serum leptin concentration was strongly correlated with adiposity, and levels were substantially higher in female subjects in all age-groups. For male subjects, percent body fat, fasting insulin level, and waist circumference were significant independent predictors of log serum leptin concentration in a multiple linear regression model (R2 = 0.582). For female subjects, these variables plus glucose tolerance status were included in the final model (R2 = 0.633). Fitness level, when included with the main effects of the above models, was a significant predictor for male subjects only.

CONCLUSIONS

In an isolated aboriginal community with high rates of diabetes, we found significant independent relationships between leptin and percent body fat and between leptin and fasting insulin. As documented in other populations, the higher leptin concentration among female subjects may reflect differential leptin production from different adipose tissue beds, or leptin resistance. Independent relationships also existed among leptin and glucose tolerance status in female subjects and fitness level in male subjects.

Application of scanning microradiography and x-ray microtomography to studies of bones and teeth

In scanning microradiography (SMR), a thin section is stepped across a 15-μm diameter X-ray beam and the transmitted intensity measured at each point. This technique has permitted more accurate measurements of the spatial variation of the mineral concentration in sections of dentin and enamel than conventional photographic microradiography. Moreover, because the section is not in close contact with an emulsion, SMR allows continuous study while the specimen is bathed in a reaction solution. The present studies have been particularly directed to gaining an understanding of the formation and repair of carious lesions in teeth: one particular puzzle is subsurface demineralization, in which the initial loss of mineral appears to take place some 20 to 50 μm below the tooth surface. SMR studies are reported here on the demineralization in dilute acids and the subsequent partial remineralization in supersaturated calcium phosphate solutions in model systems for dental caries. In order to develop a theoretical model for de- and remineralization of carious lesions, it is necessary to quantify transport processes within the tooth. To this end, we are developing a method of measuring effective diffusion coefficients of strongly X-ray-absorbing ions in water within permeable solids in which the diffusion coefficient varies with position. The method uses sequential concentration/distance profiles determined by SMR. As a test, diffusion coefficients of potassium iodide in water within a permeable glass frit have been measured. X-ray microtomography (XMT) can be carried out by adding an axis of rotation to the SMR apparatus. Using this method, linear absorption coefficients, and hence mineral concentrations, can be measured in 15 X 15 X 15-μm3 voxels. This has advantages over SMR in that superposition within the depth of the section and errors in determining its thickness are avoided. XMT studies of de- and remineralization similar to those described above for SMR, and also XMT studies of the variation in mineral concentration in the cortical bone of a rat femur along its length, are reported.

Scanning microradiographic study of the kinetics of subsurface demineralization in tooth sections under constant-composition and small constant-volume conditions

The kinetics of subsurface demineralization of tooth sections has been studied in real-time by scanning microradiography (SMR). Demineralization was carried out: (1) with a large volume of solution buffered to pH = 4 to maintain a constant composition; and (2) in a small constant volume (approximately 3 mL), buffered initially at pH = 4, so that the degree of saturation at the tooth surface increased as the tooth dissolved. At constant composition, the change in lesion depth, Y, with time, T, followed a linear relation, Y = a + bT, for T > 44 +/- 5 h. Before this time, the relation could be approximated by a linear one with different a and b constants. At constant volume, Y = q(1-e-r(T + s)) for all T, where q, r and s are constants. Similar relations, with different constants, were found for the mineral loss per unit area of lesion exposed to acid. These results showed that the process of demineralization under the rather severe conditions used was essentially a surface-controlled process. The change of slope at approximately 44 h and the presence of the constant s in the exponential function were attributed to a change in kinetics after formation of the surface layer.

Alleles at four HLA class II loci determined by oligonucleotide hybridization and their associations in five ethnic groups

The use of polymerase chain reaction (PCR) and oligonucleotide hybridization offers a new approach for the definition of HLA class II alleles. It has been possible to determine 43 alleles of DRB1, four of DRB3, two of DRB4, four of DRB5, eight of DQA1, and 14 of DQB1. These alleles are inherited together in members of families and form closely associated groups which are found repeatedly and in characteristic patterns in different populations. We have determined the HLA class II alleles and analyzed their association in 431 healthy unrelated subjects including 161 North American Caucasians, 53 Latin Americans, 61 Blacks, 88 Chinese, and 68 Israeli Jews. For-locus haplotypes (DRB1; DRB3/4/5; DQA1; DQB1) were derived from 79 B cell lines and the analysis of segregation in 34 nuclear families. The B-cell lines yielded 37 and the families showed the same, and 20 other, haplotypic combinations. In addition to these 57 haplotypes, associated alleles were assigned in the unrelated panels following certain rules. The resulting haplotypes were assigned to groups known to share associated alleles. The groups were: 1) DR1, DR2, and DRw10 (13 haplotypes); 2) DR3 and DRw6 (26 haplotypes); 3) DR5 and DRw8 (24 haplotypes); 4) DR4, DR7, and DR9 (24 haplotypes). Their distribution in populations with different ethnic backgrounds was analyzed. The expressed DRB4 allele and its null mutant were determined by PCR and oligonucleotide hybridization. The different DR7 haplotypes resulting from these determinations were analyzed in a panel of 130 North American Caucasoids. This comprehensive analysis of class II HLA haplotypes in human populations should be useful in understanding the role of these genes and in various applications including anthropology, disease susceptibility, and transplantation of allogeneic organs and tissues.

Heterogeneity in HLA-DR2-related DR,DQ haplotypes in eight populations of Asia-Oceania

The relative distributions of 480 DR2-related DR,DQ haplotypes have been determined in Australian Aborigines, Papua New Guinean Highlanders, coastal Melanesians, Micronesians, Polynesians, Javanese, and Southern and Northern Chinese. Using sequence-specific oligonucleotides (SSOs) for hybridization of polymerase chain reaction (PCR) products from DRB1, DRB5, DQA1, and DQB1 genes, 15 different DR2-related haplotypes were identified. The predominant DR2 haplotype in Oceania involved a novel combination of DRB1*1502, DRB5*0101 alleles; this haplotype occurred sporadically in Java, but not in China. In Southern China, the most frequent DR2 haplotype involved the unusual arrangement DRB1*1602,DRB5*0101; alternatively, DRB1*1602 was associated with a new DRB5 SSO pattern. This study has important implications for molecular HLA-typing protocols that assume particular DRB1, DRB5 or DR,DQ linkage relationships. Further, the novel DRB1, DRB5 haplotype in Oceania suggests that the mixed lymphocyte culture (MLC) determinants Dw2 and Dw12 are discriminated by codon 86 at the DRB1 locus.

Scanning and contact microradiographic study of the effect of degree of saturation on the rate of enamel demineralization

The effect of degree of saturation with respect to hydroxyapatite (DSHA) on enamel section demineralization was studied by contact and scanning microradiography (CMR and SMR). Two aspects were studied: (1) the effect of different values of DSHA at constant pH, and (2) the effect of constant DSHA with variable pH. In the pH range (2.5-4.5) and time scale (0-120 h) studied, the DSHA was more important in determining the rate of enamel lesion progression than was the pH.

DNA typing for HLA-DR, and -DP alleles in a Chinese population using the polymerase chain reaction (PCR) and oligonucleotide probes

We have determined alleles of HLA-DRB1, DRB3, DRB5, DQA1, DQB1, and DPB1 loci in 91 unrelated healthy individuals from North China. Group-specific PCR primers were employed for the analysis of subsets of DR1, DR2, DR4, DRw52, and DPB. With allele-specific probes, 22 DRB1, 8 DQA1, 13 DQB1, and 12 DPB1 alleles were found in this panel. Allele frequencies showed that 25.3% of the subjects had DR7 and 26.4% had DR9, only 5.5% had DRB1*0301 (DRw17). In the DR4 group, DRB1*0405 (Dw15, 8.8%) and 0406 (KT2, 9.9%) were the most prevalent alleles. DRB1*0404 (Dw14.1), 0407 (Dw13.2) and 0408 (Dw14.2) were absent and the other alleles of the DR4 group were rare. The most common DRw6 subset was DRB1*1401 (8.8%). DRB1*0802 and 0803 were present (2.2%, 6.6%), and DRB1*0801 was not found. Associations with DQA1 and DQB1 were generally similar to those found in other populations. DPB1*0501 was the most frequent (60.2%) allele at the DPB1 locus. Overall our study shows that the distribution of class II alleles in a population from Mainland China is quite different from other ethnic groups. The high frequency of the KT2 subset of DR4. (DRB1*0406) and of DPB1*0501 are the most striking features found. A new type of DR4 was determined in one subject. It was like DR4-Dw15 (DRB1*0405) but, according to our hybridization patterns, it encoded valine instead of glycine in position 86. It is now called DRB1*0410.

Immunogenetics of rheumatoid arthritis and juvenile arthritis

Starting with the historical background and ending with the most recent data obtained by DNA typing, using PCR and oligonucleotide probes, the role of HLA antigens in rheumatoid arthritis (RA) and in several forms of juvenile arthritis (JA) is reviewed. RA is thought to be associated with an epitope of the third hypervariable region of DRB1 which is shared by several alleles including DR4-Dw4, Dw14, Dw15, DR1, DRw14.2, and DRw10. Rheumatoid factor-positive JA is also associated with DR4, but in rheumatoid factor-negative JA DR4 is absent, or markedly decreased, suggesting that it has a protective effect. Typing for the HLA-DP alleles has confirmed the association of pauciarticular JA with DPBI*0201. Recent studies in the author's laboratory have shown that DPB1*0301 is the main susceptibility factor for rheumatoid factor-negative polyarticular onset JA. It is of interest that also adult rheumatoid factor-negative RA patients have an increase of DPB1*0301, suggesting that these two clinical subsets may represent related diseases.

[The observation of experimental respiratory distress syndrome and effects of anisodamine]

The respiratory distress syndrome (RDS) model induced by oleic acid injection in dogs and treated by anisodamine were observed. The clinical picture, blood gas parameters, Pap, Pwp, blood cells count, hemocoagulogram, CH50, and surface tension of BALF were studied in order to determine the pathophysiological mechanism and effects of anisodamine. According to the studies in our laboratory, it was suggested that the complement activation and neutrophil aggregation induced by C5a and mediators released by it and other way are likely to be the initiation factors. The lung injuries complicated diffuse intravascular coagulation with fibrinolysis occurred for whole 72 hours period. The anisodamine seems to exert certain therapeutic effects on RDS through preventing the complement activation and enable the lysosomal elimination decrease and stimulate the II-type epithelia to be repaired.

A variant of HLA-DR4 determines susceptibility to rheumatoid arthritis in a subset of Israeli Jews

HLA-DR4 is associated with risk for developing rheumatoid arthritis (RA) in most populations. In Israeli Jews, in whom the Dw10 subtype of DR4 predominates, no association of RA with DR4 has been found. The inability to detect an association could be due to the high frequency of DR4-Dw10. We used DNA typing with amplification by the polymerase chain reaction and dot-blotting with allele-specific oligonucleotides to determine DR4 variants in 131 Jewish RA patients living in Israel and 134 controls. In both Ashkenazi Jews and non-Ashkenazi Jews, the rare variant Dw15 (previously identified in Japanese populations and in Japanese patients with RA) was found to be the main allele associated with the risk of developing RA (relative risk = 9.2, corrected P less than 0.001). However, this low-frequency allele could be responsible for susceptibility in only 11.5% of the patients. Susceptibility for rheumatoid factor-positive RA was associated with Dw4 and Dw15; the risk for rheumatoid factor-negative RA was associated only with Dw14. The distribution of the HLA-DQ alleles associated with DR4 showed that more than half of the RA patients with Dw15 also had HLA-DQw2. The frequencies of DQw7 and DQw8 were not different in RA patients compared with controls. The results suggest that, as in other populations, susceptibility for the development of RA in Israeli Jews is associated with DRB1 locus alleles of the DR4 group.

DNA typing for class II HLA antigens with allele-specific or group-specific amplification. V. Typing for subsets of HLA-DR1 and DR'Br'

Three DRB1 alleles of the DR1 group including DRB1*0101, DRB1*0102, and DRB1*0103 are currently recognized. The first two of these are defined as HLA-DR1 by serologic typing and as either Dw1 or Dw20 by typing with T cells. DRB1*0103, previously called DR'Br' or DR'BON', is not detectable by serology. Little information exists about the population frequencies of DRB1*0102 and DRB1*0103. In the present study we have used the polymerase chain reaction (PCR) and allele-specific oligonucleotide probes to determine these alleles. To avoid cross-hybridization with other DRB genes having the same DNA sequences as those of the region to be analyzed, we performed group-specific PCR to amplify only DR1 DRB1 genes. This was accomplished using a 21-nucleotide-long primer, homologous to the first hypervariable region common to the DR1 DRB1 genes, and which under appropriate conditions amplified only DRB1 genes of the DR1 group. Five oligonucleotide probes, one matching the second hypervariable region, two spanning the third hypervariable region, and two covering codons 82 through 89, were used to determine the three alleles. DRB1*0101 (Dw1) was found to be the major type of DR1 in North American Caucasians. In North American black and Brazilian mestizo populations DRB1*0102 (Dw20) was more prevalent. DRB1*0103 (DR'Br') was detected in only six individuals in the present study.

HLA-DR alleles with naturally occurring amino acid substitutions and risk for development of rheumatoid arthritis

To determine the HLA-DR4 subtypes associated with rheumatoid arthritis (RA), we performed amplification of DR4 DRB1 genes by the polymerase chain reaction and dot-blots with oligonucleotide probes. In 52 HLA-DR4+ RA patients, Dw4 was the predominant subtype. This subtype was found in 45 of 52 patients (86.5%) compared with 33 of 59 DR4+ controls (55.9%; P less than 0.001). In the whole population, Dw4 also gave the highest relative risk for RA (RR = 5.31). Relative risk was also associated with DR1.1, the common white DR1 (Dw1) type, which has a third hypervariable region amino acid sequence similar to some forms of DR4 and has glycine at position 86. Variants of DR1 (DR1.2) or DR4 (Dw13.1, Dw14.1) with valine at position 86 appeared less able to confer risk for RA. Substitution of residues in the third hypervariable region of the first domain of DRB1 appeared to correlate with relative risk for RA. Among subjects having 0-1 amino acid substitutions, RA developed in 53%, whereas in subjects with 2-4 amino acid changes, RA was present in only 17.4% (P less than 0.00001). DQw7 (formerly DQw3.1) was slightly increased in DR4+ RA patients compared with controls, but a striking excess of Dw4,DQw7 homozygous patients was observed. The results suggest that DQw7 may have an additional effect, possibly with a recessive mechanism, since it was observed only in DR4 homozygous patients.

[Dental caries in 280 pairs of same-sex twins]

The dental caries in 280 pairs of like-sex twins (186 monozygotic, 94 dizygotic) were studied. Then, comparisons of variability of dental caries, missing and filled surface (DMFS), concordance, and correlation in the two types of twins were made. The heritability index (HI) was also calculated. There were less variance, higher concordance and higher correlation in monozygotic twins, but the results were not statistically significant. The HI of dental caries was 8.7% according to this study. It was suggested that environmental influence was dominant in caries initiation: whereas heredity was of little influence.

DNA typing for class II HLA antigens with allele-specific or group-specific amplification. I. Typing for subsets of HLA-DR4

DNA sequences that distinguish the subsets of HLA-DR4 are also found on several other alleles. This makes typing of heterozygotes with oligonucleotide probes quite impractical. We have therefore developed a procedure in which, in a first step, DNA of the genes to be analyzed is amplified selectively, using group-specific primers. In the case of DR4-DRB1, a primer matching codons 5 to 13 when used in the polymerase chain reaction resulted in products that were entirely suitable for typing for the DR4 subsets. Using appropriate probes, eight distinct subsets were identified. However, only six of them were represented in a normal North American Caucasian panel. In conjunction with a method for rapid DNA extraction, the procedure offers a simple, highly specific and reproducible method for determining subtypes of HLA-DR4 that at present cannot be recognized by serologic methods.

Class II human leukocyte antigen genes and T cell receptor polymorphisms in patients with rheumatoid arthritis

Human leukocyte antigen (HLA) typing was performed in 174 patients with rheumatoid arthritis and 222 white control subjects. Increases in HLA-DR4 and HLA-DR1 were observed as in previous studies. Each of these appeared to be inherited as dominant risk factors. Southern blotting with a DR-beta probe after digestion of genomic DNA with the restriction enzyme Bam HI showed seven bands. Three of them correlated with DR4 and were increased in rheumatoid arthritis patients. Subsets of DR4 were determined by polymerase chain reaction amplification followed by hybridization with oligonucleotide probes. Dw4 was increased in rheumatoid arthritis patients, and the frequency of the other subsets appeared to be similar in rheumatoid arthritis patients and control subjects. A polymorphism associated with the T cell receptor V-beta-8 gene family was significantly increased in rheumatoid arthritis patients.