Pregnancy in an untreated case of transverse vaginal septum with vesicovaginal fistula

An 18-year-old woman presented with history of cyclic hematuria, abdominal pain, and a mass in the hypogastrium. She was found to have transverse vaginal septum in the lower one-third of her vagina with congenital vesicovaginal fistula (VVF) and a dead fetus of approximately 20 weeks gestation. She underwent vaginotomy and removal of the dead fetus. Vaginal repair of VVF was carried out 3 months later.

Adsorption from solutions on synthetic hydroxyapatite: nonaqueous vs. aqueous solvents

It is useful in restorative dentistry and etiology of bone diseases to know that certain general rules may be derived from a priori considerations of the adsorption of chemicals to synthetic hydroxyapatite (which is the structural prototype of tooth and bone mineral). This article systematically synthesizes the extensive studies on the subject by the author, and rationalizes and extends these rules. Though not a review article, the work of some researchers may not have found an adequate representation here, because they did not determine, in the case of nonaqueous solvents, the reversibility of adsorption; or, in the case of aqueous solvents, the concentration of all constituent ions of the system, thus missing the occurrence of processes other than adsorption. The adsorption of solutes from nonaqueous solvents on hydroxyapatite is mainly regulated by the interplay of hydrogen bonding between adsorbate, adsorbent, and solvent. It does not involve any significant role of ionic nature of the apatite surface, because it is masked by the chemisorbed and physisorbed water. This interplay of hydrogen bonding in conjunction with chemical and structural characteristics of the adsorbed molecules controls their reversibility and the orientation of the adsorbates on the surface. In general, the process may be considered as true adsorption, because no other material exchange process is involved. The "adsorption" of solutes from aqueous solutions generally involves ion-exchange with the apatite surface, and may be affected by the concentrations of potential determining ions (Ca(2+), phosphates, H(+), etc.) in the solution. The solute in aqueous solution may be removed by two other mechanisms, either by formation of a surface complex or by chemically reacting with calcium or phosphate ions to form a new phase that precipitates out of solution. Therefore, the concentration of calcium and phosphate ions in solution should also be monitored to elucidate the mechanism of the process. Adsorption of polymers seems to be determined primarily by their multiple hydrogen bonding, their relative molar mass, and their ability to self-associate. The hydrogen ion concentration plays a decisive role in each one of the above mechanisms.

Adsorption from solutions on synthetic hydroxyapatite: nonaqueous vs. aqueous solvents

It is useful in restorative dentistry and etiology of bone diseases to know that certain general rules may be derived from a priori considerations of the adsorption of chemicals to synthetic hydroxyapatite (which is the structural prototype of tooth and bone mineral). This article systematically synthesizes the extensive studies on the subject by the author, and rationalizes and extends these rules. Though not a review article, the work of some researchers may not have found an adequate representation here, because they did not determine, in the case of nonaqueous solvents, the reversibility of adsorption; or, in the case of aqueous solvents, the concentration of all constituent ions of the system, thus missing the occurrence of processes other than adsorption. The adsorption of solutes from nonaqueous solvents on hydroxyapatite is mainly regulated by the interplay of hydrogen bonding between adsorbate, adsorbent, and solvent. It does not involve any significant role of ionic nature of the apatite surface, because it is masked by the chemisorbed and physisorbed water. This interplay of hydrogen bonding in conjunction with chemical and structural characteristics of the adsorbed molecules controls their reversibility and the orientation of the adsorbates on the surface. In general, the process may be considered as true adsorption, because no other material exchange process is involved. The "adsorption" of solutes from aqueous solutions generally involves ion-exchange with the apatite surface, and may be affected by the concentrations of potential determining ions (Ca(2+), phosphates, H(+), etc.) in the solution. The solute in aqueous solution may be removed by two other mechanisms, either by formation of a surface complex or by chemically reacting with calcium or phosphate ions to form a new phase that precipitates out of solution. Therefore, the concentration of calcium and phosphate ions in solution should also be monitored to elucidate the mechanism of the process. Adsorption of polymers seems to be determined primarily by their multiple hydrogen bonding, their relative molar mass, and their ability to self-associate. The hydrogen ion concentration plays a decisive role in each one of the above mechanisms.

Interaction of Citric or Hydrochloric Acid with Calcium Fluorapatite: Precipitation of Calcium Fluoride

The interaction of citric acid (H(3)Ci) with calcium fluorapatite(Ca(10) F(2)(PO(4))(6)) was explored for two reasons: (i) to determine the role of the acid in the dissolution process and hence in the mechanism of tooth fluoridation and (ii) to determine whether there is any formation of calcium citrate. It was found that the concentration of calcium or fluoride ions is not stoichiometric with respect to that of phosphate ions in the solution and the stoichiometric deficiency of the amount of fluoride ions in the solution is twice that of the calcium ions and this demonstrates that some calcium fluoride is precipitated. The interaction may be represented by the following chemical equation (pH approximately 2.5): where x (presently < 1) is related to the amount of CaF(2) that has precipitated and may be calculated from the experimental ratio of Ca to P in the solution. In order to establish that the interaction occurs generally with all acids, the reaction of hydrochloric acid with fluoroapatite was studied, and exactly analogous behavior was observed. These facts are also in accord with the solubility of fluorapatite and calcium fluoride. When the amounts of Ca and P in solution are corrected for the precipitated CaF(2), the ratio of Ca to P becomes stoichiometric (= 1.67). Preliminary X-ray analysis of the reacted fluorapatite showed that it contained calcium fluoride. The precipitated CaF(2) may act as a reservoir for the subsequent fluoridation of the mineral and may inhibit bacterial action in the mouth. The concentration of citrate ions does not change in solution, and no formation of calcium citrate is observed.

Maternal plasma leptin is increased in preeclampsia and positively correlates with fetal cord concentration

OBJECTIVE

We tested the hypothesis that the maternal leptin concentration would be increased in preeclampsia, independent of maternal obesity.

STUDY DESIGN

Maternal and cord plasma leptin concentrations were compared in 2 groups of women with either preeclampsia (n = 24) or normal pregnancy (n = 24), matched 1:1 for prepregnancy body mass index and fetal gestational age at sampling.

RESULTS

Median leptin concentrations were significantly higher (P <. 03) in women with preeclampsia (45.6 ng/mL) than in normal pregnant women (27.0 ng/mL) and fell rapidly shortly after delivery (26.7 ng/mL and 25.4 ng/mL, respectively). Cord leptin was not significantly different between groups (5.4 ng/mL and 5.8 ng/mL, respectively). Maternal and cord leptin correlated significantly (rho = 0.76, P <.01) only in preeclampsia.

CONCLUSION

Preeclampsia is associated with an increase in maternal plasma leptin concentrations that strongly correlates with the fetal cord concentration at delivery.

Interaction of ortho-Phospho-l-serine with Hydroxyapatite: Formation of a Surface Complex

ortho-Phospho-l-serine (H2Psi, where Psi represents the serinephosphato ion), a constituent of salivary proteins, seems to play an important role in the mineralization of teeth. To understand the basic mechanism of this interaction, the uptake of o-phospho-l-serine from relatively concentrated aqueous solutions (up to 100 mmol/L) onto synthetic hydroxyapatite was studied. Previous studies have shown that in the dilute concentration range (<12.5 mmol/L) the uptake followed a regular Langmuirian adsorption plot. At higher concentrations the uptake curve increased steeply, but no formation of a separate phase in the reacted apatite was discernible, either by optical or by scanning electron microscopy. The dissolution of apatite released phosphate and calcium ions into the solution in amounts linearly related to the uptake of serine with P/Psi = 1 and Ca/Psi = 2. The charge and mass balance of the reaction can be reconciled with the formation of the surface complex (shown within brackets):Ca10(OH)2(PO4)6 + 6H2Psi --> [Ca6(HPsi)2(HPO4)2(PO4)2] + 4Ca2+ + 2HPsi1- + 2Psi2- + 2H2PO1-4 + 2H2O.The formation of two other surface complexes is possible; however, the complex shown above probably disrupts the apatite lattice the least. Traces of CaPsi&middot;H2O precipitate out from the filtrates of highly concentrated solutions after 6 days. Copyright 1997 Academic Press. Copyright 1997Academic Press

Human gastric intrinsic factor expression is not restricted to parietal cells

Gastric parietal cells have been accepted as the only site of intrinsic factor production in the human stomach. In animals, however, intrinsic factor has been localised to various other cell types of foregut origin, including chief and enteroendocrine cells in gastric mucosa, and duct cells from salivary glands and pancreas. The availability of recombinant human intrinsic factor has led to production of high titre, monospecific antiserum which was used to reexamine the distribution and subcellular localisation of intrinsic factor in the human stomach. Immunolight microscopy revealed that most positively stained cells were gastric parietal cells, but at the margins of the anatomical regions (e.g. cardia/fundus, body/antrum) clusters of gastric chief cells and individual enteroendocrine cells were found to contain intrinsic factor. Immunoelectron microscopy demonstrated the highest antigen density on endocytic and apical membranes of parietal cells. Exocrine secretory granules of a subpopulation of chief cells, the secretory granules of some enteroendocrine cells, and the plasma membranes and smooth vesicles of endothelial cells of the lamina propria capillaries underlying enteroendocrine cells were also positive for the antigen. Labelling in all cells was specific, as it was abolished by preabsorption of the antisera with purified recombinant human intrinsic factor. These findings demonstrate a potential for cellular expression of human intrinsic factor in nonparietal cells. Because such expression occurs normally at the margins of anatomical gastric regions, it suggests that local factors may influence expression of intrinsic factor.

Interaction of citric acid with hydroxyapatite: surface exchange of ions and precipitation of calcium citrate

The use of citric acid is efficacious and distinctive in the demineralization of dentinal root surfaces for periodontal regeneration and in the etching and conditioning of enamel or dentin for bonding restorative resins. To decipher the role of citric acid in these applications, it is important that one have a basic understanding of its interaction with synthetic hydroxyapatite. The uptake or removal of citrate ions from aqueous solutions of citric acid (4 to 100 mmol/L, 10 mL) by hydroxyapatite (1 g) was studied at 22 degrees C after a given reaction period (from 3 hr to 11 days) by immediate spectrophotometric monitoring of the concentrations of the filtrates (214 nm). The concentrations of calcium, phosphate, and hydrogen ions were also determined in the same solutions. The interaction: (i) is a time-independent ionic-exchange process with the substrate when the initial acid concentrations are dilute (4 to 12.5 mmol/L), and (ii) is a reactive process that is time-dependent for higher acid concentrations. The exchange process shows an adsorption of about one citrate ion per (100) face of the unit cell of hydroxyapatite for a maximally exchanged surface. The curves representing the reactive process may be quantitatively or qualitatively explained on the basis of the supersaturation of the solutions with respect to calcium citrate and its slow precipitation. The physico-chemical analysis of the needle-shaped birefringent crystals of the precipitate from the supersaturated solutions confirms the precipitate to be Ca3(citrate)2.4H2O.

Indolent course of advanced neuroblastoma in children older than 6 years at diagnosis

BACKGROUND

An early observation suggests that children older than 6 years of age at diagnosis of neuroblastoma constitute a favorable prognostic group.

METHODS

Kaplan-Meier plots of survival of all such patients diagnosed at the Children's Hospital of Pittsburgh 1975-1992 were compared with curves of concurrently treated patients with Stage IV disease who were 1-6 years of age at diagnosis ("younger patients"). Known prognostic features, including stage and primary site of disease, pattern of metastases, histopathology, MYCN gene amplification, and urinary catecholamine metabolite ratios, were reviewed.

RESULTS

Of 17 children diagnosed after the age of 6 years ("older patients"), 13 patients had Evans' Stage IV disease and 4 had Stage III disease. The median survival was 3.24 years (range, 0.63-15.04 years) for the entire cohort and 3.07 years for those children with Stage IV disease. This compared with a median survival of 1.05 years in 34 concurrent younger patients (P < 0.01). In most cases, disease in these older patients was characterized by a short-lived complete or partial remission followed by aggressive recurrent disease that was partially and only transiently chemo- or radiosensitive. Only 3 patients (2 with Stage IV disease) are in continuous complete remission at 3, 5 10/12, and 14 1/2 years from diagnosis. Although poor prognostic factors were common, including the presence of bony metastases (12/17), biopsy material from pretreatment tumor specimens demonstrated a single MYCN gene copy number in all patients and favorable histology in 15 of 16 samples.

CONCLUSION

Older children with neuroblastoma have a more indolent course than do younger patients, a finding that appears to be related to favorable histology and the absence of MYCN amplification. Examination of larger numbers of such patients from cooperative groups should lead to a better understanding of what appears to be a subset of pediatric patients with neuroblastoma who may benefit from specifically tailored treatment protocols.

Fluorescence in situ hybridization (FISH) detection of MYCN oncogene amplification in neuroblastoma using paraffin-embedded tissues

The expression and degree of amplification of the MYCN oncogene in neuroblastoma provide an important indicator of disease prognosis. Detection of MYCN amplification has been described using Southern blotting or polymerase chain reaction (PCR) on DNA from fresh or frozen tissue samples, and using in situ hybridization mainly on metaphase spreads or smears of cultured neuroblastoma cells. In this article, we describe fluorescence in situ hybridization (FISH) results on detection of MYCN amplification in formalin-fixed, paraffin-embedded samples of 25 neuroblastoma and 20 nonneuroblastoma pediatric tumors. MYCN amplification was readily detectable by FISH in eight of the neuroblastomas; correlation with results obtained by Southern analysis was perfect. Of the nonneuroblastoma tumors, only one of three retinoblastoma cases showed MYCN amplification. In contrast to the Southern blot technique, FISH demonstrated the state of amplification heterogeneity of the tumor cells as well as the nature of the amplification units: double-minute chromosomes (DMs) or homogeneously staining regions (HSRs). The results indicate that FISH is a rapid and reliable method for detection of MYCN oncogene amplification in routinely processed samples and may be used to supplant the Southern blot technique.

Interaction of chlorhexidine digluconate with and adsorption of chlorhexidine on hydroxyapatite

It is well known that chlorhexidine digluconate provides an effective microbicidal activity during oral rinsing, and therefore, it was considered worthwhile to investigate its interaction with hydroxyapatite on a fundamental level. The kinetics of uptake (or reaction) of the compound from aqueous solutions by synthetic hydroxyapatite was studied at 23 degrees C for four time periods by monitoring its concentration. There was no uptake at low concentrations for any time period. The uptake curves for higher concentrations shifted towards the lower concentrations as the period increased and became more and more vertically oriented to the concentration axis. The concentrations of calcium ions increased, phosphate ions decreased and hydrogen ions decreased a little for a given period as the concentration of the compound was increased. All of these experimental facts can be qualitatively explained on the basis of the solubility considerations of hydroxyapatite and of chlorhexidine phosphate, the reaction product that slowly precipitates out of the solution. The needle-shaped birefringent crystals of the phosphate salt are clearly visible in the apatite matrix under a microscope, and its refractive index and differential Fourier transform infrared spectra match almost exactly with those of a well-characterized, synthesized phosphate salt. To explore the nature of interaction, the uptake of chlorhexidine base was studied from p-dioxane and it is irreversible. The uptake is total below a threshold equilibrium concentration and constant above it.

Genomic structure and organization of a Q-like gene in the GRC-G/C region of the rat

In the rat homologue of the mouse Q/TL region, grc-G/C, a TL-like gene (RT1.N) has been identified recently. This paper reports on a Q-like gene, designated RT1.0, that maps in the same region. It contains a 5' untranslated region (UT), signal peptide, alpha 3 domain, transmembrane region, cytoplasmic domain (three exons) and 3'UT region. Comparison with mouse class-I genes shows that the greatest similarity is to the H-2Q, K, D and L genes; it is very different from the TL genes of the mouse and rat. A sequence that includes many CT repeats occurs in the 3'UT region of RT1.0 and in three to five other class I-hybridizing fragments. Thus, the MHC-linked region of the rat contains both Q-like and TL-like class-I genes.

Adsorption of low-molecular-weight sodium polyacrylate on hydroxyapatite

Adsorption of low-molecular-weight sodium polyacrylate from aqueous solution onto synthetic hydroxyapatite was studied at room temperature so that the mechanism of adhesion of polyacrylate cements to tooth mineral could be elucidated. The adsorption isotherm of sodium polyacrylate was Langmuirian in shape and was thus qualitatively different from that of polyacrylic acid (Misra, 1991), which exhibited an adsorption maximum. The self-association of the molecules that probably causes the maximum to occur with polyacrylic acid was effectively absent for the relatively well-ionized, electrostatically repelling polyacrylate ions of the salt. With the adsorption of acrylate ions, the concentration of phosphate ions increased monotonically, while the concentration of calcium ions showed a minimum. The adsorption of sodium polyacrylate was irreversible, as it was for polyacrylic acid.

An esthetic glass-ceramic for use in composite restoration inserts

The objective of the preliminary work reported here was to prepare an improved formulation of intrinsically colored microcrystalline glass-ceramic. Applications could include "megafillers" for direct composite restorations, precision castings, and CAD-CAM prostheses. The experimental glass-ceramic reported here contained SiO2 56.9, AI2O3 19, LiO2 7, ZnO 6, MgO 5, TiO22, ZrO22, P2O52, and CeO20.1 mole%. The batch materials were melted and stirred at 1,610 degrees C for 2 h, quenched in water and also formed into a block of a clear, slightly yellow glass. To identify the crystalline phases that developed during transformation of the glass to the ceramic, x-ray diffraction was used on ten aliquots taken during 15 h of stepwise heating from 750 to 1050 degrees C. With heating, the yellow color deepened to a very translucent "dark yellow" dental shade, then lightened with gradually increasing opacity during formation of secondary crystalline phases. X-ray opacity was approximately equivalent to that of dental enamel. The refractive index of the glass, nD1.554, increased during nucleation and growth of the crystalline phases to a maximum of 1.586. Intrinsic coloration of these glass-ceramic materials can be controlled by varying the heat treatment and/or composition to match typical dental shades.

Adsorption and orientation of tetracycline on hydroxyapatite

Adsorption of tetracycline from separate solutions of ethanol, p-dioxane, and chloroform onto synthetic hydroxyapatite (containing about 1.5 monolayer of physisorbed water) was studied in order to understand its interaction with bone and teeth. The adsorption isotherms of tetracycline are reversible and Langmuirian from ethanol and p-dioxane and are almost identical. The isotherm is irreversible from chloroform, and a constant amount of adsorbate is removed from the solutions above a certain concentration. The irreversibly adsorbed compound is completely desorbed by prolonged repeated washing with ethanol. An analysis of the reversible isotherms showed that at maximum coverage the ring or polycyclic structure of the molecule stands perpendicular to the surface with appropriate hydroxyl groups and keto-oxygens hydrogen bonded to the surface. However, the adsorption from chloroform is irreversible and at maximum adsorption is about one and half times larger than that from either ethanol or p-dioxane. The process of adsorption does not affect the chemical integrity of tetracycline.

Biochemical analysis of the rat MHC class I antigens RT1.Aa, RT1.Fa and Pa

In DA strain rats, there are two other MHC class I loci (Pa and RT1.Fa) in the vicinity of the classical class I locus RT1.Aa. The Pa antigen is the pregnancy-associated antigen, and it was detected by antibodies elicited in WF females pregnant by DA males without any other immunization. The Fa antigen was detected by a monoclonal antibody raised by alloimmunization. In the present work, the Aa, Fa and the Pa antigens have been compared by HPLC peptide mapping and by isoelectric focusing after their isolation by appropriate monoclonal antibodies. All the three antigens are identical in primary structure with respect to lysine, methionine, asparagine and the aromatic amino acid residues, but they differ from one another with respect to glutamic acid and/or aspartic acid residues. The pI values of the antigens differ slightly. All three antigens have two identical N-linked glycans, but the Fa antigen has an additional N-linked glycan. Based on the available amino acid sequence of the Pa antigen, it can be concluded that both Aa and Pa antigens are devoid of glycosylation in the second domain. This lack of glycosylation of the classical antigen Aa is unique for the rat, since classical class I antigens of the mouse show glycosylation in the first and second, and sometimes in the third domain, and those in the human, in the first domain only. The high degree of similarity among the Aa, Fa, and Pa molecules that this study indicates is also unique for the rat, since antigens encoded by different class I genes of the same haplotype are quite disparate in the mouse and human.

Major histocompatibility complex class I antigens expressed on rat trophoblast cells

There is controversy about the size of the major histocompatibility complex antigens of trophoblast cells from placenta. There are some reports that the heavy chains of these molecules are smaller (39-43 kd) than those of the classical class I antigens (45-46 kd), while there are others which show that both the light and the heavy forms of class I antigens occur in the trophoblast cells. In order to investigate this problem, we studied the classical class I antigen (RT1.Aa) and the pregnancy-associated class I antigen (Pa) of the rat from 125I-labeled basal trophoblast cells, isolated from the placenta of WF females pregnant by DA males, using very mild conditions. These antigens were compared with those of the syngeneic (DA x DA) trophoblast cells or paternal (DA) lymphocytes by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Both the Aa and Pa antigens, precipitated from the two trophoblast preparations, showed a heavy chain of 46 kd associated with a 12 kd beta 2-microglobulin component, as did the same molecules precipitated from the lymphocytes. Heavy chains in the range of 39-43 kd could not be detected in any of the samples. The results suggest that the smaller molecular weight heavy chains are methodological artifacts and could arise from loss of a glycan(s) during isolation.

The RT1.G locus in the rat encodes a Qa/TL-like antigen

A new antigenic system in the rat homologous to the Qa/TL antigen system in the mouse has been characterized. It was detected by antibodies raised in donor-recipient combinations that were matched for the RT1.A, B, D, E loci in the major histocompatibility complex (MHC): (R11 X BN)F1 anti-BN.1L(LEW), (R18 X BN)F1 anti-BN.1L, and BN.1LV1(F344) anti-BN.1L. Absorption analyses using these antisera and a variety of inbred, congenic, and recombinant strains identified three alleles, RT1.Ga, Gb, Gc, of which Gc is a null allele. The strain distribution of these alleles was determined using 37 strains of rats representative of all of the prototypic haplotypes and a number of congenic and recombinant strains. The use of the congenic and recombinant strains showed that the RT1.G locus was linked to the MHC and that the most probable gene order was A-E-G. Testcross analysis showed that the map distance between A and G was 1.4 cM (4/285 recombinants). The RT1.G antigen has a heavy chain of Mr 46,000 and is present on both T and B cells.

A unique antigen, RT11, in the placenta of the rat

In the course of exploring the antibody response in the unsensitized WF (u) female pregnant by a DA (a) male, we prepared a hybridoma that secreted an antibody (mAb 213) that was specific to the a haplotype but identified an antigen different from Pa. This antigen was designated RT11. It is present from the twelfth day of gestation on the collagen fibers of the placenta and of all organs in fetal and adult rats. It is particularly prominent on red blood cells; in the yolk sac epithelium; in the walls of the endodermal sinus, blood vessels and bronchioles; and in capsules and trabeculae. A very small amount is present on DA lymphocytes, since 17-20% of them react with mAb 213 by cytofluorimetry. The RT11 antigen is absent from the basal and labyrinthine trophoblast cells, from the parenchymal cells of all organs, and from T and B cells. This distribution pattern is completely different from that of the Aa and Pa antigens. Inhibition and absorption studies showed that RT11 is not an integral part of the collagen molecule. The SDS-PAGE analysis of the immunoprecipitates of RT11 from radioiodinated whole-membrane extracts of red blood cells and from the glycoprotein fraction thereof showed that it is an unglycosylated protein of molecular weight 29,000. The evidence to date suggests that RT11 is a blood group antigen. Studies on the genetic control of the expression of RT11 were undertaken to determine whether a gene linked to the MHC was involved and whether the control mechanism was unigenic or polygenic. Backcrosses generated using inbred strains--(DA x BN)F1 x DA-- and using complementary congenic strains--(DA.1N x BN.1A) F1 x BN.1A--showed that the expression of RT11 was under polygenic control, and that both an MHC-linked gene (1.2 cM from RT1.Aa) and genes not linked to the MHC are involved. By contrast, the expression of the Pa antigen is under the control of an MHC gene only.

Beta-2-microglobulin of rat major histocompatibility complex class I antigens

Detection of the beta 2-microglobulin (beta 2m) component of the rat MHC class I antigens has been difficult. In the present report, we have addressed this issue by a systematic study of rat class I antigens from red blood cells or from lymphocytes that were freshly isolated or cultured in the presence of autologous or heterologous sera and surface-labeled with 125I or intrinsically labeled with radioactive amino acids. First, specific radioiodination of rat beta 2m in association with the antigen heavy chain on red blood cells or lymphocytes is minimal, resulting in its poor identification by SDS-PAGE. Second, labeling with radioactive methionine or lysine gives a more intense beta 2m band with respect to the heavy chain than labeling with arginine or tyrosine. Third, the beta 2m component shows a large increase in intensity compared to the heavy chain when the antigens are isolated from lymphocytes that are cultured in the presence of fetal bovine serum prior to 125I-labeling. This increase is due to exchange of endogenous rat beta 2m with bovine beta 2m and to a much higher level of radioiodination of the latter. Fourth, rat red blood cells and lymphocytes contain free surface beta 2m molecules in addition to those associated with the antigen heavy chains. The free molecules show a much higher level of radioiodination than those associated with the heavy chains, and there is little exchange between the antigen-bound and the free beta 2m after radioiodination.(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption of 4-methacryloxyethyl trimellitate anhydride (4-META) on hydroxyapatite and its role in composite bonding

The adsorption of 4-methacryloxyethyl trimellitate anhydride (4-META) was studied from ethanol and dichloromethane onto synthetic hydroxyapatite (containing about 1.5 monolayers of physisorbed water) in order to study its role in restorative composite bonding to teeth. The adsorption isotherm of 4-META was S-shaped and reversible from ethanol, and followed the Langmuir plot at lower concentrations. The isotherm was irreversible from dichloromethane, and a constant amount of adsorbate was removed from the solutions above a certain concentration. The irreversibly adsorbed compound was completely removed by washing with ethanol. Therefore, the bonding between teeth and the restorative resin containing 4-META as a coupling agent is micromechanical and not chemical in nature. An analysis of isotherms showed that the benzene rings of the adsorbate molecules lie flat on the surface for both solvents. The molecules adsorbed from ethanol rotate about the solvent-modified (esterified) or unmodified carboxylic anhydride moieties with methacrylate hydrocarbon groups which are folded upward. However, the molecules adsorbed from dichloromethane remain fixed to the surface without rotation, and their methacryloxyethyl groups are folded over the rings. The diametral tensile strength of a BIS-GMA polymer with adsorbate-covered apatite was approximately equal to that of the composite filled with untreated apatite.

Isolation and characterization of rat trophoblast cells

Previous immunohistochemical studies of the rat placenta using specific alloantisera and/or monoclonal antibodies showed that the basal zone trophoblasts stained for Pa and Aa class I major histocompatibility complex (MHC) antigens and for the human SP1-related antigen. In an effort to isolate the basal zone trophoblast cells from the rat placenta, we used these markers to assess the degree of purification of the cells separated by density gradient centrifugation using either Ficoll-Hypaque or Percoll as the gradient medium. The cells were put either on the top or at the bottom of discontinuous density gradients in the range of 1.005-1.10 g/ml. The cell separation profiles for the two media were different. With Percoll, most of the trophoblast cells (80-95%) were collected at the density gradients 1.04/1.06 and 1.06/1.08, whereas with Ficoll-Hypaque, these gradients separated only a small fraction (4-23%) of the trophoblast cells, and most of them pelleted at the bottom of the tube. The trophoblast cells separated by Ficoll-Hypaque, however, showed fewer contaminant cells than those separated by the Percoll gradients.

Differential expression of MHC class I antigens on the placenta of the rat. A mechanism for the survival of the fetal allograft

In some mating combinations in rats, there is a maternal antibody response to the maternal antigenic components of the placenta without any previous immunization of the mother. The highest response occurs in the WF (u) female mated to the DA (a) male, and it is against a unique MHC-encoded class I antigen, the Pa antigen, and not against the major allele-specific transplantation antigen of the DA strain, RT1.Aa. The development of mAbs to the Pa and Aa antigens allowed us to localize these antigens on the placenta and to explore the reason for the differential antibody response to them using immunohistochemical and biochemical techniques. Both antibodies reacted with the WF X DA placenta and stained the endovascular and interstitial trophoblast of the decidua, the basal trophoblast, Reichert's membrane, and the yolk sac epithelium, but they did not stain the labyrinthine trophoblast. Blocking studies showed that each antibody reacted with a separate molecule in the placenta. Anti-class II mAbs reactive with the a or u haplotype did not stain the WF X DA, DA X DA, or WF X WF placenta; hence, there are no class II antigens in the placenta. Electron microscopic studies of the semiallogeneic WF X DA placenta using the immunogold technique with both single- and double-labeling showed that only the Pa antigen was expressed on the surface of the basal trophoblast, but that both the Pa and Aa antigens were in the cytoplasm of these cells; neither antigen was found in the labyrinthine trophoblast. By contrast, the placenta from the syngeneic DA X DA mating expressed both the Pa and Aa antigens on the surface of the basal trophoblast as well as in the cytoplasm; neither antigen was found in the labyrinthine trophoblast. These observations were quantified morphometrically using electron photomicrographs of single-labeled tissues. Both the Pa and Aa antigens isolated from the plasma membrane of lymphocytes have heavy chains of 46 kD, but those antigens isolated from the plasma membrane of basal trophoblast cells have heavy chains of 43 kD. Based on densitometric measurements of autoradiographs, the Pa/Aa ratio in the basal trophoblast membrane is 23.5, whereas it is 0.46 in lymphocyte membranes. These studies show that there is differential regulation of the expression of class I antigens on basal trophoblast cells in semiallogeneic pregnancies, but not in syngeneic pregnancies, such that the major allele-specific transplantation antigen is scarcely expressed on the surface of the basal trophoblast.(ABSTRACT TRUNCATED AT 400 WORDS)

Adsorption of N-phenylglycine on hydroxyapatite: role in the bonding procedure of a restorative resin to dentin

The adsorption of N-phenylglycine (NPG) onto synthetic hydroxyapatite from ethanol solutions was studied to elucidate the role of surface-active moieties in determining the character of adsorption, and to explore the role of NPG in a bonding procedure of restorative resin to dentin. The adsorption isotherm of N-phenylglycine is reversible (and Langmuirian) from ethanol (99.8%). At maximum adsorption the phenyl rings of the adsorbed molecules lie flat on the surface and the carboxylate oxygens and amino nitrogens are anchored to the surface. The N-phenylglycine serves as an amine accelerator since the peroxide containing monomer polymerizes with the adsorbate-covered apatite. The diametral tensile strength of this composite is approximately equal to the composite filled with untreated apatite. The role of various factors contributing to adhesive strength in the bonding procedure is also discussed.

Carbohydrate moieties of rat MHC class I antigens

The rat major histocompatibility complex class I antigens RT1.Au and RT1.Eu from the u haplotype and RT1. An from the n haplotype were labeled with 14C-asparagine or with 3H-fucose, mannose, galactose, and N-acetylglucosamine. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis showed complete removal of radioactivity from the sugar-labeled antigen heavy chains by digestion with glycopeptidase F, an enzyme that removes N-linked glycans completely. High performance liquid chromatography analysis of the tryptic digests of the mixed sugar-labeled and asparagine-labeled antigens demonstrated that all the sugar-labeled peptides were coincident with asparagine-labeled peptides. The An antigen showed three glycopeptides, each of which had different amounts of sugar radioactivity. The antigens Au and Eu showed two glycopeptides with different amounts of radioactivity but at identical positions in the two antigens. Antigen Eu had an additional glycopeptide with a lower amount of radioactivity. The positions of the glycopeptides from the Au and Eu antigens were different from those of the An antigen. The peptide profiles of the 14C-asparagine-labeled Au and Eu antigens demonstrated distinct differences between the molecules. The results of this study show that: (a) all the glycans on rat class I antigens are N-linked, as they are on H-2 and HLA class I antigens; (b) there are compositional differences among the glycans in each of the three antigens; (c) the glycosylation pattern of the rat class I antigens is similar to that of the mouse class I antigens, which contain two or three glycans, in contrast to that of the human class I antigens, which contain only one glycan; and (d) the antigens Au and Eu from the same haplotype are more closely related to each other than they are to the An antigen.

The major histocompatibility complex of the rat

Immunogenetic studies in the rat began with the investigation of blood group antigens (1-7) and evolved into the investigation of histocompatibility antigens and transplantation phenomena (8-17). In the course of this work, several nomenclature systems evolved that were eventually reconciled in a series of comparison studies (18-24). The biennial Workshops on Alloantigenic Systems in the Rat held under the aegis of the Transplantation Society (24) have provided the forum for the continued evolution of this field. In addition, several reviews (24-31) and books (32-35) have provided periodic summaries of different aspects of rat immunogenetics. This review will focus on the structure of the major histocompatibility complex (MHC) of the rat from the serological, biochemical, and molecular points of view.

Comparison of rat MHC class I antigens by peptide mapping

Monoclonal antibodies specific for the rat major histocompatibility complex (MHC) class I antigens RT1.An, RT1.Au, and RT1.Eu were used for immunoprecipitation of antigens biosynthetically radiolabeled with 14C- or 3H-labeled arginine, lysine, and tyrosine; with arginine or tyrosine alone; and with or without tunicamycin in the culture medium. Heavy chains of the glycosylated and unglycosylated antigens were purified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and their tryptic and chymotryptic peptides were compared by high performance liquid chromatography. The antigens coded by the same locus in two different haplotypes (An and Au) differed by 30%, whereas the products of two different loci in the same haplotype (Au and Eu) differed only by 1-3%. Comparative analysis of the data for samples labeled with single amino acids indicated that two amino acids in Au have been substituted by an arginine and probably by a tyrosine residue, respectively, in Eu. The high degree of homology between the products of the A and E loci in the same haplotype accounts for the difficulty in detecting recombinational events within the MHC of the rat by classical serological approaches.

Water on apatites

Adsorption of water was studied gravimetrically at 23 degrees C in an open system at several relative humidities on a variety of apatitic calcium phosphates including enamel, deproteinized enamel, and bone mineral. The amount of adsorbed water increases linearly with the surface areas of the synthetic apatites and does not appear very sensitive to calcium to phosphorus ratio of the apatites. The adsorption results correlate very well up to about two monolayers with a conventionally determined isotherm. Higher uptake of water even by "deproteinized" enamel or bone may be due to the presence of pore structure and incompletely removed organic matter.

Adsorption of benzoic acid on pure and cupric ion-modified hydroxyapatite: implications for design of a coupling agent to dental polymer composites

The adsorption isotherms of benzoic acid on synthetic hydroxyapatite (containing about 1.5 monolayers of physisorbed water) were studied from ethanol, dimethylsulfoxide, p-dioxane, methylene chloride, and benzene to discern the role of solvent in the process. The adsorption is reversible from the first three solvents and follows the Langmuir plots. It is irreversible from the last two, and a constant amount of absorbent is removed from solutions above a certain concentration. The isotherms of potassium benzoate on the apatite from ethanol and dimethyl sulfoxide were reversible. The isotherms of the acid on cupric ion-modified apatite surfaces from ethanol and benzene were identical with those obtained on the pure hydroxyapatite. This may demonstrate that any "surface chelation" with the cation may not be a significant factor for adsorption to occur. The adsorptive behavior seems to depend upon the interplay of hydrogen-bonding among the solute, the solvent, and the hydrated apatite surface. The capability of a solvent to hydrogen-bond may determine whether adsorption from it will be reversible or irreversible. Based upon its compatibility with a solvent, the benzene ring is upright or lies flat on the surface. The adsorbed molecules rotate about the center of the carboxylate groups which are hydrogen-bonded to the surface. These factors should be considered in designing or selecting a suitable surface-active moiety for a coupling agent between tooth mineral and a restorative resin.

Complexes of iron cations with N-phenylglycinate or oxalic acid

N-phenyglycine plays a very important role in obtaining adhesion of restorative composites to dentin and enamel (Bowen et al., 1982a). In a systematic investigation, ferric or ferrous N-phenylglycinate complexes formed when aqueous ferric nitrate or ferrous chloride was combined with solutions of potassium N-phenylglycinate in stoichiometric proportions. The molal ratios of iron ion to N-phenylglycinate ion in each complex were confirmed by osmolality measurements with a freezing-point osmometer. The reaction of aqueous solutions of oxalic acid with ferric nitrate indicated formation of ferric oxalate complexes with a stoichiometry of Fe2(oxalate)3 in solution, using Job's method of continuous variations (1925;1928).

Adsorption of zirconyl salts and their acids on hydroxyapatite: use of the salts as coupling agents to dental polymer composites

Zirconyl methacrylate (I) and zirconyl-2-ethylhexanoate (II) were synthesized, and their adsorption isotherms from solutions onto synthetic hydroxyapatite were studied. The isotherms of methacrylic and 2-ethylhexanoic acids were also determined from the same solvents. The adsorption of I was irreversible from methylene chloride, and that of II was irreversible from cyclohexane. The adsorption in both cases was constant from solutions above a certain concentration, and exhaustive below this threshold concentration. Both compounds rendered the dried apatite powder extremely hydrophobic; however, the adsorbate was slowly washed off by excess water. The configuration of the adsorbate molecules, deduced from the maximum adsorption and other adsorption characteristics of the two compounds, indicated that: (i) in both cases the adsorbate may be held to the surface by concerted hydrogen bonding of the carboxylate and zirconyl oxygen atoms; and (ii) the hydrocarbon moieties in both adsorbates expose themselves toward the solution, thereby making the dried surface hydrophobic. The adsorptive behavior of the respective acids was similar to that of the salts. Polymer, filled with synthetic hydroxyapatite covered with irreversibly adsorbed I, had a diametral tensile strength about 50% greater than that of the polymer filled with untreated apatite. The strength of the composite was not affected by treatment of the apatite with II or with the acids.

Analysis of class I MHC antigens in the rat by monoclonal antibodies

Monoclonal antibodies (mAb) were made against class I MHC antigens of the i (mAb 42,70,39) and u (mAb 68-D) haplotypes in the rat by using specific strain combinations in order to obtain reagents for identifying the products of the RT1.An, RT1.Au, and RT1.Eu loci. These antibodies were hemagglutinating only; were IgG except for mAb 68-D3, which had a defective heavy chain; reacted identically with MHC-congenic strains and with their inbred donor strains; and precipitated class I MHC antigens. Strain distribution, sequential immunoprecipitation, and peptide mapping studies were used to define the specificities of the mAb, and the assignments were checked by comparing the specificities of the mAb with those of haplotype-specific alloantisera. The specificities were the following: mAb 42, An; mAb 68-D, Au; mAb 70, Eu; and mAb 39, an antigen encoded by a locus different from A and E. This new locus was designated RT1.F, and the allele detected by mAb 39, as Fa. The serologic data place RT1.F between RT1.A and RT1.D. The plasma membranes of DA.1I(BI) lymphocytes contain comparable amounts of An, Eu, and Fa antigens but express them on the cell surface in the order An much greater than Eu greater than Fa.

Analysis of class I MHC antigens in the rat by monoclonal antibodies

Monoclonal antibodies (mAb) were made against class I MHC antigens of the i (mAb 42,70,39) and u (mAb 68-D) haplotypes in the rat by using specific strain combinations in order to obtain reagents for identifying the products of the RT1.An, RT1.Au, and RT1.Eu loci. These antibodies were hemagglutinating only; were IgG except for mAb 68-D3, which had a defective heavy chain; reacted identically with MHC-congenic strains and with their inbred donor strains; and precipitated class I MHC antigens. Strain distribution, sequential immunoprecipitation, and peptide mapping studies were used to define the specificities of the mAb, and the assignments were checked by comparing the specificities of the mAb with those of haplotype-specific alloantisera. The specificities were the following: mAb 42, An; mAb 68-D, Au; mAb 70, Eu; and mAb 39, an antigen encoded by a locus different from A and E. This new locus was designated RT1.F, and the allele detected by mAb 39, as Fa. The serologic data place RT1.F between RT1.A and RT1.D. The plasma membranes of DA.1I(BI) lymphocytes contain comparable amounts of An, Eu, and Fa antigens but express them on the cell surface in the order An much greater than Eu greater than Fa.

Production of monoclonal antibodies against RT2 antigens of the rat and the definition of a new locus, RT9, linked to RT2

Efforts were made to generate hybridomas producing monoclonal antibodies against the RT2a, RT2b and RT3a antigens of the rat. While a number of hybridomas from each of five different fusions was found to produce antibodies against the RT2b antigen, no hybridoma producing antibody to the RT2a antigen could be detected among those generated in six different fusions. No stable hybridoma secreting antibody specific for the RT3a antigen could be established in three different fusions, although one positive culture was detected. In the course of this work, a monoclonal antibody against a new antigenic specificity was detected in one of the two strain combinations in which the anti-RT2b antibodies were raised. The locus controlling this antigen, which was designated RT9, maps 4.9 (2.2-12.6) cM from RT2.

Toilet facilities in a large Indian teaching hospital

While assessing the total medical care provided by any large hospital in a community, hardly any stress is laid on the sanitary facilities which the hospital provides and which form such an integral part of every hospital patient. We studied the toilet facilities of M.L.B. Medical College, Jhansi. They seem to be adequate for the ambulant patient but are insufficient for the bedridden and for those who have weak legs. The findings are discussed.

Elicitation of the maternal antibody response to the fetus by a broadly shared MHC class I antigenic determinant

The antibody response to the semiallogeneic fetus in the rat was examined in eight mating combinations that were chosen specifically to cross different major histocompatibility complex (MHC) and nonMHC loci. The BN X DA and BN X BN.1A(DA) matings (n anti-a) were the only ones to show an antibody response to the fetus, and the response occurred in 25-64% of the matings. All the other six mating combinations studied were negative by hemagglutination, cytotoxicity, and cellular radioimmunoassay. The response appeared in the postpartum period after the first litter and reached its maximal frequency during the postpartum periods of the second and third matings. There was no correlation between the litter size and the presence or absence of an antibody response to the fetal antigens. The antibodies elicited by the fetus were hemagglutinating but not cytotoxic, and consisted of only one isotype, IgG2a, whereas in the alloantiserum raised by skin grafting and the injection of lymphocytes, they were distributed among the IgG2a greater than IgG1 greater than IgM isotypes and were both hemagglutinating and cytotoxic. Using reciprocal congenic strains, the pregnancy-induced antibody response was shown to be against MHC antigens only. This finding was confirmed by testing the sera against rats from a population that was segregating for the haplotypes a/a, a/n, and n/n. Comparison of the pregnancy-induced antibody with the BN anti-DA alloantibodies by absorption studies showed that the former was less crossreactive, did not react with the RT1.Aa haplotype-specific antigenic determinant, and did react with an antigenic determinant shared among the a, d, o, i, e, f, r10, b, and m haplotypes--but not with the n, c, g, k, l, h, or u haplotypes. Using the DA.1I and r10 strains in cellular radioimmunoassay, absorption, and immunoprecipitation experiments, it was shown that the pregnancy-induced antibody was elicited by a class I antigenic determinant, provisionally designated Pa, which is encoded by a locus in the vicinity of RT1.A.

Immunochemical evidence for multiple class I antigens coded by the MHC of the rat (RT1) and their differential expression on red blood cells and lymphocytes

Five monoclonal antibodies reacting with class I MHC antigens were produced by fusing lymphocytes from WF (RT1u) rats immunized against DA (RT1a) rats with P3-X63-Ag8.653 myeloma cells. Sequential immunoprecipitation studies with the mAb and the WF anti-DA alloantiserum demonstrated the presence of four different class I molecules: all four molecules were reactive with the alloantiserum; three of them contained the determinant for mAb 155; two of the latter three molecules shared the determinants for mAb 3, 56 and 60, and one of these two molecules also contained the determinant for mAb 118. The four molecules could be isolated from the antigen preparation by sequential immunodepletion first with 118, next with 3, then with 115 and finally with the alloantiserum or by sequential absorption with affinity columns of Sepharose 4B coupled to the antibodies. The three antigens which were sequentially isolated with the mAb 118, 3, and 155, respectively, were analysed by SDS-PAGE after digestion with Staphylococcus aureus V8 protease, and they showed differences in peptide patterns. The relative amounts of the antigens expressed on red blood cells and on lymphocytes were different based on the results of sequential isolation and indirect cellular radioimmunoassay: the antigen which reacted with both mAb 3 (and 56 or 60) and 155 was the major class I antigen on red blood cells, and the antigen which reacted with mAb 118, 3 (and 56 or 60) and 155 was the major class I antigen on lymphocytes.

Growth of rat-mouse hybridomas in nude mice and nude rats

Athymic (nude) mice and rats were inoculated intraperitoneally with rat-mouse hybridoma cells secreting monoclonal antibodies to rat MHC class I antigens in order to improve the yield of antibodies. Pristane priming and subsequent intraperitoneal injection of the hybridoma cells in to nude mice yielded ascites which contained antibody in high concentration (10-15 mg/ml). Complete Freund's adjuvant, mineral oil, pristane or antibody-antigen complexes were used to induce ascites in nude rats, but only pristane priming did so consistently. The hybridoma cells in the ascitic fluid failed to secrete antibody, although they contained intracellular antibody. However, when the pristane-primed nude rats received 250-500 rads of total body radiation prior to injection with the hybridoma cells, they produced large amounts of antibody. When the nude rats were splenectomized and injected with the hybridoma cells, they also produced antibody in high titers. There was no in vitro inhibition of antibody formation by the hybridoma cells cultured in medium containing 15% serum from nude rats, but co-culture of the hybridoma cells with splenic lymphocytes from normal or nude rats markedly inhibited antibody production. These results indicate that the defect in antibody secretion by the hybridoma cells in the ascites of nude rats is due to the presence of radiation-sensitive suppressor cells in the spleen.