Recent progress in structure-function and molecular analyses of the pituitary/placental glycoprotein hormone receptors.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
J A Dias
Publications and source records attributed to J A Dias.
Identification of assembled epitopes on the alpha-subunit of human follicle stimulating hormone.
In order to characterize further the antigenic structure of human follitropin (hFSH), BALB/c mice were immunized with hFSH and anti-hFSH monoclonal antibodies (mAbs) were generated. The hFSH subunit specificity of the mAbs was assessed by a solid-phase enzyme-linked immunosorbent assay (ELISA) and a solution-phase radioimmunoassay (RIA), each using hFSH, hFSH alpha, and hFSH beta. Five mAbs bound hFSH and hFSH alpha in the ELISA and the RIA. In addition, some mAbs recognized hFSH beta, albeit to a much lower degree, as demonstrated by displacement of [125I]hFSH binding to the mAbs by hFSH beta, in the solution-phase RIAs. Next, synthetic peptides corresponding to the hFSH alpha-subunit sequence were used to identify sequences specific to the epitopes of each of the five mAbs. Using this epitope mapping strategy, two assembled epitopes were identified. mAbs 3A and 4B distinguish one discontinuous epitope comprised minimally of sequences alpha-16-21 and alpha-66-92, whereas mAbs 5F and 2E distinguish a second discontinuous epitope comprised minimally of sequences alpha-40-50 and alpha-66-72.
Amino Acid Sequence↗
Topographic analysis of human follicle-stimulating hormone-beta using anti-peptide antisera.
The purpose of this study was to identify peptide sequences of human follicle-stimulating hormone-beta (hFSH beta) which are accessible subsequent to association with hFSH alpha in heterodimeric hFSH. Antisera were raised against synthetic peptides (Abpep) corresponding to hFSH beta sequences 1-20, 16-36, 33-53, 49-67, 66-85, 81-100 and 98-111. The topography of hFSH beta was studied by testing the binding of these antisera to hFSH beta and hFSH captured by monoclonal antibodies (MAb) in an enzyme-linked immunosorbent assay (ELISA). When hFSH and hFSH beta were captured by the same MAb, binding of Ab16-36, Ab33-53, Ab81-100 and Ab98-111 to hFSH was significantly lower compared to hFSH beta. However, compared to other Abpep, binding of Ab35-53 to hFSH was strong. Similar results were obtained when hFSH was captured by an alpha-specific MAb (10.3A6). Using 10.3A6, it was also possible to demonstrate significant binding of Ab49-67 to hFSH. The data suggests that residues in regions 33-53 and 49-67 of hFSH beta appear to be accessible in the heterodimeric hFSH in addition to the glycosylated region of 1-15. Regions 16-36, 33-53, 81-100 and 98-111 of hFSH beta appear to contain subunit contact-associated sequences which are either masked or structurally altered subsequent to association with hFSH alpha in the heterodimeric hFSH.
Animals↗
Developmental regulation of ornithine decarboxylase (ODC) in rat testis: comparison of changes in ODC activity with changes in ODC mRNA levels during testicular maturation.
These studies were undertaken to analyze the changes in testicular ornithine decarboxylase (ODC) mRNA levels and ODC activity in rats from birth to maturity. Levels of ODC mRNA were initially low in animals aged 10-17 days. Beginning at 21 days, ODC mRNA levels began to rise, reaching maximal levels by 40 days (p less than 0.01). The size of the 2.2- and 2.6-kb ODC mRNAs did not appear to change with age, as determined by Northern blot analysis. The increase in ODC mRNA that began at 21 days paralleled the increase in testis weight. This increase in ODC mRNA preceded the appearance of rat protamine-1 mRNA, a germ cell-specific mRNA found in round spermatids, which was first detected on Day 40. In contrast, levels of sulfated glycoprotein-2 mRNA, which, in the testis, is found exclusively in Sertoli cells, were highest at Day 17 and thereafter declined gradually with age. Unlike the increase in ODC mRNA levels, ODC activity was highest in 10-day-old animals and thereafter declined steadily with age, reaching minimal levels by 40 days (p less than 0.01). Thus, the increase in testicular ODC mRNA levels was in marked contrast to the decrease in testicular ODC activity. Incubation of cytosolic extract from 40-day-old animals with that from 10- or 17-day-old animals inhibited ODC activity approximately 50%, when compared to cytosols from 10- or 17-day-old animals. Dialysis of cytosol from 40-day-old animals prior to incubation with cytosol from 10-day-old animals relieved this inhibition.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Enhanced sodium absorption by citrate.
Explore the source record for details and available documents.
Animals↗
Biochemical analyses of proteolytic nicking of the human glycoprotein hormone alpha-subunit and its effect on conformational epitopes.
Conformational features of two epitopes on the glycoprotein hormone alpha-subunit were investigated using two antihuman FSH (anti-hFSH) monoclonal antibodies (mAbs) 3A and 5F that recognize different epitopes and are specific for alpha-subunit. These mAbs were used to investigate whether the conformation of these epitopes was different in heterodimeric hFSH, hTSH, hLH, or hCG. Any differences in the mass of hormone in each preparation were accounted for by sodium dodecyl sulfate-polyacrylamide gel electrophoresis/Western blot analysis of all hormone preparations used in this study. Rabbit anti-hFSH alpha-(11-27) antipeptide antisera and [125I]protein-G were used in the Western blot analysis. Radioactivity associated with each band was determined and used to normalize the mass of alpha-subunit in each reference preparation used in the displacement assays. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was also performed in order to examine the integrity of each of the hormone reference preparations. hTSH alpha and, to a lesser extent, hLH alpha preparations contained an internal nick in the polypeptide chain. RIA analysis performed using heterodimeric glycoprotein hormones as competitors revealed that an average 100-fold difference in the ED50 values for hFSH compared to the other glycoprotein hormones was seen with mAb 3A. Therefore, the conformation of 3A epitope appeared to be different in hFSH than in hTSH, hLH, or hCG. In comparison, the epitope recognized by mAb 5F only had an average 7-fold difference in reactivity (ED50 values) for hFSH compared to hTSH, hLH, and hCG. Likewise, competition assays using the respective alpha-subunits and mAb 5F revealed a pattern of competition similar to that observed with heterodimers, with an average 4-fold difference in the ED50 values for hFSH alpha compared to those for hTSH alpha, hLH alpha, and hCG alpha. Therefore, the conformation of the 5F epitope appears unaffected by association of alpha-subunit with beta-subunit. Accordingly, any differences in the conformation of the four alpha-subunits, as demonstrated by these small differences in ED50 values, appear to be inherent to each alpha-subunit. In fact, the 5F epitope appears to be quite rigid, since nicked alpha-subunit preparations could compete with [125I]hFSH for binding to 5F with comparable potency to non-nicked alpha-subunits. These findings support the concept that epitopes on heterodimeric hFSH alpha may have different conformational features. Some are specific for heterodimeric hFSH alpha, and we refer to these as conformationally active (flexible). Others are common to the four human glycoprotein hormone alpha-subunits, suggesting that they are conformationally constrained (rigid).
Amino Acid Sequence↗
Identification of subunit contact sites on the alpha-subunit of lutropin.
Peptides corresponding to the entire sequence of the alpha-subunit of the human glycoprotein hormones were synthesized by using standard solid-phase procedures. Purified peptides were incubated in the presence of alpha- and beta-subunits of bovine lutropin, and subunit recombination was monitored by difference spectroscopy, reverse-phase high-pressure liquid chromatography, and gel filtration chromatography. Although the binding of alpha-peptides to either subunit could not be detected by these techniques, it was possible to demonstrate that some peptides could inhibit the recombination of alpha- and beta-subunits. Specifically, alpha-peptide 33-58 allowed only 0-11% of subunit recombination in 24 h (38-56% after 48 h), while alpha-peptide 51-65 allowed 10-60% of subunits to recombine in 24 h (65-94% in 48 h). Peptides 1-15, 11-27, 22-39, 61-78, and 73-92 of the alpha-subunit could not inhibit subunit recombination at any time or at any concentration tested. The data suggest that at least a portion of the alpha-subunit contact site has been identified, and results are discussed in terms of protein structure assessment tools.
Amino Acid Sequence↗
Lead influences translational or posttranslational regulation of Ia expression and increases invariant chain expression in mouse B cells.
The molecular mechanisms governing the increased cell surface expression of major histocompatibility complex (MHC) class II molecules (Ia) on lead-treated mouse B cells was investigated. Lead has been shown to directly cause a selective, two-fold increase in the B cell's surface density of both products of the I region of the mouse MHC, I-A and I-E. In the present study, Western blot analysis showed that Pb increases the total cellular pool of I-A beta-chain by twofold. The increase in cellular I-A was not found to be due to increased messenger RNA (mRNA) for either the alpha- or the beta-chain of I-A. Biosynthetic labeling studies showed that Pb increases the translation or the stability of the Ia-associated invariant chain (Ii or gamma) and possibly the beta-chain of Ia. Collectively these results suggest that Pb increases the B cell's surface Ia by influencing translational or posttranslational regulation of Ia and/or Ia-associated chains.
Animals↗
Retention of nondeflating balloon in small bowel. Case report and review of the literature.
Intubation of the upper gastrointestinal tract with balloon catheters has a role in the diagnosis, treatment, and research of many gastrointestinal conditions. A potential complication of this procedure, albeit rare, is failure of the balloon to deflate, thereby preventing removal of the intestinal tube. We describe a case where this problem arose and the series of maneuvers that were attempted to resolve it. Attempts at overdistending the balloon, reaching it via endoscopy, and ultrasound localization of the balloon all failed. The tube was successfully removed following CT-guided percutaneous needle puncture of the impacted balloon. The published experience with nondeflating catheter balloons in hollow viscera has been reviewed and the suggested methods for deflation or puncture are discussed.
Adult↗
Epitope mapping of human follicle stimulating hormone-alpha using monoclonal antibody 3A identifies a potential receptor binding sequence.
Five monoclonal antibodies (mabs) were generated (3A, 4B, 5F, 2E, 1E) by immunizing BALB/c mice with human (h) FSH. The mabs were used to relate antigenic structures (epitopes) to function (receptor binding). All five mabs could immunoneutralize (inhibit binding to receptor) hFSH and could be placed into two groups based on potency (degree of neutralization). Group I mabs (5F, 2E, 1E) were less potent than group II mabs (3A, 4B) even though group I mabs had a 2-fold higher average affinity constant than group II. Those data suggested that group II mabs recognize an epitope near or in the receptor binding site of hFSH. Immunoradiometric epitope cross-matching demonstrated that group I and group II mabs recognize different epitopes. Further characterization of 5F and 3A (representative of group I and group II, respectively) utilized an enzyme-linked immunosorbent assay (ELISA) and a RIA. In the ELISA, both mabs bound hFSH and hFSH alpha but not hFSH beta. In the RIA, 3A bound [125I]hFSH and [125I]hFSH alpha but not [125I]hFSH beta. In contrast, 5F bound only [125I]hFSH. hFSH effectively competed with [125I]hFSH for 5F and 3A. In contrast, hFSH alpha competed with [125I]hFSH for 5F but not for 3A even though 3A could bind hFSH alpha in the ELISA and the RIA. These results suggest that 3A and 5F recognize different epitopes. The epitope recognized by 3A is unique in that its conformation appears to be dependent on association with hFSH beta. Since 3A was a more potent inhibitor of receptor binding than 5F, its epitope specificity was characterized further by epitope mapping. This was accomplished utilizing a peptide ELISA and by affinity chromatography. The results from epitope mapping demonstrated that 3A recognizes sequences 61-78 and 73-92 with binding to 73-92 being 4-fold greater than to 61-78. Thus, the epitope comprised of sequence 73-92 (and to a lesser extent 61-78) appears to be important for receptor binding.
Antibodies, Monoclonal↗
Determination of subunit contact-associated epitopes of the beta-subunit of human follicle-stimulating hormone.
Three different experimental approaches were used to assess the regions on the beta-subunit of human FSH (hFSH beta) that may be altered or masked by its association with the alpha-subunit of hFSH (hFSH alpha) in the heterodimeric hFSH molecule. In a direct approach, we tested whether synthetic peptides corresponding to hFSH beta sequences 1-20, 16-36, 33-53, 49-67, 66-85, 81-100, and 98-111 inhibited association of hFSH alpha and hFSH beta in an enzyme-linked immunosorbent assay. Synthetic peptides-(81-100), -(98-111), and -(66-85) caused greater than 50% inhibition of subunit association, whereas other peptides showed 26% or less inhibition. These data suggested that the C-terminal sequences of hFSH beta, particularly 81-100, are at a subunit interface with hFSH alpha in heterodimeric hFSH. In another approach we reasoned that antibodies with a higher affinity for free hFSH beta than for heterodimeric hFSH bind to epitopes on hFSH beta that are masked or altered by hFSH alpha subunit. To test this hypothesis, epitopes of hFSH beta were mapped using synthetic peptides of hFSH beta sequences, three monoclonal antibodies (3G3, 4D5, and 4G8), and a polyclonal antiserum (NIDDK anti-hFSH beta). Compared to 3G3 all the other antibodies exhibited minimal reactivity with hFSH, but bound strongly to hFSH beta. The epitope-mapping data with both 4D5 and NIDDK anti-hFSH beta identified peptide 81-100, which was not recognized by 3G3. The epitope map with 4G8 identified the same three peptides as with 3G3. However, in the case of 4G8 its reactivity with peptide 33-53 was the least, whereas it was ranked first for 3G3. Since both 3G3 and 4G8 had an identical affinity for hFSH beta, it was hypothesized that sequences in peptide 33-53 may be altered or masked by hFSH alpha. To test this, we determined the specificity of anti-hFSH beta-(33-53) peptide antiserum for hFSH beta and hFSH in an enzyme-linked immunosorbent assay. The antipeptide antiserum bound strongly to free hFSH beta and weakly to hFSH, suggesting that part of the sequence in peptide-(33-53) was masked or altered by association with hFSH alpha in heterodimeric hFSH. Taken together, the subunit association studies, the epitope-mapping data, and the specificity of anti-hFSH beta-(33-53) peptide antiserum have suggested that sequences in peptide-(81-100) and -(33-53) are masked or conformationally altered by hFSH alpha in heterodimeric hFSH.
Amino Acid Sequence↗
High-affinity binding of fibronectin to cultured Kupffer cells.
Hepatic Kupffer cells are a major component of the reticuloendothelial or macrophage system. They were the first phagocytic cell type whose phagocytosis was shown to be influenced by plasma fibronectin, a dimeric opsonic glycoprotein. In the current study, the binding of soluble radioiodinated fibronectin purified from rat serum to isolated rat hepatic Kupffer cells was investigated using a cultured Kupffer cell monolayer technique. Binding was specific, since unlabeled purified fibronectin competed in a dose-dependent manner with the 125I-fibronectin for binding to the Kupffer cells. Addition of gelatin enhanced the binding of 125I-fibronectin to Kupffer cells. The phagocytosis of gelatinized-coated red cells by Kupffer cells was increased either by preopsonizing the target particles with purified fibronectin or by the addition of purified fibronectin to the culture medium. In contrast, exposure of the Kupffer cells to medium containing purified fibronectin followed by wash-removal of the fibronectin did not increase the uptake of gelatin-coated red blood cells, even though fibronectin was detected on the surface of the Kupffer cells by immunofluorescence. Trypsinized monolayers expressed decreased capacity to bind 125I-fibronectin as well as fibronectin-coated sheep erythrocytes. The binding of 125I-fibronectin-gelatin complexes was inhibited by excess unlabeled fibronectin. We calculated that specific high-affinity (Kd = 7.46 x 10(-9) M) binding sites for fibronectin exist on Kupffer cells. There are approximately 2,800-3,500 binding sites or putative "fibronectin receptors" per Kupffer cell. These sites appear to mediate the enhanced phagocytosis of gelatin-coated particles opsonized by fibronectin.
Animals↗
Topographic analysis of the alpha-subunit of human follicle-stimulating hormone using site-specific antipeptide antisera.
Structure-function investigations were undertaken to increase understanding of the surface topology of the alpha-subunit of human FSH (hFSH). The objectives were to determine which sequences of the alpha-subunit of hFSH are surface-oriented (exposed to antibody) and to identify which of these surface-oriented sequences are in contact with the beta-subunit of hFSH in the alpha/beta heterodimer. Seven overlapping synthetic peptides spanning the primary structure of hFSH alpha were used for immunizing rabbits to generate site-specific antipeptide antisera. The antisera were characterized with respect to their reactivity to the seven synthetic peptides, as well as hFSH, hFSH alpha, hFSH beta, and hFSH alpha r/a (reduced and alkylated), using an enzyme-linked immunosorbent assay. All of the peptides successfully generated antipeptide antisera with titers that range from 1:1,600 to 1:80,000. Anti-1-15 bound exclusively to hFSH alpha. Anti-11-27 and anti-33-58 bound to hFSH alpha to a much greater extent than to hFSH. In contrast, anti-73-92 had only slightly higher binding to hFSH alpha than to hFSH. Anti-22-39, anti-51-65, and anti-61-78 all failed to bind to either hFSH or hFSH alpha. With the exception of anti-22-39, all of the remaining antisera bound to hFSH alpha r/a. None of the antisera bound to hFSH beta. These data strongly suggest the following. Sequences 1-15, 11-27, and 33-58 contain residues that are masked by hFSH beta and are thus in or near the alpha/beta-subunit interface. In addition, sequences 11-27 and 33-58 contain other distinct residues that are surface-oriented in the hFSH heterodimer. In contrast, sequence 73-92 appears to be surface-oriented in the hFSH heterodimer. Lastly, sequences 51-65 and 61-78 appear to be buried within the native alpha-subunit and, thus, are unable to interact with antibodies. These results agree with and extend previous findings and will prove useful to those currently investigating the surface topology and structure-function relationships of the glycoprotein hormones.
Amino Acid Sequence↗
Mapping of an assembled epitope of human follicle-stimulating hormone-beta utilizing monoclonal antibodies, synthetic peptides, and hormone-receptor inhibition.
Monoclonal antibodies (mabs) to human (h) FSH were utilized to probe epitopes of the beta-subunit of hFSH (hFSH beta). These mabs had an average approximate affinity constant (Ka) of 10(8) M-1 for hFSH beta and 10(7) M-1 for heterodimeric hFSH. Hormone specificity of mabs for hFSH beta was demonstrated by a lack of cross-reactivity with hCG alpha, FSH alpha, or LH alpha. Epitope specificity of each mab was initially assessed by determining whether solid phase mab could bind to [125I]hFSH already bound to mabs in liquid phase. In addition, it was determined whether [125I]mab could bind to hFSH already bound to solid-phase mabs. Both epitope cross-matching protocols indicated that all mabs bound to the same epitopes on hFSH beta. Next, synthetic peptides corresponding to the sequence of hFSH beta were used in an enzyme-linked immunosorbent assay to map this epitope. All mabs bound to peptides 7-19, 1-20, 33-53 and 66-85 but did not bind or bound weakly to peptides 81-100, 95-103, and 103-110. Titration experiments were performed using different concentrations of peptide (0.3-41 nmol) and one mab 3G3 (500 ng-25 ng) in the enzyme-linked immunosorbent assay. The product of the lowest mass of both peptide and antibody which gave a positive result was used to rank the peptides for their binding with mab 3G3. Peptides were ranked in the following descending order of potency: 33-53, 49-67, 66-85 much greater than 16-36, 1-20, 95-103, 52-65, 81-100, and 103-110. Ability of the mabs to inhibit binding of [125I]hFSH to bovine testis membrane receptor (Rec) was also studied. When [125I]hFSH was preincubated with increments of each mab for 2 h at 25 C before adding Rec with further incubation for 16 h, all mabs inhibited [125I]hFSH binding to Rec. The data suggest that most of the hFSH beta molecule has a conformation enabling all antibody recognizable regions to be in close proximity to each other. The present study provides evidence for an assembled epitope comprising in part, amino acids 33-53, which has been previously shown to be involved in receptor binding. Peptide sequences 49-67 and 66-85 are neighboring sequences in this assembled epitope which contains the determinants for receptor binding.
Amino Acid Sequence↗
Protein synthesis is required for testosterone to decrease ornithine decarboxylase messenger RNA levels in rat Sertoli cells.
We have previously shown that pretreatment of Sertoli cells, derived from 21-day-old Wistar rats, with 5 x 10(-7) M testosterone decreases ornithine decarboxylase (ODC) mRNA levels. In the present study we examined the mechanism of this inhibition. Pretreatment of Sertoli cells for 48 h with 5 x 10(-7) M testosterone decreased ODC mRNA levels 30% at all time points examined. Addition of 25 micrograms/ml cycloheximide (CHX) to the testosterone-pretreated cells resulted in a loss of the testosterone-mediated decrease in ODC mRNA levels by 4 h. Surprisingly, a further 1.8-fold increase in ODC mRNA was observed at 8 h compared to that in untreated cells. Addition of CHX to control cells also resulted in a measurable increase in ODC mRNA levels by 4 h, with a further 1.6-fold increase at 8 h. Identical effects were observed using the protein synthesis inhibitor puromycin (200 micrograms/ml), which has a mechanism of action different from that of CHX. Analysis of the half-life of ODC mRNA after actinomycin-D (5 micrograms/ml) inhibition demonstrated that testosterone did not alter ODC mRNA half-life compared to that in control cells (2.63 vs. 2.55 h). These results demonstrate that the mechanism by which testosterone decreases ODC mRNA levels requires continual protein synthesis, since the effect can be abolished by treating the cells with CHX or puromycin. The data also demonstrate that the testosterone effect is exerted primarily at the transcriptional level, since the half-life of ODC mRNA was not affected by testosterone.
Animals↗
Testosterone decreases ornithine decarboxylase messenger RNA levels in primary cultures of rat Sertoli cells.
We have previously reported that testosterone decreased ornithine decarboxylase (ODC) activity in primary cultures of rat Sertoli cells. In this report we examined the mechanism of this reduction. In cells pretreated with testosterone (5 x 10(-7) M) for 48 h before the start of the experiment ODC activity was decreased, on the average, 43% at all time points examined. ODC mRNA levels were also decreased an overall 33%. The testosterone-mediated decrease in ODC activity was first seen 8 h after the addition of testosterone to the cells. Testosterone had no significant affect on the levels of actin or transferrin mRNA. The effect of testosterone was androgen specific. Neither ODC activity nor mRNA was affected by the nonandrogenic steroids progesterone or cortisol. These results suggest that testosterone decreases ODC mRNA in Sertoli cells either through an inhibition of transcription or through a decrease in message stability. Testosterone does not appear to affect ODC mRNA translation, since the percent decreases in ODC activity and mRNA in response to testosterone were essentially equivalent. Regulation of Sertoli cell ODC expression by testosterone may reflect one mechanism by which Sertoli cell function is integrated with surrounding cell types. The Sertoli cell, unlike any other cell, secretes putrescine, the product of ODC catalysis of ornithine. We suggest that the modulation of ODC by testosterone and, hence, the amount of putrescine secreted by the Sertoli cell may be significant in the process of spermatogenesis.
Animals↗
Down's syndrome and coeliac disease.
The association of congenital abnormalities and gastrointestinal tract diseases has been described. The coincidence of Down's syndrome and coeliac disease has been occasionally reported, but a clear relation is not definitely established. Reviewing 190 patients with coeliac disease diagnosed at Queen Elizabeth Hospital, London, from 1960 to 1985 an increased incidence of Down's syndrome compared to the natural incidence of this abnormality in the general population was found. The age of the mothers was well below that where a reverse in the incidence of Down's syndrome is expected, and it appears therefore that this anomaly and coeliac disease may be linked. This possibility should be bourne in mind when evaluating children with Down's syndrome and gastrointestinal symptoms.
Autoimmune Diseases↗
Rise and fall of coeliac disease 1960-85.
A total of 192 children who presented with coeliac disease to Queen Elizabeth Hospital for Children from 1960-85 were reviewed in order to investigate the frequency and the age of presentation. There was a clear peak in the number of children presenting from 1971-5, and although the numbers declined subsequently they have remained at a level similar to numbers found before 1971. There was no difference in the mode of presentation but there was a definite increase in the age of presentation over the time period reviewed. Breast fed babies presented later than bottle fed babies (14 compared with 9 months) despite a similar age of gluten introduction. Similarly bottle fed babies and breast fed babies presented later after 1975 (10.5 compared with 7 months, and 18 compared with 9.5 months, respectively). Before 1975 the median age of gluten introduction was significantly less than that after 1975 (2 compared with 4 months) and the age of gluten introduction correlated with the age of presentation. It is concluded that breast feeding and the age of gluten introduction may influence the age of presentation of childhood coeliac disease but no clear reasons for the rise in incidence in the 1970s have been determined. It does not appear that the disease is declining, however, in recent years children have tended to present later in life.
Acute Disease↗