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H B Burch

Publications and source records attributed to H B Burch.

At least 37 records · Page 2Linked to original sources
PubMed1993

Expression polymerase chain reaction for the in vitro synthesis and epitope mapping of autoantigen. Application to the human thyrotropin receptor.

The clinical applicability of a newly described polymerase chain reaction directed protein expression system was assessed for the in vitro synthesis and partial epitope mapping of large radiolabeled human thyrotropin receptor (hTSH-R) protein segments. PCR amplification of targeted regions within the hTSH-R cDNA followed by in vitro transcription and translation permitted rapid synthesis of protein segments ranging in size from 18 to 62 kDa. Initial epitope mapping was directed at a 52 amino acid segment unique to the hTSH-R compared to otherwise homologous glycoprotein hormone receptors. Sera from Graves' disease patients known to have autoantibodies against the hTSH-R were used to immunoprecipitate two protein fragments differing only by the presence of the unique region in the larger fragment (E5) but not in the smaller fragment (E4). Dense precipitation bands were obtained using Graves' sera to immunoprecipitate E5 whereas little or no specific immunoprecipitation of E4 occurred. Normal sera gave only weak immunoprecipitation bands of E5. The technique provides significant advantages over conventional cloning methods and should have general applicability in the study of other protein targets of autoimmune disease.

Amino Acid Sequence↗
PubMed1993

Graves' ophthalmopathy: current concepts regarding pathogenesis and management.

Referring to the hyperadrenergic theory on the pathogenesis of Graves' ophthalmopathy, a 1934 JAMA editorial (513) stated "the mechanism of exophthalmos is well understood though the knowledge would seem to be poorly disseminated." Several subsequent theories on pathogenesis, stated equally emphatically, have experienced a similar fate to that prompting this remark, but not before negatively impacting upon the management of patients suffering from this disorder. Thus, it is with an element of caution that we conclude that the sequence of events contributing to the pathogenesis of Graves' ophthalmopathy has become progressively more lucid, due to the assiduous efforts of many investigators in this field. Demonstration of an inextricable link between the eye and the thyroid in Graves' ophthalmopathy seems limited only by our ability to detect subtle involvement of one or the other of these two organs in exceptional cases, although not all authors share this viewpoint (514). The factors modulating the degree of expression of the thyroid component, such as concurrent lymphocytic thyroiditis or qualitative differences in TRAb seem more tangible than those affecting the clinical expression of eye involvement. Environmental factors such as smoking are associated, to a degree that matches or surpasses that known for genetic predisposition to this disorder. Local anatomy, including such factors as vulnerability to obstruction of venous drainage, must play a role as evidenced by asymmetric eye involvement and rapid relief of inflammatory changes after orbital decompression surgery. The transition from palliative to curative measures in Graves' ophthalmopathy will require further advances in our understanding of the putative shared thyroid-eye antigens, demonstration that these antigens are etiologically important and concomitant advances in antigen-specific immune therapy.

Eye Diseases↗
PubMed1993

Life-threatening thyrotoxicosis. Thyroid storm.

Although important strides in recognition and therapy have significantly reduced the mortality in this disorder from the nearly 100% fatality rate noted by Lahey, survival is by no means guaranteed. More recent series have yielded fatality rates between 20% and 50%. Although some authors have attributed this improvement, in part, to a relaxation of the diagnostic criteria for thyroid storm, it more likely represents improvements in early recognition and the beneficial effects of the serial addition of antithyroid, corticosteroid, and antiadrenergic therapies to the treatment of this disorder. Thyroid storm is a dreaded, fortunately rare complication of a very common disorder. Most cases of thyroid storm occur following a precipitating event or intercurrent illness. Effective management is predicated on a prompt recognition of impending thyroid storm which is, in turn, dependent on a thorough knowledge of both the typical and atypical presentations of this disorder. An unwavering commitment to an aggressive, multifaceted therapeutic intervention as outlined herein is critical to the obtainment of a satisfactory outcome.

Humans↗
PubMed1992

Graves' IgG recognizes linear epitopes in the human thyrotropin receptor.

Twenty-nine peptides covering the full extracellular domain of the human thyrotropin receptor have been synthesized and tested for reactivity with Graves' patients' and normal sera in ELISA. Two peptides, amino acids 331-350 and the second extracellular loop of the transmembrane segment, bound IgG-s from 5 and 4 of 10 Graves' disease patients' sera, respectively. Neither of these two peptides showed enhanced binding to normal IgG. There were no apparent differences between the Graves' disease and normal group with respect to the other 27 peptides. We conclude that peptide 331-350 and the second extracellular loop carry important linear epitopes which may contribute to the disease process in selected Graves' patients.

Enzyme-Linked Immunosorbent Assay↗
PubMed1992

Reactive hypoglycemic coma due to insulin autoimmune syndrome: case report and literature review.

Recurrent episodes of postprandial hypoglycemic symptoms culminated in hypoglycemic coma in a hypertensive but otherwise healthy man while he was taking hydralazine. The patient was found to have an extreme elevation in the immunoreactive insulin level, leading to the discovery of insulin antibodies in the absence of prior exposure to exogenous insulin. Negative results of an anatomic study of the pancreas and an inability to reproduce hypoglycemia during a prolonged fast helped to exclude insulinoma. In contrast, symptomatic hypoglycemia developed in response to oral glucose loading and was associated with an elevation in total and free insulin as well as C-peptide levels. The patient was diagnosed with insulin autoimmune syndrome, which, although a common source of hypoglycemia in Japan, has been well documented in only 15 cases from other countries. HLA typing revealed the patient to be positive for groups Cw4 and DR4, a combination that has been preliminarily associated with insulin autoimmune syndrome in Japan. Unlike the majority of cases previously reported, this patient had no clinical or serologic evidence of an underlying autoimmune disorder and had not been exposed to drugs containing sulfhydryl groups. This case adds to the world literature on insulin autoimmune syndrome, lends support to a postulated HLA association, and documents the presence of insulin autoantibodies in the absence of another underlying autoimmune disorder.

Adult↗
PubMed1992

Analysis of human TSH receptor gene and RNA transcripts in patients with thyroid disorders.

Human TSH receptor (hTSH-R) gene and RNA transcripts were analyzed by Southern and Northern blots in patients with various thyroid disorders, and in tissue cell lines. A 1.4 Kb cDNA encoding the extracellular human TSH-R domain was used as a probe. Southern analysis revealed two constant bands of 11.0 and 5.0 Kb (hTSH-R) in the thyroid and human white cell samples studied, regardless of the disease process. Northern analysis showed a predominant band at about 4.4 Kb in the thyroid tissues but not in non-thyroid tissue or cell lines tested. There were no gene rearrangements or abnormal transcripts in Graves' disease or multinodular goiter samples. In contrast, the labelled cDNA TSH-R probe did not bind to RNA isolated from 1 of 2 papillary cancer samples. A portion of the unique area of the h-TSH receptor (approximately nucleotides 1100-1230) was directly sequenced in thyroid glands from patients with Graves' disease, multinodular goiter, and differentiated thyroid cancer. No mutations or polymorphisms were identified in these samples, as compared to normal thyroid or control placenta, although further definition of sequence variation in other areas of the TSH receptor, as well as in more samples, needs to be performed. The present study indicates the normal patterns of DNA and RNA hybridization in a variety of thyroid tissues and disease states, and demonstrates that pathologic thyroid samples, with the possible exception of thyroid cancer, were not associated with specific nucleotide abnormalities in the unique area of the TSH receptor that was studied.

Adult↗
PubMed1991

Nucleotide and amino acid homology between the human thyrotropin receptor and the HIV-1 Nef protein: identification and functional analysis.

A comparison of the nucleotide sequence of the human thyrotropin receptor (hTSH-R) with that of HIV-1 revealed 61% homology between a 161 base pair region encoding a unique portion of the hTSH-R and an immunogenic HIV-1 regulatory protein, nef. Amino acid analysis of this region shows 27% homology, including a segment in which 7/10 consecutive amino acids are identical. Sera from rabbits successfully immunized with a 16 amino acid portion of the hTSH-R (352-367, p1) was assessed for reactivity against a partially homologous nef peptide (nef-1) by ELISA, with a finding five-fold higher post-immunization values compared to pre-immune sera. The specificity of this response was verified with Western blot, using recombinant nef protein. An ELISA using nef-1 gave 64% higher values with sera from Graves' disease patients than with normal controls. This homology and immunologic cross-reactivity suggests an avenue through which a shared immune response against an HIV-1 related retrovirus could play a role in the pathogenesis of Graves' disease.

Amino Acid Sequence↗
PubMed1991

Lymphocytes express thyrotropin receptor-specific mRNA as detected by the PCR technique.

Human lymphocytes are known to play a critical role in autoimmune diseases both by producing antibodies and by participating in lymphokine-cellular interactions. TSH, a classic pituitary hormone, may be secreted by human lymphocytes, and controversy has existed whether a specific, authentic TSH receptor also was present on the surface of these cells. The objective of our study was to identify TSH receptor transcripts after designing specific oligonucleotides that would recognize a unique putative TSH binding area of the thyroidal TSH receptor. The existence of TSH receptor transcripts was probed by employing these primers in a PCR reaction with cDNA derived from normal peripheral human lymphocytes and human thyroid tissue, as well as with cDNA from a medullary cancer cell line and rat liver. Human lymphocytes and thyroid tissue, but not medullary cancer cells or rat liver, demonstrated specific TSH receptor amplification product both by ethidium bromide staining and by Southern blot hybridization with labeled TSH receptor cDNA. The lymphocyte cDNA was partially sequenced and found to be identical to the thyroid-derived cDNA. These findings indicate that normal, nonactivated, human lymphocytes produce transcript for a TSH receptor that appears identical to that in thyroid tissue. Future studies should focus on the regulation of this transcript, as well as on the role TSH and TSH receptor may play in modulating local lymphokine activation of T and B cells, both in normal conditions and in autoimmune thyroid disease.

Base Sequence↗
PubMed1991

[Arthritis following osteosynthesis of supra-/intercondylar femoral fractures].

Of 104 supra-/intercondylar femur fractures in adults (AO/ASIF Classification types A 1-3 and C 1-3), who were treated by open reduction and internal fixation from 1975 to 1985 59 fractures in 57 patients could be traced and reviewed clinically and radiographically after a mean follow-up period of 5 years and 7 months (range: 2-11 years). Among these, 47 knees/patients without preexisting knee-joint pathology were analyzed for the development of degenerative arthritis. The incidence for grade 2 and 3 changes in the femoropatellar compartment were 23% for supracondylar fractures (A type) and 62% for intercondylar lesions (C type). In the femorotibial compartment the incidence for supracondylar fractures was 38% and 23% for intercondylar fractures. In 93% of the patients the arthritic changes were radiographical findings, which did not cause relevant symptoms. The development of radiographical degenerative changes depends mainly on the type of the fracture; it is favoured by axial malalignment of more than 5 degrees of varus or valgus and local complications.

Adolescent↗
PubMed1990

Clinical experience with titanium implants, especially with the limited contact dynamic compression plate system.

AO/ASIF with its collaborating laboratories has developed cold worked pure titanium material for implants with an outstanding biocompatibility. The first prospectively controlled clinical series dates back to 1966 and was reported to be most successful. Pure titanium also became the material of choice for implants to be used in patients suffering from metal allergy. Today, a long-term and well-documented experience with these implants exists. It therefore seemed logical to use pure titanium for the new limited contact dynamic compression plate (LC-DCP) system described in the previous article by Perren. Pilot clinics started to implant titanium LC-DCP in 1987, and already 271 plates have been used, mainly for the treatment of fresh fractures. Some 57 plates have so far been removed. The preliminary results are most favourable; they confirm especially the outstanding biocompatibility of pure titanium.

Biocompatible Materials↗
PubMed1989

The unstable intertrochanteric fracture in the elderly. A technical note on valgus resection osteotomy and fixation with 150 degrees dynamic hip screw.

Valgus resection osteotomy has proven its effectiveness for the treatment of unstable intertrochanteric fractures in the elderly. A modified technique is presented, which consists in (a) resection of triangular fragments proximally and distally, (b) reduction and impaction in valgus, (c) fixation through the osteotomy site by a 150 degrees dynamic hip screw, and (d) reattachment of the greater trochanter by an 8-shaped wire cerclage. The postulated advantage is that the implant acts as an intramedullary splinting in crossing the "osteotomy" site, with minimization of implant cutting out compared with a 130 degrees angled blade plate or an I-Beam Nail Plate.

Aged↗
PubMed1988

Progressive enzyme changes within anatomically defined segments of rabbit nephron: demonstration with a new technique.

The kidney is an extremely heterogeneous organ, with morphological, physiological, and metabolic changes occurring from segment to segment along each nephron. To determine the heterogeneity that might exist within discrete anatomical segments of rabbit nephron, we developed a technique for making quantitative enzyme assays in serial samples, about 100 micron long, along identified segments of the nephron. Results for three enzymes in proximal convoluted and straight tubules show that adenylate kinase, an enzyme of high-energy phosphate metabolism, gradually decreases along the S1 and S2 segments of the proximal tubule, with no abrupt changes. Fructose bisphosphatase, a gluconeogenic enzyme, is high along the major portion of the proximal tubule but plummets along the final millimeter of S3. Conversely, phosphofructokinase, a glycolytic enzyme, is very low along the proximal tubule but increases sharply within the final millimeter. These data underscore the biochemical heterogeneity of the nephron, illustrating the enzyme levels may change markedly even within anatomically defined regions. They also suggest the importance of further studies of this type and demonstrate a practical means for such studies.

Adenylate Kinase↗
PubMed1987

Change in energy reserves in different segments of the nephron during brief ischemia.

Rat kidneys were made ischemic for 5 to 120 seconds. Segments of individual nephrons were dissected from freeze dried sections and analyzed for ATP, phosphocreatine, glycogen, glucose, glucose-6-phosphate, lactate and creatine kinase. ATP fell most rapidly in proximal convoluted and straight tubules (PCT, PST) and distal convoluted tubules (DCT), and most slowly in glomerulus and papilla. Phosphocreatine levels ranged fivefold and was highest in DCT, where it approached that of brain. Creatine kinase ranged 100-fold with lowest level in PCT, where the ischemic fall in phosphocreatine was so slow as to suggest a function other than that of an energy reserve. Glycogen varied tenfold from modest levels in distal segments to very low levels in PST, and was not used rapidly in any segment. Glucose consumption and lactate production were most rapid in distal portions. High-energy phosphate consumption for the first 7.5 seconds of ischemia, calculated from these data, indicates roughly-equal energy metabolism in proximal and distal segments, with lower levels in papilla, and especially in glomerulus. The absolute values suggest that the in vivo metabolic rate of the nephron continued almost unabated for 5 or 10 seconds of ischemia.

Adenosine Triphosphate↗
PubMed1985

A method for branched-chain amino acid aminotransferase activity in microgram and nanogram tissue samples.

A method for branched-chain amino acid aminotransferase is described which is based on running the reaction in the reverse of the usual direction with glutamate and alpha-ketoisocaproate as substrates. The alpha-ketoglutarate generated is reduced with glutamate dehydrogenase and NADH. For sensitivity in the nanomole range, the NAD+ generated is measured directly by converting to the highly fluorescent strong alkali product. For smaller samples, down to the 0.2- to 2-pmol range, the NAD+ is amplified by enzymatic cycling.

Animals↗
PubMed1985

Branched-chain amino acid aminotransferase along the rabbit and rat nephron.

The activity of branched-chain amino acid aminotransferase (EC 2.6.1.42) is reported for four or five different segments of the rat and rabbit nephron as well as for patches from the papilla. In the rat the levels ranged 40-fold, from a high in the thick ascending limb of Henle to a low in the proximal convoluted tubule. The peak activity is far above that reported for most other parts of the body. Maximum activity was located also in the thick ascending limb in the rabbit, but the level was only one-third as high as in the rat. It is postulated that ammonia liberated by this amino transferase, in cooperation with glutamate dehydrogenase, could diffuse readily into the adjacent proximal straight tubule where all of the renal glutamine synthase and the highest level of alanine aminotransferase are located. Thus alanine and glutamine could be produced when the ammonia was not needed to neutralize excess acidity.

Amino Acids, Branched-Chain↗
PubMed1984

The distribution of six enzymes of oxidative metabolism along the rat nephron.

Using quantitative methods, citrate synthase (CS), fumarase, beta-hydroxyacyl-coenzyme A (CoA) dehydrogenase (beta OAC), 3-keto-acid CoA transferase (KCT), malic dehydrogenase (MDH), and malic enzyme were measured in seven defined parts of the nephron and in thin limb and papilla areas dissected from freeze-dried microtome sections of rat kidney. The results not only show a wide range of activity along the nephron for each of the enzymes, but that the proportions between the enzymes vary markedly among the different parts of the nephron. This suggests the existence of major regional differences in the capacity to oxidize specific metabolites. The ratio between two citrate cycle enzymes, fumarase and CS, was 4- or 5-fold higher in proximal segments than in the glomerulus or thin limb areas. The ratio between beta OAC (an enzyme of fatty acid oxidation) and CS was 3- to 5-fold higher in the middle proximal segments than in glomeruli or thin limb and papilla areas. The key enzyme for ketone body metabolism, KCT, was essentially confined to the thick tubule segments. Malic enzyme, in contrast to the other five enzymes, was highest in the proximal straight segments. New methods, sufficiently sensitive for this histochemical study, are described for malic enzyme and 3-keto-acid CoA transferase.

3-Hydroxyacyl CoA Dehydrogenases↗