Breast cancer risk in elderly women with systemic autoimmune rheumatic diseases: a population-based case-control study

Systemic autoimmune rheumatic diseases (SARDs) are chronic inflammatory and immuno-modulatory conditions that have been suggested to affect cancer risk. Using the Surveillance, Epidemiology and End Results–Medicare-linked database, women aged 67–99 years and diagnosed with incident breast cancer in 1993–2002 (n=84 778) were compared with an equal number of age-matched cancer-free female controls. Diagnoses of SARDs, including rheumatoid arthritis (RA, n=5238), systemic lupus erythematosus (SLE, n=340), Sjogren's syndrome (n=374), systemic sclerosis (n=128), and dermatomyositis (n=31), were determined from claim files for individuals from age 65 years to 1 year before selection. Associations of SARD diagnoses with breast cancer, overall and by oestrogen receptor (ER) expression, were assessed using odds ratio (OR) estimates from multivariable logistic regression models. The women diagnosed with RA were less likely to develop breast cancer (OR=0.87, 95% confidence interval (CI)=0.82–0.93). The risk reduction did not differ by tumour ER-status (OR=0.83, 95% CI=0.78–0.89 for ER-positive vs OR=0.91, 95% CI=0.81–1.04 for ER-negative, P for heterogeneity=0.14). The breast cancer risk was not associated with any of the other SARDs, except for a risk reduction of ER-negative cases (OR=0.49, 95% CI=0.26–0.93) among women with SLE. These findings suggest that systemic inflammation may affect breast epithelial neoplasia.

Activation of clindamycin phosphate by human skin

AIMS

To investigate the relative antimicrobial activity of clindamycin phosphate (CP) and clindamycin (Cly) and to examine the effect of skin homogenates on the activity of CP.

METHODS AND RESULTS

Minimum inhibitory concentrations (MIC) were determined against dermally relevant organisms and bactericidal activity was studied using time-kill methodology. The effect of skin homogenates on the antimicrobial activity of CP was studied by well-diffusion assay. The MIC of Cly was substantially lower than that of CP in all susceptible organisms. Clindamycin also showed greater bactericidal activity (rate of kill) than CP. Phosphatases in skin homogenates activated CP at pH 4-8 with a maximal activation at pH 4.

CONCLUSION

Phosphatases within the skin have been shown to convert CP to the more potent form Cly.

SIGNIFICANCE AND IMPACT OF THE STUDY

Conversion to Cly is a major determinant of antimicrobial activity in the skin layers following topical application of CP.

A cluster of fulminant myocarditis cases in children, Baltimore, Maryland, 1997

The true incidence of myocarditis in children is difficult to estimate because many mild cases go undetected. This study describes an unusual cluster of myocarditis cases that occurred in young children living in the greater Baltimore area between May and October 1997. A search of multiple comprehensive databases and interviews with area pediatric cardiologists were conducted to identify unreported cases and determine the background rate of myocarditis in the area. Seven cases of myocarditis were found as well as two with a similar clinical picture and myocardial fibrosis on tissue examination. Six case patients with active myocarditis and one child with fibrosis died. The case children were predominantly black (eight of nine) and male (seven of nine), with no identifiable risk factors. The disease was characterized by a fulminant course with malignant arrhythmias. The greatest number of pediatric myocarditis deaths reported in 1 year prior to 1997 was three. Myocardial tissues were examined using immunohistochemistry, in situ hybridization, and polymerase chain reaction but no etiologic agent was identified. This outbreak is unusual because of both the number of cases and the fulminant course of the disease in this group of children.

Transverse subgluteal-ilioinguinal approach to the acetabulum

An approach to the acetabulum is described. This approach consists of an anterior and a posterior part. The anterior part is nearly identical with the ilioinguinal approach. The posterior part resembles Kocher's (Gibson, J Bone Joint Surg 1950;32B:183-186) original description in that the plane of dissection passes between the motor territories of the superior gluteal nerve anterolaterally and the inferior gluteal nerve posteromedially. Two modifications have been introduced, however. First, the incision is a transverse one; superior and inferior fasciocutaneous flaps are elevated. Second, the gluteus maximus is not only disinserted from the fascia lata and the gluteal tuberosity at the upper end of the femur but from the iliac crest as well. After ligating the superficial branch of the superior gluteal artery to the gluteus maximus, the muscle itself is reflected posteromedially. We have used this approach to explore the lumbosacral plexus and its branches, particularly the sciatic nerve at the greater sciatic notch. Due to the excellent exposure of both columns of the acetabulm, this approach may be equally used in fractures of the acetabulum.

Lecithin:cholesterol acyltransferase (LCAT) activity during lipid infusion in premature infants

Plasma cholesterol and lecithin concentrations are regulated by the serum enzyme lecithin: cholesterol acyltransferase (LCAT). LCAT activity is low in cord blood of premature infants, suggesting that in these infants the hypercholesterolemia associated with Intralipid infusion might be due to low LCAT activity. The serum LCAT activity has not been quantitated in preterm infants receiving intravenous fat emulsions. We have therefore quantitated LCAT activity in eleven premature infants maintained on total parenteral nutrition (TPN). Ten infants were studied during the first 2 weeks after birth; they received daily infusions of Intralipid at a rate of 0.5-2.0 g/kg/day over 15 h. One infant received 3.8 g/kg/day during the second week. In addition to LCAT, serum apoprotein A1 (the cofactor of LCAT), cholesterol, triglycerides, and free fatty acids were quantitated. Blood specimens were taken before the start of the infusion and 15-45 min before its completion. The LCAT activity and apoprotein A1 concentrations remained, respectively, 21-24% and 30-35% of adult levels. However, serum cholesterol levels remained in the normal range during the fat infusion. It remains to be established whether low LCAT activity and apoprotein A1 levels are due to the administration of Intralipid (which lowers LCAT activity in rats), to the lack of enteral feedings, or to prematurity per se. Our data suggest that administration of Intralipid at a rate not exceeding 1-2 g/kg/day does not impair the clearing of Intralipid-lecithin and the metabolism of cholesterol.

Effect of intralipid infusion on lecithin:cholesterol acyltransferase and lipoprotein lipase in young rats

We compared the effects of Intralipid and dextrose infusion on plasma lecithin:cholesterol acyltransferase (LCAT), plasma lipid profiles and lipolytic activity. We used 5-week-old male Sprague-Dawley rats which were given total parenteral nutrition (TPN) with either Intralipid (3 g/kg body weight) or an equicaloric amount of 25% dextrose in the presence or absence of heparin (1 or 10 IU/ml of TPN). 40 min after the end of 4 h of infusion, plasma LCAT activity was significantly decreased (P less than 0.001), while total cholesterol and free fatty acid levels were significantly (P less than 0.05) increased in rats given Intralipid as compared to those given dextrose. We found associations (P less than 0.005) between LCAT activity and total cholesterol and between LCAT and free fatty acid levels; the coefficients of negative correlation were 0.543 and 0.607, respectively. Concomitantly to the increment in plasma total cholesterol levels, there was a decrease in the high-density lipoprotein (HDL) cholesterol fraction; the latter, which was 40% of the total plasma cholesterol in control and dextrose-infused rats, declined to 9% in rats given Intralipid. Administration of heparin during Intralipid infusion, even up to 10 IU/ml of TPN, did not affect any of these changes. After dextrose infusion, the values of all three parameters were similar to those of the control group. Plasma lipolytic activity was not significantly different between rats given infusion (Intralipid or dextrose) and controls. However, in the presence of heparin, plasma lipolytic activity increased similarly in both infused groups. These data indicate that in young rats, Intralipid infusion leads to an increase in plasma total cholesterol and free fatty acid levels, which correlates with a decrease in LCAT activity; the concurrent decrease in HDL cholesterol levels might account, in part, for the loss of LCAT activity. The administration of heparin results in an elevation of plasma lipolytic activity; however, it does not prevent the hypercholesterolemia, nor the decline in LCAT activity associated with Intralipid infusion.

Ketamine hydrochloride as sole anesthetic for open liver biopsy

We evaluated the use of ketamine as sole anesthetic agent for open liver biopsy, with particular reference to its effect on liver function and hepatotoxicity and its effect on cardiovascular stability and respiration. From 386 patients who underwent liver biopsy at Jordan University Hospital, 12 had open liver biopsy because of contra-indications for closed needle biopsy. The surgical procedure consisted of a small right paramedian incision allowing inspection of the liver surface and a wedge and needle biopsy. Ketamine HCl was used in a dose of 2 mg/kg I.V. with supplemental doses as necessary. No significant fluctuations in cardio-respiratory vital signs were observed. Muscle rigidity and respiratory tagging movements necessitated addition of a muscle relaxant and artificial ventilation in three patients. Six patients reported dreams, two of which were described as nightmares. There was no liver function decompensation, or significant bilirubin or transaminase elevations in the week following the biopsy. Ketamine is a safe anesthetic to use for open liver biopsy in patients with underlying liver disease, although poor muscle relaxation and nightmares may be significant side effects.

Low levels of apolipoprotein A1 are not contributors to the low lecithin-cholesterol acyl transferase activity in premature newborn infants

Umbilical cord sera were obtained from three groups of newborn infants; group I (n = 8) and group II (n = 12) weighed less than 1500 g and between 1500 and 2500 g, respectively. Group III (n = 16) was full term and weighed more than 2500 g. Lecithin-cholesterol acyl transferase activities, determined as the rates of esterification of [3H]cholesterol, were 0.13 +/- 0.01, 0.17 +/- 0.01, and 0.26 +/- 0.01 (mean +/- SEM) nmol/h/ml for groups I, II, and III, respectively. The adult value (n = 8) was 0.96 +/- 0.01 nmol/h/ml. The respective apolipoprotein A1 (apo-A1) levels were 52 +/- 6, 59 +/- 4, and 67 +/- 4 (mean +/- SEM) mg/dl. Serum level of apo-A1 in adults was 137 +/- 6 mg/dl. Plasma high-density lipoprotein cholesterol levels increased with gestational age. However, in newborn infants, high-density lipoprotein apo-lipoprotein B, total cholesterol, and triglyceride levels, were significantly lower than in adults. These data indicate that serum levels of lecithin-cholesterol acyl transferase activity significantly (p less than 0.01) increase whereas the levels of apo-A1 do not significantly change with the gestational age. Also, in full-term newborns, lecithin-cholesterol acyl transferase activity is only 27%, whereas apo-A1 levels are 49% of adult values. Therefore, lower levels of apo-A1 do not account for the significantly lower activity of lecithin-cholesterol acyl transferase in preterm as compared to full-term newborn infants.

Characterization of antisera distinguishing carbohydrate structures in the beta-carboxyl-terminal region of human chorionic gonadotropin

The beta-COOH-terminal peptide region (beta CTP) of hCG is an important immunochemical domain that is specific to hCG but absent from homologous hLH. Three types of polyclonal antibodies can be elicited to the beta CTP portion of hCG. The first and most common recognizes the beta CTP amino acid sequence independent of its carbohydrate content (carbohydrate-oblivious). It can be elicited against synthetic beta CTP as well as against native or asialo beta CTP. The second type binds best to desialylated beta CTP, (galactose-requiring). The third type binds well only to sialylated beta CTP (sialic acid-requiring). All three types of antisera recognize the sialylated beta CTP as equivalent to the whole hormone on a molar basis, indicating that this peptide region of the whole hormone is neither sequestered nor conformationally altered. We have characterized the epitopes for the sialic acid-requiring and galactose-requiring beta CTP antisera. Both require elements of the primary amino acid sequence of beta hCG as well as specific elements of the carbohydrate side-chains and, therefore, are not directed solely to either peptide or carbohydrate determinants. The galactose-requiring beta CTP antiserum was generated to an ovalbumin conjugate of a desialylated form of beta CTP, beta 123-145. It binds desialylated forms 1000 times better than it binds native hCG, and binds neither synthetic beta CTP nor asialo-agalacto beta 123-141. The antiserum requires residues 123-141 and a portion of an O-serine-linked oligosaccharide chain. Its binding requirements are, thus, very different from those of the carbohydrate-oblivious beta CTP antiserum, which requires the last two residues of the hCG beta polypeptide chain and is not sensitive to the presence or absence of carbohydrate. The sialic acid-requiring beta CTP antiserum, which was generated to sialylated beta 123-145-thyroglobulin conjugate, binds well to sialylated beta CTP, but poorly to asialo beta CTP and not at all to the carbohydrate-free synthetic peptide. This antiserum requires the entire beta 123-145 sequence as well as sialic acid-terminated oligosaccharide side-chains. Since the sialylated peptide beta 115-141 binds poorly to it, this antiserum resembles the carbohydrate-oblivious anti-beta CTP; both require the COOH-terminal amino acids of hCG beta. However, the former requires intact O-linked carbohydrate moieties for binding. These antisera can be used to assess the primary protein and carbohydrate structures of beta CTP at low concentrations in urine.(ABSTRACT TRUNCATED AT 400 WORDS)

Structural and functional studies of the tryptic core of the human chorionic gonadotropin beta-subunit

The beta-subunit of hCG was digested with trypsin to produce a modified form of the subunit for structure-function and immunological studies. After digestion of hCG beta with trypsin, the residual disulfide-linked core was isolated and found to be lacking the carboxy-terminal peptide (residues 115-145) and to contain bond cleavages between residues 2-3, 43-44, 74-75, and 95-96. The locations of these bond cleavages within the disulfide-bridged core were identified by isolation of the following peptides after reduction and S-carboxymethylation of the trypsin beta-core: beta 1-43, beta 3-43, beta 44-74, beta 44-95, beta 75-95, and beta 96-114. The circular dichroic spectrum of the tryptic beta-core over the wavelength region of about 200-320 nm was similar to that of the native subunit. In addition, the tryptic beta-core retained nearly full immunopotency in both polyclonal and monoclonal competitive RIAs and could combine with complementary native alpha-subunit. The hybrid, composed of the tryptic beta-core and native alpha, was purified and displayed a molar potency of about 0.1% relative to intact hCG in both a radioreceptor assay and an adenylate cyclase assay. Thus, the hybrid retained little biological activity. Although the extensive bond cleavages in the tryptic beta-core did not appear to change its secondary and tertiary structure sufficiently to significantly alter the circular dichroic spectrum, the immunoreactivity, or the capability to combine with its alpha-subunit complement, the biological functional integrity of the tryptic beta-core-containing hybrid was essentially abolished. Hence, the tryptic beta-core provides a useful derivative for detailed structure-function studies aimed at defining the necessary determinants for subunit association, receptor binding, and subsequent biological actions.

Effects of TRH on thyrotroph function and number in rat pituitaries transplanted to renal capsule

We investigated the function of thyrotrophs in rat pituitaries that were transplanted under the renal capsule of 3-wk-old male Sprague-Dawley rats, which were either intact or hypophysectomized. Groups of 12 animals were implanted with osmotic minipumps that delivered a constant infusion of either thyrotropin-releasing hormone (TRH; 1 mg X kg-1 X day-1) or normal saline for 1 wk. In hypophysectomized rats, TRH infusion led to the appearance of substantial amounts of biologically active serum TSH and prevented the hypothyroidism that occurred in the control group. However, TRH did not change the transplant contents of DNA, immunoactive TSH, and mRNA levels for TSH subunits. Comparison of sellar and renal pituitary tissues, obtained from intact rats after 1 wk of either saline or TRH infusion, showed that removal of the pituitary from hypothalamic influence resulted in a 90% depletion of the thyrotroph TSH content. TRH infusion depleted only 63% of the TSH content of sellar thyrotrophs. The mRNA levels for TSH beta-subunit were similar in sellar and transplanted pituitaries and did not significantly change after TRH infusion. When immunocytochemically stained using rat TSH antiserum, the thyrotrophs in pituitary transplants were morphologically and numerically indistinguishable from the thyrotrophs in sellar pituitaries, in the presence or absence of TRH. These data indicate that in transplanted pituitary, for up to 1 wk of a constant infusion, TRH does not significantly affect either the number of thyrotrophs or their ability to synthesize TSH subunit mRNA. However, it is required to maintain released TSH in circulation, since TSH levels were low in the absence of TRH.(ABSTRACT TRUNCATED AT 250 WORDS)

Tryptic digestion of the alpha subunit of human choriogonadotropin

In order to further characterize chemical, physicochemical, and immunochemical properties, as well as structure-function relationships, of the common alpha subunit of human glycoprotein hormones, a tryptic core was prepared from the alpha subunit of human choriogonadotropin. The core was purified in greater than 80% yield using gel permeation and anion-exchange chromatography, and, following reduction and S-carboxymethylation, the constituent peptides were purified by gel permeation and high performance liquid chromatography. The disulfide-bridged peptides comprising the alpha core were identified as residues 1-35 and residues 52-91 by amino acid composition and amino acid carboxyl sequence analyses of the reduced, S-carboxymethylated peptides. The alpha tryptic core contained both N-asparagine carbohydrate moieties, but was devoid of residues 36-51 and the carboxyl-terminal serine at position 92. The small peptides cleaved from residues 36-51, a known potential O-glycosylation region of the alpha subunit, were purified and identified. The tryptic core retained full immunopotency relative to the intact subunit in the binding to polyclonal and monoclonal antibodies directed against the alpha subunit. The region consisting of residues 36-51 is not part of the epitope recognized by these antibodies. With antisera generated to the reduced, S-carboxymethylated subunit, peptide 1-35, but not 52-91, was immunoreactive. This finding is consistent with the known dominant antigenicity of the amino-terminal region in the reduced, S-carboxymethylated molecule. The core exhibited no appreciable interaction with the complementary beta subunit, and, not surprisingly, was unable to compete with intact hormone binding in a radioreceptor assay using rat testicular homogenates. Circular dichroic spectroscopy was used to probe gross features of tertiary structure (240-300 nm) and secondary structure (190-240 nm). The tryptic core and each of the two constituent peptides exhibited spectra above 240 nm that resembled that of the reduced, S-carboxymethylated subunit more than that of the native material, thus suggesting a significant loss of tertiary structure in the core and isolated peptides. This finding is unexpected in consideration of the full retention of immunopotency by the alpha core although consistent with failure of the core to combine with intact complementary beta subunit. The intact subunit as well as the isolated constituent peptides exhibit little if any helicity in aqueous solution. Interestingly, the reduced, S-carboxymethylated chain and peptide 52-91 displayed helicity in 80% trifluoroethanol, a helicogenic solvent.

Discordant effects of thyrotropin (TSH)-releasing hormone on pre- and posttranslational regulation of TSH biosynthesis in rat pituitary

To investigate whether TRH regulates TSH production through a pre- or posttranslational mechanism, we determined the pituitary levels of mRNAs for alpha-subunit and TSH beta in male Sprague-Dawley rats given TRH in the presence or absence of thyroid hormones, with or without hypothalamic influence. In normal rats, serum TSH increased 6-fold after a single sc injection of TRH (7 micrograms/kg BW), but the levels of mRNA for both TSH subunits did not differ from the control values. Infusion of TRH, achieved by osmotic minipumps that were implanted sc, increased serum TSH for 3 days. Conversely, the pituitary content of TSH dropped to and remained 35% of that in the controls. In these normal rats, throughout the TRH infusion, the pituitary levels of mRNA for the TSH subunits did not differ from those in the controls. Thyroidectomy increased, by 27 and 75 times, the normal levels of mRNAs for alpha and TSH beta, respectively. TRH, given either as a single injection or a 3-day infusion, did not further elevate these levels. We then studied thyroidectomized animals whose pituitaries were transplanted under their renal capsules. These pituitaries responded to TRH infusion by releasing TSH. T4 injection inhibited this response significantly, but not completely. In spite of this evidence of normal responsiveness to TRH, infusion of TRH for a week did not increase the level of mRNAs for either TSH subunit in transplanted pituitaries. We conclude that in the presence or absence of thyroid hormones, with or without concurrent hypothalamic influence, TRH did not affect rat pituitary level of mRNA for either TSH subunit despite persistent high levels of serum TSH. Therefore, TRH does not regulate TSH production through a pretranslational mechanism. Although a translational regulation cannot be completely excluded, the present data, in conjunction with previous findings, support the hypothesis that TRH regulates TSH production primarily by stimulating both posttranslational carbohydrate processing and secretion of this hormone.

Endocrine, biochemical, and morphological studies of a pituitary adenoma secreting growth hormone, thyrotropin (TSH), and alpha-subunit: evidence for secretion of TSH with increased bioactivity

A 40-yr-old man who had acromegaly and hyperthyroidism due to a GH/TSH-secreting pituitary adenoma is described. Serum free T4 was 2.8 ng/dl, free T3 was 1.1 ng/dl, and TSH was 1.2-1.5 microU/ml; the latter was measured in an immunoradiometric assay with a sensitivity of 0.07 microU/ml. Serum TSH was immunologically identical to standard TSH and did not decrease during a T3 suppression test. Serum free alpha-subunit and the molar alpha-subunit to TSH ratio were high (6.1 ng/ml and 31.2, respectively). TRH administration induced significant increases in both GH (+129%) and alpha-subunit (+156%) levels. Conversely, dopamine infusion resulted in a decrease in serum GH (-66%) and alpha-subunit (-43%) levels, and subsequent administration of the dopamine antagonist sulpiride induced significant increases in both GH and alpha-subunit (+393% and +106%, respectively). Similarly, somatostatin infusion inhibited GH (-43%) and alpha-subunit (-61%) secretion. Serum TSH levels were not affected by TRH, dopamine, or somatostatin. The biological to immunological activity ratio of serum TSH purified by immunoaffinity chromatography and measured in an adenylate cyclase assay was significantly increased compared to that in serum from hypothyroid or euthyroid subjects [biological to immunological activity ratio, 6.9 +/- 0.2 (+/- SD) vs. 4.4 +/- 1.1; P less than 0.001]. In gel chromatography, the apparent mol wt of the patient's TSH was smaller than that of the controls. After adenomectomy, all of the altered parameters of pituitary function became normal. Double gold particle immunostaining of the adenomatous tissue showed that all of the cells contained secretory granules positive for GH and alpha-subunit, while very few cells were positive for TSH beta as well as GH and alpha-subunit. These data indicate that in this patient serum TSH had an apparent mol wt smaller than that of normal TSH and an increased biological activity which, along with the autonomous TSH secretion, account for hyperthyroidism in the presence of low normal TSH levels; alpha-subunit originated from the same adenomatous cells that secreted GH but not TSH, thus explaining the in vivo observation that alpha-subunit responses to several agents were dissociated from TSH responses and parallel to GH responses; and TSH and GH were colocalized in a minority of the neoplastic cells.

Activities of deglycosylated thyrotropin at the thyroid membrane receptor-adenylate cyclase system

A bovine thyrotropin (bTSH) preparation was deglycosylated by treatment with anhydrous hydrogen fluoride (HF) in the presence of anisole. The resulting material consisted of TSH derivatives that exhibited different molecular sizes, all smaller than the native hormone. The majority (62%) of the deglycosylated TSH derivatives did not bind to the lectin concanavalin A, while 98% of the native TSH was able to bind. The deglycosylated TSH derivatives bound to the high affinity-high specificity TSH binding sites in human thyroid membranes with a potency more than twice that of equivalent immunological amounts of the native bTSH. Despite the enhanced binding affinity for the TSH receptor, the deglycosylated TSH derivatives were unable to stimulate adenylate cyclase fully. Maximal stimulation achieved with bTSH derivatives was only 9 to 17% of the maximal stimulation achieved with native bTSH. Further, the deglycosylated derivatives competitively inhibited stimulation of the thyroidal adenylate cyclase by native bTSH. We conclude that HF treatment of bTSH results in partially deglycosylated TSH derivatives that exhibit enhanced ability to bind to the TSH receptor and markedly diminished adenylate cyclase-stimulating activity.

Carboxyterminal peptide fragments of the beta subunit are urinary products of the metabolism of desialylated human choriogonadotropin

Previous investigations of patients with gestational trophoblastic neoplasia have shown that their urines often contain carboxyterminal peptide (CTP) fragments of the choriogonadotropin (hCG) beta-subunit as well as forms of hCG deficient in sialic acid. In order to determine whether beta-CTP fragments are among the urinary products of the peripheral degradation of desialylated hCG (as-hCG), using a continuous infusion technique, we gave highly purified as-hCG to humans. Six healthy subjects were given a loading dose of 0.8 mg of as-hCG followed by an infusion of the same preparation. An overall mean infusion rate of 62.9 micrograms/min was maintained for 6 h, and the mean serum concentration of as-hCG achieved during the infusion was 72.1 ng/ml. In all six subjects, beta-CTP fragments were the predominant immunoreactive forms of as-hCG in urine obtained during the infusion. In contrast, the urine of subjects infused with hCG has been shown to contain hCG itself, but nil beta-CTP fragments or as-hCG. After the as-hCG infusion was stopped, the excretion of the beta-CTP fragments in urine declined rapidly. There were no beta-CTP fragments detectable in sera obtained during the infusion or in sera incubated with as-hCG at 37 degrees C. After incubation with as-hCG for 4 h, the urine of normal subjects contained small amounts of beta-CTP fragments; however, the apparent proteolytic activity was too low to account for either the quantity of beta-CTP fragments produced during the infusion or the extremely low levels of as-hCG in the urine. These data demonstrate the existence in humans of a peripheral metabolic pathway that cleaves beta-CTP fragments from as-hCG and allows their excretion in urine. Thus, the frequent presence of beta-CTP fragments in the urines of patients with gestational trophoblastic neoplasia can be accounted for in part by the metabolism of the forms of hCG that bear an altered carbohydrate structure, which are prevalent in this disease.

Decreased receptor binding of biologically inactive thyrotropin in central hypothyroidism. Effect of treatment with thyrotropin-releasing hormone

Previous studies have suggested that certain cases of idiopathic central hypothyroidism of hypothalamic origin may result from the secretion of biologically inactive thyrotropin. To investigate this possibility and to define the mechanism of defective hormone action, we measured the adenylate cyclase-stimulating bioactivity (B) and receptor-binding (R) activity of purified immunoreactive serum thyrotropin (I) from seven patients with hypothalamic hypothyroidism. We found a strikingly decreased R/I ratio (less than 0.15) in patients as compared with controls (0.6 to 2.7) and a similarly decreased B/I ratio (less than 0.2 vs 2.8 to 5.6). After acute injection of thyrotropin-releasing hormone (TRH, 200 micrograms intravenously), the R/I ratio increased in two of three patients, but the B/I ratio became normal in only one. After administration of TRH for 20 to 30 days, an increase in immunoreactive serum thyrotropin was observed in all patients. Moreover, both ratios returned to normal in all but one patient, who had apparent desensitization. The increase in the amount and bioactivity of secreted thyrotropin after long-term TRH therapy resulted in enhanced secretion of serum thyroid hormones in all patients studied. We conclude that in certain cases of hypothalamic hypothyroidism, secreted thyrotropin lacks biologic activity because of impaired binding to its receptor; TRH treatment can correct both defects. These data suggest that TRH regulates not only the secretion of thyrotropin but also its specific molecular and conformational features required for hormone action.

Effect of desialylation of human chorionic gonadotropin on its metabolic clearance rate in humans

We determined the MCR and other kinetic parameters of desialylated hCG (as-hCG) in eight subjects (four men and four women), aged 20-47, using a single injection of 1 mg of a highly purified preparation. The plasma disappearance curve was fitted to a single exponential equation, with a half-time of disappearance of 3.56 +/- 0.62 min (mean +/- SD) and an initial volume of distribution of 1790 +/- 582 ml/m2. The mean MCR of as-hCG was 349 +/- 96 ml/min X m2. The mean transit time of as-hCG was 373 times shorter than that of hCG. The rapid plasma disappearance of as-hCG could not be accounted for by renal clearance into urine, since less than 0.05% of the as-hCG injected was excreted in the urine, nor could it be explained by degradation by plasma proteases, since as-hCG was not appreciably degraded during incubation in human serum at 37 C for 3 h. These data show that desialylation markedly accelerates the MCR of hCG in the human in spite of reduced renal excretion and, therefore, indicate the presence of a highly active pathway for uptake of desialylated glycoproteins.

Relevance of the low and high affinity thyrotropin-binding sites of human thyroid membranes to the stimulation of adenylate cyclase

TSH is known to interact on thyroid membranes with two classes of binding sites that differ in affinity and capacity. To assess the relevance of the class of TSH-binding sites characterized by low affinity and high capacity to the stimulation of adenylate cyclase, we studied the interactions of desialylated hCG (as-hCG) and its beta-subunit (as-hCG beta) with human thyroid membranes. In low ionic strength buffer, pH 7.8, where both classes of sites are operant, as-hCG fully inhibited and as-hCG beta partially inhibited [125I] bovine (b) TSH binding. Scatchard analysis of the [125I]bTSH binding inhibition curve in the presence of 1.0 X 10(-5) M as-hCG beta clearly indicated that as-hCG beta interacted only with the low affinity class of binding sites, leaving the high affinity class unaffected. In the presence of 140 mM NaCl, [125I]bTSH interacted predominantly with the high affinity class of binding sites; as-hCG fully inhibited [125I]bTSH binding to this class of sites, whereas as-hCG beta displayed essentially no interaction. Scatchard analysis of [125I]as-hCG beta binding to human thyroid membranes in low ionic strength buffer revealed a single apparent class of sites with low affinity (Kd = approximately 1.0 X 10(-6) M) and high capacity (Q = approximately 300 pmol/mg membrane protein). The bTSH preparation (Thytropar) showed a 10-fold greater binding inhibition potency at these sites than either the as-hCG or the as-hCG beta preparation, in keeping with the inference that as-hCG beta interacts with the low affinity class of TSH-binding sites. At a concentration more than 3 times that necessary to inhibit TSH binding to the low affinity class of sites, the as-hCG beta molecule neither stimulated adenylate cyclase nor inhibited the ability of TSH to do so. In contrast, the as-hCG molecule, which interacts with both classes of TSH-binding sites, fully inhibited TSH stimulation of adenylate cyclase. We conclude that the low affinity class of TSH-binding sites is not the class of sites through which TSH stimulates adenylate cyclase, and that this role is best ascribed to the high affinity class of TSH-binding sites.

Role of the carbohydrate moiety of human choriogonadotropin in its thyrotropic activity

To investigate the role of the carbohydrate moiety of human choriogonadotropin (hCG) in its thyrotropic activity, highly purified hCG and its desialylated subunits were treated with anhydrous HF/anisole (1 h, 0 degree C). The deglycosylated alpha- and beta-subunits were recombined with their native complementary subunits, and the interactions of these hCG congeners with the thyrotropin (TSH) receptor-adenylate cyclase system were investigated using human thyroid membranes. Deglycosylated hCG (dghCG) bound to the high affinity-low capacity TSH-binding sites of thyroid membranes; its equilibrium dissociation constant was lower than that of asialo-hCG (ashCG) (ED50: 2.6 and 6 microM, respectively). Like ashCG, dghCG did not stimulate thyroidal adenylate cyclase, but rather inhibited TSH stimulation of this enzyme in a dose-dependent manner. Thus, dghCG behaved as an antagonist and exhibited an inhibition constant of 0.78 microM while ashCG exhibited a constant of 1.50 microM. As might be predicted from the behavior of dghCG, absence of carbohydrate from either subunit enhanced the ability of the hCG hybrid recombinants to interact with the TSH receptor-adenylate cyclase system. However, only the hybrid recombinant lacking carbohydrate on its alpha-subunit lacked intrinsic thyrotropic activity; the hybrid recombinant lacking carbohydrate on its beta-subunit not only displayed intrinsic thyrotropic activity, but was of even higher potency than intact hCG in stimulating thyroidal adenylate cyclase. These results demonstrate that the carbohydrate moieties of both hCG subunits impede the process of recognition of hCG by the TSH receptor, while the carbohydrate moiety of the alpha-subunit, but not that of the beta-subunit, is essential for the process of hCG activation of thyroidal adenylate cyclase.

Surgical treatment of pathological subtrochanteric fractures due to benign lesions in children and adolescents

Twelve children and adolescents with pathological subtrochanteric fractures due to benign tumors or tumorlike lesions were treated by curettage, autologous cancellous bone graft, and internal fixation. The healing of the lesion and the fracture in nine patients was without complications. In the remaining three, the healing was complicated. In one, with nonunion and shortening due to 35 degrees varus deformity following conservative treatment, a 1-cm shortening due to 15 degrees varus deformity remained after surgery. In the same patient, a small recurrence was curetted when removing the plate and the screws. In the second, a stress fracture with varus deformity and shortening followed surgical treatment. These were corrected by valgus osteotomy. In both patients the final result was good. In the third, a femoral head collapse occurred. It was due to a lesion in the head that was overlooked on the initial roentgenogram. Although the fracture and the lesion were healed, the final result was poor. It was concluded that internal fixation of these fractures allows thorough curettage and bone grafting and results in the least amount of immobilization and the most rapid resolution of the lesion and the fracture.

Ovarian tumors complicating pregnancy

Between the years 1977 and 1981, 9037 patients gave birth at Jordan University Hospital (JUH). Among these ten patients were found to have an associated ovarian tumor, an incidence of one in 900 deliveries. Benign cystic teratomas were the most common ovarian tumors found, followed by mucinous cystadenomas. All of the tumors were benign except one case of Burkitt's lymphoma.

Characterization of a carboxyterminal peptide fragment of the human choriogonadotropin beta-subunit excreted in the urine of a woman with choriocarcinoma

We have observed low-molecular weight carboxyterminal fragments of the human choriogonadotropin (hCG) beta-subunit in the urines of several women with choriocarcinoma, and we have characterized one fragment in detail. Its apparent molecular weight by gel chromatography on Sephadex G-100 was 14,200. The fragment was not adsorbed to concanavalin A-Sepharose, indicating that it lacked the asparagine-linked carbohydrate groups of intact hCG beta. It was active in radioimmunoassays (RIA) using antisera either to the hCG beta carboxyterminal peptide (CTP) or to the desialylated hCG beta CTP (hCG beta as-CTP), indicating the presence of not only the hCG beta carboxyterminus but also desialylated O-serine-linked carbohydrate side chains on the fragment. It lacked luteinizing hormone/choriogonadotropin radioreceptor activity and hCG beta conformational immunoreactivity (SB6 RIA). On Sephadex G-100 gel chromatography, the elution profiles of this fragment and the hCG beta as-CTP(115-145) prepared by trypsin digestion of as-hCG were essentially indistinguishable (apparent molecular weights 14,200 and 14,000, respectively). The immunological characteristics of the fragment in both hCG beta CTP and hCG beta as-CTP RIA were indistinguishable from those of the hCG beta as-CTP(115-145) glycopeptide. Carboxyterminal fragments of hCG beta were evident in urine specimens obtained from 10 of 11 patients with choriocarcinoma but not in those obtained from normal subjects who were given an intravenous infusion of highly purified hCG. Of six pregnant women, only the one at term excreted carboxyterminal fragments of hCG beta and then only in trace amounts. We conclude that hCG beta carboxyterminal fragments, including one that is indistinguishable from the tryptic glycopeptide hCG beta as-CTP(115-145), can occur naturally in the urine of patients with choriocarcinoma.

Coupling defect of thyrotropin receptor and adenylate cyclase in a pseudohypoparathyroid patient

A patient with type I pseudohypoparathyroidism was found to have mild hypothyroidism. The patient had an elevated basal TSH level and an exaggerated TSH response to TRH. There was no goiter despite increased TSH levels, and the 131I thyroidal uptake was low before and after exogenous TSH administration. These studies suggested that the patient might have partial resistance to TSH. The binding of radioiodinated TSH to thyroid membranes obtained by biopsy was next studied. The displacement of iodinated TSH by unlabeled TSH was found to be identical to that in normal control membranes. The adenylate cyclase stimulation by a supramaximal dose of TSH, however, was blunted (120.1 +/- 11.5 vs. 387.2 +/- 40.3 pmol cAMP/min/mg protein), while basal and NaF-stimulated activities were quite similar to the activities in normal membranes. These findings suggested a lack of signal transmission between the TSH receptor and the catalytic unit. Incubation of control membranes with TSH and GTP resulted in a synergistic effect on the adenylate cyclase activity. This was not found with the patient's membranes and suggested that the coupling failure was due to a defective guanine nucleotide regulatory protein. We conclude that in this case of type I pseudohypoparathyroidism, the associated mild primary hypothyroidism was due to a partial TSH refractoriness caused by a coupling defect between the TSH receptor and adenylate cyclase. This observation suggests that a common pathogenetic mechanism might underly type I pseudohypoparathyroidism and its associated hypothyroidism.

Heterogeneous forms of thyroid-stimulating hormone in mouse thyrotropic tumor and serum: differences in receptor-binding and adenylate cyclase-stimulating activity

Thyroid-stimulating hormone (TSH) in tumor and serum of mice with thyrotropic tumors was studied by radioimmunoassay (RIA), radioreceptor assay (RRA) and thyroid adenylate cyclase assay (ACA). In unfractionated samples, serum TSH displayed significantly higher ACA/RIA (0.69 +/- 0.10) and ACA/RRA ratios (0.79 +/- 0.04) than TSH in tumor extracts (0.45 +/- 0.05 and 0.31 +/- 0.01, respectively). After gel chromatography, both tumor and serum TSH activity measured in RIA and RRA eluted in broad, heterogeneous peaks with an apparent molecular weight range of 26,000 - 44,000 daltons. The ACA activity of tumor TSH eluted in 2 sharp peaks (26,000 and 44,000) while that of serum TSH eluted in 3 peaks (26,000, 33,000 and 44,000). The ACA/RIA and ACA/RRA ratios varied greatly among the chromatography fractions, the lowest ratios being detected in the tumor TSH of 33,000 daltons (0.02 for each) and the highest ratios in both tumor and serum TSH of 26,000 (ACA/RIA = 1.60 - 1.90, ACA/RRA = 1.12 - 1.20). Since previous biosynthetic studies have suggested that such heterogeneous forms of mouse tumor TSH differ solely in carbohydrate content, our data suggest that the biologic activity of TSH may be modulated by its glycosylation.

Effect of carboxypeptidase digestion of the human choriogonadotropin molecule on its thyrotropic activity

Digestion of hCG by a mixture of carboxypeptidases B and Y results in an enzyme dose- and incubation time-dependent increase in its ability to stimulate the adenylate cyclase (AC) of human thyroid membranes. Treated under the same conditions [3 h at 37 C; enzyme to hCG ratio, 0.04 (wt/wt)], partially and highly purified hCG preparations display an increase of about 300% in thyroid AC-stimulating activity, while TSH displays a 30% decrease. In contrast, carboxypeptidase digestion of hCG under these conditions has no significant effect on its activity in the rat testis AC assay. The carboxypeptidase digestion results in cleavage of carboxyl-terminal amino acid residues 142--145 from the hCG beta-subunit; digestion of the hCG alpha-subunit is much less effective, as the carboxy-terminal amino acid residue 92 is removed from only about 13% of the hCG molecules. In accord with the results of amino acid analysis, a slight, if any, decrease in apparent molecular weight is found by gel filtration and polyacrylamide gel electrophoresis. In addition, carboxypeptidase digestion results in antigenic alterations of the molecule, as shown by a flatter slope of the dose-response curve in a hCG RIA and a 70% decrease in potency in a RIA that uses an antiserum to the hCG beta carboxy-terminal peptide. These data demonstrate that partial digestion of the hCG molecule with carboxypeptidase results in an increase in human thyroid AC-stimulating activity, with retention of the rat testis AC-stimulating activity.