Lexicon of disease spread modelling terms

Over the past decade there has been a notable increase in the magnitude and variety of modelling work in the realm of animal health. Similarly, there has been an increase in the extent to which modelling is used as a component in the development of animal health policy. The increased dependency on modelling creates a need to enhance understanding and linkages between policy-makers (those that pose the policy or scientific questions, commission modelling work and use model outputs in the development of policy), intermediaries (those that are responsible for working with modellers and communicating model results to policy-makers), and modellers. Development of a lexicon of disease spread modelling terms can help support clear communication and collaboration between all players.

Satisfactory long-term results after Nissen fundoplication

BACKGROUND

Complications and unsatisfactory long-term results after antireflux surgery in children have received increased attention. The aim of this study was to report parental assessment of outcome after Nissen fundoplication.

METHODS

Ninety-three patients operated with primary Nissen fundoplication between 1990 and 2001 were included. Medical records were reviewed, and parents were interviewed for evaluation of postoperative results.

RESULTS

Of the 93 children, 51 were neurologically impaired and 14 children had repaired esophageal atresia. Median follow-up time was 6.0 years. Total mortality for the patient population was 13%. Five children died as a complication of the surgery, whereas eight deaths were unrelated to the Nissen fundoplication. Ninety-two percent of the parents reported better well-being of the child after the Nissen fundoplication, and 83% were completely satisfied with the postoperative results. Pulmonary symptoms were reduced in 59%, and quality of sleep improved in 68% of the children. Nine children (10%) had been operated with a redo NF.

CONCLUSION

The majority of parents were satisfied with the long term results of the Nissen fundoplication.

Superiority of high-dose platinum (cisplatin and carboplatin) compared to carboplatin alone in combination chemotherapy for small-cell lung carcinoma: a prospective randomised trial of 280 consecutive patients

PURPOSE

A prospective randomized trial in small-cell lung cancer (SCLC) was performed to determine if intensification of the platinum dose by giving cisplatin and carboplatin in combination to patients with SCLC yields higher response rates and survival, than carboplatin alone in a combination chemotherapy regimen.

PATIENTS AND METHODS

Between September 1992 and October 1997, 280 patients were included in a two armed prospective randomized trial, stratified by stage of disease, LDH and performance status. The treatment was in arm A: three courses induction chemotherapy with carboplatin (AUC = 4, day 1), cisplatin (35 mg/m2, days 2 and 3), teniposide (50 mg/m2, day 1-5), vincristine (1.3 mg/m2, day 1) every four weeks, followed by cyclophosphamide (3 g/m2, day 84), 4-epirubicin (4-epidoxorubicin) (150 mg/m2, day 112), and finally one course cisplatin, carboplatin, teniposide and vincristine, (days 140-144). Arm B also comprised a total of six courses, identical to those in arm A except for omission of cisplatin.

RESULTS

There were no significant differences in the overall treatment outcome for A vs. B, in terms of response rates (72% in both arms), complete response rates (40% and 34%, respectively), or median survival (314 days and 294 days, respectively). However, for patients with limited disease both the CR rate (54% vs. 37%, P < 0.05), overall survival (log-rank test, P < 0.05), and the two-year survival rate (11% vs. 6%, P < 0.05) were higher in the high-dose platinum arm compared to the carboplatin alone arm.

CONCLUSIONS

The intensification of platinum dose (cisplatin plus carboplatin) in combination chemotherapy significantly increased the complete response rate, overall survival and number of two-year survivors among SCLC patients with limited disease compared to combination therapy with carboplatin alone, suggesting that a more aggressive treatment to this category of patients is worthwhile, while no difference in treatment outcome was observed for patients with extensive disease.

Dimeric fragment of the insulin receptor alpha-subunit binds insulin with full holoreceptor affinity

The insulin receptor (IR) is a dimeric receptor, and its activation is thought to involve cross-linking between monomers initiated by binding of a single insulin molecule to separate epitopes on each monomer. We have previously shown that a minimized insulin receptor consisting of the first three domains of the human IR fused to 16 amino acids from the C-terminal of the alpha-subunit was monomeric and bound insulin with nanomolar affinity (Kristensen, C., Wiberg, F. C., Schäffer, L., and Andersen, A. S. (1998) J. Biol. Chem. 273, 17780-17786). To investigate the insulin binding properties of dimerized alpha-subunits, we have reintroduced the domains containing alpha-alpha disulfide bonds into this minireceptor. When inserting either the first fibronectin type III domain or the full-length sequence of exon 10, the receptor fragments were predominantly secreted as disulfide-linked dimers that both had nanomolar affinity for insulin, similar to the affinity found for the minireceptor. However, when both these domains were included we obtained a soluble dimeric receptor that bound insulin with 1000-fold higher affinity (4-8 pm) similar to what was obtained for the solubilized holoreceptor (14-24 pm). Moreover, dissociation of labeled insulin from this receptor was accelerated in the presence of unlabeled insulin, demonstrating another characteristic feature of the holoreceptor. This is the first direct demonstration showing that the alpha-subunit of IR contains all the epitopes required for binding insulin with full holoreceptor affinity.

An evaluation of the physicochemical risk for renal stone disease during pregnancy

Seventeen subjects were studied during the third trimester of pregnancy (PG) and post partum (NPG) to evaluate the effect of pregnancy on the physicochemical risk of renal stone disease. Levels of urinary saturation for calcium oxalate (CaOx), brushite (Br), uric acid (UA), and monosodium urate (NaU) were determined as well as urinary excretions of stone-forming elements. In addition to urinary calcium excretion, assessment of calcium metabolism included serum calcium and parathyroid hormone. Urinary calcium excretion was 251 +/- 127 mg/day during pregnancy and 121 +/- 67 mg/day post partum (p < 0.001). This was associated with a higher intake of dietary calcium and altered renal handling of calcium with an increase in the filtered load and a decrease in renal tubular reabsorption. The increase in urinary calcium resulted in a higher level of saturation of the urine for calcium oxalate (NPG 2.1 +/- 1.0 vs PG 3.0 +/- 1.1, p < 0.02) and brushite (NPG 1.2 +/- 0.9 vs PG 1.9 +/- 1.1, p < 0.05) compatible with an increased risk of stone formation.

[Emergency room patients and alcohol consumption]

To investigate the consumption of alcohol among emergency room patients, we included 395 patients above 18 years old entering the emergency room during a period of ten days. The patients completed a questionnaire about alcohol consumption, smoking habits and medication. In our investigation 56% of the men and 25% of the women had a daily consumption above the limits recommended by the Ministry of Health (three drinks daily for men and two for women), while 41% men and 14% women consumed at least five drinks daily or 35 per week. Trauma seen in male patients with high alcohol consumption was characterised by excessive damage to the head, trauma of the lower limb and blows from an object, person or an animal. The alcoholic women were characterised by excessive chemical injuries, incisions and stab wounds, and trauma of the upper limb. In conclusion a surprisingly large amount of emergency room patients can be defined as alcohol abusers and drinking is found to be associated with excessive damage.

Ligand-induced conformational change in the minimized insulin receptor

Within the class of insulin and insulin-like growth factor receptors, detailed information about the molecular recognition event at the hormone-receptor interface is limited by the absence of suitable co-crystals. We describe the use of a biologically active insulin derivative labeled with the NBD fluorophore (B29NBD-insulin) to characterize the mechanism of reversible 1:1 complex formation with a fragment of the insulin receptor ectodomain. The accompanying 40 % increase in the fluorescence quantum yield of the label provides the basis for a dynamic study of the hormone-receptor binding event. Stopped-flow fluorescence experiments show that the kinetics of complex formation are biphasic comprising a bimolecular binding event followed by a conformational change. Displacement with excess unlabeled insulin gave monophasic kinetics of dissociation. The rate data are rationalized in terms of available experiments on mutant receptors and the X-ray structure of a non-binding fragment of the receptor of the homologous insulin-like growth factor (IGF-1).

A new secreted insect protein belonging to the immunoglobulin superfamily binds insulin and related peptides and inhibits their activities

Insulin and related peptides are key hormones for the regulation of growth and metabolism. Here we describe a novel high affinity insulin-related peptide-binding protein (IBP) secreted from cells of the insect Spodoptera frugiperda. This IBP is composed of two Ig-like C2 domains, has a molecular mass of 27 kDa, binds human insulin with an affinity of 70 pm, and inhibits insulin signaling through the insulin receptor. The binding protein also binds insulin-like growth factors I and II, proinsulin, mini-proinsulin, and an insulin analog lacking the last 8 amino acids of the B-chain (des-octa peptide insulin) with high affinity, whereas an insulin analog with a Asp-B10 mutation bound with only 1% of the affinity of human insulin. This binding profile suggests that IBP recognizes a region that is highly conserved in the insulin superfamily but distinct from the classical insulin receptor binding site. The closest homologue of the Spodoptera frugiperda binding protein is the essential gene product IMP-L2, found in Drosophila, where it is implicated in neural and ectodermal development (Garbe, J. C., Yang, E., and Fristrom, J. W. (1993) Development 119, 1237-1250). Here we show that the IMP-L2 protein also binds insulin and related peptides, offering a possible functional explanation to the IMP-L2 null lethality.

Correlations of receptor binding and metabolic and mitogenic potencies of insulin analogs designed for clinical use

In recent years, analogs of human insulin have been engineered with the aim of improving therapy for people with diabetes. To ensure that the safety profile of the human hormone is not compromised by the molecular modifications, the toxico-pharmacological properties of insulin analogs should be carefully monitored. In this study, we compared the insulin and IGF-I receptor binding properties and metabolic and mitogenic potencies of insulin aspart (B28Asp human insulin), insulin lispro (B28Lys,B29Pro human insulin), insulin glargine (A21Gly,B31Arg,B32Arg human insulin), insulin detemir (NN304) [B29Lys(epsilon-tetradecanoyl), desB30 human insulin], and reference insulin analogs. Receptor affinities were measured using purified human receptors, insulin receptor dissociation rates were determined using Chinese hamster ovary cells overexpressing the human insulin receptor, metabolic potencies were evaluated using primary mouse adipocytes, and mitogenic potencies were determined in human osteosarcoma cells. Metabolic potencies correlated well with insulin receptor affinities. Mitogenic potencies in general correlated better with IGF-I receptor affinities than with insulin receptor off-rates. The 2 rapid-acting insulin analogs aspart and lispro resembled human insulin on all parameters, except for a slightly elevated IGF-I receptor affinity of lispro. In contrast, the 2 long-acting insulin analogs, glargine and detemir, differed significantly from human insulin. The combination of the B31B32diArg and A21Gly substitutions provided insulin glargine with a 6- to 8-fold increased IGF-I receptor affinity and mitogenic potency compared with human insulin. The attachment of a fatty acid chain to LysB29 provided insulin detemir with reduced receptor affinities and metabolic and mitogenic potencies but did not change the balance between mitogenic and metabolic potencies. The safety implications of the increased growth-stimulating potential of insulin glargine are unclear. The reduced in vitro potency of insulin detemir might explain why this analog is not as effective on a molar basis as human insulin in humans.

Specificity of insulin and insulin-like growth factor I receptors investigated using chimeric mini-receptors. Role of C-terminal of receptor alpha subunit

We have investigated the role of the C-terminal of the alpha-subunit in the insulin receptor family by characterizing chimeric mini-receptor constructs comprising the first three domains (468 amino acids) of insulin receptor (IR) or insulin-like growth factor I receptor (IGFIR) combined with C-terminal domain from either insulin receptor (IR) (residues 704-719), IGFIR, or insulin receptor-related receptor (IRRR). The constructs were stably expressed in baby hamster kidney cells and purified, and binding affinities were determined for insulin, IGFI, and a single chain insulin/IGFI hybrid. The C-terminal domain of IRRR was found to abolish binding in IR and IGFIR context, whereas other constructs bound ligands. The two constructs with first three domains of the IR demonstrated low specificity for ligands, all affinities ranging from 3.0 to 15 nM. In contrast, the constructs with the first three domains of the IGFIR had high specificity, the affinity of the novel minimized IGFIR for IGFI was 1.5 nM, whereas the affinity for insulin was more than 3000 nM. When swapping the C-terminal domains in either receptor context only minor changes were observed in affinities (<3-fold), demonstrating that the carboxyl-terminal of IR and IGFIR alpha-subunits are interchangeable and suggesting that this domain is part of the common binding site.

Expression and characterization of a 70-kDa fragment of the insulin receptor that binds insulin. Minimizing ligand binding domain of the insulin receptor

In order to characterize regions of the insulin receptor that are essential for ligand binding and possibly identify a smaller insulin-binding fragment of the receptor, we have used site-directed mutagenesis to construct a series of insulin receptor deletion mutants. From 112 to 246 amino acids were deleted from the alpha-subunit region comprising amino acids 469-729. The receptor constructs were expressed as soluble insulin receptor IgG fusion proteins in baby hamster kidney cells and were characterized in binding assays by immunoblotting and chemical cross-linking with radiolabeled insulin. The shortest receptor fragment identified was a free monomeric alpha-subunit deleted of amino acids 469-703 and 718-729 (exon 11); the mass of this receptor fragment was found by mass spectrometry to be 70 kDa. This small insulin receptor fragment bound insulin with an affinity (Kd) of 4.4 nM, which is similar to what was found for the full-length ectodomain of the insulin receptor (5.0 nM). Cross-linking experiments confirmed that the 70-kDa receptor fragment specifically bound insulin. In summary we have minimized the insulin binding domain of the insulin receptor by identifying a 70-kDa fragment of the ectodomain that retains insulin binding affinity making this an interesting candidate for detailed structural analysis.

Alanine scanning mutagenesis of insulin

Alanine scanning mutagenesis has been used to identify specific side chains of insulin which strongly influence binding to the insulin receptor. A total of 21 new insulin analog constructs were made, and in addition 7 high pressure liquid chromatography-purified analogs were tested, covering alanine substitutions in positions B1, B2, B3, B4, B8, B9, B10, B11, B12, B13, B16, B17, B18, B20, B21, B22, B26, A4, A8, A9, A12, A13, A14, A15, A16, A17, A19, and A21. Binding data on the analogs revealed that the alanine mutations that were most disruptive for binding were at positions TyrA19, GlyB8, LeuB11, and GluB13, resulting in decreases in affinity of 1,000-, 33-, 14-, and 8-fold, respectively, relative to wild-type insulin. In contrast, alanine substitutions at positions GlyB20, ArgB22, and SerA9 resulted in an increase in affinity for the insulin receptor. The most striking finding is that B20Ala insulin retains high affinity binding to the receptor. GlyB20 is conserved in insulins from different species, and in the structure of the B-chain it appears to be essential for the shift from the alpha-helix B8-B19 to the beta-turn B20-B22. Thus, replacing GlyB20 with alanine most likely modifies the structure of the B-chain in this region, but this structural change appears to enhance binding to the insulin receptor.

Relationship between tumor response and the ratio of nucleotide triphosphates to inorganic-phosphate in small-cell lung-cancer xenografts

We examined whether grossly similar tumor responses, obtained by different therapies, induce similar patterns of change in the ratios of nucleotide triphosphate (NTP) to inorganic phosphate (P-i) in two human tumor lines, derived from the tumor of the same patient. The tumor responses were induced by doxorubicin 10 mg/kg i.p. or 5 Gy X-radiation in the human small cell lung cancer (SCLC) lines 54A and 54B, grown as xenografts in athymic nude mice. In vivo P-31 magnetic resonance spectroscopy of tumors was performed pretherapeutically, and on days 1, 4, 8, and 15 following therapy, in a 4.7 T magnet. Individual NTP/P-i ratios were calculated relative to the pretherapeutic values, and treated (n=28) versus controls (n=28) were compared. In both tumor lines, doxorubicin induced a significant drop in NTP/P-i at day 1. In 54A tumors 5 Gy induced a significant increase in NTP/P-i, whereas no difference between the NTP/P-i of irradiated and controls was found in 54B tumors. Thus three distinct NTP/P-i patterns were observed in tumors during response to therapy: (i) A decrease, (ii) an increase, and (iii) no change. Our findings indicate that changes in this ratio do not correlate independently with tumor response in the SCLC sublines 54A and 54B.

A single-chain insulin-like growth factor I/insulin hybrid binds with high affinity to the insulin receptor

1. To investigate the structure/function relationship of the interaction between ligand and receptor in the insulin-like growth factor I (IGF-I) and insulin receptor systems we have prepared and characterized a single-chain insulin/IGF-I hybrid. The single-chain hybrid consists of the insulin molecule combined with the C domain of IGF-I. The single-chain hybrid was found to bind with high affinity to both truncated soluble insulin receptors and membrane-bound holoreceptors. The affinity for interacting with the soluble truncated insulin receptors was 55-94% relative to insulin, and affinity for membrane-bound insulin receptors was 113% of that of insulin. Furthermore we found that the affinity of the single-chain hybrid molecule for IGF-I receptors was 19-28% relative to IGF-I. 2. The affinity of the single-chain hybrid for chimeric insulin/IGF-I receptors exceeded that of either natural ligand. This indicates that coordinately changing domains of the receptors and the ligands can induce higher affinity of ligand for receptor, supporting the idea that these receptors have a common ligand-binding site [Kjeldsen, Andersen, Wiberg, Rasmussen, Schäffer, Balschmidt, Møller and Møller (1991) Proc. Natl. Acad. Sci. U.S.A. 88, 4404-4408]. 3. In contrast with what was generally assumed about the ligand structure required for binding to the insulin receptor we demonstrate the first single-chain insulin analogue that can bind with high affinity to the insulin receptor.

Outbreak of hemodialysis-associated non-A, non-B hepatitis and correlation with antibody to hepatitis C virus

Between January 1987 and October 1988, 35 (45%) of 77 patients undergoing chronic hemodialysis at one unit developed serum alanine aminotransferase (ALT) elevations suggestive of non-A, non-B hepatitis (NANBH). Patients were grouped by level of ALT elevation and presence of other etiologies for liver injury. All dialysis patients and staff were tested for antibody to hepatitis C virus (anti-HCV) by enzyme immunoassay on three occasions, 9 months apart; anti-HCV repeatedly reactive specimens were tested by the HCV neutralization assay. Household and sexual contacts of patients were tested once for anti-HCV. Case-patients were classified on the basis of clinical case definitions as probable, possible, questionable, and noncases, and by anti-HCV testing. Case-patients who had no history of transfusions or parenteral drug use were compared with noncases for common exposures. A total of 35% (27/77) of patients and none (0/24) of staff were anti-HCV-positive. Anti-HCV was found in 82% of probable cases, compared with 44% of possible cases, 44% of questionable cases, and 12% of noncases (P less than 0.01). Neither a common source nor direct person-to-person transmission could be documented; however, inadequate infection control measures demonstrated by lack of glove use and poor handwashing occurred during the exposure period. The incidence of HCV infection in patients over an 18-month period was 5%. Transmission of HCV to household or sexual contacts of patients did not appear to occur.(ABSTRACT TRUNCATED AT 250 WORDS)

Reduced glomerular filtration rate and hypercalciuria in primary struvite nephrolithiasis

Struvite nephrolithiasis is caused by infection with bacteria that possess the enzyme urease, and convert urea to ammonia that raises urine pH and crystallizes with magnesium and trivalent phosphate ion. Of the 75 of our 1431 stone patients with struvite stones 52 were women. Struvite stones occurred almost exclusively in women; a minority of women and most men had mixed stones of struvite and calcium oxalate. Increased serum creatinine levels and reduced creatinine clearance were common in patients with struvite stones, not in those with mixed stones; both were rare in calcium stone disease. Men and women with mixed struvite, calcium oxalate stones were hypercalciuric, but women with struvite stones were not. Patients with mixed stones usually had initial symptoms of stone passage, and were less likely to need surgery, including nephrectomy, or to form contralateral stones. Patients with struvite stones usually presented with infection or no symptom, not passage. We conclude that struvite stones occur in two forms. The struvite stone is a disease of women, presumably occurring de novo from infection. The mixed stones occur in both sexes, presumably from secondary infection in hypercalciuric patients who begin with calcium-oxalate stone disease.