A phase II clinical and pharmacodynamic study of temsirolimus in advanced neuroendocrine carcinomas

Standard cytotoxic treatments for neuroendocrine tumours have been associated with limited activity and remarkable toxicity. A phase II study was designed to evaluate the efficacy, safety and pharmacodynamics of temsirolimus in patients with advanced neuroendocrine carcinoma (NEC). Thirty-seven patients with advanced progressive NEC received intravenous weekly doses of 25 mg of temsirolimus. Patients were evaluated for tumour response, time to progression (TTP), overall survival (OS) and adverse events (AE). Twenty-two archival specimens, as well as 13 paired tumour biopsies obtained pretreatment and after 2 weeks of temsirolimus were assessed for potential predictive and correlative markers. The intent-to-treat response rate was 5.6% (95% CI 0.6–18.7%), median TTP 6 months and 1-year OS rate 71.5%. The most frequent drug-related AE of all grades as percentage of patients were: fatigue (78%), hyperglycaemia (69%) and rash/desquamation (64%). Temsirolimus effectively inhibited the phosphorylation of S6 (P=0.02). Higher baseline levels of pmTOR (phosphorylated mammalian target of rapamycin) (P=0.01) predicted for a better response. Increases in pAKT (P=0.041) and decreases in pmTOR (P=0.048) after treatment were associated with an increased TTP. Temsirolimus appears to have little activity and does not warrant further single-agent evaluation in advanced NEC. Pharmacodynamic analysis revealed effective mTOR pathway downregulation.

Phase II study of erlotinib (OSI-774) in patients with metastatic colorectal cancer

Erlotinib (Tarceva™, OSI-774), a potent epidermal growth factor receptor tyrosine kinase inhibitor (EGFR), was evaluated in a phase II study to assess its activity in patients with metastatic colorectal cancer. In all, 38 patients with metastatic colorectal cancer were treated with erlotinib at a continuous daily oral dose of 150 mg. Radiological evaluation was carried out every 8 weeks and tumour biopsies were performed before treatment and on day 8. Of 31 evaluable patients, 19 (61%) had progressive disease and 12 (39%) had stable disease (s.d.). The median time to progression for those patients having s.d. was 123 days (range 108–329 days). The most common adverse events were rash in 34 patients and diarrhoea in 23 patients. Correlative studies were conducted to investigate the effect of erlotinib on downstream signalling. Tumour tissue correlations were based on usable tissue from eight match paired tumour samples pre- and on therapy, and showed a statistically significant decrease in the median intensity of both pEGFR (P=0.008) and phospho-extracellular signal-regulated kinase (ERK) (P=0.008) a week after commencement of treatment. No other statistically significant change in tumour markers was observed. Erlotinib was well tolerated with the most common toxicities being rash and diarrhoea. More than one-third of evaluable patients had s.d. for a minimum of 8 weeks. Correlative studies showed a reduction in phosphorylated EGFR and ERK in tumour tissue post-treatment.

Systemic lupus erythematosus with concurrent protein-losing enteropathy and primary sclerosing cholangitis: a unique association

We describe a 24-year old male patient with systemic lupus erythematosus (SLE) with the gastrointestinal manifestations of protein-losing enteropathy (PLE) and primary sclerosing cholangitis (PSC). He presented with periorbital, scrotal and lower limb oedema. PLE was diagnosed because of hypoalbuminaemia together with an elevation of alpha-1-antitrypsin stool clearance and absence of proteinuria. PSC was diagnosed on the basis of an elevated serum alkaline phosphatase and lymphocytic and fibrous cholangitis. His disease was also complicated by neuropsychiatric lupus and hypogonadism. All the manifestations of SLE resolved with systemic corticosteroids and pulsed cyclophosphamide treatment. This case report documents the unusual association of SLE with PLE and PSC, and this relationship suggests that autoimmunity underlie the pathogenesis of these conditions.

Characterization of a novel founder rearrangement mutation of BRCA1 in high-risk Hispanic families

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Background: Large rearrangements are estimated to account for 5–10% of all mutations in BRCA1 and BRCA2. Prevalent founder rearrangement mutations have been described in European populations. We sought to identify rearrangements in the BRCA genes in a cohort of Hispanic patients. Methods: We identified 34 deleterious BRCA mutations via full sequence analysis among 110 unrelated high-risk Hispanic families enrolled in an IRB approved registry who underwent cancer risk assessment (CEBP 2005;14:1–6). DNA from 67 of 76 patients without an identifiable mutation was subjected to multiplexed quantitative differential PCR (MQDP, per B. Erickson and T. Scholl, Myriad Genetics Laboratory) for detection of large rearrangements. An apparent deletion of BRCA1 exons 9–12, indicated by a 50% loss of signal was identified by MQDP in 3 unrelated families (ASHG, 2005). Long range PCR resulted in the generation of a 2.7kb product in these samples, consistent with a deletion event of 15.1kb. This putative mutation was further characterized by cloning and sequencing the breakpoint in all 3 families. RNA splicing was evaluated by sequencing RT-PCR products from lymphoblastoid cell line RNA for each family. Results: Sequence analysis identified the breakpoint within Alu elements in introns 8 and 12, and all 3 unrelated families shared the same breakpoint. Analysis of cDNA demonstrated direct splicing of exons 8–13 predicting a frameshift mutation and premature truncation of the BRCA1 protein, thus confirming the deleterious nature of this mutation. Conclusion: We identified the same novel large deletion in three unrelated families of Mexican ancestry, suggesting potential founder effect. The frequency was 2.7% of the 110 high-risk Hispanic families screened for BRCA mutations, bringing the overall prevalence of deleterious mutations to 33.6%(37/110) in this cohort. This BRCA1 rearrangement may account for a substantial proportion of high-risk Hispanic families, and should be included in all subsequent studies of this ethnic group.

No significant financial relationships to disclose.

Readmission to Surgical Intensive Care Increases Severity-Adjusted Patient Mortality

BACKGROUND

This study aims to determine whether severity-adjusted outcomes including mortality are adversely impacted by readmission to a surgical intensive care unit (SICU) during the same hospital stay.

METHODS

The study included all patients admitted to the 20-bed tertiary care SICU in an urban teaching Level I trauma center and multiorgan transplant center from January 1, 1996 to December 31, 2001. This was a prospective observational study with secondary data analysis. Acute Physiology and Chronic Health Evaluation (APACHE II) and Simplified Acute Physiology (SAPS) severity scores were calculated by a clinical information system. Outcomes were extracted from a computerized data warehouse.

RESULTS

In-hospital mortality and SICU length of stay (LOS) were measured for patients admitted and readmitted to the SICU. Of 10,840 patients admitted to the SICU, 296 (2.73%) required readmission to the SICU during the same hospital stay. The length of the original SICU stay was 4.9 +/- 6.7 days for readmitted patients compared with 3.2 +/- 6.0 days for nonreadmitted patients (p < 0.001). Readmitted patients had a higher mean APACHE II score on the day of original SICU discharge compared with nonreadmitted patients, 15.7 +/- 6.7 versus 13.8 +/- 7.1 (p < 0.001). The average APACHE II score increased from 15.7 +/- 6.7 to 18.1 +/- 8.6 between the day of SICU discharge and readmission (p < 0.001) and SAPS increased from 12.2 +/- 4.8 to 13.5 +/- 5.4 (p < 0.001). The distributions of severity-adjusted hospital mortality for both APACHE II and SAPS revealed that readmission to the SICU significantly increased mortality independent of the admission severity score.

CONCLUSIONS

Readmission to the SICU significantly increases the risk of death beyond that predicted by the APACHE II or SAPS scores alone. Higher APACHE II and SAPS scores upon discharge from the SICU and longer SICU LOS are associated with an increased incidence of readmission to the SICU on the same hospital stay. These results may be used to optimize the timing of SICU discharge and reduce the chance of readmission to intensive care.

Functional categories of TP53 mutation in colorectal cancer: results of an International Collaborative Study

BACKGROUND

Loss of TP53 function through gene mutation is a critical event in the development and progression of many tumour types including colorectal cancer (CRC). In vitro studies have found considerable heterogeneity amongst different TP53 mutants in terms of their transactivating abilities. The aim of this work was to evaluate whether TP53 mutations classified as functionally inactive (< or=20% of wildtype transactivation ability) had different prognostic and predictive values in CRC compared with mutations that retained significant activity.

MATERIALS AND METHODS

TP53 mutations within a large, international database of CRC (n = 3583) were classified according to functional status for transactivation.

RESULTS

Inactive TP53 mutations were found in 29% of all CRCs and were more frequent in rectal (32%) than proximal colon (22%) tumours (P < 0.001). Higher frequencies of inactive TP53 mutations were also seen in advanced stage tumours (P = 0.0003) and in tumours with the poor prognostic features of vascular (P = 0.006) and lymphatic invasion (P = 0.002). Inactive TP53 mutations were associated with significantly worse outcome only in patients with Dukes' stage D tumours (RR = 1.71, 95%CI 1.25-2.33, P < 0.001). Patients with Dukes' C stage tumours appeared to gain a survival benefit from 5-fluorouracil-based chemotherapy regardless of TP53 functional status for transactivation ability.

CONCLUSIONS

Mutations that inactivate the transactivational ability of TP53 are more frequent in advanced CRC and are associated with worse prognosis in this stage of disease.

Nonequilibrium domain pattern formation in mesoscopic magnetic thin film elements assisted by thermally excited spin fluctuations

The dynamic behavior in the evolving pattern of thermally assisted, nonequilibrium domains in magnetic thin-film elements undergoing ultrafast 180 degrees magnetization reversal was studied. Magnetization reversal enters a fully dynamic regime when the external field conditions are changed much faster than the sample is able to respond. The dynamic pathway develops a complexity not seen in quasistatic reversal but still retains a high level of order with well-developed dynamic domain patterns formed in response to subnanosecond transitions of the external applied magnetic field.

Primary anaplastic large cell lymphoma of the pancreas

Most solid pancreatic tumors are exocrine adenocarcinomas. We presented a patient with primary ALCL of the pancreas masquerading as a carcinoma of the head of pancreas. She was scheduled for a Whipple's operation and the intra-operative frozen section showed anaplastic carcinoma. The proper diagnosis was only derived later with CD30 immunohistochemical study. This carries important implications on the management, as radical surgery is indicated in resectable carcinoma but not for a chemosensitive lymphoma.

Multicentre randomized-controlled clinical trial of Ipocol, a new enteric-coated form of mesalazine, in comparison with Asacol in the treatment of ulcerative colitis

BACKGROUND

5-Aminosalicylates remain important in the treatment of ulcerative colitis, but it is uncertain if the various preparations currently available are equivalent given the different delivery systems that exist. Generic prescription of mesalazine (mesalamine) is therefore inappropriate. Ipocol has recently become available as an alternative to Asacol-MR.

AIM

To compare the two agents in a controlled trial using a non-inferiority design.

METHODS

Eighty-eight ulcerative colitis patients with a mild to moderate clinical relapse were randomized to one of the two drugs at a daily dose of 2.4 g for 8 weeks. Safety was the key concern; the primary measured end-point was efficacy as judged from a colitis activity index.

RESULTS

There were no unexpected adverse events of clinical consequence. The colitis score improved similarly in both patient groups (by 2.3 with Ipocol and by 1.5 with Asacol: not significant), and a similar proportion was in clinical remission at the end of the study (26.1% for Ipocol and 28.6% for Asacol: not significant). Systemic steroids were needed in 11.9% of the Asacol-treated patients compared with 6.5% with Ipocol (not significant).

CONCLUSION

It appears appropriate to conclude that, while not identical to Asacol-MR, Ipocol offers a safe and similarly effective alternative.

Assessment of bacterial endospore viability with fluorescent dyes

AIM

To validate three fluorescence viability assays designed primarily for vegetative cells on pure Bacillus endospores.

METHODS AND RESULTS

Purified fresh and gamma-irradiated Bacillus endospores (Bacillus cereus, B. coagulans and two strains of B. subtilis) were used. The viability assays were: 5-cyano-2,3-diotolyl tetrazolium chloride (CTC) to test respiratory activity and early germination, DiBAC4(3) and Live/Dead BacLight to measure membrane energization and permeabilization, respectively. Gamma irradiation treatment completely eliminated spore culturability and was used as negative control. The untreated spores showed respiratory activity after 1 h of incubation and this was characteristic of almost 100% of spores after 24 h. The membrane potential assessment gave no answer about spore viability. A lower proportion of untreated spores had permeabilized membrane compared with gamma-irradiated spores using Live/Dead BacLight (P < 0.02).

CONCLUSION

It is possible to use CTC and Live/Dead BacLight to rapidly test endospore viability and evaluate the proportion of spores in a preparation that could not be recovered with plate count.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study shows that fluorescence tests could be applied to assess viability in potentially pathogenic Bacillus spore preparations within 1 h.

A sensitive guaiac faecal occult blood test is less useful than an immunochemical test for colorectal cancer screening in a Chinese population

BACKGROUND

Colorectal cancer screening by guaiac faecal occult blood test has been shown to reduce the incidence and mortality of colorectal cancer in Western populations. The optimal faecal occult blood test, whether guaiac or immunochemical, for colorectal cancer screening in the Chinese population remains to be defined.

AIM

To compare the performance characteristics of a sensitive guaiac-based faecal occult blood test (Hemoccult SENSA) and an immunochemical faecal occult blood test (FlexSure OBT) in a Chinese population referred for colonoscopy.

METHODS

One hundred and thirty-five consecutive patients who were referred for colonoscopy and who met the study inclusion criteria took samples for the two faecal occult blood tests simultaneously from three successive stool specimens, with no dietary restrictions. All tests were developed and interpreted by a single experienced technician who was blind to the clinical diagnosis. The sensitivity, specificity and positive predictive value for the detection of colorectal adenomas and cancers were estimated for the two tests.

RESULTS

The sensitivity, specificity and positive predictive value for the detection of significant colorectal neoplasia (adenomas > or = 1.0 cm and cancers) were 91%, 70% and 18% for Hemoccult SENSA and 82%, 94% and 47% for FlexSure OBT. The specificity and positive predictive value were significantly higher for FlexSure OBT than for Hemoccult SENSA (P < 0.001 and P = 0.016, respectively). Combining the positive results from both faecal occult blood tests did not improve the accuracy.

CONCLUSION

The positive predictive value of the immunochemical faecal occult blood test for the detection of significant colorectal neoplasia was 29% better than that of the sensitive guaiac-based test. This may relate to the Chinese diet and requires further study. The poor specificity of the sensitive guaiac-based test, without dietary restriction, makes it less useful for colorectal cancer screening in a Chinese population.

Loss of CD117 (c-kit)- and CD34-positive ICC and associated CD34-positive fibroblasts defines a subpopulation of chronic intestinal pseudo-obstruction

Chronic idiopathic intestinal pseudo-obstruction is a syndrome in which symptoms of intestinal obstruction are present in the absence of mechanical obstruction. Lack of normal pacemaker activity, usually generated by the interstitial cells of Cajal (ICC), could account for the apparent obstruction. ICC are normally located around and between the myenteric plexus ganglia and within muscle and also in the deep muscular plexus of the small bowel and the submuscular plexus of the large intestine, just within the circular muscle. ICC can be demonstrated immunohistochemically with CD117 (c-kit) as well as with CD34, although this is less specific. CD34 also stains a population of fibroblasts that are intimately associated with ICC. To determine whether there is a relative deficiency of ICC and CD34-positive fibroblasts in patients with chronic idiopathic intestinal pseudo-obstruction, tissue from 30 patients of large intestine and eight patients with small intestine pseudo-obstruction was obtained. Controls (large intestinal specimens from 12 patients, small intestinal specimens from six patients) were chosen from resections for Crohn's disease and colorectal neoplasia, both with and without dilatation. Examination of pseudo-obstruction cases identified 10 patients (nine large intestinal and one small intestinal) in which both CD117 and CD34 were absent or severely reduced in all three of the examined areas. In contrast, the control cases, including those with preobstructive dilatation, showed relatively constant ICC staining. These results suggest that there is a proportion of pseudo-obstruction cases in which the ICC are markedly reduced. These results also demonstrate that, in these cases, loss of the kit immunoreactivity is correlated with the loss of CD34 staining: this indicates that both the ICC and the CD34-positive fibroblasts associated with the ICC are absent. These findings will allow surgical pathologists to identify this subpopulation of patients with CIIP using tissue obtained by laparoscopic biopsy of the muscularis propria or surgical resection.

Regulation of plasminogen activator inhibitor-1 secretion by growth factors in smooth muscle cells

Epithelioid-type vascular smooth muscle cells are metabolically active and secrete many proteases and protease inhibitors. We have previously cloned epithelioid-type smooth muscle cells from rat carotid arteries, and showed that polypeptide growth factors basic fibroblast growth factor (bFGF) and platelet-derived growth factor (PDGF) could dose-dependently induce plasminogen activator inhibitor-1 (PAI-1) secretion from these cells. In the present study, we have used these cells to investigate the growth factor-induced signal transduction pathways leading to PAI-1 secretion. We report here that PAI-1 induction was dependent on protein kinase C (PKC) and tyrosine kinase but not on protein kinase A (PKA), ras and phosphoinositol-3-kinase inhibitor. Induction of PAI-1 by bFGF and PDGF was also accompanied by activation of a mitogen-activated protein kinase pathway involving Raf/Mek/Erk1/2, and the family non-receptor tyrosine kinases., another non-receptor tyrosine kinase, on the contrary, behaved differently from in that it was part of a pathway leading to PAI-1 induction by bFGF, but not when PDGF was used as the stimulating reagent. Activation of a PKA-dependent pathway(s) opposed PAI-1 induction. One mechanism for PKA activators to inhibit PAI-1 secretion was that they markedly inhibited the phosphorylations of Mek and mitogen-activated protein kinase that were up-regulated in the presence of bFGF and PDGF.

Promiscuous antigen presentation by the nonclassical MHC Ib Qa-2 is enabled by a shallow, hydrophobic groove and self-stabilized peptide conformation

BACKGROUND

Qa-2 is a nonclassical MHC Ib antigen, which has been implicated in both innate and adaptive immune responses, as well as embryonic development. Qa-2 has an unusual peptide binding specificity in that it requires two dominant C-terminal anchor residues and is capable of associating with a substantially more diverse array of peptide sequences than other nonclassical MHC.

RESULTS

We have determined the crystal structure, to 2.3 A, of the Q9 gene of murine Qa-2 complexed with a self-peptide derived from the L19 ribosomal protein, which is abundant in the pool of peptides eluted from the Q9 groove. The 9 amino acid peptide is bound high in a shallow, hydrophobic binding groove of Q9, which is missing a C pocket. The peptide makes few specific contacts and exhibits extremely poor shape complementarity to the MHC groove, which facilitates the presentation of a degenerate array of sequences. The L19 peptide is in a centrally bulged conformation that is stabilized by intramolecular interactions from the invariant P7 histidine anchor residue and by a hydrophobic core of preferred secondary anchor residues that have minimal interaction with the MHC.

CONCLUSIONS

Unexpectedly, the preferred secondary peptide residues that exhibit tenuous contact with Q9 contribute significantly to the overall stability of the peptide-MHC complex. The structure of this complex implies a "conformational" selection by Q9 for peptide residues that optimally stabilize the large bulge rather than making intimate contact with the MHC pockets.

Results of anterior levatorplasty for rectocele

OBJECTIVE

Transanal and transvaginal repair of rectocele have been advocated in the treatment of rectocele, with mixed results. The aim of this study was to assess our experience using anterior levatorplasty in the surgical management of rectocele.

PATIENTS AND METHODS

Sixty of 90 women who had undergone anterior levatorplasty for rectocele over a seven year period were traced, and 44 (33 with rectocele only and 11 with rectocele and faecal incontinence) responded to a standardized questionnaire 6 months to 7 years (mean 3.5 years) after anterior levatorplasty. Results were expressed in general and specific improvement of symptoms and were classified as excellent, good, fair, or poor. The effects on social activities, sexual function, and employment were also assessed.

RESULTS

General satisfaction with the operation was rated as good or excellent in 27 of 33 (82%) and 18 of 24 (75%) patients with rectocele only at 2 and 3.2 years follow-up, respectively, and in 7 of 11 (64%) and 5 of 11 (45%) patients with rectocele and faecal incontinence at 2 and 4 years follow-up, respectively. 31 (70%) and 34 (77%) of all patients reported an improvement in sensation and the ability to defaecate, respectively. An improvement in social activities, sexual satisfaction and employment was noted in 10 of 21 (48%), 10 of 23 (43%), and 7 of 12 (58%) patients, respectively.

CONCLUSION

Anterior levatorplasty provides good short and long-term symptomatic improvement in patients with rectocele and avoids complications associated with rectal or vaginal approaches.

Clonal cytotoxic T cells are expanded in myeloma and reside in the CD8(+)CD57(+)CD28(-) compartment

The occurrence of clonal T cells in multiple myeloma (MM), as defined by the presence of rearrangements in the T-cell receptor (TCR)-beta chains detected on Southern blotting, is associated with an improved prognosis. Recently, with the use of specific anti-TCR-variable-beta (anti-TCRV(beta)) antibodies, the presence in MM patients of expanded populations of T cells expressing particular V(beta) regions was reported. The majority of these T-cell expansions have the phenotype of cytotoxic T cells (CD8(+)CD57(+) and perforin positive). Since V(beta) expansions can result from either a true clonal population or a polyclonal response, the clonality of CD8(+)TCRV(beta)(+) T cells was tested by TCRV(beta) complementarity-determining region 3 length analysis and DNA sequencing of the variable region of the TCR. In this report, the CD57(+) and CD57(-) subpopulations within expanded TCRV(beta)(+)CD8(+) cell populations are compared, and it is demonstrated that the CD57(+) subpopulations are generally monoclonal or biclonal, whereas the corresponding CD57(-) cells are frequently polyclonal. The oligoclonality of CD57(+) expanded CD8(+) T cells but not their CD57(-) counterparts was also observed in age-matched controls, in which the T-cell expansions were mainly CD8(-). The CD8(+)CD57(+) clonal T cells had a low rate of turnover and expressed relatively lower levels of the apoptotic marker CD95 than their CD57(-) counterparts. Taken together, these findings demonstrate that MM is associated with CD57(+)CD8(+) T-cell clones, raising the possibility that the expansion and accumulation of activated clonal CD8(+) T cells in MM may be the result of persistent stimulation by tumor-associated antigens, combined with a reduced cellular death rate secondary to reduced expression of the apoptosis-related molecule CD95.

Mortality and morbidity of the small for gestational age (SGA) very low birth weight (VLBW) Malaysian infant

OBJECTIVE

To compare the neonatal course of small for gestational age (SGA) and appropriate for gestational age (AGA) preterm infants 1500 g or less birthweight.

METHOD

A total of 116 infants SGA infants 32 weeks or less were matched with 116 AGA infants of the same gestation, ethnic group, sex and where possible inborn or outborn status.

RESULTS

Significantly more SGA infants had a 1-minute Apgar scores of 3 or less, odds ratio (OR) 2.54 (95% Confidence Interval (CI) 1.25, 5.20) and a Critical Risk Index in Babies (CRIB) score > 5, OR 2.09 (95% CI 1.07, 4.09). They were significantly more likely to have hypotension, 35.5 versus 22.3%, OR 1.90 (95% CI 1.01, 3.59). There was no difference in the frequency of respiratory distress syndrome, mechanical ventilation, infection or rate of congenital malformation. Mortality before hospital discharge was significantly greater for the SGA infant (52.6 versus 28.4%, OR 2.79 (95% CI 1.56, 5.02)). This difference remained significant after exclusion of congenital abnormalities. Survivors had a longer mean duration of stay, (54.4 versus 41.2 days, p < 0.001).

CONCLUSION

The higher mortality seen in SGA infants appears to be due to a poorer condition at birth. There is no evidence that SGA infants have more mature lungs so antenatal corticosteroids should not be withheld on these grounds.

In vitro reconstitution of recognition and activation complexes between interleukin-6 and gp130

Gp130 is a shared signal-transducing receptor for a family of four-helix cytokines, of which interleukin-6 is a prototypic member. IL-6-type cytokines activate gp130 to elicit downstream intracellular JAK/STAT signaling cascades through formation of hetero-oligomeric receptor complexes. Interleukin-6 must first complex with its specific alpha-receptor (Ralpha) in order to bind and activate gp130. We have dissected the extracellular activation pathway of human gp130 by human IL-6 through reconstitution of soluble complexes representing intermediate and final states in the hierarchical assembly of the IL-6/IL-6Ralpha/gp130 signaling complex. To isolate these hetero-complexes, we have applied a protein engineering strategy of covalently linking IL-6 to its Ralpha, which results in a "hyperactive" single-chain complex (hyper-IL-6) which we express in both Escherichia coli and insect cells. We have determined that IL-6/IL-Ralpha and the cytokine-binding homology region (CHR) of gp130 (D2D3) form a stable trimolecular "recognition" complex (trimer) consisting of 1IL-6,1 IL-6Ralpha, and 1 gp130-CHR. Addition of the N-terminal (D1) Ig-like domain (IGD) of gp130 to the CHR results in a transition to a hexameric "activation" complex containing 2 IL-6, 2IL-6Ralpha, and 2 gp130. These results clearly demonstrate that the recognition and activation complexes are disparate hetero-oligomeric molecular species linked by the recruitment of the gp130 IGD by the unique site III epitope present on all gp130-class cytokines. The results of these studies are relevant to other members of the IL-6 family of gp130-cytokines and address a longstanding question concerning the respective roles of the gp130 CHR and IGD in assembly of the active signaling oligomer.

Kinetics and thermodynamics of T cell receptor- autoantigen interactions in murine experimental autoimmune encephalomyelitis

In the current study, cellular and molecular approaches have been used to analyze the biophysical nature of T cell receptor (TCR)-peptide MHC (pMHC) interactions for two autoreactive TCRs. These two TCRs recognize the N-terminal epitope of myelin basic protein (MBP1-11) bound to the MHC class II protein, I-A(u), and are associated with murine experimental autoimmune encephalomyelitis. Mice transgenic for the TCRs have been generated and characterized in other laboratories. These analyses indicate that the mice either develop encephalomyelitis spontaneously (172.10 TCR) or only if immunized with autoantigen in adjuvant (1934.4 TCR). Here, we show that the 172.10 TCR binds MBP1-11:I-A(u) with a 4-5-fold higher affinity than the 1934.4 TCR. Consistent with the higher affinity, 172.10 T hybridoma cells are significantly more responsive to autoantigen than 1934.4 cells. The interaction of the 172.10 TCR with cognate ligand is more entropically unfavorable than that of the 1934.4 TCR, indicating that the 172.10 TCR undergoes greater conformational rearrangements upon ligand binding. The studies therefore suggest a correlation between the strength and plasticity of a TCR-pMHC interaction and the frequency of spontaneous disease in the corresponding TCR transgenic mice. The comparative analysis of these two TCRs has implications for understanding autoreactive T cell recognition and activation.

Ras regulates the polarity of the yeast actin cytoskeleton through the stress response pathway

Polarized growth in yeast requires cooperation between the polarized actin cytoskeleton and delivery of post-Golgi secretory vesicles. We have previously reported that loss of the major tropomyosin isoform, Tpm1p, results in cells sensitive to perturbations in cell polarity. To identify components that bridge these processes, we sought mutations with both a conditional defect in secretion and a partial defect in polarity. Thus, we set up a genetic screen for mutations that conferred a conditional growth defect, showed synthetic lethality with tpm1Delta, and simultaneously became denser at the restrictive temperature, a hallmark of secretion-defective cells. Of the 10 complementation groups recovered, the group with the largest number of independent isolates was functionally null alleles of RAS2. Consistent with this, ras2Delta and tpm1Delta are synthetically lethal at 35 degrees C. We show that ras2Delta confers temperature-sensitive growth and temperature-dependent depolarization of the actin cytoskeleton. Furthermore, we show that at elevated temperatures ras2Delta cells are partially defective in endocytosis and show a delocalization of two key polarity markers, Myo2p and Cdc42p. However, the conditional enhanced density phenotype of ras2Delta cells is not a defect in secretion. All the phenotypes of ras2Delta cells can be fully suppressed by expression of yeast RAS1 or RAS2 genes, human Ha-ras, or the double disruption of the stress response genes msn2Deltamsn4Delta. Although the best characterized pathway of Ras function in yeast involves activation of the cAMP-dependent protein kinase A pathway, activation of the protein kinase A pathway does not fully suppress the actin polarity defects, suggesting that there is an additional pathway from Ras2p to Msn2/4p. Thus, Ras2p regulates cytoskeletal polarity in yeast under conditions of mild temperature stress through the stress response pathway.

Vascular patterning defects associated with expression of activated Notch4 in embryonic endothelium

Notch proteins function as receptors for membrane-bound ligands (Jagged and Delta-like) to regulate cell-fate determination. We have investigated the role of Notch signaling in embryonic endothelium of the mouse by expressing an activated form of the Notch4 protein in vasculature under the regulation of the Flk1 (VEGFR) locus. Expression of activated Notch4 results in a growth and developmental delay and embryonic lethality at about 10 days postcoitum. The extent of the developing vasculature in mutant embryos was restricted, fewer small vessels were seen, and vascular networks were disorganized. The brain periphery of mutant embryos contained large dilated vessels with evidence of compromised vessel-wall integrity and large areas of necrosis; yolk-sac vasculature was abnormal. Expression of an activated form of Notch4 in embryonic vasculature leads to abnormal vessel structure and patterning, implicating the Notch pathway in phases of vascular development associated with vessel patterning and remodeling.

Time saved with the use of emergency warning lights and siren while responding to requests for emergency medical aid in a rural environment

OBJECTIVE

To determine whether the use of warning lights and siren saves a significant amount of time for ambulances responding to requests for emergency medical aid in a rural emergency medical services (EMS) setting.

METHODS

A prospective design was used to determine run times for ambulances responding to calls with lights and siren (code 3) and for a similarly equipped "chase" ambulance traveling to the same destination via the same route without lights and siren, while obeying all traffic laws (code 2) within a rural setting. Data were collected for run time intervals, distance traveled, visibility, road surface conditions, time of day, and day of the week. Descriptive statistics, a paired Student's t-test, and analysis of variance were used to test for significant differences between code 2 and code 3 operations, as well as the other variables listed above.

RESULTS

Sixty-seven runs were timed during a 21-month period. The average code 3 response interval was 8.51 minutes. The average code 2 response interval was 12.14 minutes. The 3.63 minutes saved on average represents significant time savings of 30.9% (p < 0.01). Shorter runs had higher time savings per mile than the longer runs. Run distance was the only variable that was statistically significant in affecting time saved during a code 3 response.

CONCLUSION

Code 3 operation by EMS personnel in a rural EMS setting saved significant time over code 2 operation when traveling to a call.

Anuretes grandis sp. n., a caligid copepod (Siphonostomatoida) parasitic on Diagramma pictum (Pisces) in Taiwan, with discussion of Anuretes Heller, 1865

A new species of caligid copepod (Siphonostomatoida), Anuretes grandis sp. n., parasitic on the painted sweetlips [Diagramma pictum (Thunberg)] in Taiwan is described. The new species is distinguished from its congeners by having: (1) free margin of cephalothorax not covering fourth pediger, (2) large genital complex longer than 2/3 of the cephalic shield, (3) no maxillary whip, (4) leg 3 with 9 setae on the terminal segment of exopod and 8 plumose setae on the terminal segment of endopod, and (5) armature of I,III on leg 4 exopod. Genus Anuretes Heller, 1865 is reviewed and redefined. Based on the new diagnosis three species (A. chelatus Prabha et Pillai, A. fedderni Price and A. parvulus Wilson) were transferred to Pseudanuretes, and two species (A. furcatus Capart and A. renalis Heegaard) were transferred to Lepeophtheirus. In addition, the following three species of caligids were transferred to Anuretes: Lepeophtheirus fallolunulus Lewis, Heniochophilus indicus Pillai, and Lepeophtheirus rotundigenitalis Prabha et Pillai. The latter is renamed Anuretes occultus nom. n. due to the homonym encountered through this transfer. "Anuretes plectorhynchi Yamaguti" reported by Prabha and Pillai (1986) is renamed Anuretes similis sp. n. and Anuretes yamagutii Prabha et Pillai is relegated to the synonym of Anuretes anomalus Pillai. A key to the 18 species of Anuretes is provided.