Polymorphism within the tumor necrosis factor alpha (TNF) promoter region in patients with ankylosing spondylitis

In addition to HLA-B27, other genetic factors are thought to be involved in the pathogenesis of ankylosing spondylitis (AS). Because of the location of the TNF gene in the vicinity of the HLA-B locus, and the prominent role in inflammation of its product, we investigated the association between AS and two G to A transition polymorphisms located at position -238 and -376 in the promoter region of the TNF gene. The distribution of the TNF alleles was determined in 86 HLA-B27+ AS patients and 163 healthy controls. From the 86 AS patients, 33 suffered from acute anterior uveitis (AAU). No significant difference for the TNF-376 polymorphism in AS and healthy controls was observed. The frequency of the TNF-238A allele in HLA-B27+ AS patients was significantly decreased compared to random controls (p = 0.021). However, the frequency of the TNF-238A allele in HLA-B27+ AS patients was not significantly different from that observed in HLA-B27+ healthy individuals (p = 0.6). Assessment of association showed that the TNF-238G allele is in linkage disequilibrium with the HLA-B27 allele (delta = 0.053; P = 0.008). Therefore, we conclude that the association between TNF-238G and AS is secondary to the HLA-B27 gene and that TNF-238 and-TNF-376 alleles are not likely to be involved in the susceptibility to AS.

A phase I study of docetaxel and 5-fluorouracil in patients with advanced solid malignancies

PURPOSE

This study was undertaken to evaluate the feasibility of administering docetaxel (Taxotere; Rhône-Poulenc-Rorer) as a one-hour intravenous (i.v.) infusion on day 1 combined with 5-fluorouracil (5-FU) as a bolus i.v. injection for five (days 1-5) or three (days 1-3) consecutive days every four weeks.

PATIENTS AND METHODS

Thirty-seven patients with advanced solid malignancies were treated with 115 total courses involving seven dose levels of the two regimens of docetaxel and 5-FU (docetaxel/5-FU [mg/m2]/mg/m2/d]). In an effort to reduce fluid retention and hypersensitivity phenomena related to docetaxel, patients received premedication with dexamethasone 8 mg orally twice daily for three consecutive days beginning 24 hours before treatment.

RESULTS

Severe (grade 4) neutropenia lasting longer than seven days with or without fever and/or severe mucositis, precluded further dose escalation above docetaxel 60 mg/m2 on day 1 and 5-FU 300 mg/m2/day administered on days 1-5 every four weeks. The rates of these toxic effects were also unacceptably high above docetaxel 60 mg/m2 on day 1 and 5-FU 300 mg/m2/day administered on days 1-3 every four weeks. Nine patients experienced various manifestations of fluid-retention that were potentially related to study drugs. However, neither treatment delay nor discontinuation of treatment was required. Nausea, vomiting, diarrhea, and fatigue, were mild to modest in severity and occurred infrequently (< 10% of courses). Two patients with metastatic breast cancer experienced complete responses and a partial response occurred in a patient with metastatic non-small-cell lung cancer.

CONCLUSION

Based on the results of this study, the regimen of docetaxel 60 mg/m2 on day 1 followed by 5-FU 300 mg/m2/d i.v. for three or five days every four weeks is well tolerated and these doses are recommended for further evaluations. The feasibility of administering docetaxel 60 mg/m2 followed by 5-FU 300 mg/m2 for three or five days every four weeks and the preliminary antitumor activity noted indicate that further disease-directed studies of docetaxel and 5-FU are warranted in patients with relevant solid malignancies.

Developing an effective program to complete ictal SPECT in the epilepsy monitoring unit

With the availability of more stable radiopharmaceuticals, the ictal single photon emission computed tomography (SPECT) perfusion study has emerged as a useful noninvasive functional neuroimaging tool in the presurgical evaluation of patients with medically intractable partial epilepsy. The purpose of this study was to determine whether the development of a program using trained electroencephalography (EEG) technologists to perform ictal injections in the epilepsy monitoring unit enabled a more efficient delivery of radiopharmaceuticals and therefore a higher specificity and sensitivity of outcome. All patients admitted to the epilepsy monitoring unit for prolonged video/EEG monitoring as part of the presurgical evaluation were eligible for completion of an ictal SPECT study using a three-way needle-free apparatus. Over a 19-month period, 85 (77%)) of 110 eligible patients were successfully injected during typical partial seizures. Various factors were analyzed including latency of ictal injection (27.3+/-20.8 [S.D.] s), radiopharmaceutical wastage (40% dose utilization), radiation safety parameters (1.6% contamination rate), and preliminary data of localizing value. Our results show that ictal SPECT can be a safe, noninvasive procedure completed on a routine basis in the epilepsy monitoring unit when appropriately trained support staff are utilized as part of a structured multidisciplinary program.

Shift length as a determinant of retrospective on-shift alertness

OBJECTIVES

This study examined the combined effects of shift length (8 versus 12 hours) and night-to-morning-shift changeover time (0600 versus 0700) on retrospective on-shift alertness ratings.

METHODS

An abridged version of the Standard Shiftwork Index, which included retrospective alertness ratings, was completed by 4 groups of industrial shift workers. Two groups worked 8-hour shift systems and started their morning shifts at either 0600 or 0700; the other 2 groups worked 12-hour systems, starting their day shifts at either 0600 or 0700.

RESULTS

The 8-hour workers reported considerably higher levels of alertness in the afternoon, while the 12-hour workers were more alert than the 8-hour workers in the morning and at 2200. Workers who started their shift around 0600 were less alert during the morning than those who started around 0700. The data suggested that the combined effects of working 8-hour shifts and starting the morning shift at around 0600 have particularly deleterious effects upon alertness.

CONCLUSIONS

Effects on alertness can be explained in terms of differences in elapsed time on duty, sleep duration, sleep disruption, and chronic fatigue. The findings of this study appear to contradict previous research demonstrating that the major deleterious effects of extended shifts and delayed changeovers upon alertness occur at night. However, it is acknowledged that the absence of a difference in alertness at night may have been due to floor effects. Nevertheless, the implications of the alertness ratings for performance and safety, particularly during the afternoon, should not be ignored.

Tyrosine-dependent and -independent mechanisms of STAT3 activation by the human granulocyte colony-stimulating factor (G-CSF) receptor are differentially utilized depending on G-CSF concentration

The granulocyte colony-stimulating factor receptor (G-CSF-R) activates multiple STAT proteins. Although the membrane-proximal cytoplasmic region of the G-CSF-R is necessary and sufficient for activation of STAT1 and STAT5, activation of STAT3 requires the membrane distal region that contains four tyrosines. Although one of these (Y704) has previously been shown to be involved in STAT3 activation from a truncated G-CSF-R derived from a patient with severe chronic neutropenia (SCN), this tyrosine is not required for STAT3 activation by the full-length G-CSF-R. To investigate possible alternative mechanisms of STAT3 activation, we generated a series of Ba/F3 cell transfectants expressing the wild-type G-CSF-R or mutant receptors that either completely lack tyrosines or retain just one of the four cytoplasmic tyrosines of the G-CSF-R. We show that, at saturating G-CSF concentrations, STAT3 activation from the full-length G-CSF-R is efficiently mediated by the C-terminal domain in a manner independent of receptor tyrosines. In contrast, at low G-CSF concentrations, Y704 and Y744 of the G-CSF-R play a major role in STAT3 activation. Both tyrosine-dependent and -independent mechanisms of STAT3 activation are sensitive to the Jak2 inhibitor AG-490, follow similar kinetics, and lead to transactivation of a STAT3 reporter construct, indicating functional equivalence. STAT3 activation is also impaired, particularly at nonsaturating G-CSF concentrations, in bone marrow cells from mice expressing a truncated G-CSF-R (gcsfr-triangle up715). These findings suggest that G-CSF-induced STAT3 activation during basal granulopoiesis (low G-CSF) and "emergency" granulopoiesis (high G-CSF) are differentially controlled. In addition, the data establish the importance of the G-CSF-R C-terminus in STAT3 activation in primary cells, which has implications for understanding why truncated G-CSF-R derived from SCN patients are defective in maturation signaling.

Building a Picture of Heteroborane Isomerisation: Synthesis and Characterisation of the 10-(Dialkyl- sulfane)-7,8-diphenyl-7,8-dicarba-nido-undecaboranes 7,8-Ph2-10-L-7,8-nido-C2B9H10 (L = SMe2, SMeEt, SEt2) and of Intermediate and Isomerised Products Arising from Metallation of the First of These

Three new, substituted, nido carboranes, 7,8-Ph2-10-(SMe2)-7,8-nido-C2B9H10 (1a), 7,8-Ph2-10- (SMeEt)-7,8-nido-C2B9H10 (1b) and 7,8-Ph2-10-(SEt2)-7,8-nido-C2B9H10 (1c) have been synthesised and characterised, including a crystallographic study of the first. Deprotonation of 1a followed by treatment with (MeCN)2(CO)2MoBr(η-C3H5) at 0 °C affords the non-icosahedral 1,2-Ph2-4-(SMe2)-5-(η-C3H5)-5,5-(CO)2-5,1,2-closo-MoC2B9H8 (2a), which on subsequent warming transforms into icosahedral 2,8-Ph2-5-(SMe2)-1-(η-C3H5)-1,1-(CO)2-1,2,8-closo- MoC2B9H8 (3a). It is argued that under the conditions of these rearrangements the B-S bond is likely to remain intact, and consequently that the identity of the SMe2-labelled boron atom in 3a affords useful experimental information on the course of the isomerisation.

Mutations in the N- and D-helices of the N-domain of troponin C affect the C-domain and regulatory function

Troponin C contains a 14-residue alpha-helix at the amino terminus, the N-helix, that calmodulin lacks. Deletion of the first 11-14 residues of troponin C alters function. In the present investigation a mutant lacking residues 1-7 of the N-helix has normal conformation, Ca2+ binding, and regulatory function. Thus, residues 8-14 of the N-helix are generally sufficient for troponin C function. In the x-ray structures of troponin C there is a salt bridge between Arg 11 in the N-helix and Glu 76 in the D-helix. Destroying the salt bridge by individually mutating the residues to Cys has no effect on function. However, mutation of both residues to Cys reduces troponin C's affinity for the troponin complex on the thin filament, reduces the stability of the N-domain in the absence of divalent cations, increases the Ca2+ affinity and reduces the cooperativity of the Ca2+Mg2+ sites in the C-domain, and alters the conformational change that takes place upon Ca2+ binding (but not Mg2+ binding) to the C-domain. Cross-linking with bis-(maleimidomethylether) partially restores function. The Ca2+-specific sites in the N-domain, those closest to the sites of the mutations, are unaffected in the assays employed. These results show that the N-helix is a critical structural element for interaction with and activation of the thin filament. Moreover, mutations in the N-helix affect the C-terminal domain, consistent with recent structural studies showing that the N-helix and C-terminal domain are physically close.

Welfare reform: advocacy and intervention in the health care setting

Welfare reform has drastically altered the lives of poor families in the US. In its wake, many former recipients are not receiving whatever transitional benefits and other safeguards to which they remain entitled under federal and state laws. Families are losing access to Medicaid and are not receiving the child care assistance or Food Stamps for which they continue to be eligible. Ill-served by stringent time limits and work requirements, lack of child care assistance, and lack of training and educational opportunities for the development of skills that will lead to better jobs, families need help to navigate the complexities of the new welfare system. Boston Medical Center's Department of Pediatrics has instituted a welfare screening project to educate families about their rights under welfare reform and assist them in advocating for themselves and their children.

Recent advances in cassava pest management

Cassava (Manihot esculenta) occupies a uniquely important position as a food security crop for smallholder farmers in ares of the tropics where climate, soils, or societal stresses constrain production. Given its reliability and productivity, cassava is the most important locally produced food in a third of the world's low-income, food-deficit countries. It is the fourth most important source of carbohydrates for human consumption in the tropics, after rice, sugar, and maize. World production of cassava from 1994-1996 averaged 166 million tons/year grown on 16.6 million hectares (ha), for an average yield of 9.9 tons/ha. Approximately 57% is used for human consumption, 32% for animal feed and industrial purposes, and 11% is waste. Africa accounts for 51.3% of the production; Asia, 29.4%; and Latin America, 19.3%. The area planted to cassava in Africa, Asia, and Latin America is 10.3, 3.7, and 2.6 million ha, respectively.

The p53 codon 249 mutational hotspot in hepatocellular carcinoma is not related to selective formation or persistence of aflatoxin B1 adducts

Sequence-dependent formation and lack of repair of polycyclic aromatic hydrocarbon-induced DNA adducts correlates well with the positions of p53 mutational hotspots in smoking-related lung cancers (Denissenko et al, 1996, 1998). The mycotoxin aflatoxin B1 (AFB1) is considered to be a major causative agent in hepatocellular carcinoma (HCC) in regions with presumed high food contamination by AFB1. A unique mutational hotspot, a G to T transversion at the third base of codon 249 of the p53 gene is observed in these tumors. To test whether a selectivity of AFB1 adduct formation is related to this peculiar mutational spectrum, we have mapped AFB1-DNA adducts at nucleotide resolution using ligation-mediated PCR and terminal transferase-dependent PCR. Human HepG2 cells were exposed to AFB1 metabolically activated in the presence of rat liver microsomes. Significant adduct formation was seen at the third base of codon 249. However, this was not the major site of AFB1 adducts and strong adduction was also observed at codons 226, 243, 244, 245 and 248 in exon 7 of the p53 gene and at several codons in exon 8. The damage at codon 249 does not consist of a unique abasic site or ring-opened aflatoxin B1 adduct but rather is consistent with the principal N7-guanine adduct of AFB1. Time course experiments indicate that, under the conditions used, AFB1 adducts are not removed in a strand-selective manner and adduct removal from the third base of codon 249 proceeds at a relatively fast rate (50% in 7 h). The incomplete correspondence between sites of persistent AFB1 damage and the specific codon 249 mutation suggests that AFB1 may not be involved in mutation of this site or that additional mechanisms such as parallel infection with hepatitis B virus may be required for selection of codon 249 mutants in HCC.

Genetically transmitted cholinergic hyperresponsiveness predisposes to experimental asthma

The excitatory innervation of the airway smooth muscle is primarily cholinergic in nature. However, the potential neural mechanism(s) underlying airway hyperresponsiveness, one of the hallmarks of asthma, is not fully understood. In this study, cholinergic hyperresponsive Flinders sensitive line (FSL) rats and their control counterparts, Flinders resistant line (FRL) rats, were repeatedly challenged with different doses of nebulized methacholine (0, 4, 16, 64, and 256 mg/ml) for 5 min. Airway responsiveness was assessed in spontaneously breathing, unrestrained animals by means of whole body plethysmography. Increased airway responsiveness of FSL rats was evidenced as a more pronounced increase in Penh value (enhanced pause, an index of bronchoconstriction) across different concentrations of methacholine. In subsequent experiments, FSL and FRL rats were sensitized to ovalbumin and challenged with nebulized antigen. Our results indicate that the genetically transmitted cholinergic hyperresponsiveness of the FSL rat is paralleled by an increased susceptibility to allergen-induced bronchoconstriction and inflammation of the airways. This study provides further evidence that neural factors can play an important role in determining airway responsiveness and thus may be relevant for the expression of asthma. In addition, the FSL rat may be a useful model for studies of airway hyperresponsiveness.

Novel ITGB4 mutations in lethal and nonlethal variants of epidermolysis bullosa with pyloric atresia: missense versus nonsense

Epidermolysis bullosa with pyloric atresia (EB-PA), an autosomal recessive genodermatosis, manifests with neonatal cutaneous blistering associated with congenital pyloric atresia. The disease is frequently lethal, but nonlethal cases have also been reported. Expression of the alpha6 beta4 integrin is altered at the dermal-epidermal basement-membrane zone; recently, mutations in the corresponding genes (ITGA6 and ITGB4) have been disclosed in a limited number of patients, premature termination codons in both alleles being characteristic of lethal variants. In this study, we have examined the molecular basis of EB-PA in five families, two of them with lethal and three of them with nonlethal variants of the disease. Mutation analysis disclosed novel lesions in both ITGB4 alleles of each proband. One of the patients with lethal EB-PA was a compound heterozygote for premature termination-codon mutations (C738X/4791delCA), whereas the other patient with a lethal variant was homozygous for a missense mutation involving a cysteine residue (C61Y). The three nonlethal cases had missense mutations in both alleles (C562R/C562R, R1281W/R252C, and R1281W/R1281W). Immunofluorescence staining of skin in two of the nonlethal patients and in one of the lethal cases was positive, yet attenuated, for alpha6 and beta4 integrins. These results confirm that ITGB4 mutations underlie EB-PA and show that missense mutations may lead to nonlethal phenotypes.

A phase I trial of vinorelbine in combination with mitoxantrone in patients with refractory solid tumors

Vinorelbine (Navelbine) is a unique semi-synthetic vinca-alkaloid with a favorable safety profile that has demonstrated significant antitumor activity in patients with non-small cell lung cancer, advanced breast cancer, advanced ovarian cancer and Hodgkin's disease. The most common dose-limiting toxicity is neutropenia, while other reported toxicities are minimal. Mitoxantrone (Novantrone) is an anthracene derivative that has demonstrated antitumor activity in patients with breast cancer, ovarian cancer, acute leukemia, and lymphoma. Mitoxantrone also has a very favorable toxicity profile with significantly less nausea and vomiting, alopecia, and stomatitis as compared with anthracyclines. The dose-limiting toxicity for mitoxantrone is leukopenia. The study was designed to determine the safety and maximally tolerated dose of IV vinorelbine used in combination with a fixed dose of mitoxantrone for the treatment of patients with refractory solid tumors. Vinorelbine was administered on days 1 and 8 of the treatment regimen as a short IV infusion. The starting dose was 15 mg/m2. Mitoxantrone was administered as a 20-min infusion on day 1 only at a fixed dose of 10 mg/m2. Seventeen patients with solid malignancies were entered in the study. For personal reasons, one patient decided to discontinue the treatment after day 1 of cycle 1. Therefore, 16 patients were evaluable for toxicity. The main toxicity was myelosuppression which was dose-limiting and resulted in dose reductions and delays. The use of G-CSF had a minimal overall impact on this regimen. Stable disease was observed in three cases. In patients previously treated with chemotherapy, the maximally tolerated dose was defined as vinorelbine 20 mg/m2 on days 1 and 8 and mitoxantrone 10 mg/m2 on day 1 without growth factor support. These doses can be recommended for phase II study of the regimen as salvage treatment.

Impact of the Libby Zion case on graduate medical education in internal medicine

Residency training in New York State was substantially altered by the Libby Zion case. Work-hour limitations and augmented supervisory requirements changed the patterns of training--particularly in internal medicine--but with uncertain impacts on the quality of education and patient care. In this historical analysis, we review another major effect of the case: a substantial augmentation of the number of trainees. The need to maintain adequate inpatient staffing--within the ground rules of the Residency Review Committee, and in consideration of the reimbursement formulae and financial climate of New York State--conspired to promote substantial residency program expansion. Similar forces contributed to a national trend to increase the number of trainees. The history, cost and impact of these personnel changes are reviewed.

Typing of dengue viruses in clinical specimens and mosquitoes by single-tube multiplex reverse transcriptase PCR

In recent years, dengue viruses (serotypes 1 to 4) have spread throughout tropical regions worldwide. In many places, multiple dengue virus serotypes are circulating concurrently, which may increase the risk for the more severe form of the disease, dengue hemorrhagic fever. For the control and prevention of dengue fever, it is important to rapidly detect and type the virus in clinical samples and mosquitoes. Assays based on reverse transcriptase (RT) PCR (RT-PCR) amplification of dengue viral RNA can offer a rapid, sensitive, and specific approach to the typing of dengue viruses. We have reduced a two-step nested RT-PCR protocol to a single-tube reaction with sensitivity equivalent to that of the two-step protocol (1 to 50 PFU) in order to maximize simplicity and minimize the risk of sample cross-contamination. This assay was also optimized for use with a thermostable RT-polymerase. We designed a plasmid-based internal control that produces a uniquely sized product and can be used to control for both reverse transcription or amplification steps without the risk of generating false-positive results. This single-tube RT-PCR procedure was used to type dengue viruses during the 1995 and 1997-1998 outbreaks in Nicaragua. In addition, an extraction procedure that permits the sensitive detection of viral RNA in pools of up to 50 mosquitoes without PCR inhibition or RNA degradation was developed. This assay should serve as a practical tool for use in countries where dengue fever is endemic, in conjunction with classical methods for surveillance and epidemiology of dengue viruses.

Enhanced phenotypic expression of alpha-1-antitrypsin deficiency in an MZ heterozygote with chronic hepatitis C

A middle-aged white man of Scotch-Irish ancestry, being treated for chronic hepatitis C, was found to be heterozygous for alpha1-antitrypsin deficiency (PiMZ phenotype) after diagnostic PAS-positive, diastase-resistant globules were detected in a liver biopsy. The globules had not been present in a biopsy obtained 4 yr previously. He was also found to be heterozygous for the cys282tyr mutation of the HFE gene, which is the chief cause of HLA-linked hereditary hemochromatosis (HHC). His liver disease progressed over 4 yr from mild hepatitis to moderate hepatitis with cirrhosis despite therapy with interferon-alpha, and phlebotomy plus interferon. These conditions appeared to have synergistic effects, with the chronic viral hepatitis unmasking the alpha1AT deficiency, and the alpha1AT deficiency (and possibly the heterozygosity for HHC), exacerbating the course of the hepatitis C.

Expression and function of recombinant endothelial nitric oxide synthase gene in canine basilar artery after experimental subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Gene transfer with recombinant viral vectors encoding vasodilator proteins may be useful in therapy of cerebral vasospasm after subarachnoid hemorrhage (SAH). Relaxations mediated by nitric oxide are impaired in cerebral arteries affected by SAH. The present study was designed to determine the effect of SAH on the efficiency of ex vivo adenovirus-mediated gene transfer to canine basilar arteries and to examine whether expression of recombinant endothelial nitric oxide synthase (eNOS) gene may have functional effects on vasomotor reactivity of spastic arteries affected by SAH.

METHODS

Replication-deficient recombinant adenovirus vectors encoding bovine eNOS (AdCMVeNOS) and Escherichia coli beta-galactosidase (AdCMVbeta-Gal) genes were used for ex vivo gene transfer. Rings of basilar arteries obtained from control dogs and dogs exposed to SAH were incubated with the vectors in minimum essential medium. Twenty-four hours after gene transfer, expression and function of the recombinant genes were evaluated by (1) histochemical or immunohistochemical staining, (2) beta-galactosidase protein measurement, and (3) isometric tension recording.

RESULTS

Transduction with AdCMVbeta-Gal and AdCMVeNOS resulted in the expression of recombinant beta-galactosidase and eNOS proteins mostly in the vascular adventitia. The expression of beta-galactosidase protein was approximately 2-fold higher in SAH arteries than in normal arteries. Endothelium-dependent relaxations caused by bradykinin and substance P were suppressed in SAH arteries. The relaxations to bradykinin were significantly augmented in both normal and SAH arteries after AdCMVeNOS transduction but not after AdCMVbeta-Gal transduction. The relaxations to substance P were augmented by AdCMVeNOS transduction only in normal arteries. Bradykinin and substance P caused relaxations even in endothelium-denuded arteries, when the vessels were transduced with AdCMVeNOS. These endothelium-independent (adventitia-dependent) relaxations to bradykinin observed after AdCMVeNOS transduction were similar between normal and SAH arteries, whereas those to substance P were significantly reduced in SAH arteries compared with normal arteries.

CONCLUSIONS

These results suggest that expression of recombinant proteins after adenovirus-mediated gene transfer may be enhanced in cerebral arteries affected by SAH and that successful eNOS gene transfer to spastic arteries can at least partly restore the impaired nitric oxide-mediated relaxations through local (adventitial) production of nitric oxide.

Phase I and pharmacokinetic study of paclitaxel in combination with biricodar, a novel agent that reverses multidrug resistance conferred by overexpression of both MDR1 and MRP

PURPOSE

To evaluate the feasibility of administering biricodar (VX-710; Incel, Vertex Pharmaceuticals Inc, Cambridge, MA), an agent that modulates multidrug resistance (MDR) conferred by overexpression of both the multidrug resistance gene product (MDR1) P-glycoprotein and the MDR-associated protein (MRP) in vitro, in combination with paclitaxel. The study also sought to determine the maximum-tolerated dose (MTD) of paclitaxel that could be administered with biologically relevant concentrations of VX-710 and characterize the toxicologic and pharmacologic profiles of the VX-710/ paclitaxel regimen.

PATIENTS AND METHODS

Patients with solid malignancies were initially treated with VX-710 as a 24-hour infusion at doses that ranged from 10 to 120 mg/m2 per hour. After a 2-day washout period, patients were re-treated with VX-710 on an identical dose schedule followed 8 hours later by paclitaxel as a 3-hour infusion at doses that ranged from 20 to 80 mg/m2. The pharmacokinetics of both VX-710 and paclitaxel were studied during treatment with VX-710 alone and VX-710 and paclitaxel. Thereafter, patients received VX-710 and paclitaxel every 3 weeks.

RESULTS

VX-710 alone produced minimal toxicity. The toxicologic profile of the VX-710/paclitaxel regimen was similar to that reported with paclitaxel alone; neutropenia that was noncumulative was the principal dose-limiting toxicity (DLT). The MTD levels of VX-710/ paclitaxel were 120 mg/m2 per hour and 60 mg/m2, respectively, in heavily pretreated patients and 120/60 to 80 mg/m2 per hour in less heavily pretreated patients. At these dose levels, VX-710 steady-state plasma concentrations (Css) ranged from 2.68 to 4.89 microg/mL, which exceeded optimal VX-710 concentrations required for MDR reversal in vitro. The pharmacokinetics of VX-710 were dose independent and not influenced by paclitaxel. In contrast, VX-710 reduced paclitaxel clearance. At the two highest dose levels, which consisted of VX-710 120 mg/m2 per hour and paclitaxel 60 and 80 mg/m2, pertinent pharacokinetic determinants of paclitaxel effect were similar to those achieved with paclitaxel as a 3-hour infusion at doses of 135 and 175 mg/m2, respectively.

CONCLUSION

VX-710 alone is associated with minimal toxicity. In combination with paclitaxel, biologically relevant VX-710 plasma concentrations are achieved and sustained for 24 hours, which simulates optimal pharmacologic conditions required for MDR reversal in vitro. The acceptable toxicity profile of the VX-710/ paclitaxel combination and the demonstration that optimal pharmacologic conditions for MDR reversal are achievable support a rationale for further trials of VX710/paclitaxel in patients with malignancies that are associated with de novo or acquired resistance to paclitaxel caused by overexpression of MDR1 and/or MRP.

Industrial shift systems

This technical report describes the identification of shift systems worked by industrial shiftworkers in England, Scotland and Wales. A diverse range of shift systems were reported to be in operation across 27 industrial sectors. Companies employed up to 14 different shift systems at a particular site. The numbers of shiftworkers on a given shift schedule ranged from 1 to 2977. Most systems employed fewer than 100 people. The majority of rotas were regular, rotating systems. The most common shift durations were 8 or 12 h. Compared to earlier surveys of shiftwork prevalence in certain industries there appeared to be a substantial increase over the past 3 decades in the proportion of the workforce who work shifts. Information about the average numbers of hours worked per week on major system types is given. In addition, data for the range of shifts per cycle, the distribution of shifts and distributions of their start and end times are presented.