Tirapazamine plus cisplatin versus cisplatin in advanced non-small-cell lung cancer: A report of the international CATAPULT I study group. Cisplatin and Tirapazamine in Subjects with Advanced Previously Untreated Non-Small-Cell Lung Tumors

PURPOSE

A phase III trial, Cisplatin and Tirapazamine in Subjects with Advanced Previously Untreated Non-Small-Cell Lung Tumors (CATAPULT I), was designed to determine the efficacy and safety of tirapazamine plus cisplatin for the treatment of non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Patients with previously untreated NSCLC were randomized to receive either tirapazamine (390 mg/m(2) infused over 2 hours) followed 1 hour later by cisplatin (75 mg/m(2) over 1 hour) or 75 mg/m(2) of cisplatin alone, every 3 weeks for a maximum of eight cycles.

RESULTS

A total of 446 patients with NSCLC (17% with stage IIIB disease and pleural effusions; 83% with stage IV disease) were entered onto the study. Karnofsky performance status (KPS) was >/= 60 for all patients (for 10%, KPS = 60; for 90%, KPS = 70 to 100). Sixty patients (14%) had clinically stable brain metastases. The median survival was significantly longer (34.6 v 27. 7 weeks; P =.0078) and the response rate was significantly greater (27.5% v 13.7%; P <.001) for patients who received tirapazamine plus cisplatin (n = 218) than for those who received cisplatin alone (n = 219). The tirapazamine-plus-cisplatin regimen was associated with mild to moderate adverse events, including acute, reversible hearing loss, reversible, intermittent muscle cramping, diarrhea, skin rash, nausea, and vomiting. There were no incremental increases in myelosuppression, peripheral neuropathy, or renal, hepatic, or cardiac toxicity and no deaths related to tirapazamine.

CONCLUSION

The CATAPULT I study shows that tirapazamine enhances the activity of cisplatin in patients with advanced NSCLC and confirms that hypoxia is an exploitable therapeutic target in human malignancies.

Lipoprotein (a) levels in normal pregnancy and in pregnancy complicated with pre-eclampsia

Lipoprotein (a) (Lp(a)) is recognised as a risk factor for arterial and venous thrombosis, a property which may relate to its structural similarity to plasminogen. Pregnancy is associated with a hypofibrinolytic state. Elevated Lp(a) may influence fibrinolysis and have an unfavourable role in pregnancy outcome. In this study alterations in plasma Lp(a) concentrations during normal pregnancy was examined, in a detailed longitudinal investigation, in ten women together with changes in other lipid parameters. In addition, Lp(a) concentrations were examined in subjects with pre-eclampsia (n=10) relative to matched controls (n=10), since it has recently been reported that a substantial increase in circulating Lp(a) occurs in this disorder. Lp(a) concentration increased steadily in normal pregnancy between 10 and 35 weeks with a doubling of the median value from 14.5 to 27.0 mg/dl (P=0.01). A significant increase in Lp(a) values was observed in all subjects with increasing gestation (median rise 190%, range 117-340%). This increase was intermediate to those seen in plasma triglyceride and cholesterol. No significant difference in Lp(a) values was observed in subjects with pre-eclampsia, compared with matched normal pregnancy controls (median 14 mg/dl [IQR 4.7-69.0] in pre-eclampsia vs 20 mg/dl [9.0-56. 3] in controls; P=0.57), at a median gestation of 32 weeks. In conclusion, there is a 2-fold increase in Lp(a) during normal pregnancy, which may influence fibrinolysis. Circulating Lp(a) is not significantly elevated in women with pre-eclampsia, and thus is unlikely to play a role in the pathophysiology of this disorder.

Syringe pressure irrigation of subdermic tissue after appendectomy to decrease the incidence of postoperative wound infection

To evaluate syringe pressure irrigation of the surgical wound to decrease its infection after appendectomy, we designed a randomized control trial at the Emergency Department of Mexico City General Hospital, including 350 patients with acute abdomen suggestive of appendicitis, without any other infection clinically evident. The trial was randomized into 2 groups. Group I patients received prophylactic systemic antibiotics before surgery. Group II patients received the same prophylactic systemic antibiotics plus syringe pressure irrigation of the surgical wound with 300 ml of saline solution using a 20-ml syringe with 19-gauge intravenous (IV) catheter to measure the incidence of postoperative wound infection. In our results, 283 patients had appendicitis. Of these, 188 were uncomplicated (66.4%) and 95 (33.6%) were complicated. Of the complicated cases, 40 were assigned to group I, and of these, 29 (72. 5%) developed wound infection. In group II there were 55 patients and only 9 (16.3%) developed wound infection after syringe pressure irrigation [p = 0.000001; 95% confidence interval (CI) = 0.02-0.22]. We conclude that syringe pressure irrigation of the surgical wound after appendectomy contributes significantly to decrease the incidence of postoperative wound infection in complicated cases. It is a cheap, safe, and accessible method in any surgical room.

Injectable gold for rheumatoid arthritis

OBJECTIVES

To estimate the short-term benefit and risk of side-effects of injectable gold for rheumatoid arthritis.

SEARCH STRATEGY

We searched the Cochrane Musculoskeletal Group trials register, and Medline, up to July 1997, using the search strategy developed by the Cochrane Collaboration (Dickersin 1994). The search was complemented with bibliography searching of the reference list of the trials retrieved from the electronic search. Key experts in the area were contacted for further published and unpublished articles.

SELECTION CRITERIA

Randomized clinical trials (RCT) comparing injectable gold against placebo in patients with rheumatoid arthritis were included.

DATA COLLECTION AND ANALYSIS

Methodological quality of the RCTs was asessed by two reviewers (MS, BS) (kappa=1.0). Rheumatoid arthritis outcome measures were extracted by two reviewers from the publications for the 6 month endpoint. Sufficient data was obtained to conduct a pooled analysis of the number of swollen joints, physician global assessment, patient global assessment and erythrocyte sedimentation rate (ESR). Results were analyzed as standardized weighted mean differences for swollen joints and global assessments and weighted mean differences for ESR. Toxicity was evaluated with pooled odds ratios for withdrawals. Heterogeneity was estimated using a chi-square test. Fixed effects models were used throughout.

MAIN RESULTS

Four trials and 415 patients were included. A statistically significant benefit was observed for injectable gold when compared to placebo. The standardized weighted difference (effect size) between gold and placebo for the number of swollen joints was -0.5, translating into a percentage change of 30% in favour of gold adjusted for placebo. Statistically significant differences were also observed for ESR and patient and physician assessments. Twenty two percent of the treated patients withdrew from toxicity compared to 4% of controls (OR=3.9 - 95%Cl: 2.1 - 7.2).

REVIEWER'S CONCLUSIONS

Although its use can be limited by the incidence of serious toxicity, injectable gold has an important clinically and statistically significant benefit in the short term treatment of patients with rheumatoid arthritis.

Prediction of over-response to ovarian stimulation in an intrauterine insemination programme

Prediction of poor-response is of equal importance to prediction of over-response in intrauterine insemination programmes. The gonadotrophin-releasing hormone agonist (GnRHa) stimulation test (GAST) was assessed as a predictor of over-response to ovarian stimulation in 81 patients. Blood samples were taken on cycle day 2 (before and 24 h after starting the GnRHa). Day 2 and 3 samples were assayed for oestradiol, follicle stimulating hormone (FSH) and luteinizing hormone (LH). Linear and logistic regression analyses were used to assess age, day 2 FSH, day 2 FSH/LH, oestradiol ratio (oestradiol on day 3/oestradiol on day 2) and FSH ratio (FSH on day 3/FSH on day 2) as predictors of the number of follicles (total and > or = 14 mm), oestradiol on HCG day, and clinical pregnancy rate as appropriate. Several parameters were also compared between the patients who produced < or = 3 (> or = 14 mm) follicles (group A) and those who produced >3 (> or = 14 mm) follicles (group B). The mean +/- SEM age of the patients in the study was 32 +/- 0.4 years. The mean total dose of recombinant FSH was 800 +/- 20 IU and the mean duration of stimulation was 7.6 +/- 0.2 days. Nine (11%) and 12 (15%) patients were cancelled for poor and over-response respectively. The oestradiol ratio was significantly positively correlated with oestradiol on HCG day (P < 0.001), and with the number of mature follicles (> or = 14 mm) (P = 0.01). Age, day 2 FSH and FSH ratio were not significantly correlated with oestradiol on HCG day, total follicles and follicles > or = 14 mm. None of the above-mentioned variables was correlated with clinical pregnancy rate. Group A had significantly lower oestradiol ratio (P = 0.007), longer duration of stimulation (P = 0.002), higher total FSH dose (P = 0.001), and lower oestradiol on HCG day (P = 0.001). GAST is therefore useful in predicting the high responders to gonadotrophin stimulation.

Missense mutations in the insulin promoter factor-1 gene predispose to type 2 diabetes

The transcription factor insulin promoter factor-1 (IPF-1) plays a central role in both the development of the pancreas and the regulation of insulin gene expression in the mature pancreatic beta cell. A dominant-negative frameshift mutation in the IPF-l gene was identified in a single family and shown to cause pancreatic agenesis when homozygous and maturity-onset diabetes of the young (MODY) when heterozygous. We studied the role of IPF-1 in Caucasian diabetic and nondiabetic subjects from the United Kingdom. Three novel IPF-1 missense mutations (C18R, D76N, and R197H) were identified in patients with type 2 diabetes. Functional analyses of these mutations demonstrated decreased binding activity to the human insulin gene promoter and reduced activation of the insulin gene in response to hyperglycemia in the human beta-cell line Nes2y. These mutations are present in 1% of the population and predisposed the subject to type 2 diabetes with a relative risk of 3.0. They were not highly penetrant MODY mutations, as there were nondiabetic mutation carriers 25-53 years of age. We conclude that mutations in the IPF-1 gene may predispose to type 2 diabetes and are a rare cause of MODY and pancreatic agenesis, with the phenotype depending upon the severity of the mutation.

Interaction of the protein C/protein S anticoagulant system, the endothelium and pregnancy

Normal pregnancy is associated with significant changes in haemostasis, lipid metabolism and endothelial function. This suggests that maternal adaptation in these systems is required for successful pregnancy outcome. A number of acquired and heritable prothrombotic abnormalities are associated with complications in pregnancy. A common feature of these abnormalities is their ability to alter endothelial function or the protein C/protein S system and increase thrombin generation. In this review the normal function of the endothelium and the protein C/protein S system is detailed. The changes which characterize normal and complicated pregnancies are outlined and the evidence for the impact of heritable and acquired disorders of the protein C/protein S system on pre-eclampsia and fetal loss are discussed.

Stem cell factor in combination with filgrastim after chemotherapy improves peripheral blood progenitor cell yield and reduces apheresis requirements in multiple myeloma patients: a randomized, controlled trial

Stem cell factor (SCF) has been shown to synergize with filgrastim to mobilize CD34(+) cells into the peripheral blood. To determine if addition of SCF to chemotherapy and filgrastim reduces the number of leukaphereses required to achieve a target yield of 5 x 10(6) CD34(+) cells/kg, 102 patients with multiple myeloma were randomized to receive mobilization chemotherapy with cyclophosphamide (4 g/m(2)) and either SCF (20 micrograms/kg/d) combined with filgrastim (5 micrograms/kg/d) or filgrastim alone (5 micrograms/kg/d), administered daily until leukaphereses were completed. After collection, patients were treated with myeloablative therapy supported by autologous peripheral blood progenitor cell (PBPC) infusion and filgrastim (5 micrograms/kg/d). There was a significant difference between the treatment groups in the number of leukaphereses required to collect 5 x 10(6) CD34(+) cells/kg (median of 1 v 2 for SCF + filgrastim and filgrastim alone, respectively, P =.008). Patients receiving the combination of SCF plus filgrastim had a 3-fold greater chance of reaching 5 x 10(6) CD34(+) cells/kg in a single leukapheresis compared with patients mobilized with filgrastim alone. The median CD34(+) cell yield was significantly increased for the SCF group in the first leukapheresis (11.3 v 4.0 x 10(6)/kg, P =.003) and all leukaphereses (12.4 v 8.2 x 10(6)/kg, P =.007). Total colony-forming unit-granulocyte-macrophage (CFU-GM) and mononuclear cell counts were also significantly higher in the SCF group in the first leukapheresis and in all leukaphereses. As expected for patients mobilized to an optimal CD34(+) cell yield, the time to engraftment was similar between the 2 treatment groups. Cells mobilized with the combination of SCF plus filgrastim were thus considered effective and safe for achieving rapid engraftment. Treatment with SCF plus filgrastim was well tolerated, with mild to moderate injection site reactions being the most frequently reported adverse events. There were no serious allergic-like reactions to SCF. The addition of SCF to filgrastim after cyclophosphamide for PBPC mobilization resulted in a significant increase in CD34(+) cell yield and a concomitant reduction in the number of leukaphereses required to collect an optimal harvest of 5 x 10(6) CD34(+) cells/kg.

Relative potency of controlled-release oxycodone and controlled-release morphine in a postoperative pain model

OBJECTIVE

The relative analgesic potency of single doses of oral controlled-release oxycodone and oral controlled-release morphine were compared in a randomized, double-blind trial using a postoperative pain model.

METHODS

Women (n = 169) with moderate to severe pain following abdominal hysterectomy received single oral doses of controlled-release oxycodone, 20 mg or 40 mg, or controlled-release morphine, 45 mg or 90 mg. Assessments were made at 30 min, 60 min, then hourly after dosing for 12 h or until remedication.

RESULTS

The most precise estimates of relative potency showed that controlled-release oxycodone was 1.8 times more potent than controlled-release morphine for total effect (95% confidence limits 1.09-2.42; lambda 0.44) and 2.2 times more potent for peak effect (95% confidence limits 0.96-4.59; lambda 0.71). Controlled-release oxycodone at doses of 20 mg or 40 mg was comparable with controlled-release morphine at doses of 45 mg or 90 mg, respectively, for total and peak analgesic effects. For the two higher doses, time to peak relief was approximately 1 h shorter with controlled-release oxycodone than with controlled-release morphine. Most patients reported onset of analgesia within 1 h with all doses. Side effects were similar with the two opioids.

CONCLUSION

Oral controlled-release oxycodone was twice as potent as oral controlled-release morphine in this single-dose, relative potency assay. When converting patients from oral morphine to oral oxycodone, an initial oral oxycodone dose of one-half the oral morphine dose is recommended.

Calcium oxalate crystalluria in a goat

As part of a routine health evaluation of an 8-month-old female Nubian goat, serum biochemical analyses and urinalysis were performed. Most serum biochemical values including concentrations of blood calcium and indicators of urinary system dysfunction, such as blood urea nitrogen, creatinine, and phosphorous concentrations, were within reference ranges. An aliquot of voided urine was hypersthenuric and acidic and contained numerous typical cuboidal-bipyramidal calcium oxalate dihydrate crystals and unique rectangular parallelepiped crystals that were confirmed by energy dispersive X-ray microanalysis as being of calcium oxalate dihydrate composition. We hypothesize that the calcium oxalate crystals resulted from a diet containing calcium and oxalic acid. Treatment was not administered, and the goat remained healthy during the ensuing year.

Amniotic fluid matrix metalloproteinase-9 levels in women with preterm labor and suspected intra-amniotic infection

OBJECTIVE

To determine the accuracy of amniotic fluid (AF) matrix metalloproteinase-9 measurements for diagnosing intra-amniotic infection in women with preterm labor.

METHODS

We performed amniocenteses in 44 women between 22 and 35 weeks' gestation who presented to our center with preterm labor and clinical suspicion of intra-amniotic infection. Each sample was analyzed by glucose measurement, Gram stain, and culture for aerobes, anaerobes, and mycoplasmas. We tested the AF for matrix metalloproteinase-9 using gelatin zymography and a commercial enzyme-linked immunosorbent assay (ELISA) system. We calculated accuracy and confidence intervals (CIs) for AF matrix metalloproteinase-9, glucose, and Gram stain for diagnosing intra-amniotic infection, using culture as the criterion standard.

RESULTS

All patients who had matrix metalloproteinase-9 detectable by ELISA also demonstrated matrix metalloproteinase-9 by zymography. Six cases of intra-amniotic infection were confirmed by culture (prevalence 14%). The performance statistics of AF matrix metalloproteinase-9 for diagnosing intra-amniotic infection were: sensitivity 83% (95% CI 53, 99), specificity 95% (95% CI 88, 99), positive predictive value 71% (95% CI 37, 99), and negative predictive value 97% (95% CI 92, 99). Two women had false-positive results; one had gram-negative rods on the AF Gram stain and developed clinical signs and symptoms of chorioamnionitis several hours after amniocentesis and the other had a purulent vaginal discharge and an AF glucose level less than 15 mg/dL. Both delivered within 24 hours of amniocentesis.

CONCLUSION

Measuring matrix metalloproteinase-9 in the AF appeared to be reliable for diagnosing intra-amniotic infection. An elevated matrix metalloproteinase-9 concentration in the AF at a preterm gestational age may portend imminent delivery regardless of microbiologic confirmation of intra-amniotic infection.

Topiramate pharmacokinetics in infants

PURPOSE

This study's goal was to provide preliminary data on the pharmacokinetics of topiramate (TPM) in a cohort of infants (younger than 4 years) participating in an open-label trial of TPM in refractory infantile spasms.

METHODS

The pharmacokinetics of TPM were assessed in infants receiving a stable TPM dose for >7 days during the extension phase of this trial. Blood samples were drawn just before and 0.5. 1, 1.5, 2, 4, 6, 8, and 12 h after the morning TPM dose. TPM plasma concentrations were determined by fluorescence polarization immunoassay. The noncompartmental analysis module of WinNonlin was used to calculate individual patient pharmacokinetics profiles.

RESULTS

Five infants (ages, 23.5-29.5 months) formed the study cohort. These infants had been given TPM for a median of 9 months (range, 6-11 months) and were currently receiving between 11 and 38.5 mg/kg/day TPM. One was receiving TPM monotherapy, whereas four were taking concomitant antiepileptic medications (AEDs; n = 2, enzyme-inducing agents; n = 2, non-enzyme-inducing drugs). TPM pharmacokinetics in infants appears to be linear. In this cohort, mean TPM plasma clearance (CL/F, 66.6+/-27.4 ml/h/kg) was slightly higher than that reported for children and adolescents and therefore substantially higher than that reported for adults. TPM CL/F was higher and the calculated half-life shorter in the infants receiving concomitant enzyme-inducing AEDs.

CONCLUSIONS

Based on this small cohort of patients, it appears that infants may require significantly larger TPM doses, based on weight, than children, adolescents, or adults. Titration to effect and not absolute TPM dose should guide therapy in this age group.

Curvature of dinucleotide poised for formation of trinucleotide in transcription with Escherichia coli RNA polymerase

A frequently used schematic model of transcriptional elongation shows an RNA polymerase molecule moving along a linear DNA. This model is of course highly idealized and not compatible with promoter sequences [Gralla, J. D. (1991) Cell 66, 415-418; Schleif, R. (1992) Annu. Rev. Biochem. 61, 199-223] and regulatory proteins [Koleske, A. J., and Young, R. A. (1995) Trends Biochem. Sci. 20, 113-116; Dunaway, M., and Dröge, P. (1989) Nature 341, 657-659; Müller, H. P., Sogo, J. M., and Schaffner, W. (1989) Cell 58, 767-777] located some distance away from the point of transcription initiation [Karsten, R., von Hippel, P. H., and Langowski, J. (1995) Trends Biochem. Sci. 20, 500-506]. These circumstances lead to the expectation of curvature along the DNA strand and require looping between sometimes distant points. We have now shown curvature in a dinucleotide formed at the very onset of transcription when it is poised for reaction with a mononucleotide to form a trinucleotide. The curvature became evident from the demonstration that a metal ion bound with a mononucleotide in the i+1 (elongation) site is approximately equidistant from bases at the 5' end (i-1 site) and 3' end (i site) of the dinucleotide. Similar results were obtained with three different dinucleotides and four mononucleotides. Curvature of the RNA initiate may reflect curvature of the DNA to which it is bound. These studies show curvature to be a significant feature in the interaction between DNA template and RNA elongate even at the very beginning of transcription.

Structure elucidation of a purple peptide found during the purification of a recombinant protein from Escherichia coli

A purple substance (4) partially co-purified with a recombinant human B-type natriuretic peptide (hBNP), following an E. coli fermentation. The structure of the compound was elucidated by NMR, electrospray and FAB mass spectrometry. The chromophore is a 1,4-naphthoquinone condensed with the N-terminal cysteine of a heptapeptide by its NH2- and SH-groups to form a dihydro-thiazine ring. The peptide sequence was determined as Cys-Lys-Val-Leu-Arg-Arg-His by mass spectrometric techniques. CID and data base matching identified it as the C-terminus of the 32-amino-acid recombinant peptide hBNP. This modification of an N-terminal Cys may be a more general phenomenon with implications for the production of heterologous proteins by microorganisms.

Maternal and neonatal infection rates with three different protocols for prevention of group B streptococcal disease

OBJECTIVES

We compared maternal and neonatal infection rates under 3 different group B streptococcal prevention strategies and also evaluated reasons for each protocol's failures in preventing neonatal disease.

STUDY DESIGN

Women who were delivered at our center from August 1, 1991, through April 30, 1998, were managed by 1 of 3 protocols for prevention of early-onset neonatal group B streptococcal infection: a selective screening protocol, The American College of Obstetricians and Gynecologists protocol, and the Centers for Disease Control and Prevention-recommended universal screening strategy. We compared maternal infection rates and neonatal group B streptococcal infection rates under each protocol. We also compared reasons for each protocol's failures in preventing neonatal infection.

RESULTS

Clinical chorioamnionitis rates were 7.4% with selective screening, 7.7% under The American College of Obstetricians and Gynecologists' protocol, and 5.2% with universal screening (relative risk 0.7, 95% confidence interval 0.6-0.8). Endometritis rates were 4.0% with selective screening, 4.6% with The American College of Obstetricians and Gynecologists protocol, and 2. 8% with universal screening (relative risk 0.7, 95% confidence interval 0.6-0.8). Overall neonatal group B streptococcal infection rates were lower under the 2 more recent strategies, but not significantly so. Despite the ability of universal screening to find more women at risk for group B streptococcal transmission, half of the neonatal infections under this protocol occurred when the mothers were not considered candidates for prophylaxis.

CONCLUSIONS

The Centers for Disease Control and Prevention-endorsed universal screening strategy for group B streptococcal infection prevention was associated with significantly lower rates of clinical chorioamnionitis and endometritis than were the other strategies. We were unable to document statistically significant improvement in neonatal outcome under the universal screening protocol.

The contribution of the intrinsic muscles to grip and pinch strength

Profound deficiencies occur in the intrinsic minus hand with loss of the interossei, thenar, hypothenar, and adductor pollicis muscles. The purpose of this study was to define the load-generating deficiencies of grip and pinch after simulated low median and/or low ulnar nerve lesions. Twenty-one healthy volunteers underwent median and ulnar nerve blocks at the wrist level with mepivacaine HCI injection. Key pinch and grip data were recorded before injection and after each nerve block was determined to be effective. A computerized dynamometer that simultaneously recorded individual force data from each digit and cumulative grip was used to record grip strength. Grip strength data showed a significant decrease in total grasp at all 3 handle sizes after initial median or ulnar nerve block. The average decrease in grip strength was 38% after ulnar nerve block and 32% after median nerve block. The total grip loss after both injections averaged 49% compared with the preinjection strength. After ulnar or median nerve block there was a significant decrease in the force production of the long, ring, and small fingers but not the index finger. Pinch data revealed a significant decrease in key pinch of 77% after ulnar block and 60% after median block with a further significant change after combined block to decrease pinch 85%.

Risk factors for osteoporotic hip fractures in Mexicans

BACKGROUND

Osteoporosis (OP) and its fractures are a major problem due to their impact in morbidity and mortality in the elderly. Although this entity is well studied in other countries, OP and its fractures have not been evaluated carefully in our population. The objective was to assess risk factors for osteoporotic hip fracture in Mexicans.

METHODS

A total of 295 subjects, 152 cases and 143 controls, were studied. Cases were patients with hip fracture, of both sexes and 45 years of age or older. Controls were healthy subjects who were in hospital waiting rooms accompanying patients without hip fractures. A questionnaire covering known possible risk factors for osteoporotic hip fracture was administered by the same evaluator to all subjects. Pelvic roentgenograms, anterior-posterior view, were obtained in both cases and controls to perform the Singh index and the cortical index of the femur.

RESULTS

Fractures were present in (72.2%) of women. Weight and any alcohol ingestion were associated with an increased risk of hip fracture. The odds ratio (OR) for low weight by the Quetelet Index was 4.03 (95% CI 1.93-8.39) p < 0.001. Any alcohol intake was associated with an OR of 1.73 (95% CI 1.04-2.90) p < or = 0.03 for the total group, and 2.78 (95% CI 1.25-6.14) p < or = 0.003 for women. Controls had a significantly higher mean daily calcium intake compared to cases (mean, SD 575.9 +/- 297.2 vs. 490.4 +/- 245.5, p < or = (0.007). Family history, smoking, physical activity, pregnancies, breastfeeding or concomitant diseases were not associated with risk of hip fracture.

CONCLUSIONS

This study confirmed the risk factors for osteoporotic hip fracture in Mexicans, previously shown for other ethnic groups. Further research in different factors, such as rate of bone turnover, anthropometric dimensions, and genetic studies (osteoporosis gene) are needed in order to define the differences among ethnic groups.

Prevalence of fibromyalgia in children: a clinical study of Mexican children

OBJECTIVE

To determine the prevalence of fibromyalgia (FM) in schoolchildren according to the 2 stage classification process proposed by the 1990 American College of Rheumatology (ACR) Multicenter Criteria Committee on Fibromyalgia.

METHODS

Stage 1: we administered a pain questionnaire to a sample of 548 schoolchildren (264 boys, 284 girls; mean age 11.9 yrs, range 9-15). Stage 2: two rheumatologists examined all children with diffuse pain. Using thumb palpation, they examined 18 fibromyalgia tender points and 3 pairs of controls points followed by dolorimetry. Additionally, a random sample of 79 children with no pain were selected as controls, following the same procedures (thumb palpation and dolorimetry). The Wilcoxon test was used to compare the distribution of tenderness thresholds between FM and non-FM groups. Kappa statistics for multiple raters was used to assess interobserver agreement.

RESULTS

Seven children, all girls, fulfilled the ACR diagnostic criteria for FM. Thus, the prevalence of FM in this group of schoolchildren reached only 1.2%. The girls with FM had a mean of 14 tender points, whereas controls (n = 79) had 2.4. Pain thresholds were 3.4 kg in children with FM and 5.1 kg in controls (p = 0.004).

CONCLUSION

The prevalence of FM in our study was 5-fold lower than a previous report. This variance may be due to (1) racial and sociocultural differences between populations; and (2) differences in methodological approach. The difficulties of making accurate estimates of FM across different studies are highlighted.

A randomized trial comparing methotrexate and vinblastine (MV) with cisplatin, methotrexate and vinblastine (CMV) in advanced transitional cell carcinoma: results and a report on prognostic factors in a Medical Research Council study. MRC Advanced Bladder Cancer Working Party

Transitional cell carcinomas may arise at any site within the urinary tract and are a source of considerable morbidity and mortality. In particular, patients with metastatic disease have a poor prognosis, with less than 5% alive at 5 years. A multicentre randomized trial comparing methotrexate and vinblastine (MV) with cisplatin, methotrexate and vinblastine (CMV) in advanced or metastatic transitional cell carcinoma was conducted in the UK. From April 1991 to June 1995, 214 patients were entered by 16 centres, 108 randomized to CMV and 106 to MV. A total of 204 patients have died. The hazard ratio (relative risk of dying) was 0.68 (95% CI 0.51-0.90, P-value = 0.0065) in favour of CMV. This translates to an absolute improvement in 1-year survival of 13%, 16% in MV and 29% in CMV. The median survival for CMV and MV was 7 months and 4.5 months respectively. Two hundred and eight patients objectively progressed or died. The hazard ratio was 0.55 (95% CI 0.41-0.73, P-value = 0.0001) in favour of CMV. Two hundred and nine patients symptomatically progressed or died. The hazard ratio was 0.48 (95% CI 0.36-0.64, P-value = 0.0001) in favour of CMV. The most important pretreatment factors influencing overall survival were WHO performance status and extent of disease. These two factors were used to derive a prognostic index which could be used to categorize patients into three prognostic groups. We conclude that the addition of cisplatin to methotrexate and vinblastine should be considered in patients with transitional cell carcinoma, taking into account the increased toxicity.

Impaired activation of NFkappaB in T cells from a subset of renal cell carcinoma patients is mediated by inhibition of phosphorylation and degradation of the inhibitor, IkappaBalpha

Activation of the transcription factor NFkappaB in peripheral blood T cells from patients with renal cell carcinoma (RCC) is compromised. This impaired signaling function results from a failure of RelA and c-Rel to translocate to the nucleus though normal levels of Rel proteins are present in the cytoplasm. We demonstrate here in a subset of RCC patients that the defect in NFkappaB activation is attributable to the absence of phosphorylation and degradation of the inhibitor IkappaBalpha. In patient T cells there was no stimulus dependent decrease in the cytoplasmic level of IkappaBalpha. Coimmunoprecipitation studies showed that RelA was in complex with IkappaBalpha and was not released after stimulation. Moreover, the phosphorylated form of IkappaBalpha detected in normal T cells after activation is absent in patient T cells. Additional experiments showed that soluble products from RCCs (RCC-S) can reproduce the same phenotype in T cells from healthy individuals. Supernatant fluid from cultured explants of RCC, but not normal kidney, inhibited the stimulus dependent nuclear translocation of NFkappaB without altering the cytoplasmic levels of RelA, c-Rel, and NFkappaB1. Phosphorylation and degradation of IkappaBalpha was also blocked by RCC-S. The mechanistic similarities between patient-derived T cells and normal T cells cultured with RCC-S suggest that the tumor-derived products may be the primary mediators of impaired T-cell function in this tumor system.

The neutrophil and preeclampsia

Endothelial injury is common to all pathological features of preeclampsia. Neutrophil activation has been implicated in the pathophysiology of preeclampsia and requires binding and transmigration of neutrophils through the endothelium. This occurs via an interaction of endothelial adhesion molecules and surface receptors on neutrophils. Upon activation, neutrophil granules are released, the contents of which are capable of mediating vascular damage. In addition, leukotrienes are synthesized, and superoxide is generated in a respiratory burst. These products also provoke vascular damage. Neutrophil recruitment to the endothelium involves express of P-selectin and released of platelet activating factor from the endothelium. In preeclampsia there is evidence of an increase in neutrophil activation with up-regulation of neutrophil integrin expression and increased regulation of the protease elastase. Furthermore, these markers of neutrophil activation correlate with established markers of disease severity. The primary mechanism of neutrophil activation is unknown, but neutrophils in preeclampsia appear to have normal motor activity. Several potential mechanisms of neutrophil activation have been identified. They include up-regulation of cellular adhesion molecules on the endothelial surface, increased generation of tumor necrosis factor-alpha, and endothelial activation from hyperlipidemia. In additional to activation of neutrophils in preeclampsia, there may be involvement of the interleukin-6 and endothelin-1 in "priming" neutrophils for subsequent superoxide production. Activated neutrophils are likely to play a large part in the arteriopathy and endothelial damage associated with preeclampsia, but it is unclear whether neutrophil activation is the cause or the consequence of endothelial damage.

The association of asymptomatic bacterial vaginosis with upper genital tract infection

Objective: To determine whether asymptomatic bacterial vaginosis (BV) is associated with upper genital tract inflammation or bacterial colonization.Methods: Fifty nonpregnant women with intact uteri who planned to undergo gynecologic surgery and had no recent symptoms of vaginal infection were enrolled. We obtained a vaginal swab for Gram stain, endocervical swab for chlamydia and gonorrhea DNA probe testing, and Pipelle endometrial biopsy for aerobic and anaerobic cultures and histology. We correlated surgical findings and histology of available surgical specimens with the microbiologic results. The diagnosis of BV was made according to Speigel's criteria. Bacteria isolated from the uterus were classified as high virulence versus low virulence. Contingency tables were analyzed using the chi-square or Fisher Exact tests.Results: Twenty-one of 50 patients had BV on Gram stain, 3 had intermediate BV, and 3 had unreadable slides. Eleven patients had histologic endometritis, including 7 of the 21 with BV. The association between BV and endometritis was not statistically significant. Thirty-eight patients had a positive endometrial culture; 18 of these also had BV and 3 had intermediate BV. Of patients with a positive endometrial culture, isolates from those who also had BV or intermediate BV were more likely to be highly virulent pathogens compared to those who tested negative for BV (P <.05). No patients had positive gonorrhea or chlamydia tests. Of the 37 patients who underwent abdominal surgery, 20 had visible adhesions. The association between adhesions and endometritis, BV, or positive endometrial cultures was not significant.Conclusion: Patients with asymptomatic BV are more likely than patients without BV to have highly virulent bacteria isolated from the endometrium. BV may predispose to upper genital tract infection.

The novel combination of fat clearance and immunohistochemistry improves prediction of the outcome of patients with colorectal carcinomas: a preliminary study

To evaluate the significance of micrometastases in relation to survival rate, specimens from 48 colorectal carcinoma patients were analysed after fat clearance. The number and size of the lymph nodes harbouring metastases and the significance of micrometastases for patients' survival were assessed. We found that although the majority of metastatic lymph nodes (71.8%) were 5 mm or less in diameter, their size had no effect on survival. Immunohistochemical staining of lymph nodes revealed that 15 of 25 patients with Dukes' stage B diagnosed by routine staining had micrometastases, 86% of these lymph nodes being less than 5 mm in diameter. The survival rate of this subgroup was found to be considerably poorer than that of Dukes' stage B patients with no micrometastases. None of the three patients with Dukes' stage A carcinoma had micrometastases. Since most of the metastases and micrometastases occur in lymph nodes of 5 mm and less and can be easily missed by routine examination, we suggest that fat clearance and routine immunohistochemical analysis of Dukes' stage B improve the prediction of outcome of colorectal cancer patients.

Activated protein C sensitivity, protein C, protein S and coagulation in normal pregnancy

A prospective study of activated protein C sensitivity, protein C, protein S, and other coagulation factors in 239 women during normal pregnancy was carried out. Protein C activity appeared unaffected by gestation, although an elevation of protein C activity was observed in the early puerperium. A fall in total and free protein S with increasing gestation was observed. Activated protein C sensitivity ratio (APC:SR) showed a progressive fall through pregnancy. This fall correlated with changes in factor VIIIc, factor Vc and protein S. 38% of subjects, with no evidence of Factor V Leiden or anticardiolipin antibodies, showed a low APC:SR (APC:SR <2.6) in the third trimester of pregnancy. Aside from a significant reduction in birth weight, no difference in pregnancy outcome was observed between these subjects and those with a normal APC:SR. Activated protein C sensitivity ratio, modified by pre-dilution of patient samples with factor V depleted plasma, showed no consistent trend with gestation.

Allogeneic bone marrow transplantation vs filgrastim-mobilised peripheral blood progenitor cell transplantation in patients with early leukaemia: first results of a randomised multicentre trial of the European Group for Blood and Marrow Transplantation

In a multicentre trial involving 20 transplant centres from 10 countries haematopoietic stem cells were obtained either from the bone marrow of 33 sibling donors or from the peripheral blood of 33 such donors after administration of filgrastim (10 microg/kg/day). The haematopoietic stem cells were infused into their HLA-identical recipients suffering from acute leukaemias in remission or chronic myeloid leukaemia in chronic phase. PBPC donors tolerated filgrastim administration and leukapheresis well with the most frequent side-effects being musculoskeletal pain, headache, and mild increases of LDH, AP, Gamma-GT or SGPT. Pain and haematoma at the harvest site and mild anaemia were the most frequent complaints of BM donors. Severe or life-threatening complications were not seen with any type of harvest procedure. Time to platelet recovery greater than 20 x 10(9)/l was 15 days (95% confidence interval (CI) 13-16 days) in the PBPCT group and 19 days (CI 16-25) in the BMT group. Time to neutrophil recovery greater than 0.5 x 10(9)/l was 14 days (CI 12-15 days) in the PBPCT group as compared to 15 days (CI 15-16 days) in the BMT group. The numbers of platelet transfusions administered to PBPCT and BMT patients were 12 (range: 1-28) and 10 (range: 3-39), respectively. Sixteen patients (48%) transplanted with bone marrow and 18 patients (54%) transplanted with PBPC developed acute GVHD of grades II-IV; acute GVHD of grades III or IV developed in six (18%) and seven (21%) patients, respectively. Kaplan-Meier plots for transplant-related mortality until day 100 and leukaemia-free survival at a median of 400 days after BMT or PBPCT showed no significant differences. Administration of filgrastim and leukapheresis in normal donors were feasible and well tolerated. The number of days with restricted activity and of nights spent in hospital was lower in donors of PBPC. Transplantation of PBPC to HLA-identical siblings with early leukaemia resulted in earlier platelet engraftment. The incidence of moderate to severe acute GVHD, transplant-related mortality, and leukaemia-free survival did not show striking differences. Further investigation of allogeneic PBPCT as a substitute for allogeneic BMT is warranted.

Capsular polysaccharide types of group B streptococcal isolates from neonates with early-onset systemic infection

The distribution of serotypes of group B streptococci (GBS) isolated from 67 infants with early-onset sepsis are described. Case-infants were assembled from 13 hospitals across the United States from 15 July 1995 to 5 February 1997 through prospective active surveillance. The distribution of GBS serotypes was Ia, 40%; Ib, 9%; II, 6%; III, 27%; V, 15%; and nontypeable, 3%. Type V occurred more frequently in the northeast region (New York and New Jersey) than in other regions (29% vs. 9%, P = .06). Conversely, type III occurred significantly less frequently in the northeast region than other regions (10% vs. 35%, P = .04). GBS types Ia, III, and V accounted for 82% of the isolates. This report supports previous observations about the emergence of GBS type V, but our data caution that conclusions about serotype distributions based on one geographic location or on a small number of patients may not be generally applicable. Continued monitoring seems necessary for the design of a GBS vaccine.

CO2 laser safety considerations in facial skin resurfacing

Carbon dioxide lasers have been used increasingly in the field of aesthetic plastic surgery, specifically for facial resurfacing procedures. As many plastic surgeons are now venturing into the arena of laser surgery for the first time, it is paramount to understand basic laser safety principles to protect our patients, the operating room personnel, and the laser surgeon. This article reviews basic laser principles and practices and delineates the safety requirements needed to perform laser resurfacing using the CO2 laser system. We subjected several common objects present in the operative field during resurfacing procedures to multiple passes of both the Coherent 5000 C laser and the Laser Industries (Sharplan) model 150XJ laser Silktouch to assess flammability and margins of safety. We tested endotracheal tubes, wet and dry towels, wet and dry gauze sponges, cottonoids, eye protectors, and ophthalmic ointments. Neither flame nor burn was incited in the moistened preparations. The dry objects tested produced flame. The plastic corneal protectors began to melt by the third pass and produced significant heat. Lastly, both the Lacrilube and Bacitracin ophthalmic ointments began to vaporize after three laser passes. On the basis of our findings in this study, we recommend guidelines for prudent and safe CO2 laser usage in facial skin resurfacing.

Correlation between cervical cytologic results and Gram stain as diagnostic tests for bacterial vaginosis

OBJECTIVE

Our purpose was to determine the reliability of the Papanicolaou smear in making the diagnosis of bacterial vaginosis with the vaginal Gram stain used as the diagnostic standard.

STUDY DESIGN

We conducted a prospective, blinded, cross-sectional study of 210 consecutive patients referred to the Colposcopy Clinic for evaluation of abnormal cervical cytologic results. Each patient had a standard Papanicolaou smear and Gram stain of vaginal discharge. The sensitivity, specificity, positive predictive value, and negative predictive value of the Papanicolaou smear were determined with the Gram stain used as the standard for diagnosis of bacterial vaginosis.

RESULTS

Of the 210 patients, 80 (38.1%) had Gram stains that were positive for bacterial vaginosis and 118 (56.2%) had negative Gram stains. Twelve (5.7%) had intermediate Gram stains that were also considered negative. Of the 80 patients with positive Gram stains, 44 had cervical smears consistent with bacterial vaginosis and 36 had negative smears. Of the 130 patients with negative Gram stains, two had a positive cervical smear. Therefore, compared to the Gram stain, cervical cytologic test results had a sensitivity of 55% and a specificity of 98%. The respective positive predictive and negative predictive values were 96% and 78%.

CONCLUSION

Compared to Gram stain of vaginal secretions, the cervical Papanicolaou smear has fair sensitivity (55%) and excellent positive predictive value (96%) in diagnosing bacterial vaginosis.

Tetrahydrobiopterin binding to macrophage inducible nitric oxide synthase: heme spin shift and dimer stabilization by the potent pterin antagonist 4-amino-tetrahydrobiopterin

The characteristics of tetrahydrobiopterin (H4biopterin) binding to pteridine-free recombinant macrophage inducible nitric oxide synthase expressed in Escherichia coli were investigated with a special focus given to effects caused by 2,4-diamino-5,6,7, 8-tetrahydro-6-(l-erythro-1,2-dihydroxypropyl)pteridine (4-amino-H4biopterin), a novel pterin-based inhibitor of nitric oxide synthase. The 4-amino compound completely inhibited enzyme stimulation by 10 microM H4biopterin with a half-maximally active concentration of 7.2 +/- 0.39 microM, whereas H2biopterin and sepiapterin were much less potent. Binding studies using [3H]H4biopterin at 4 degrees C revealed biphasic association of the radioligand according to two first-order reactions with apparent rate constants of 2.2 and 0.05 min-1, each accounting for approximately 50% of total binding. Dissociation of [3H]H4biopterin occurred with rate constants of 0.005 and 0.0028 min-1 in the absence and presence of l-arginine, respectively. Specific binding of 10 nM [3H]H4biopterin was antagonized by unlabeled H4biopterin and its 4-amino analog with half-maximal effects at 84 +/- 6 and 34 +/- 3.2 nM, respectively. Binding of H4biopterin and 4-amino-H4biopterin was accompanied by a partial low spin to high spin conversion of the heme that was completed by l-arginine. Similarly, the active cofactor and the inhibitory 4-amino derivative both induced significant formation of stable protein dimers that survived during SDS electrophoresis, suggesting that the allosteric effects caused by H4biopterin do not explain sufficiently the essential role of the pteridine cofactor in NO biosynthesis.

Primary adenocarcinoma of the gland of the nictitating membrane in a cat

An 11-year-old, neutered, male domestic shorthair was presented with a five-month history of recurrent, unilateral, seromucoid discharge from the right eye. A verrucous mass extended from the posterior aspect of the nictitating membrane. Adenocarcinoma of the gland of the nictitating membrane (GNM) was diagnosed upon biopsy. The cat subsequently developed metastases to the lungs, pleura, mediastinum, liver, and kidneys and died six months after clinical signs first were observed. Little is known about the biological behavior of adenocarcinoma of the GNM in cats. This is the first report that describes the natural progression of this disease.

Preferential adhesion to and survival on patterned laminin organizes myogenesis in vitro

We have examined a potential role for differential adhesiveness in muscle development using an in vitro model which employed the culture of myoblasts and myotubes, (conditionally immortal myogenic cells, H2k(b)-tsA58), on micropatterned surfaces. These surfaces are made up of multiple alternating tracks of hydrophobic organosilane-treated glass and untreated glass (track width ranging from 5 to 100 microm). We found that myoblasts were aligned on patterns in the presence of serum, by adhering to the tracks of untreated glass, which had preferentially adsorbed serum attachment factors. However, as serum attachment factors are not sufficient for maintenance of adhesion of mature myotubes, we determined whether precoating patterns with laminin, which maintains adhesion, could still provide a differential adhesive cue. Laminin preferentially adsorbs to the hydrophobic regions resulting in alternating tracks that have adsorbed laminin or serum attachment factors. Myoblasts were less well aligned on these patterns as they could adhere both to the untreated glass and to laminin on the previously hydrophobic tracks, but did show a preference for laminin. However, cell alignment increased upon differentiation into myotubes and continued to increase as the myotubes matured. We found that the alignment of myoblasts and myotubes on patterns increased as track width increased. In addition, adhesion to laminin was required for long term survival of the myotubes. Myotubes that had formed on nonlaminin surfaces began to detach after 2 days of differentiation. Although we found that myoblasts preferentially clustered on laminin tracks, this arrangement did not influence the diameter of the myotubes formed, upon differentiation. Instead, the number of myotubes per track increased with track width, while the myotube diameter remained constant. This uniformity of myotube diameter suggests that a mechanism exists which restricts the ability of myoblasts to undergo lateral fusion. Overall, these findings suggest that differential adhesiveness could be an important mechanism for formation and survival of myotubes, and by using these patterns we have demonstrated a mechanism controlling the formation of linear myotubes by restricting the geometry of cell-cell adhesion.

Repetitive cycles of cyclophosphamide, thiotepa, and carboplatin intensification with peripheral-blood progenitor cells and filgrastim in advanced breast cancer patients

PURPOSE

As an alternative to single-cycle cyclophosphamide, thiotepa, and carboplatin (CTCb) intensification, we evaluated the feasibility of administering one-quarter dose CTCb for four cycles with peripheral-blood progenitor-cell (PBPC) and filgrastim (granulocyte colony-stimulating factor [G-CSF]) in advanced-stage breast cancer patients.

PATIENTS AND METHODS

From June 1992 to August 1993, 20 stage IIIB (n = 7) and IV (n = 13) breast cancer patients received 78 cycles of induction with doxorubicin 90 mg/m2 by intravenous (IV) bolus with G-CSF 5 microg/kg/d by subcutaneous injection (SC) repeated every 14 to 21 days for four cycles. PBPC were collected by 2-hour single-blood volume leukapheresis on 2 consecutive days at the time of hematologic recovery from each cycle of doxorubicin. Eighteen patients received 61 cycles of intensification with cyclophosphamide 1,500 mg/m2, thiotepa 125 mg/m2, and carboplatin 200 mg/m2 by IV continuous infusion with G-CSF 10 microg/kg/d SC and PBPC support repeated every 21 to 42 days for four cycles.

RESULTS

Twelve of 20 patients (60%) completed all four planned cycles of doxorubicin induction followed by four cycles of one-quarter dose CTCb intensification. Statistically significantly decreases in the yield of mononuclear cells (MNC) (median slope per day, -0.032; P = .03), granulocyte-macrophage colony-forming unit (CFU-GM) (median slope per day, -0.57; P = .0008), and burst-forming unit-erythroid (BFU-E) (median slope per day, -1.18; P = .006) were observed over the course of the eight leukaphereses. Of 18 patients who began CTCb, 12 (67%) completed four cycles. Six patients were removed from study during intensification: two for progressive disease (PD), one refused further treatment, and three for dose-limiting hematologic toxicity. A fourth patient fulfilled the criteria for dose-limiting hematologic toxicity after cycle 4. The toxicity of the multiple cycle CTCb intensification regimen consisted of grade IV leukopenia, grade IV thrombocytopenia, and febrile neutropenia in 100%, 100%, and 26% of cycles, respectively. The median duration of each CTCb cycle was 24 days (range, 18 to 63), and the median duration of an absolute neutrophil count (ANC) < or = 500/microL and platelet count < or = 20,000/microL during each cycle was 6 days (range, 2 to 15) and 4 days (range, 0 to 38), respectively.

CONCLUSION

It is feasible to administer repetitive cycles of one-quarter dose CTCb intensification with PBPC and G-CSF. Additional studies are required to determine whether multiple cycles of CTCb intensification might offer a therapeutic advantage over a single high-dose cycle.

Studies to detect carriers of haemophilia A in German shepherd dogs using diagnostic DNA polymorphisms in the human factor VIII gene

The current study investigated whether the DNA polymorphisms in the human FVIII gene, that are used for the diagnosis of carriers of haemophilia A, were diagnostically useful in dogs. Genomic DNA from 20 German Shepherd dogs (13 females, three normal males and four haemophilic males) was tested using five restriction site polymorphisms [HindIII/F8 (exon 17-18), Taq I/ST14.1, BclI/ST14.1, BclI F8 (exon 17-18) and Bgl II/DX13]. The DNA probes (with the exception of DX13) all hybridized to the canine DNA at high stringency, indicating significant homology between the human and canine FVIII gene. A BclI polymorphism (13.5/13.5 + 12.8 kb) was detected with the ST14.1 probe.

Crystal structures of 8-Cl and 9-Cl TIBO complexed with wild-type HIV-1 RT and 8-Cl TIBO complexed with the Tyr181Cys HIV-1 RT drug-resistant mutant

Human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) is an important target for chemotherapeutic agents used in the treatment of AIDS; the TIBO compounds are potent non-nucleoside inhibitors of HIV-1 RT (NNRTIs). Crystal structures of HIV-1 RT complexed with 8-Cl TIBO (R86183, IC50 = 4.6 nM) and 9-Cl TIBO (R82913, IC50 = 33 nM) have been determined at 3.0 A resolution. Mutant HIV-1 RT, containing Cys in place of Tyr at position 181 (Tyrl81Cys), is highly resistant to many NNRTIs and HIV-1 variants containing this mutation have been selected in both cell culture and clinical trials. We also report the crystal structure of Tyrl81Cys HIV-1 RT in complex with 8-Cl TIBO (IC50 = 130 nM) determined at 3.2 A resolution. Averaging of the electron density maps computed for different HIV-1 RT/NNRTI complexes and from diffraction datasets obtained using a synchrotron source from frozen (-165 degrees C) and cooled (-10 degrees C) crystals of the same complex was employed to improve the quality of electron density maps and to reduce model bias. The overall locations and conformations of the bound inhibitors in the complexes containing wild-type HIV-1 RT and the two TIBO inhibitors are very similar, as are the overall shapes and volumes of the non-nucleoside inhibitor-binding pocket (NNIBP). The major differences between the two wild-type HIV-1 RT/TIBO complexes occur in the vicinity of the TIBO chlorine substituents and involve the polypeptide segments around the beta5-beta6 connecting loop (residues 95 to 105) and the beta13-beta14 hairpin (residues 235 and 236). In all known structures of HIV-1 RT/NNRTI complexes, including these two, the position of the beta12-beta13 hairpin or the "primer grip" is significantly displaced relative to the position in the structure of HIV-1 RT complexed with a double-stranded DNA and in unliganded HIV-1 RT structures. Since the primer grip helps to position the template-primer, this displacement suggests that binding of NNRTIs would affect the relative positions of the primer terminus and the polymerase active site. This could explain biochemical data showing that NNRTI binding to HIV-1 RT reduces efficiency of the chemical step of DNA polymerization, but does not prevent binding of either dNTPs or DNA. When the structure of the Tyr181Cys mutant HIV-1 RT in complex with 8-Cl TIBO is compared with the corresponding structure containing wild-type HIV-1 RT, the overall conformations of Tyr181Cys and wild-type HIV-1 RT and of the 8-Cl TIBO inhibitors are very similar. Some positional changes in the polypeptide backbone of the beta6-beta10-beta9 sheet containing residue 181 are observed when the Tyr181Cys and wild-type complexes are compared, particularlty near residue Val179 of beta9. In the p51 subunit, the Cys181 side-chain is oriented in a similar direction to the Tyr181 side-chain in the wild-type complex. However, the electron density corresponding to the sulfur of the Cys181 side-chain in the p66 subunit is very weak, indicating that the thiol group is disordered, presumably because there is no significant interaction with either 8-Cl TIBO or nearby amino acid residues. In the mutant complex, there are slight rearrangements of the side-chains of other amino acid residues in the NNIBP and of the flexible dimethylallyl group of 8-Cl TIBO; these conformational changes could potentially compensate for the interactions that were lost when the relatively large tyrosine at position 181 was replaced by a less bulky cysteine residue. In the corresponding wild-type complex, Tyr181 iin the p66 subunit has significant interactions with the bound inhibitor and the position of the Tyr181 side-chain is well defined in both subunits. Apparently the Tyr181 --> Cys mutation eliminates favorable contacts of the aromatic ring of the tyrosine and the bou

Patterns of dissociation in clinical and nonclinical samples

Research has consistently found elevated mean dissociation scores in particular diagnostic groups. In this study, we explored whether mean dissociation scores for different diagnostic groups resulted from uniform distributions of scores within the group or were a function of the proportion of highly dissociative patients that the diagnostic group contained. A total of 1566 subjects who were psychiatric patients, neurological patients, normal adolescents, or normal adult subjects completed the Dissociative Experience Scale (DES). An analysis of the percentage of subjects with high DES scores in each diagnostic group indicated that the diagnostic group's mean DES scores were a function of the proportion of subjects within the group who were high dissociators. The results contradict a continuum model of dissociation but are consistent with the existence of distinct dissociative types.