A uniform strategy of primary repair of tetralogy of Fallot: Transventricular approach results in low reoperation rate in the first decade

OBJECTIVES

To review outcomes after a uniform strategy of transventricular repair of tetralogy of Fallot.

METHODS

A total of 244 consecutive patients underwent transventricular primary repair of tetralogy of Fallot from 2004 to 2019. Median age at operation was 71 days; 57 (23%) patients were premature; 57 (23%) patients had low birth weight (<2.5 kg), and 40 (16%) had genetic syndromes. The diameter of pulmonary valve annulus, right pulmonary artery (PA), and left PA were 6.0 ± 1.8 mm (z score, -1.7 ± 1.3), 4.3 ± 1.4 mm (z score, -0.9 ± 1.2) and 4.1 ± 1.5 mm (z score, -0.5 ± 1.3).

RESULTS

Three (1.2%) operative deaths were recorded. Ninety patients (37%) underwent transannular patching. Postoperative echocardiographic peak right ventricular outflow tract gradient decreased from 72 ± 27 mm Hg to 21 ± 16 mm Hg. Median intensive care unit and hospital stay were 3 and 7 days. The survival rate at 10 years was 94.6% ± 1.8%. Reintervention was required 86 times (55 catheter interventions) in 56 patients following tetralogy of Fallot repair. The freedom from all-cause reintervention rate at 10 years was 70.5% ± 3.6%. Cyanotic spells (hazard ratio, 2.14; 95% CI, 1.22-3.90; P < .01) and smaller pulmonary valve annulus z score (hazard ratio, 1.26; 95% CI, 1.01-1.59; P = .04) were associated with increasing risk of all reinterventions. Freedom from redo surgery for right ventricular outflow tract obstruction and right ventricular dilatation at 10 years were, respectively, 85.0% ± 3.1% and 98.7% ± 0.9%. Freedom from valve implantation was 96.7% ± 1.5% at 10 years.

CONCLUSIONS

A uniform strategy of primary repair of tetralogy of Fallot through a transventricular approach resulted in low reoperation rate in the first decade. The need of pulmonary valve implantation was limited to <4% at 10 years.

Neutron Capture on the s-Process Branching Point ^{171}Tm via Time-of-Flight and Activation

The neutron capture cross sections of several unstable nuclides acting as branching points in the s process are crucial for stellar nucleosynthesis studies. The unstable ^{171}Tm (t_{1/2}=1.92  yr) is part of the branching around mass A∼170 but its neutron capture cross section as a function of the neutron energy is not known to date. In this work, following the production for the first time of more than 5 mg of ^{171}Tm at the high-flux reactor Institut Laue-Langevin in France, a sample was produced at the Paul Scherrer Institute in Switzerland. Two complementary experiments were carried out at the neutron time-of-flight facility (n_TOF) at CERN in Switzerland and at the SARAF liquid lithium target facility at Soreq Nuclear Research Center in Israel by time of flight and activation, respectively. The result of the time-of-flight experiment consists of the first ever set of resonance parameters and the corresponding average resonance parameters, allowing us to make an estimation of the Maxwellian-averaged cross sections (MACS) by extrapolation. The activation measurement provides a direct and more precise measurement of the MACS at 30 keV: 384(40) mb, with which the estimation from the n_TOF data agree at the limit of 1 standard deviation. This value is 2.6 times lower than the JEFF-3.3 and ENDF/B-VIII evaluations, 25% lower than that of the Bao et al. compilation, and 1.6 times larger than the value recommended in the KADoNiS (v1) database, based on the only previous experiment. Our result affects the nucleosynthesis at the A∼170 branching, namely, the ^{171}Yb abundance increases in the material lost by asymptotic giant branch stars, providing a better match to the available pre-solar SiC grain measurements compared to the calculations based on the current JEFF-3.3 model-based evaluation.

The Bcl-2 repertoire of mesothelioma spheroids underlies acquired apoptotic multicellular resistance

Three-dimensional (3D) cultures are a valuable platform to study acquired multicellular apoptotic resistance of cancer. We used spheroids of cell lines and actual tumor to study resistance to the proteasome inhibitor bortezomib in mesothelioma, a highly chemoresistant tumor. Spheroids from mesothelioma cell lines acquired resistance to bortezomib by failing to upregulate Noxa, a pro-apoptotic sensitizer BH3-only protein that acts by displacing Bim, a pro-apoptotic Bax/Bak-activator protein. Surprisingly, despite their resistance, spheroids also upregulated Bim and thereby acquired sensitivity to ABT-737, an inhibitor of anti-apoptotic Bcl-2 molecules. Analysis using BH3 profiling confirmed that spheroids acquired a dependence on anti-apoptotic Bcl-2 proteins and were ‘primed for death'. We then studied spheroids grown from actual mesothelioma. ABT-737 was active in spheroids grown from those tumors (5/7, ∼70%) with elevated levels of Bim. Using immunocytochemistry of tissue microarrays of 48 mesotheliomas, we found that most (33, 69%) expressed elevated Bim. In conclusion, mesothelioma cells in 3D alter the expression of Bcl-2 molecules, thereby acquiring both apoptotic resistance and sensitivity to Bcl-2 blockade. Mesothelioma tumors ex vivo also show sensitivity to Bcl-2 blockade that may depend on Bim, which is frequently elevated in mesothelioma. Therefore, mesothelioma, a highly resistant tumor, may have an intrinsic sensitivity to Bcl-2 blockade that can be exploited therapeutically.

Comparison of prenatal care coverage in early adolescents, late adolescents, and adult pregnant women in the Peruvian Amazon

OBJECTIVE

To compare prenatal care coverage between adolescent (early and late) and adult pregnant women in Iquitos, Peru.

METHODS

A random sample of 4467 birth records was collected. Multivariate analyses were performed to compare prenatal care coverage in all adolescent (10-14 years, 15-19 years) and adult (>or=20 years) age groups and then for primiparous women only.

RESULTS

The mean number of visits was 5.0 for adolescents aged 10-14 years, 6.1 for adolescents aged 15-19 years, and 6.2 for women aged 20 years or older. For primiparous women, the means were 5.1, 6.2, and 6.8, for the respective age groups. Both the proportion attending and the number of prenatal visits were significantly lower in primiparous adolescents aged 10-14 years than in primiparous women aged 20 years or older (aOR 0.25; 95% CI, 0.10-0.62 and aRR 0.83; 95% CI, 0.74-0.94, respectively).

CONCLUSION

All women attended prenatal care more frequently than the WHO's recommended 4 visits; however, early adolescents attended significantly less often than late adolescents or adult women. Further study of this inequality is warranted to adequately inform local health services.

micro-XANES and micro-XRF investigations of metal binding mechanisms in biosolids

Micro-X-ray fluorescence (micro-XRF) microprobe analysis and micro-X-ray absorption near-edge structure (micro-XANES) spectroscopy were employed to identify Fe and Mn phases and their association with selected metals in two biosolids (limed composted [LC] and Nu-Earth) before and after treatment to remove organic carbon (OC). Spatial correlations derived from elemental mapping of XRF images showed strong correlations between Fe and Cd, Cr, Pb, or Zn (r2= 0.65-0.92) before and after removal of most of the OC. The strong correlation between Fe and Cu that was present in intact samples disappeared after OC removal, suggesting that Cu was associated with OC coatings that may have been present on Fe compounds. Except for Fe and Cr, the spatial correlations of metals with Mn were improved after treatment to remove OC, indicating that the treatment may have altered more than the OC in the system. The Fe micro-XANES spectra of the intact biosolids sample showed that every point had varying mixtures of Fe(II and III) species and no two points were identical. The lack of uniformity in Fe species in the biosolids sample illustrates the complexity of the materials and the difficulty of studying biosolids using conventional analytical tools or chemical extraction techniques. Still, these microscopic observations provide independent information supporting the previous laboratory and field hypothesis that Fe compounds play a major role in retention of environmentally important trace elements in biosolids. This could be due to co-precipitation of the metals with Fe, adsorption of metals by Fe compounds, or a combination of both mechanisms.

Methods for speciation of metals in soils: a review

The inability to determine metal species in soils hampers efforts to understand the mobility, bioavailability, and fate of contaminant metals in environmental systems, to assess health risks posed by them, and to develop methods to remediate metal contaminated sites. Fortunately, great strides have been made in the development of methods of species characterization and in their application to the analysis of particulates and mixtures of solid phases in physics, analytical chemistry, and materials science. This manuscript highlights a selection of the analytical methods available today offering the greatest promise, briefly describes the fundamental processes involved, examines their limitations, points to how they have been used in the environmental and geochemical literature, and offers some suggested research directions in the hope of stimulating further investigation into the application of these powerful tools to the problems outlined above.

Trace element chemistry in residual-treated soil: key concepts and metal bioavailability

Trace element solubility and availability in land-applied residuals is governed by fundamental chemical reactions between metal constituents, soil, and residual components. Iron, aluminum, and manganese oxides; organic matter; and phosphates, carbonates, and sulfides are important sinks for trace elements in soil-residual systems. The pH of the soil-residual system is often the most important chemical property governing trace element sorption, precipitation, solubility, and availability. Trace element phytoavailability in residual-treated soils is often estimated using soil extraction methods. However, spectroscopic studies show that sequential extraction methods may not be accurate in perturbed soil-residual systems. Plant bioassay is the best method to measure the effect of residuals on phytoavailability. Key concepts used to describe phytoavailability are (i) the salt effect, (ii) the plateau effect, and (iii) the soil-plant barrier. Metal availability in soil from metal-salt addition is greater than availability in soil from addition of metal-containing residuals. Plant metal content displays plateaus at high residual loadings corresponding to the residual's metal concentration and sorption capacity. The soil-plant barrier limits transmission of many trace elements through the food chain, although Cd (an important human health concern) can bypass the soil-plant barrier. Results from many studies that support these key concepts provide a basis of our understanding of the relationship between trace element chemistry and phytoavailability in residual-treated soils. Research is needed to (i) determine mechanisms for trace element retention of soil-residual systems, (ii) determine the effect of residuals on ecological receptors and the ability of residuals to reduce ecotoxicity in metal-contaminated soil, and (iii) predict the long-term bioavailability of trace elements in soil-residual systems.

Use of fish liver PLHC-1 cells and zebrafish embryos in cytotoxicity assays

Heat shock proteins (HSPs) indicate exposure to cellular stress and adverse cellular effects, thus serving as biomarkers of these effects. The highly conserved Hsp70 proteins are expressed under proteotoxic conditions, whereas small HSPs are expressed in response to stressors acting on the cytoskeleton and cell signaling pathways. Poeciliopsis lucida hepatocellular carcinoma line 1 (PLHC-1) cells have been used extensively for studying effects of cytotoxicity. A number of assays have been developed to examine DNA levels, protein levels, growth rate, morphological changes, and viability. The boundary between sub-lethal and lethal effects of particular stressors has been determined. The methodology and analytical framework for these techniques along with sample assays using cadmium stressed PLHC-1 cells are described. A range of methodologies have been developed in the past decade that allow the analysis and interpretation of gene expression and function in vivo in zebrafish embryos, and many of these are now being applied to the development of embryotoxicity assays. Here we provide the theoretical background and methodology for utilizing Hsp70 expression as an indicator of toxicity in the zebrafish embryo. Hsp70 expression is activated in a tissue-specific manner in zebrafish larvae following exposure to a number of different toxicants, including cadmium. This has allowed the development of an hsp70/eGFP reporter gene system in stable transgenic zebrafish that serves as a reliable yet extremely quick indicator of cell-specific toxicity in the context of the multicellular, living embryo.

Psychopathology in people with epilepsy and intellectual disability; an investigation of potential explanatory variables

OBJECTIVES

There are few studies on epilepsy and psychopathology in people with intellectual disability (mental retardation) despite epilepsy prevalence rates that are thirty times higher than in the general population. The aims of this study, therefore, were to identify reliable, epilepsy-specific predictors of psychiatric and behavioural disorder in these patients, and to investigate reliable predictors of carer stress.

METHODS

A database of 685 patients was compiled, from which 250 were randomly selected. Structured interviews were completed on 186 of these 250 patients (74%) (108 men, 78 women; mean age (SD) 35.5 (10.1)) comprising descriptive, clinical and functional components, and validated measures of psychopathology for which comparative data were available. Logistic and linear regression methods were used to identify predictors.

RESULTS

One-third of patients with epilepsy and intellectual disability met criteria for possible psychiatric disorder, particularly affective/neurotic disorder; twice the comparison rates for intellectual disability alone. Behavioural problem levels, however, were lower than population norms. Regression models explaining modest amounts of variance (R(2)< or =24%) suggested certain seizure phenomena (greater seizure severity, more seizures in past month, lesser tendency to loss of consciousness during seizures) as particular risk factors for psychiatric disorder. General disability factors such as level of intellectual, sensory or motor disability and side effects of medication, however, contributed more to explaining behavioural problems. Around half of the family carers reported significant stress, and one-third exhibited clinically significant anxiety symptoms. Younger carers were more stressed, and side effects from patients' medication also contributed to carer stress.

CONCLUSIONS

Although epilepsy in itself may be a risk factor for psychopathology in a minority of people with intellectual disability, some epilepsy-specific factors may predict psychiatric disorder. Behavioural problems need to be considered separately from psychiatric disorder because general factors, more closely associated with disability, are stronger predictors of their occurrence.

Formation of chloropyromorphite in a lead-contaminated soil amended with hydroxyapatite

Conversion of soil Pb to pyromorphite [Pb5(PO4)3Cl] was evaluated by reacting a Pb contaminated soil collected adjacent to a historical smelter with hydroxyapatite [Ca5(PO4)3OH]. In a dialysis experiment where the soil and hydroxyapatite solids were placed in separate dialysis bags suspended in 0.01 M NaNO3 solution a crystalline precipitate, identified as chloropyromorphite, formed on the dialysis membrane containing the soil. The aqueous composition of the solution indicated that dissolution of solid-phase soil Pb was the rate-limiting step for pyromorphite formation. Addition of hydroxyapatite to the soil caused a decrease in each of the first four fractions of sequential extractable Pb and a 35% increase in the recalcitrant extraction residue. After a 240-d incubation at field-moisture content there was a further increase in the recalcitrant extraction residue fraction of the hydroxyapatite-amended soil to 45% of the total soil Pb. The increase in the extraction residue fraction in the hydroxyapatite amended 0-d incubated soil as compared to the control soil illustrates that the chemical extraction procedure itself caused changes in extractability. Thus, the chemical extraction procedure cannot easily be utilized to confirm changes occurring in amended soils. The further increase after the 240-d incubation implies that the reaction also occurs in the soil during incubation. Extended X-ray absorption fine structure (EXAFS) spectroscopy indicated that after the 240-d incubation the hydroxyapatite treatment caused a change in the average, local molecular bonding environment of soil Pb. Low-temperature EXAFS spectra (chi data and radial structure functions--RSFs) showed a high degree of similarity between the chemical extraction residue and synthetic pyromorphite, providing additional evidence that the change of soil Pb to pyromorphite is possible by simple amendments of hydroxyapatite to soil.

Effects of pH on dechlorination of trichloroethylene by zero-valent iron

The surface normalized reaction rate constants (k(sa)) of trichloroethylene (TCE) and zero-valent iron (ZVI) were quantified in batch reactors at pH values between 1.7 and 10. The k(sa) of TCE linearly decreased from 0.044 to 0.009l/hm(2) between pH 3.8 and 8.0, whereas the k(sa) at pH 1.7 was more than an order higher than that at pH 3.8. The degradation of TCE was not observed at pH values of 9 and 10. The k(sa) of iron corrosion linearly decreased from 0.092 to 0.018l/hm(2) between pH 4.9 and 9.8, whereas it is significantly higher at pH 1.7 and 3.8. The k(sa) of TCE was 30-300 times higher than those reported in literature. The difference can be attributed to the pH effects and precipitation of iron hydroxide. The k(sa) of TCE degradation and iron corrosion at a head space of 6 and 10ml were about twice of those at zero head space. The effect was attributed to the formation of hydrogen bubbles on ZVI, which hindered the transport the TCE between the solution and reaction sites on ZVI. The optimal TCE degradation rate was achieved at a pH of 4.9. This suggests that lowering solution pH might not expedite the degradation rate of TCE by ZVI as it also caused faster disappearance of ZVI, and hence decreased the ZVI surface concentration.

Management and long-term follow-up of hepatic cysts

PURPOSE

To provide an algorithm for the management of hepatic cysts through an analysis of our series over 16 years.

METHOD

We reviewed the surgical management and outcome of patients with hepatic cysts between 1984 and 2000 at a single institution. Data were collected by chart review, telephone interview, and follow-up hepatic ultrasonography.

RESULTS

Forty-four patients (36 females, 8 males) underwent a total of 46 operations for hepatic cysts (mean size 12.0 +/- 5.2 cm) with a mean follow-up of 5.1 +/- 4.0 years. We treated 28 simple cysts, 4 polycystic liver disease (PCLD), 7 cystadenomas, 2 hydatid cysts, 1 cystadenocarcinoma, 1 endometrioma, and 1 hepatic foregut cyst. Operations included simple drainage, wide unroofing (open and laparoscopic), and hepatic resection. Four patients experienced a symptomatic recurrence after definitive treatment; 3 of these patients had PCLD. Four of the 7 patients with cystadenomas had undergone previous operations that required subsequent definitive resection without a recurrence.

CONCLUSIONS

The preoperative distinction between simple cysts and cystadenomas/cystadenocarcinomas can be difficult, yet the management is different. Unroofing is a safe and effective operation for patients with simple cysts. Patients with PCLD frequently have recurrences. Cystadenomas should be completely resected owing to the likelihood of recurrence after partial excision and the risk of eventual cystadenocarcinoma. We present a treatment algorithm for the preoperative evaluation and management of hepatic cysts based on the largest number of patients with the longest follow-up reported to date.

Adsorption of cadmium on biosolids-amended soils

Debate exists over the biosolid phase (organic or inorganic) responsible for the reduction in phytoavailable Cd in soils amended with biosolids as compared with soils amended with inorganic salts. To test the importance of these two phases, adsorption isotherms were developed for soil samples (nine biosolids-amended soils and their five companion controls) and two biosolids samples from five experimental sites with documented histories of biosolids application. Subsamples were treated with 0.7 M NaClO to remove organic carbon. Cadmium nitrate was added to both moist soil samples and their soil inorganic fractions (SIF) in a 0.01 M Ca(NO3)2 solution at three pH levels (6.5, 5.5, and 4.5), and equilibrated at 22 +/- 1 degrees C for at least 48 h. Isotherms of Cd adsorption for biosolids-amended soil were intermediate to the control soil and biosolids. Decreasing pH did not remove the difference between these isotherms, although adsorption of Cd decreased with decreasing pH level. Organic matter removal reduced Cd adsorption on all soils but had little influence on the observed difference between biosolids-amended and control soils. Thus, increased adsorption associated with biosolids application was not limited to the organic matter addition from biosolids; rather, the biosolids application also altered the adsorptive properties of the SIF. The greater affinity of the inorganic fraction of biosolids-amended soils to adsorb Cd suggests that the increased retention of Cd on biosolids-amended soils is independent of the added organic matter and of a persistent nature.

The social predictors of adolescent alcohol misuse: a test of the social development model

OBJECTIVE

This study was conducted to investigate the ability of the social development model (SDM) to predict alcohol misuse at age 16 and to investigate the ability of the SDM to mediate the effects of alcohol use at age 14 on alcohol misuse at age 16.

METHOD

The sample of 807 (411 males) is from the longitudinal panel of the Seattle Social Development Project which, in 1985, surveyed all consenting fifth-grade students from 18 elementary schools serving high-crime neighborhoods in Seattle, Washington. Alcohol use was measured at age 14, predictors of alcohol misuse were measured at age 15 and alcohol misuse was measured at age 16. Structural equation modeling was used to examine the fit of the model to the data.

RESULTS

All factor loadings were highly significant and the measurement model achieved a good fit with the data (Comparative Fit Index [CFI] = 0.93). A second-order structural model fit the data well (CFI = 0.91) and also explained 45% of the variance in alcohol misuse at age 16. The SDM partially and significantly mediated the direct effect of age-14 alcohol use on age-16 alcohol misuse.

CONCLUSIONS

The risk and protective processes specified by the SDM serve as potential targets for the prevention or reduction of adolescent alcohol misuse.

Benefits and safety of hepatic resection for colorectal metastases

BACKGROUND

Metastatic colorectal carcinoma to the liver is a potentially curable disease. The purpose of this study was to determine the safety and efficacy of hepatic resection for metastatic colorectal carcinoma.

METHODS

One hundred twenty-one consecutive hepatic resections in 110 patients with metastatic colorectal cancer between January 1978 and September 1998 performed by a single surgeon were reviewed.

RESULTS

The actuarial 5-year survival for all patients in the series was 46%. Of the patients operated on before 1993, the actual 5-year survival was 43% and actual disease-free 5-year survival was 28%. The actual 10-year survival was 27%, and of all patients operated on in the last 20 years, 48% are alive today. When comparing initial regional lymph node status, the 5-year survival was 54% for the patients with negative lymph nodes and 40% for patients with positive nodes. Only 18% of patients required a perioperative blood transfusion, and the median length of stay was 7 days. There were complications in 34% of cases, and the operative mortality was 4%.

CONCLUSIONS

Hepatic resection for metastatic colon cancer is safe, and significant longevity and cure can be obtained after resection.

Severe neutropenia as an adverse effect of methimazole in the treatment of hyperthyroidism

Ms. K., a white, 47-year-old female with a history of hyperthyroidism had been treated with methimazole daily for a period of 9 years. She presented with a 2-day history of fever higher than 103 degrees F and cellulitis of the right arm after a scratch injury. White blood cell count (WBC) was noted at 0.4 x 10(3)/microL and neutrophils at 5.6%, indicating agranulocytosis. Methimazole was discontinued by the patient with the onset of symptoms. Appropriate intravenous antibiotic therapy and reverse isolation were provided in the acute-care setting, as well as administration of the granulocyte colony-stimulating factor (G-CSF) filgrastim. No recovery of the granulocyte count or improvement of clinical condition was noted until her sixth day of admission, at which time her WBC increased to 2.6 x 10(3)/microL. The administration of intravenous antifungals and antibiotics prevented overwhelming sepsis, while giving the G-CSF the opportunity to stimulate growth of granulocytes to finally fight the offending organisms and save this patient.

Serogroup B, electrophoretic type 15 Neisseria meningitidis in Canada

Invasive meningococcal disease is nationally reportable in Canada. In recent years, a serogroup C genotype, designated electrophoretic type 15 (ET15), has been the most frequently isolated meningococcal genotype in Canada and has caused epidemics across the country. Between August 1993 and September 1995, there were 9 cases of invasive meningococcal disease caused by a variant of this genotype, expressing group B capsular polysaccharide. The appearance of serogroup B:ET15 was related temporally and geographically to mass immunization campaigns designed to control serogroup C meningococcal disease in Canada. Since there is no vaccine available to control serogroup B meningococcal disease, the appearance of this variant may have public-health significance if it demonstrates the same epidemic potential as its serogroup C counterpart.

Intraductal neoplasms of the pancreas

BACKGROUND

Since 1980 a group of pancreatic tumors have been termed intraductal papillary mucinous tumors (IPMT). Because these tumors occupy an intraductal position they are demonstrated by pancreatography to reside in the main pancreatic duct (MPD) or side branch ducts (SBD). Lesions of IPMT result in abdominal pain or pancreatitis symptoms because mucin production or papillary growth results in ductal obstruction. Only 104 cases had been reported in the literature by 1996 but more are being presented in abstract form. We reviewed our own 33 cases to assist defining operative decision-making criteria.

METHODS

All cases of IPMT between 1989 and 1997 were reviewed for clinical presentation, anatomy by endoscopic retrograde cholangiopancreatography and computed tomography, histologic findings, and long-term outcomes.

RESULTS

Our cases were older (65 years) and presented with disease centered mainly in the head of the gland. Clinical presentation was epigastric pain (82%), pancreatitis (56%), weight loss (36%), diabetes (27%), and jaundice (9%). Operations were pancreatectomy in 31 (Whipple n = 15, total n = 5, distal n = 10, local n = 1), bypass only (n = 1), and no operation (n = 1). Malignancy was found in 14 of 33 (42%). Factors significantly associated (P <0.05 Fisher exact test) with malignancy were history of alcohol abuse or death from disease. Jaundice or presence in both MPD and SBD approached a significant association with malignancy but not abdominal pain, weight loss, diabetes, preoperative serum elevations of amylase, SGOT, CA-19-9, or CEA; diffuse MPD dilation, gland region, gross mucus in ducts or filling defects, cytology, calcifications, or a pancreatic mass. In 31 resected patients after a follow-up of 37 months (1 to 103) death had occurred in 6 of 13 malignant cases and 0 of 18 with benign disease. Three-year actuarial survival was 82% (all) and 56% (malignant). Symptom recurrence after resection was found in 6 of 31 at a mean of 13 months postoperatively and was associated with death from disease (P <0.05) or presence of pain preoperatively.

CONCLUSION

Malignancy is common with IPMT and is more likely to be present with the clinical history of alcohol abuse or jaundice and if the tumor involves both the MPD and the SBD. The prognosis after resection is better than pancreatic cancer but the 19% recurrence of symptoms was equally seen with benign or malignant cases owing to residual disease in pancreatic remnants. The amount of resection should be extensive in patients likely to have malignancy (alcohol, jaundice, MPD+SBD). In those likely to redevelop symptoms, ie, those with preoperative pain, a careful assessment should be made via imaging studies for extent of disease.

Photodynamic therapy of the ciliary body with tin ethyl etiopurpurin and tin octaethyl benzochlorin in pigmented rabbits

BACKGROUND AND OBJECTIVES

The authors used a pigmented rabbit model to investigate two photosensitizers, tin ethyl etiopurpurin (SnET2) and tin octaethyl benzochlorin (BNZ 203), to determine their potential for creating ciliary body injuries during photodynamic therapy (PDT).

MATERIALS AND METHODS

The biodistribution of SnET2 (n = 10) and BNZ 203 (n = 9) was studied by fluorescence microscopy using a low light detection system, based on charged-coupled device photography, with digital image processing at 1 and 24 hours after injection. PDT with SnET2 (n = 8; 664 +/- 7-nm light; 75 mW/cm2; 50 or 100 J/cm2; 1-mm spot size) and BNZ 203 (n = 6; 689 nm; 75 mW/cm2; 50 or 100 J/cm2; 1-mm spot size) was performed at 24 hours post-injection. The control subjects for SnET2 (n = 5) and BNZ 203 (n = 3) were given a maximal light dose (100 J/cm2).

RESULTS

Both photosensitizers demonstrated an intravascular distribution at 1 hour that shifted to a ciliary body distribution at 24 hours (SnET2 much greater than BNZ 203). In addition, the SnET2 demonstrated suborgan localization to the nonpigmented ciliary body epithelium. Both photosensitizing agents were able to produce selective injury to the rabbit ciliary body (SnET2 much greater than BNZ 203), with evidence of a small component of thermal damage (SnET2 greater than BNZ 203).

CONCLUSIONS

PDT with SnET2 or BNZ 203 can produce selective injury to the pigmented rabbit ciliary body. The nonpigmented ciliary body epithelium exhibits selective retention of SnET2. This finding warrants further investigation.

Efficacy of selective unilateral exploration in hyperparathyroidism based on localization tests

OBJECTIVES

To determine the success of unilateral exploration vs bilateral exploration for primary hyperparathyroidism and to analyze the validity of preoperative localization tests.

DESIGN

Case-control study of patients who underwent surgical exploration (unilateral, n = 43; bilateral, n = 57) by 1 surgeon from January 1991 through May 1996 and who had ultrasound examination of the neck and thallium-technetium scintigraphy performed before parathyroid surgery. Initially, unilateral exploration was used sparingly, but it became the standard approach in 1994 if localization was correct.

SETTING

Urban multispecialty clinic, teaching hospital.

PATIENTS

One hundred consecutive patients who underwent surgical exploration for primary hyperparathyroidism.

INTERVENTIONS

Ultrasonography of the neck, thallium-technetium scintigraphy, and parathyroidectomy.

MAIN OUTCOME MEASURES

Imaging success, operative success, and operative time.

RESULTS

In 94 patients with solitary adenomas, the adenoma was demonstrated by ultrasound scans in 66%, by thallium-technetium scintigraphy in 83%, and by either test in 87%. Correct identification by ultrasonography was 59%; by thallium-technetium scintigraphy, 75%; and together, 73%. Of 6 patients with multiple-gland disease, 2 were correctly identified by localization tests and 9 of 15 abnormal glands were demonstrated. Of the 43 unilateral explorations, 43 single adenomas and no cases of multiple-gland disease were identified; of the 57 bilateral explorations, 51 single adenomas and 6 cases of multiple-gland disease were identified. No complications occurred in either group. Hypercalcemia persisted in 3 patients who underwent bilateral exploration and recurrent hypercalcemia developed in 1 patient in each group. The average operative time for the unilateral procedure was 105 minutes, and for the bilateral procedure, 184 minutes (P < .001). Since 1994, 31 (66%) of 47 patients have had unilateral exploration based on correct localization tests.

CONCLUSIONS

Unilateral exploration that is based on the results of localization tests requires less operative time and produces results similar to bilateral exploration.

Cavernous hemangiomas of the liver: enlargement over time

OBJECTIVE

It has been reported that cavernous hemangiomas of the liver either do not enlarge over time, or, of the very few lesions that have shown an increase in diameter on follow-up imaging studies, the increase has been minimal. The objective of this paper is to report growth of four cavernous hemangiomas that were shown to have doubled to tripled in diameter on follow-up imaging studies done between 34 months and 10.5 years after the initial diagnosis.

CONCLUSION

This report indicates that hepatic hemangiomas can grow significantly in diameter, although such growth is unusual. Despite the growth of the lesion, however, if the imaging features are characteristic of hemangioma an imaging diagnosis can still be made confidently.

Transpapillary stenting for pancreaticocutaneous fistulas

Because transpapillary stents have been successfully placed to treat the ductal disruptions associated with pseudocysts, pancreatic ascites and pleural effusions, and pancreaticoenteric fistulas, we reviewed our experience with endoscopically placed prostheses in patients who had persistent pancreaticocutaneous fistulas but an otherwise intact duct. Nine patients who underwent endoscopic transpapillary stent placement for ongoing pancreaticocutaneous fistulas at our institution were retrospectively reviewed. Fistulas were present for a mean (+/-SEM) of 35 +/- 11 days and averaged 225 +/- 55 ml of output daily. Etiology of the fistulas included percutaneous pseudocyst drainage in four patients, pancreatic necrosis in two, complications of pancreatic surgery in two, and perforation of the duct of Santorini at the time of minor sphincterotomy in one. All patients had an otherwise intact duct at the time of endoscopic retrograde cholangiopancreatography. Six patients had transpapillary stents placed that did not bridge the area of leakage and three had prostheses placed across the ductal disruption. Eight of nine fistulas were successfully closed by means of this technique including five within 48 hours. There was one instance of stent migration and one patient developed prosthesis occlusion and an infected pseudocyst, which was treated with stent exchange. Stents were retrieved 10 to 14 days after fistula closure and no patient has had a recurrence at a median follow-up of 3 years. Transpapillary stents appear to effect closure of pancreaticocutaneous fistulas that fail to respond to conventional therapy.

Effectiveness and safety of 100 consecutive parathyroidectomies

BACKGROUND AND METHODS

In order to evaluate the indications for operation for patients with primary hyperparathyroidism, prospective information was gathered on 100 consecutively operated patients from 1991 to 1996. A standard evaluation for outcomes and patient satisfaction was instituted. Patients consisted of 73 women and 27 men. Major symptoms existed in 48 patients, and 52 patients were referred to as "asymptomatic" because they fit the National Institutes of Health Consensus Development Conference Statement with abnormal laboratory values. The pathology was 94 single adenomas, 4 double adenomas, and 2 cases of hyperplastic multiglandular disease.

RESULTS

All 100 patients had abnormal parathyroids removed, resulting in normocalcemia in 97. Three patients had persistent hypercalcemia until a second operation removed additional abnormal parathyroids, resulting in normocalcemia. No operative complications or mortality occurred. Overnight stay occurred in 88 patients. During long-term follow-up of patients, only 2 developed recurrent hyperparathyroidism. When asked whether the operation improved their health, 94% of patients with major symptoms and 72% of asymptomatic patients responded affirmatively.

CONCLUSION

Parathyroidectomy is an efficient and safe operation with excellent normalization of serum calcium and a high rate of patient satisfaction.

Resection of malignant primary liver tumors

BACKGROUND

Malignant primary liver tumors are an uncommon and challenging surgical problem. In spite of multimodality therapies, surgical resection remains the mainstay of treatment and the most likely chance for cure. We reviewed the 13-year resection experience of a single surgeon at our institution to evaluate the results.

METHODS

A retrospective review from July 1982 to June 1995 was performed for patients presenting with a diagnosis of primary liver cancer. Those undergoing resection of their primary liver tumors form the basis of this report.

RESULTS

One hundred eighty-four patients with a diagnosis of primary liver cancer were seen at our institution. Of these, 43 patients underwent 46 resections of their cancers by a single surgeon. There were 22 females (51%) and 21 males (49%). The average age was 61 years with a median age of 63 years (range, 19-85 years). Tumors resected included 27 hepatomas, 16 cholangiocellular carcinomas, 1 carcinoid tumor, 1 low grade mucinous cystadenocarcinoma, and 1 cystadenocarcinoma. Resections were as follows: 9 right trisegmentectomies, 8 right lobectomies, 1 left trisegmentectomy, 4 left lobectomies, 7 left lateral segmentectomies, and 17 partial lobectomies. Major complications occurred in 11 patients (26%). There were 3 deaths, for a 30-day perioperative death rate of 7%. Of the 43 patients, 13 had follow-up of less than 12 months and 30 had follow-up for more than 1 year. The mean survival of the 30 patients who had their tumors resected and were followed up for more than 1 year was 27.2 months and the median survival was 21 months. The median survival of patients not undergoing resection was less than 6 months. The 1-, 2-, 3-, and 5-year survival rates were 57%, 52%, 40%, and 33%, respectively.

CONCLUSIONS

Primary liver cancer can be treated by resection with acceptable results. This remains the standard treatment of any liver cancer. Survival rates of patients after resection are much better than survival rates of patients who do not undergo surgery.

Pancreatitis caused by a gastric duplication communicating with an aberrant pancreatic lobe

Developmental anomalies of the pancreas and its ductal drainage system are an important cause of pancreatitis. Patients with such anomalies require appropriate surgical intervention. This report concerns an uncommon foregut anomaly that causes pancreatitis. A 9-year-old girl had recurrent pancreatitis secondary to a gastric duplication communicating with an aberrant pancreatic lobe. Appreciation of the relevant anatomy led to successful surgical management of the pancreatitis.

Stress proteins as molecular biomarkers for environmental toxicology

Biomarkers are increasingly being used in environmental monitoring to provide evidence that organisms have been exposed to, or affected by, xenobiotic chemicals. Usually, these biomarkers rely on biochemical, histological, morphological, and physiological changes in whole organisms; however, changes at the cellular and molecular levels of organization, especially in nucleic acids and proteins, are increasingly being used to supplement these more traditional biomarkers. This chapter starts by giving a brief overview of biomarkers and some of the basic requirements for their effective use. Then stress-inducible proteins that are potentially useful as environmental biomarkers are explored, and some examples of their application as biomarkers and methods of detecting them are presented.

Hydrocephalus and shunts in children with brain tumors

Children with brain tumors are at risk for developing hydrocephalus necessitating placement of a permanent shunt catheter. As comprehensive, interdisciplinary, multispecialty care is required for these patients, the pediatric oncology nurse must become knowledgeable about caring for children with a shunt. This article focuses on the care of the pediatric neuro-oncology patient requiring shunting for hydrocephalus, including a review of cerebrospinal fluid flow and hydrocephalus, determinants of shunt placement, complications of ventriculoperitoneal shunts, and nursing considerations.

Spectroscopic characterization of tick anticoagulant peptide

Tick anticoagulant peptide (TAP) is a disulfide rich potent inhibitor of factor Xa. Although this peptide is of potential clinical utility, very little is known about its higher order structure. Therefore, the secondary structure of recombinant TAP (rTAP) has been examined by circular dichroism (CD) and Fourier transform infrared (FTIR) spectroscopy. Both techniques suggest that rTAP is rich in beta-sheet structure. Disulfide bonds play a significant role in the folding and structural stability of rTAP. This is apparent from the resistance of rTAP to fluorescence-detected unfolding by guanidinium chloride (Gdn-HCl), unless disulfides are first reduced. The protein's tryptophan and tyrosine residues exhibit greater solvent exposure upon reduction of the cystines as indicated by fluorescence spectra and second derivative UV spectroscopy. A considerable amount of beta-structure appears to be retained after reduction of disulfides, although the CD spectrum manifests an increased amount of disordered structure in the reduced peptide. While rTAP does not bind the hydrophobic fluorescence probe 2-p-toludinylnaphthalene-6-sulfonate (TNS) at neutral or acidic pH, the reduced peptide binds TNS at pH 2.0 but not at pH 7.0. The secondary structure of the reduced peptide at pH 2 is, however, similar to that at pH 7 as judged by CD spectroscopy. The reduced form of rTAP at acidic pH thus resembles a molten globule-like state.

Comparison of continuous ST-segment recovery analysis with methods using static electrocardiograms for noninvasive patency assessment during acute myocardial infarction. Thrombolysis and Angioplasty in Myocardial Infarction (TAMI) 7 Study Group

Continuous ST-segment recovery analysis and 5 static methods using ST-segment comparison between a pre- and post-treatment electrocardiogram were compared for their ability to predict infarct-related artery patency in 82 patients with acute myocardial infarction who underwent angiography a median of 124 minutes after onset of thrombolytic treatment. Accuracy at the moment of angiography was 85% (95% confidence interval [CI] 77% to 93%) for the continuous method, and 68% (CI 57% to 78%), 78% (CI 69% to 87%), 83% (CI 74% to 91%), 82% (CI 73% to 90%), and 80% (CI 71% to 89%) for the static methods. At the moment of angiography the most accurate static method and the continuous method agreed in patency assessment in 90% of the patients (CI 84% to 97%). Agreement was reduced to 83% (CI 75% to 91%) of patients when a patency assessment was performed earlier at 90 minutes after treatment onset, and was only 77% (CI 68% to 86%), at 60 minutes. Early disagreement was mainly seen when the continuous ST recording showed ST recovery from a delayed peak ST elevation after the pretreatment static electrocardiogram or when dynamic ST changes suggesting cyclic reperfusion occurred. Continuous ST-segment recovery analysis appears to be as accurate as the most accurate static methods. Continuously updated reference points appear to give important additional information when ST recovery follows a delayed peak ST elevation or when re-elevation occurs, suggesting cyclic flow changes. Such findings appear to affect about half of patients with acute myocardial infarction treated with intravenous thrombolysis, particularly early after administration of therapy.

Genomic fingerprinting of Neisseria meningitidis associated with group C meningococcal disease in Canada

A single electrophoretic type (ET15) of Neisseria meningitidis has been associated with an increased incidence of group C meningococcal disease in Canada. Genomic fingerprinting through pulsed-field gel electrophoresis of chromosomal DNA was used to characterize the clonal relationship among meningococcal isolates of different electrophoretic types and among isolates within ET15. The genomic fingerprints of the ET15 isolates, while similar as a group, were sufficiently distinct to confirm linkage for four pairs of strains from focal outbreaks and differed markedly from those of the other common electrophoretic types, ET5, ET9, and ET21.

Partially structured self-associating states of acidic fibroblast growth factor

A combination of near- and far-UV circular dichroism, Fourier-transform infrared spectroscopy, tryptophan fluorescence, size-exclusion chromatography, and a fluorescent extrinsic hydrophobic probe has been employed to characterize partially structured states of human recombinant acidic fibroblast growth factor (aFGF). At low pH, the addition of specific polyanionic ligands or moderate amounts of salts induces states with high secondary but low tertiary structure content. At neutral pH, intermediate amounts of chaotropic agents impose similar partially structured conformational states which also display noncooperative unfolding transitions. Kinetic evidence indicates that similar forms of the protein exist in the first few hundred milliseconds in the refolding pathway of aFGF. The kinetics of their formation appear to be temperature-independent, implying lack of an energy barrier, which is characteristic for further slow folding into the native state. Unlike the native and fully unfolded states, these partially structured conformations exhibit very low solubility, resulting in irreversible aggregation. Potential physiological implications of the existence of such "molten globule" states with regard to the growth factor's transport and biological activity are considered.

Continuous 12-lead ST-segment recovery analysis in the TAMI 7 study. Performance of a noninvasive method for real-time detection of failed myocardial reperfusion

BACKGROUND

If a practical, reliable, noninvasive marker of failed reperfusion was available in real time, the benefits of further therapy in this patient subgroup could be tested. We developed a method of 12-lead ST-segment recovery analysis using continuously updated reference points to provide such a marker.

METHODS AND RESULTS

In this study, our method was prospectively tested in 144 patients given thrombolytic therapy early in myocardial infarction. All patients had 12-lead continuous ST-segment monitoring and acute angiography, each analyzed in an independent, blinded core laboratory. ST-segment recovery and re-elevation were analyzed up to the moment of angiography, at which time patency was predicted. Predictions were correlated to angiographic infarct artery flow, with TIMI flow 0 to 1 as occluded and TIMI flow 2 to 3 as patent. Infarct artery occlusion was seen on first injection in 27% of patients. The positive predictive value of incomplete ST recovery or ST re-elevation by our method was 71%, negative predictive value 87%, with 90% specificity and 64% sensitivity for coronary occlusion. ST recovery analysis predicted patency in 94% of patients with TIMI 3 flow versus 81% of patients with TIMI 2 flow and predicted occlusion in 57% of patients with collateralized occlusion versus 72% of patients with non-collateralized occlusion. In a regression model including other noninvasive clinical descriptors, ST recovery alone contained the vast majority of predictive information about patency.

CONCLUSIONS

In a blinded, prospective, angiographically correlated study design, 12-lead continuous ST-segment recovery analysis shows promise as a practical noninvasive marker of failed reperfusion that may contribute substantially to currently available bedside assessment. Our data also suggest that patients with TIMI 2 flow or with collateralized occlusions may represent a physiological spectrum definable with ST-segment recovery analysis.

Structure of synthetic peptide analogues of an eggshell protein of Schistosoma mansoni

The peptide (Gly-L-Tyr-L-Asp-L-Lys-L-Tyr)6, referred to as F4-6, was synthesized as a model for a schistosome eggshell protein in which the Gly-Tyr-Asp-Lys-Tyr consensus sequence is repeated over 40 times. Analysis by CD, Fourier transform infrared spectroscopy, potentiometric and spectrophotomertric titrations, NMR, and molecular modeling suggests that F4-6 forms some type of left-handed structure. A likely possibility appears to be a left-handed alpha-helix stabilized by Lysi-Aspi +4 salt bridges and possibly Aspi-Tyri +4 hydrogen bonding and Tyr-Tyr interactions. Spectroscopic studies of a number of F4-6 analogues support this conclusion. For example, substitution of D-Ala for Gly produces a peptide with enhanced left-handed helical spectral characteristics, whereas an L-Ala substitution results in a peptide with minimal structure. These studies suggest that the F4 protein from Schistosoma mansoni may be the first example of a naturally occurring protein devoid of proline and carbohydrate that forms a left-handed helix composed of L-amino acids, although alternative forms of other left-handed structures have yet to be rigorously excluded.

Diagnosis and staging of pancreatic adenocarcinoma with dynamic computed tomography

We assessed the accuracy of dynamic contrast-enhanced computed tomography (CT) in the diagnosis and staging of 213 patients with pancreatic carcinoma and compared it with the accuracy of angiography and surgery. A correct CT diagnosis of pancreatic carcinoma was made in 207 of 213 (97%) patients. Tumors were located in the pancreatic head in 64%, the body in 22%, and the tail in 10%, and enlarged the pancreas diffusely in 4%. CT staged 25 (12%) patients as having potentially resectable tumors and 188 (88%) as having unresectable tumors on the basis of local extension (72%), contiguous organ invasion (43%), vascular invasion (82%), and distant metastases (50%). Compared with angiography in 60 patients, CT detected vascular invasion missed on angiography in 20%, and angiography detected invasion missed by CT in 5%. In these latter cases, other CT criteria of unresectability were present, and angiography provided no significant staging information. Compared with surgery in 71 patients, CT accurately predicted unresectable tumors in 100% of patients and resectable tumors in 72% of patients. Eleven of the patients with CT-resectable tumors underwent resection. Median survival was 22.7 months, with four patients alive at a median of 15.5 months postoperatively. Palliative resections were performed in six patients, and median survival was 14.4 months.

Endoscopic retrograde cholangiopancreatography after laparoscopic cholecystectomy

We assessed the use of endoscopic retrograde cholangiopancreatography (ERCP) after laparoscopic cholecystectomy (LC) at our hepatobiliary referral center. This assessment included patients from outside institutions with post-LC problems. Between May 1990 and September 1992, we performed 522 LCs and 1,723 ERCP examinations. There were 78 patients who underwent 143 ERCP examinations after LC, 65% of whom were referred. ERCP findings were categorized as follows: normal results (8%), problems inherent to stone disease (65%), and iatrogenic injury (27%). The types of inherent problems were common bile duct (CBD) stones, pancreatitis, and papillary stenosis/microlithiasis. Within the CBD stone group, 5 of 26 patients also had papillary stenosis, and, within the pancreatitis group, 9 of 11 patients also had papillary stenosis, making papillary stenosis the most frequent observation (55%). Almost all of these patients (96%) required endoscopic papillotomy for successful treatment. The iatrogenic injury group was comprised of 21 patients, 16% of whom had cystic duct leak and 84% of whom had CBD injury. These patients required a variety of endoscopic procedures including endoscopic papillotomy (67%), CBD endoscopic stenting (76%), percutaneous drainage of biloma (29%), and percutaneous transhepatic biliary drainage (24%). Open surgical procedures after endoscopic assessment or treatment were required in only three patients in the iatrogenic group and in none in the inherent group. At this time, long-term follow-up is not possible with regard to biliary stricture. We conclude that the majority of problems after LC are either due to papillary stenosis/microlithiasis with or without CBD stones or to biliary injury. Both can be successfully diagnosed and treated with endoscopic techniques.

Preoperative visceral angiography alters intraoperative strategy during the Whipple procedure

To determine the importance of preoperative visceral angiography prior to pancreaticoduodenectomy, all Whipple procedures performed between 1985 and 1991 at the Virginia Mason Medical Center were retrospectively reviewed. During this period, 77 pancreaticoduodenectomies were performed for both neoplastic disease (n = 54, 70%) and chronic pancreatitis (n = 23, 30%). Sixty-four preoperative angiograms were obtained, of which 39 (61%) were abnormal findings. Thirty percent (19 of 64) of the angiograms revealed a significant vascular abnormality that required specific preoperative or intraoperative measures that might not have been performed without knowledge of these findings. Examples include celiac axis revascularization for celiac occlusion, hepatic artery preservation for replaced vessels, preoperative embolization for pseudoaneurysm or arteriovenous fistula, and splenectomy for splenic vein thrombosis. Because of the high percentage of significant findings requiring an intraoperative or preoperative technical change, we recommend the use of angiography in order to diminish morbidity in all patients preparing to undergo pancreaticoduodenectomy.

Development of monoclonal antibodies for the detection of Mycoplasma pneumoniae

Mycoplasma pneumoniae-specific monoclonal antibodies were constructed for the purpose of developing reagents for clinical diagnostics. The monoclonal antibodies, designated Mp2B12 and Mp3A11, recognize surface exposed antigens of 28 kDa and 170 kDa, respectively. Mp3A11 recognizes an epitope on a cytadhesin molecule, P1, which is not shared on the analogous cytadhesin of M. genitalium. Both monoclonal antibodies are capable of detecting 1 x 10(5) M. pneumoniae in a standard ELISA test.

Nature of the interaction of growth factors with suramin

Suramin inhibits the binding of a variety of growth factors to their cell surface receptors. The direct interaction of suramin with acidic fibroblast growth factor has been detected by the enhancement of the drug's fluorescence in the presence of the protein with the maximum effect occurring at a molar ratio of suramin to aFGF of 2:1. This interaction stabilizes aFGF to thermal denaturation and partially protects a free thiol in its polyanion binding site from oxidation. The binding of suramin to aFGF also induces aggregation of the growth factor to at least a hexameric state as detected by static and dynamic light scattering as well as by gel filtration studies. Both CD and amide I' FTIR spectra of aFGF in the presence and absence of suramin suggest that the drug may also be causing a small conformational change in the growth factor. Suramin produces an even greater aggregation of bFGF and PDGF but not of EGF or IGF-1. Evidence for a suramin-induced conformational change in IGF-1 but not EGF is found by CD, however. It is concluded that suramin binds to many growth factors and that this induces microaggregation and, in some cases, conformational changes. In the case of aFGF, suramin interacts at or near its heparin binding site. The relationship between these phenomena and the anti-growth factor activity of suramin remains to be clearly elucidated.

Structural implications of spectroscopic characterization of a putative zinc finger peptide from HIV-1 integrase

The N-terminal domain of human immunodeficiency virus (HIV-1) integrase (IN) contains the sequence motif His-Xaa3-His-Xaa23-Cys-Xaa2-Cys, which is strongly conserved in all retroviral and retrotransposon IN proteins. This structural motif constitutes a putative zinc finger in which a metal ion may be coordinately bound by the His and Cys residues. A recombinant peptide, IN(1-55), composed of the N-terminal 55 amino acids of HIV-1 IN was expressed in Escherichia coli and purified. Utilizing a combination of techniques including UV-visible absorption, circular dichroism, Fourier transform infrared, and fluorescence spectroscopies, we have demonstrated that metal ions (Zn2+, Co2+, and Cd2+) are bound with equimolar stoichiometry by IN(1-55). The liganded peptide assumes a highly ordered structure with increased alpha-helical content and exhibits remarkable thermal stability. UV-visible difference spectra of the peptide-Co2+ complexes directly implicate thiols in metal coordination, and Co2+ d-d transitions in the visible range indicate that Co2+ is tetrahedrally coordinated. Mutant peptides containing conservative substitutions of one of the conserved His or either of the Cys residues displayed no significant Zn(2+)-induced conformational changes as monitored by CD and fluorescence spectra. We conclude that the N terminus of HIV-1 IN contains a metal-binding domain whose structure is stabilized by tetrahedral coordination of metal by histidines 12 and 16 and cysteines 40 and 43. A preliminary structural model for this zinc finger is presented.