Churg-Strauss syndrome presenting with pulmonary capillaritis and diffuse alveolar hemorrhage

Churg-Strauss syndrome (CSS) is a rare disorder characterized by the histopathological triad of systemic necrotizing vasculitis, extravascular granuloma, and eosinophilic infiltrate, occurring in individuals with asthma or a history of allergy. We report a case of CSS with rare presentation of diffuse pulmonary hemorrhage. A transbronchial lung biopsy showed necrotizing vasculitis, pulmonary capillaritis, and prominent eosinophilic infiltrate. At autopsy, necrotizing granuloma and diffuse alveolar hemorrhage were found in the lungs. Laboratory data showed hypereosinophilia, disseminated intravascular coagulopathy, and positive anti-proteinase 3 antineutrophil cytoplasmic antibody (ANCA). This case emphasize that CSS should be considered in the differential diagnosis of ANCA-positive vasculitis with diffuse alveolar hemorrhage.

Electrostatics, allostery, and activity of the yeast chorismate mutase

The predicted active site of chorismate mutase of baker's yeast Saccharomyces cerevisiae has been studied by continuum electrostatics, molecular surface/volume calculations, and molecular modeling. Our study shows that despite being subject to an allosteric transition, the enzyme's active-site pocket neither decreased in volume nor deformed significantly in shape between the active R state and the inactive T state. We find that the polar atmosphere in the pocket is responsible for the enzyme's affinity. A single amino acid, Glu23, can adequately account for the atmospheric variation. This residue swings into the active-site pocket from the R state to the T state. In the R state, Glu23 on helix H2 doubly pairs with Arg204 and Lys208 of H11, which is packed against H2. In the T state, a slide occurs between H11 and H2 such that Glu23 can no longer interact with Lys208 and competes with Asp24 for interacting with Arg204. Consequently, Glu23 is found in the T state to couple with Arg157, an active-site residue critical to substrate binding. The tandem sliding of H11 in both monomers profoundly changes the interactions in the dimer interface. The loop between H11 and H12 demonstrates the largest conformational change. Hence, we establish a connection between the allosteric transition and the activity of the enzyme. The conformational change in the transition is suggested to propagate into the active-site pocket via a series of polar interactions that result in polarity reversal in the active-site pocket, which regulates the enzyme's activity.

Absence of a seasonal variation in myocardial infarction onset in a region without temperature extremes

To evaluate whether the incidence of acute myocardial infarction (AMI) attack would have circadian, weekly and monthly variations in a subtropical area, 540 consecutive patients with AMI who were admitted to our coronary care units were analyzed. Six-hour intervals over 24 h, daily intervals in a week (7 days) and monthly intervals in a year (12 months) were studied, respectively. Results showed that there was a circadian variation in the onset of AMI with a morning (6 a.m. to noon) peak (34%, p < 0.01) but no secondary late evening (18-24 p.m.) peak. The incidence of AMI was significantly lower on Sundays (9%) than on the other weekdays (Monday through Saturday; p < 0.05). However, no monthly and seasonal variations in the incidence of AMI (no winter or summer peaks) were observed in this series. This study demonstrated a circadian variation in the onset of AMI attack with a predominant morning peak. The fewer AMI cases on Sundays compared to the other weekdays suggested that freedom from 'stress' or 'work-load' on Sundays might have an important impact on this low incidence of AMI. Unlike the large ranges in cold or hot weather found in temperate regions, the warm climate of a subtropical region does not affect the frequency of AMI.

Primary intracranial leiomyoma: case report

We present a case of intracranial parenchymal leiomyoma in a 20-year-old woman with a chief complaint of numbness and a painful sensation over the right limbs for several years. CT and MRI revealed an intensely enhancing calcified mass. The patient was well, without recurrence, 2 years after surgery.

Molecular shape comparisons in searches for active sites and functional similarity

Here we examine the reliability of surface comparisons in searches for active sites in proteins. Detection of a patch of surface on one protein which is similar to an active site in another, may suggest similarities in enzymatic mechanisms, in enzyme functions and implicate a potential target for ligand/inhibitor design. Specifically, we compare the efficacy of molecular surface comparisons with comparisons of surface atoms and of C(alpha) backbone atoms. We further investigate comparisons of specific atoms, belonging to a predefined pattern of catalytic residues versus comparisons of molecular surfaces and, separately, of surface atoms. This aspect is particularly relevant, as catalytic residues may be (partially) buried. We also explore active site comparisons versus comparisons in which the entire molecular surfaces are scanned. While here we focus on the geometrical aspect of the problem, we also investigate the effect of adding residue labels in these comparisons. Our extensive studies cover the serine proteases, containing the highly conserved triad motif, and the chorismate mutases. Since such active site comparisons entail comparisons between unconnected points in 3D space, an order-independent comparison technique is necessary. The geometric hashing algorithm is ideally suited to handling such a task. It can perform both global shape matching for the whole surfaces of large protein molecules and searching for local shape similarities for small surface motifs. Our results show that molecular surface comparisons work best when the similarity is high. As the similarity deteriorates, the number of potential solutions increases rapidly, making their ranking difficult, particularly when scanning entire molecular surfaces. Utilizing atomic coordinates directly appears more adequate under such circumstances.

Spindle cell carcinoma of the lung: a clinicopathologic presentation of three cases

Three patients with spindle cell carcinoma located in the lower respiratory tract are presented, including cases of two monophasic and one biphasic tumor. On light microscopic examination, the spindle cell components of the tumors were histologically characterized by sheets of fusiform spindle cells that closely resembled a sarcoma. Keratin expression in the spindle cell components of these tumors, as shown by anti-cytokeratin antibody staining, demonstrated their epithelial nature. It is supposed that the spindle cell component displays a spectrum of phenotypes originating from epithelial cells with varying degrees of mesenchymal transformation. It is difficult to establish a diagnosis of this rare primary pulmonary malignancy prior to surgical intervention. A review of the literature allowed for a summary of the clinicopathologic characteristics of this tumor.

Role of UEV-1, an inactive variant of the E2 ubiquitin-conjugating enzymes, in in vitro differentiation and cell cycle behavior of HT-29-M6 intestinal mucosecretory cells

By means of differential RNA display, we have isolated a cDNA corresponding to transcripts that are down-regulated upon differentiation of the goblet cell-like HT-29-M6 human colon carcinoma cell line. These transcripts encode proteins originally identified as CROC-1 on the basis of their capacity to activate transcription of c-fos. We show that these proteins are similar in sequence, and in predicted secondary and tertiary structure, to the ubiquitin-conjugating enzymes, also known as E2. Despite the similarities, these proteins lack a critical cysteine residue essential for the catalytic activity of E2 enzymes and, in vitro, they do not conjugate or transfer ubiquitin to protein substrates. These proteins constitute a distinct subfamily within the E2 protein family and are highly conserved in phylogeny from yeasts to mammals. Therefore, we have designated them UEV (ubiquitin-conjugating E2 enzyme variant) proteins, defined as proteins similar in sequence and structure to the E2 ubiquitin-conjugating enzymes but lacking their enzymatic activity (HW/GDB-approved gene symbol, UBE2V). At least two human genes code for UEV proteins, and one of them, located on chromosome 20q13.2, is expressed as at least four isoforms, generated by alternative splicing. All human cell types analyzed expressed at least one of these isoforms. Constitutive expression of exogenous human UEV in HT-29-M6 cells inhibited their capacity to differentiate upon confluence and caused both the entry of a larger proportion of cells in the division cycle and an accumulation in G2-M. This was accompanied with a profound inhibition of the mitotic kinase, cdk1. These results suggest that UEV proteins are involved in the control of differentiation and could exert their effects by altering cell cycle distribution.

Identification of novel farnesyl protein transferase inhibitors using three-dimensional database searching methods

Generation of a three-dimensional pharmacophore model (hypothesis) that correlates the biological activity of a series of farnesyl protein transferase (FPT) inhibitors, exemplified by the prototype 1-(4-pyridylacetyl)- 4-(8-chloro-5,6-dihydro-11H-benzo [5,6]cyclohepta[1,2-b]pyridin-11-ylidene)piperidine, Sch 44342, 1, with their chemical structure was accomplished using the three-dimensional quantitative structure-activity relationship (3D-QSAR) software program, Catalyst. On the basis of the in vitro FPT inhibitory activity of a training set of compounds, a five-feature hypothesis containing four hydrophobic and one hydrogen bond acceptor region was generated. Using this hypothesis as a three-dimensional query to search our corporate database identified 718 compounds (hits). Determination of the in vitro FPT inhibitory activity using available compounds from this "hitlist" identified five compounds, representing three structurally novel classes, that exhibited in vitro FPT inhibitory activity, IC50 < or = 5 microM. From these three classes, a series of substituted dihydrobenzothiophenes was selected for further structure-FPT inhibitory activity relationship studies. The results from these studies is discussed.

Incidence of NIDDM and the effects of gender, obesity and hyperinsulinaemia in Taiwan

Our aim is to determine non-insulin-dependent diabetes mellitus (NIDDM) incidence in Taiwan and examine its relation to obesity and hyperinsulinaemia in Chinese men and women. A total of 995 men and 1195 women aged 35-74 years free from diabetes in two townships in Taiwan were followed up with a second examination. At baseline general and metabolic data were recorded, and detailed anthropometric parameters and plasma glucose and insulin were assessed. World Health Organisation (WHO) criteria of fasting glucose 7.8 mmol/l or greater was utilized for defining diabetes. The age-standardized incidence rate based on the United States population in 1970 was 9.3/1000 (CI 5.8-12.8) in men and 9.3/1000 (CI 6.2-12.4) in women and the based on the WHO population in 1976 was 8.9/1000 (CI .5-12.3) in men and 8.9/1000 (CI 5.9-11.9) in women for the Chinese who had a mean BMI slightly greater than 24 (kg/m2). The predictability of the plasma glucose level was greater than that of the insulin level and the obesity indices. NIDDM incidence increased approximately threefold with each 0.67 mmol/l increase in plasma glucose level in men and women. The present study demonstrated the essential relationship of not only BMI but also central obesity indices (such as subscapular and waist circumference) to the incidence of NIDDM among men and women and a stronger relationship between NIDDM incidence and obesity in women than in men. The predictive effects of obesity indices and fasting plasma insulin values on NIDDM risk were independent of each other in men. Obesity and hyperinsulinaemia each without the presence of the other can lead to an increased risk of NIDDM. In women the NIDDM incidence increased more than additively in those with both obesity and hyperinsulinaemia compared to those with single obesity or hyperinsulinaemia. A slightly higher incidence of NIDDM in Taiwan than in western countries was found. The importance of obesity is indicated for predicting NIDDM in the community. Hyperinsulinaemia was found to play a significant role in predicting NIDDM incidence independent of obesity in men and synergistically with obesity in women.

Minimally-invasive early prenatal diagnosis using fluorescence in situ hybridization on samples from uterine lavage

A two-phase study was undertaken to examine the efficiency of using transcervical cells (TCCs) collected by uterine lavage and fluorescence in situ hybridization (FISH) for early prenatal diagnosis of fetal chromosome aneuploidy. Uterine lavage was performed in 50 women scheduled for elective termination of pregnancy (TOP, n = 35) or chorionic villus sampling (CVS, n = 15) between 6 and 11 weeks of gestation. TCCS were dissociated by trypsin and collagenase, and interphase FISH was carried out for chromosomes X, Y, 13/21, and 18. The phase I study comprised 36 women. The FISH results were compared with the cytogenetic analysis from long-term culture of villus samples collected at TOP or CVS. Among the 36 samples, 15 had a normal male karyotype and 21 had a normal female karyotype. FISH on TCCs correctly identified 13 out of the 15 pregnancies with a male fetus. In phase II, uterine lavage was performed on 14 women. The samples were first tested for the presence of trophoblasts with an anti-trophoblast antibody, GB25, by immunohistochemical staining. Among 12 GB25-positive samples, the FISH results corresponded to the fetal karyotype. One of the GB25-positive samples had five signals for the chromosome 13/21 probe. The cytogenetic analysis confirmed that the fetus had a karyotype of 47, XX, +21. In the GB25-negative samples, FISH failed to identify one male pregnancy. Follow-up was carried out on 13 ongoing pregnancies and no maternal or fetal complications were discovered. This study demonstrates that fetal chromosome numeration can be carried out using FISH on uterine lavage samples in early pregnancy. However, a specific fetal cell marker, such as specific anti-trophoblast antibody, is necessary to avoid a false-negative result.

Predicting the outcome of hemodialysis arteriovenous fistulae using duplex ultrasonography

Duplex ultrasonography is a reliable method for assessing the anatomic features and blood flow rate of a vascular access point of hemodialysis. We assessed the value of measurement of cross-sectional area and blood flow rate of the major outflow veins using duplex ultrasonography in predicting the outcome of fistulae. Radiocephalic arteriovenous fistulae were created in 126 consecutive end-stage renal failure patients (55 men, 71 women; aged 20-83 yr) and examined using duplex ultrasonography in the second week following surgery. Examinations were repeated in 45 of the 126 fistulae in the third week. The outcome of new fistulae was classified as success or failure. The failure group fistulae were further classified as delayed maturation or primary failure. The cross-sectional area (12.1 +/- 3.5 vs 6.9 +/- 2.4 mm2) and blood flow rate (825.6 +/- 424.3 vs 303.7 +/- 114.5 mL/min) were significantly lower in the failure group, but there was no difference between the subgroups of primary failure and delayed maturation. Receiver-operating characteristic plots were generated for cross-sectional area and blood flow rate. The best cut-off point for distinguishing successful outcome from failure was 8.5 mm2 for cross-sectional area (sensitivity 0.823, specificity 0.867, positive predictive value 0.952, negative predictive value 0.605) and 425 mL/min for blood flow rate (sensitivity 0.813, specificity 0.933, positive predictive value 0.975, negative predictive value 0.609). Our findings show the cross-sectional area and blood flow rate, as measured using duplex ultrasonography, are useful in predicting the outcome of vascular access points of hemodialysis.

Reference spirometric values in healthy Chinese neversmokers in two townships of Taiwan

The present community-based study was performed to provide predictive equations and lower boundaries of normal values for forced expiratory volume in one second (FEVI), forced vital capacity (FVC), and their percent ratio (FEV1%) in non-smoking, healthy adult men and women residing in communities, using ATS-recommended techniques and equipment. Use was made of data collected cross-sectionally from Nov. 1990 to Dec. 1993 in an ongoing longitudinal study on evolution of cardiovascular disease risk factors in Chinese. The spirometric values in our population reached their peak at around age 20. After age 20, a downward age trend was observed for FVC, FEV1, and FEV1%. Linear and negative relations were found in adults for each of the three spirometric values with age. Linear and positive relations were found between height and FVC or FEV1, but not between height and FEV1%. The age trends of FVC and FEV1 in Chinese adults were similar to those in Caucasians. Mean FVC and FEV1 levels of Chinese in Taiwan were systematically lower than those of Caucasians for a given height and a given age. Age and height specific percentile values of FVC and FEV1 and the age-specific percentile value of FEV1% are provided for adult men and women in this community study.

Investigation of the enzymatic mechanism of the yeast chorismate mutase by docking a transition state analog

The structure of the complex of the chorismate mutase from the yeast Saccharomyces cerevisiae with a transition state analog is constructed using a suite of docking tools. The construction finds the best location for the active site in the enzyme, and the best orientation of the analog compound in the active site. The resulting complex shows extensive salt links and hydrogen bonds between the enzyme and the compound, including those mediated by water molecules. A network of polar interactions between amino acid residues is found to solidify the active site of the enzyme. The enzymatic mechanism suggested for a bacterial chorismate mutase, that the active site is by design capable of selecting an active conformer of the substrate, and of stabilizing the transition state, is apparently intact in the yeast enzyme. No direct evidence is found to support an alternative mechanism which involves specific catalytic groups, although the possibility is not eliminated. This finding reinforces the notion of a function being evolutionarily conserved via a common mechanism, rather than via sequential or structural homology.

Salmonella typhimurium brain abscess in a six-month-old infant: a case report and review of the literature

We report the case of a six-month-old male infant with brain abscess caused by Salmonella typhimurium. Upon admission, he was suffering from fever, diarrhea, drowsiness and convulsion. Salmonella meningitis was identified by CSF examination. Following failure of antibiotic therapy to control his fever, brain computerized tomography (CT) was ordered 5 days later and revealed a brain abscess. He received surgical excision of the abscess and recovered completely after receiving ceftriaxone therapy for 8 weeks. The case of our patient, together with 11 cases of Salmonella brain abscess from the English literature are reviewed. There was a male preponderance among these patients (male: female = 2.67 : 1) and the majority were less than one year old. Salmonella typhimurium, typhi, and enteritidis occurred most frequently. Fever, seizure, signs and symptoms of increased intracranial pressure and change in mental status were the most common clinical features. Purulent meningitis was a major predisposing factor. Successful treatment was associated with early identification, prompt surgical intervention, high dose, long-term antibiotic therapy, and close follow-up for possible recurrence and to determine the presence of neurological sequelae.

CROC-1 encodes a protein which mediates transcriptional activation of the human FOS promoter

The cloning of signal transducing molecules capable of activating the human FOS proto-oncogene promoter was achieved by co-transfecting a modified human FOS promoter-driven polyomavirus large T antigen gene (P(f)LAG-8) with a human brain cDNA library, incorporated into a replication-competent mammalian retroviral expression vector whose replication occurs in the presence of T antigen. In murine cells, transcriptional activation of the P(f)LAG-8 promoter by a biologically active, cDNA-encoded signalling molecule resulted in plasmid replication. Replicated plasmids, following selective cleavage of unreplicated plasmids by Dpn1, were recovered by transformation into competent bacteria. Successive P(f)LAG-8/cDNA library co-transfections, using library plasmids resulting from prior transfections, ultimately resulted in the identification of individual plasmids capable of transcriptionally activating the FOS promoter. DNA sequencing revealed the first plasmid, denoted CROC-1, to contain a 1.8-kb cDNA encoding a 16.5-kDa nuclear protein possessing a bipartite structure comprised an amino-terminal acidic domain and a carboxy-terminal basic domain, and displaying partial homology to the HMG domain of the TAF(II)250 transcription cofactor. Co-transfection of CROC-1 with various FOS/CAT reporter genes revealed that the human FOS promoter region spanning -56 to - 105, encompassing two identical 8-bp DR enhancer sequences, was necessary for CROC-1-mediated transcriptional activation. Results suggest that CROC-1 participates in intracellular signalling pathways involved in induction of the human FOS promoter.

The relation between thickened aortic valve and coronary artery disease

BACKGROUND

The relationship between the site of aortic valve thickening and ipsilateral coronary artery stenosis has not been reported previously. This study was undertaken to test the hypothesis that left-sided coronary cusp thickening may be associated with a left-sided coronary artery stenosis, and also as would be in the right-sided relationship.

METHODS

Two-dimensional echocardiography and cardiac catheterization were used to evaluate 420 consecutive patients. One hundred and six patients who had echocardiographic evidence of a single aortic valve thickening were studied to determine whether there was a relation between the coronary artery stenosis and the aortic valve thickening at the same side. Thickened aortic valve was defined as an aortic valve thickness to aortic wall thickness ratio > or = 1.0. Coronary artery disease (CAD) was defined as a > 50% luminal diameter narrowing of the left main coronary artery or a > 70% luminal diameter narrowing of the coronary artery other than the left main coronary artery.

RESULTS

Patients with a thickened aortic valve had a greater incidence of CAD (89/132, 67.4%) than those without (141/288, 49.0%) (p < 0.05). In patients with thickened aortic valves, the incidence of CAD was 45.5% in the fifth decade, 60% in the sixth decade, 69.6% in the seventh decade and 74.1% in the eighth decade. Progressive increase of the incidence of CAD was not found in patients without a thickened aortic valve. In the 106 cases with a single aortic valve thickening, 30 patients (28.3%) had a left coronary cusp thickening; 12 of them (40%) had a left-sided coronary artery stenosis, 3 patients (10%) had right coronary artery stenosis and 7 patients (23.3%) had no coronary artery stenosis. In the 34 patients with right coronary cusp thickening, the stenosis occurred at the left coronary artery in 13 patients (38.2%), at the right coronary artery in 3 patients (8.8%) and with normal coronary artery in 5 patients (14.7%). This finding did not support the relationship between thickened aortic valve and coronary artery disease at the same side (chi 2 = 0.06, p = 0.96).

CONCLUSIONS

There was a significantly greater incidence of CAD in patients with a thickened aortic valve than in those without. The incidence of CAD in patients with thickened aortic valves increased with age. There was no direct relationship observed between the site of aortic valve thickening and ipsilateral coronary artery stenosis.

Transitional cell and uncommon urothelial carcinoma of renal pelvis/ureter and bladder: low incidence of human papilloma virus

BACKGROUND

Recently, it has been proposed that human papilloma virus (HPV) infection may play a role in the carcinogenesis of bladder urothelial malignancy. However, there is still controversy about the prevalence of HPV in such malignancies. With similar techniques of in situ hybridization (ISH) or polymerase chain reaction (PCR), either high or rare frequency have been detected. To evaluate the prevalence of HPV in the urothelial malignancies based on presentations here, 118 cases of urothelial malignancies were analysed, including those of the renal pelvis and ureter which have rarely been reported before.

METHODS

Non-isotopic ISH technique was used to detect HPV on paraffin sections, including 51 bladder transitional cell carcinoma (TCC), 48 renal pelvic/ureter TCC, 5 bladder adenocarcinoma, 3 bladder small cell carcinoma, 2 bladder undifferentiated carcinoma, 1 multiple synchronous pelvic and ureteric squamous cell carcinoma (SCC) and 8 bladder SCC. An FITC-labelled probe of wide spectrum HPV was used for screening, and probes of HPV 6/11, 16, 18, 31, 33 were used for typing.

RESULTS

By the technique of ISH, wide spectrum HPV was detected in only three of the eight cases of bladder SCC. Of the three positive cases, two were subsequently shown to be uterine cervical SCC with bladder invasion. Therefore, HPV was positive in only one case of primary bladder SCC, occurring in a patient with systemic lupus erythematosus under steroid and cyclophosphamide therapy. Further subtyping was negative for HPV 6/11, 16, 18, 31, and 33. The result indicated that the positive staining by wide spectrum probe was caused by types 30, 35, 45, 51, and/or 52. HPV was not detected in any of the 51 bladder TCC, 48 renal pelvic/ ureter TCC, 5 bladder adenocarcinoma, 3 bladder small cell carcinoma, and 2 bladder undifferentiated carcinoma.

CONCLUSIONS

The results are in agreement with the majority of recent reports which suggest that HPV is unlikely to be involved in the etiology of urothelial malignancies; however, it seems probable that immunosuppressed patients are at greater risk for HPV-associated bladder SCC.

Three-dimensional model of sensory rhodopsin I reveals important restraints between the protein and the chromophore

A structural model is constructed for the integral membrane protein, sensory rhodopsin I (SRI), the phototaxis receptor of the archaeon Halobacterium salinarium. The model is built on the template of the homologous bacteriorhodopsin (BR). The modeling procedure includes sequence alignment, a side chain rotamer search and simulated annealing by restricted molecular dynamics. The structure is in general agreement with previous results from mutagenesis experiments, chromophore substitution and room and cryogenic temperature spectroscopy. In particular, a residue near the beta-ionone ring of the retinylidene chromophore is found to be critical in maintaining the proper isomeric conformation of the chromophore; a layer of residues lying on the cytoplasmic side of the chromophore pocket is found to modulate the restraints around the C13 region of the chromophore, affecting the isomerizations around its 13 = 14 bond that are important to the protein's activity. The restraints in these regions are more stringent in SRI than in BR. The tightened restraints are chiefly due to van der Waals interactions, where the attractive and repulsive components play separable roles. Aromatic residues account for a majority of the restrictive interactions. It is hypothesized that the enhanced barriers due to these restrictions regulate the progress of SRI's photocycle, so that it can couple with the phototaxis reaction chain in the bacterium. A possibility is also suggested that conformational changes of the protein provide the signal recognized by the transducer.

Factors related to detection of blood flow by color Doppler ultrasonography in intussusception

Color Doppler ultrasonography was performed in 125 patients with 134 intussusceptions. Color flow was present in 121 cases of intussusception (group A) and was absent in 13 cases (group B). Young age and duration of symptoms greater than 48 hr were significantly related to the nonvisualization of blood flow detected by color Doppler sonography (P < 0.05). The successful rate of air reduction was significantly higher in group A than in group B (109 of 121 versus 4 of 13). Color Doppler ultrasonography is useful to predict the reducibility of an intussuscepted intestine. The nonvisualization of blood flow by this method is not a contraindication for air reduction.

Protein binding versus protein folding: the role of hydrophilic bridges in protein associations

The role of hydrophilic bridges between charged, or polar, atoms in protein associations has been examined from two perspectives. First, statistical analysis has been carried out on 21 data sets to determine the relationship between the binding free energy and the structure of the protein complexes. We find that the number of hydrophilic bridges across the binding interface shows a strong positive correlation with the free energy; second, the electrostatic contribution of salt bridges to binding has been assessed by a continuum electrostatics calculation. In contrast to protein folding, we find that salt bridges across the binding interface can significantly stabilize complexes in some cases. The different contributions of hydrophilic bridges to folding and to binding arise from the different environments to which the involved hydrophilic groups are exposed before and after the bridges are formed. These groups are more solvated in a denatured protein before folding than on the surface of the combining proteins before binding. After binding, they are buried in an environment whose residual composition can be much more hydrophilic than the one after folding. As a result, the desolvation cost of a hydrophilic pair is lower, and the favorable interactions between the hydrophilic pair and its surrounding residues are generally stronger in binding than in folding. These results complement our recent finding that while hydrophobic effect in protein-protein interfaces is significant, it is not as strong as that observed in the interior of monomers. Taken together, these studies suggest that while the types of forces in protein-protein interaction and in protein folding are similar, their relative contributions differ. Hence, association of protein monomers which do not undergo significant conformational change upon binding differs from protein folding, implying that conclusions (e.g. statistics, energetics) drawn from investigating folding may not apply directly to binding, and vice versa.

Studies of protein-protein interfaces: a statistical analysis of the hydrophobic effect

Data sets of 362 structurally nonredundant protein-protein interfaces and of 57 symmetry-related oligomeric interfaces have been used to explore whether the hydrophobic effect that guides protein folding is also the main driving force for protein-protein associations. The buried nonpolar surface area has been used to measure the hydrophobic effect. Our analysis indicates that, although the hydrophobic effect plays a dominant role in protein-protein binding, it is not as strong as that observed in the interior of protein monomers. Comparison of interiors of the monomers with those of the interfaces reveals that, in general, the hydrophobic amino acids are more frequent in the interior of the monomers than in the interior of the protein-protein interfaces. On the other hand, a higher proportion of charged and polar residues are buried at the interfaces, suggesting that hydrogen bonds and ion pairs contribute more to the stability of protein binding than to that of protein folding. Moreover, comparison of the interior of the interfaces to protein surfaces indicates that the interfaces are poorer in polar/charged than the surfaces and are richer in hydrophobic residues. The interior of the interfaces appears to constitute a compromise between the stabilization contributed by the hydrophobic effect on the one hand and avoiding patches on the protein surfaces that are too hydrophobic on the other. Such patches would be unfavorable for the unassociated monomers in solution. We conclude that, although the types of interactions are similar between protein-protein interfaces and single-chain proteins overall, the contribution of the hydrophobic effect to protein-protein associations is not as strong as to protein folding. This implies that packing patterns and interatom, or interresidue, pairwise potential functions, derived from monomers, are not ideally suited to predicting and assessing ligand associations or design. These would perform adequately only in cases where the hydrophobic effect at the binding site is substantial.

New secoiridoid glucosides from Jasminum lanceolarium

Two new secoiridoid glucosides, the trans-P-coumaroyl and trans-feruloyl esters of 10-hydroxyoleoside, jaslanceosides A (2) and B (3), were isolated from the leaves and stems of Jasminum lanceolarium (Oleaceae) in addition to jasminoside (1) and 10-hydroxyoleoside dimethyl ester (8). The structures of these compounds have been elucidated on the basis of spectral and chemical methods.

Expression of estrogen and progesterone receptors in non-small-cell lung cancer: immunohistochemical study

Estrogen receptor (ER) and progesterone receptor (PgR) have been recognized as being involved in the tumourigenesis of non-small-cell lung cancer (NSCLC). Forty-nine resected NSCLC (39 males and 10 females) were studied immunohistochemically in formalin-fixed, paraffin-embedded sections for ER and PgR. There were 26 squamous cell carcinomas, 22 adenocarcinomas and one adenosquamous carcinoma. 38.8% (19/49)NSCLC had either a positive ER or PgR status of which one was ER+/PgR+, 2 were ER+/PgR- and 16 were ER-/PgR+. There was no statistical difference in hormone receptors status for sex and histological subtypes (p > 0.05). The immunohistochemical assay of formalin-fixed paraffin-embedded sections allows the retrospective analysis of ER and PgR in NSCLC. The ER-/PgR+ status was detected in about one third NSCLC. The discordance between these receptors is suggested to be due to either the presence of functioning variant ER or the constitutive synthesis of PgR independent of estrogen induction in certain ER-/PgR+ NSCLC.