Sentinel lymph node BIOPSY after neoadjuvant therapy in breast cancer patients with lymph node involvement at diagnosis. Could wire localization of clipped node improve our results?

INTRODUCTION: Sentinel lymph node biopsy (SLNB) after neoadjuvant therapy (NAT) in node-positive (N+) breast cancer patients at diagnosis remains a controversial issue, with no consensus on implementation or safety. OBJECTIVES: We sought to assess the accuracy of SLNB after NAT in biopsy-proven N+ cases at diagnosis and the efficacy and accuracy of wire localization of the clipped node to improve results. MATERIAL AND METHODS: A cross-sectional diagnostic technique validation study in N+ patients following NAT was performed. The biopsy-proven affected lymph node was clipped at diagnosis. SLNB and axillary lymph node dissection (ALND) were performed in cases of clinical-radiological lymph node response after NAT. For the purposes of our study we added wire localization of the clipped node. RESULTS: 103 patients were included (mean age, 54.4 years [± 12.7]). Wire marking was performed in 28 cases. The overall identification rate (IR) of SLN was 81.6%. The median number of nodes removed was 2 (range 2). The overall false negative rate (FNR) was 6.1%. Sensitivity and overall accuracy were 93.9% and 95.2%, respectively (area under curve 0.97). In the double-marked (clip and wire) group the FNR decreased to 0% and accuracy was 100%. Axillary pathologic complete response was observed in 24.3% of cases. CONCLUSIONS: SLNB is useful in node-positive patients at diagnosis who respond to NAT. Combining this with preoperative wire localization of the biopsied lymph node reduces the FNR without increasing the number of complications.

A structural basis for the preferential binding of hemimethylated DNA by HhaI DNA methyltransferase.

The crystal structure of HhaI methyltransferase complexed with non-palindromic duplex DNA, containing a hemimethylated recognition sequence, and with the cofactor analog S-adenosyl-L-homocysteine (AdoHcy), has been determined. The structure provides an explanation for the stronger affinities of DNA methyltransferases for hemimethylated DNA than for unmethylated or fully methylated DNA in the presence of AdoHcy. The unmethylated target 2'-deoxycytidine flips out of the DNA helix and the CH group at position 5 makes van der Waals' contacts with the sulfur atom of AdoHcy. Selectivity/preference for hemimethylated over fully methylated DNA may thus reflect interactions among the chemical substituent (H or CH3) at the C5 position of the flipped cytosine, protein and the bound AdoHcy. The 5-methyl-2'-deoxycytidine on the complementary strand remains in the DNA helix, with the methyl group almost perpendicular to the carboxylate group of Glu239, which is part of the sequence recognition loop. Thus, selectivity/preference for hemimethylated over unmethylated DNA appears to result largely from van der Waals' contacts between the planar Glu239 carboxylate and the methyl group of the 5-methyl-2'-deoxycytidine. Furthermore, the positive electrostatic potential originating from the bound AdoHcy extends to the DNA phosphate groups flanking the flipped cytosine. The increased binding to DNA by long-range electrostatic interactions should also occur with the methyl donor S-adenosyl-L-methionine.

Universal catalytic domain structure of AdoMet-dependent methyltransferases.

The DNA methyltransferases, M.HhaI and M.TaqI, and catechol O-methyl-transferase (COMT) catalyze the transfer of a methyl group from the cofactor S-adenosyl-L-methionine (AdoMet) to carbon-5 of cytosine, to nitrogen-6 of adenine, and to a hydroxyl group of catechol, respectively. The catalytic domains of the bilobal proteins, M.HhaI and M.TaqI, and the entire single domain of COMT have similar folding with an alpha/beta structure containing a mixed central beta-sheet. The functional residues are located in equivalent regions at the carboxyl ends of the parallel beta-strands. The cofactor binding sites are almost identical and the essential catalytic amino acids coincide. The comparable protein folding and the existence of equivalent amino acids in similar secondary and tertiary positions indicate that many (if not all) AdoMet-dependent methyltransferases have a common catalytic domain structure. This permits tertiary structure prediction of other DNA, RNA, protein, and small-molecule AdoMet-dependent methyltransferases from their amino acid sequences.

Enzymatic C5-cytosine methylation of DNA: mechanistic implications of new crystal structures for HhaL methyltransferase-DNA-AdoHcy complexes.

The refined crystal structures of HhaI methyltransferase complexed with cognate unmethylated or methylated DNA together with S-adenosyl-L-homocysteine, along with the previously-solved binary and covalent ternary structures, offer a detailed picture of the active site at individual stages throughout the reaction cycle. This picture supports and extends a proposed mechanism for C5-cytosine methylation that may be general for the whole family of C5-cytosine methyltransferases. The structures of the two new complexes have been refined to crystallographic R-factors of 0.189 and 0.178, respectively, at 2.7 A resolution. We observe that both unmethylated 2'-deoxycytidine and 5-methyl-2'-deoxycytidine flip out of the DNA helix and fit into the active site of the enzyme. The catalytic sulfur atom of Cys81 interacts strongly with C6. The C5 methyl group of the flipped 5-methyl-2'-deoxycytidine is bent approximately 50 degrees out of the plane of the cytosine ring and towards the sulfur atom of S-adenosyl-L-homocysteine. This unusual position is probably due to partial sp3 character at C5 and C6 and to steric effects of the conserved amino acid residues Pro80 and Cys81. Two water molecules are held near the hydrophobic edge (C5 and C6) of the flipped cytosine by two conserved amino acid residues (Gln82 and Asn304) and the phosphoryl oxygen atom of the phosphate group 3' to the flipped nucleotide, and one of them may serve as the general base for eliminating the proton from C5. Protonation of the cytosine N3 during the methylation reaction may involve Glu119, which itself might be protonated via a water-mediated interaction between the terminal carboxyl group of Glu119 and the amino group of the methionine moiety of S-adenosyl-L-methionine. The cofactor thus plays two key roles in the reaction.

Structure of a binary complex of HhaI methyltransferase with S-adenosyl-L-methionine formed in the presence of a short non-specific DNA oligonucleotide.

We have determined a structure for a complex formed between HhaI methyltransferase (M.HhaI) and S-adenosyl-L-methionine (AdoMet) in the presence of a non-specific short oligonucleotide. M.HhaI binds to the non-specific short oligonucleotides in solution. Although no DNA is incorporated in the crystal, AdoMet binds in a primed orientation, identical with that observed in the ternary complex of the enzyme, cognate DNA, and AdoMet or S-adenosyl-L-homocysteine (AdoHcy). This orientation differs from the previously observed unprimed orientation in the M.HhaI-AdoMet binary complex, where the S+-CH3 unit of AdoMet is protected by a favorable cation-pi interaction with Trp41. The structure suggests that the presence of DNA can guide AdoMet into the primed orientation. These results shed new light on the proposed ordered mechanism of binding and explains the stable association between AdoMet and M.HhaI.

Mechanism of inhibition of DNA (cytosine C5)-methyltransferases by oligodeoxyribonucleotides containing 5,6-dihydro-5-azacytosine.

A key step in the predicted mechanism of enzymatic transfer of methyl groups from S-adenosyl-l-methionine (AdoMet) to cytosine residues in DNA is the transient formation of a dihydrocytosine intermediate covalently linked to cysteine in the active site of a DNA (cytosine C5)-methyltransferase (DNA C5-MTase). Crystallographic analysis of complexes formed by HhaI methyltransferase (M.HhaI), AdoMet and a target oligodeoxyribonucleotide containing 5-fluorocytosine confirmed the existence of this dihydrocytosine intermediate. Based on the premise that 5,6-dihydro-5-azacytosine (DZCyt), a cytosine analog with an sp3-hybridized carbon (CH2) at position 6 and an NH group at position 5, could mimic the non-aromatic character of the cytosine ring in this transition state, we synthesized a series of synthetic substrates for DNA C5-MTase containing DZCyt. Substitution of DZCyt for target cytosines in C-G dinucleotides of single-stranded or double-stranded oligodeoxyribonucleotide substrates led to complete inhibition of methylation by murine DNA C5-MTase. Substitution of DZCyt for the target cytosine in G-C-G-C sites in double-stranded oligodeoxyribonucleotides had a similar effect on methylation by M. HhaI. Oligodeoxyribonucleotides containing DZCyt formed a tight but reversible complex with M.HhaI, and were consistently more potent as inhibitors of DNA methylation than oligodeoxyribonucleotides identical in sequence containing 5-fluorocytosine. Crystallographic analysis of a ternary complex involving M.HhaI, S-adenosyl-l-homocysteine and a double-stranded 13-mer oligodeoxyribonucleotide containing DZCyt at the target position showed that the analog is flipped out of the DNA helix in the same manner as cytosine, 5-methylcytosine, and 5-fluorocytosine. However, no formation of a covalent bond was detected between the sulfur atom of the catalytic site nucleophile, cysteine 81, and the pyrimidine C6 carbon. These results indicate that DZCyt can occupy the active site of M.HhaI as a transition state mimic and, because of the high degree of affinity of its interaction with the enzyme, it can act as a potent inhibitor of methylation.

Structure-based sequence alignment of three AdoMet-dependent DNA methyltransferases.

M.HhaI, M.TaqI and COMT are DNA methyltransferases (MTases) which catalyze the transfer of a methyl group from the cofactor AdoMet to C5 of cytosine, to N6 of adenine and to a hydroxyl group of catechol, respectively. The larger catalytic domains of the bilobal proteins, M.HhaI and M.TaqI, and the entire single domain of COMT have an alpha/beta structure containing a mixed central beta-sheet. These domains have very similar folding. By allowing appropriate 'insertions' or 'deletions' in the backbones of the three structures, it was possible to find more conserved motifs in M.TaqI and COMT. The similarity in protein folding and the equivalence of amino-acid sequences revealed by the structural alignment indicate that many AdoMet-dependent MTases may share a common catalytic domain structure.

Self-structure in schizophrenia.

This study used a set-theoretical model to construct self-perception structures and person-perception structures for 10 recently hospitalized schizophrenic patients, 10 nonschizophrenic patients recently hospitalized for depression, and 10 nonpsychiatric subjects. Overall self-perception structures were significantly less elaborated in the schizophrenic patients when compared with either the psychiatric or the nonpsychiatric comparison group. No comparable differences were found for measures taken from the person-perception structures. The degree of elaboration of self in the particular context of self as psychiatric patient was found to be correlated (r = .74, p less than .01) with Global Assessment Scale ratings of current functional level in the schizophrenic group.

Perception of self and other in major depression.

Previous research on the nature of person perception in depression has been inconclusive. This investigation differs from earlier studies in that extensive free-response descriptions of other people and self were collected from patients with major depression and from nonpsychiatric control Ss. In comparison with control Ss, depressed patients described fewer positive aspects not only of self but also of parents and significant others and reported more negative aspects of these people. Cluster analysis (HICLAS) also showed that more cognitive differentiation of negative self-perceptions (negative self-complexity) was characteristic of clinical depression. In both control Ss and patients, a positive (or negative) view of self was highly correlated (.85 or more) with a positive (or negative) view of parents and significant others. These correlations were significantly stronger than those between self and less important others.

DSM-IV hypochondriasis in primary care.

The object of this study was to assess the prevalence and correlates of the DSM-IV diagnosis of hypochondriasis in a primary care setting. A large sample (N = 1456) of primary care users was given a structured interview to make diagnoses of mood, anxiety, and somatoform disorders and estimate levels of disability. The prevalence of hypochondriasis (DSM-IV) was about 3%. Patients with this disorder had higher levels of medically unexplained symptoms (abridged somatization) and were more impaired in their physical functioning than patients without the disorder. Of the various psychopathologies examined, major depressive syndromes were the most frequent among patients with hypochondriasis. Interestingly, unlike somatization disorder, hypochondriasis was not related to any demographic factor. Hypochondriasis is a relatively rare condition in primary care that is largely separable from somatization disorder but seems closely intertwined with the more severe depressive syndromes.

Self-complexity, self-evaluation, and depression: an examination of form and content within the self-schema.

Six studies examined the relationship between self-complexity and variables related to self-evaluation. Self-complexity was found to comprise two components: positive self-complexity and negative self-complexity. Positive self-complexity was sensitive to methodological factors, namely, variations in stimulus materials used for self-ratings. Negative self-complexity was relatively stable in the face of different rating stimuli and tasks and was related to trait measures of self-evaluation, psychic distress, and psychopathology. These findings were observed and replicated. Higher negative self-complexity was associated with increases in depression symptoms over time. Higher negative self-complexity also predicted a poorer prognosis and less complete recovery from depression in a clinical sample. Results are discussed in light of related research and possible social-cognitive mechanisms.

A hierarchical classes analysis (HICLAS) of primary care patients with medically unexplained somatic symptoms.

This study used a clustering model, Hierarchical Classes Analysis (HICLAS), to examine patient groupings in a multiethnic sample of 1456 patients using primary care services at a university-affiliated community clinic in southern California. Somatic symptoms, psychiatric diagnoses and disability were studied using a survey instrument that included portions of the Composite International Diagnostic Interview (CIDI), the Diagnostic Interview Schedule (DIS) and the RAND-MOS Short Form Health Survey's (SF-36) 'physical functioning' dimension. HICLAS identified 11 clusters of patients with distinct patterns of medically unexplained somatic symptoms. These patient clusters varied with respect to psychiatric diagnoses and symptoms, gender, immigration status and disability. Results of this study suggest that the type of presenting symptom(s) and their various combinations may have diagnostic and prognostic value in primary care settings. These new findings may lead to further refinement of current diagnostic constructs for somatizing syndromes.

Immigration and mental health: Mexican Americans in the United States.

The Hispanic population in the United States continues to expand rapidly due primarily to a large flow of immigrants from Mexico. Historical observations of disadvantage in the immigrant population, when compared to the native population, had helped to shape prevailing theories on immigration and mental health. However, data emerging from new research on Mexican Americans have come to challenge the old idea that immigrants are necessarily disadvantaged. The goal of this article is to review these new studies critically, to draw conclusions concerning the relationship between immigration and psychopathology, and to offer potential explanations for the major findings. We review five recent large-scale studies that examined the prevalence of mental disorders among Mexican-born immigrants and U.S.-born Mexican Americans in the United States. Results of these studies are inconsistent with traditional tenets on the relationship among immigration, acculturation, and psychopathology. They show that Mexico-born immigrants, despite significant socioeconomic disadvantages, have better mental health profiles than do U.S.-born Mexican Americans. Possible explanations for the better mental health profile of Mexican immigrants include research artifacts such as selection bias, a protective effect of traditional family networks, and a lower set of expectations about what constitutes "success" in America. The elevated rates of psychopathology in U.S.-born Mexican Americans may be related to easier access to abused substances and an elevated frequency of substance abuse among the U.S.-born.

Cognitive behavior therapy for somatization disorder: a preliminary investigation.

Patients diagnosed with somatization disorder have high rates of disability and often prove refractory to treatment. This preliminary investigation examines the effect of a 10-session cognitive behavior therapy (CBT) protocol on the physical discomfort and disability of severely impaired somatizers. The severity of patients' physical discomfort and disability was assessed at baseline, post-treatment, and eight months following treatment. Patients reported significant improvement in symptomatology and physical functioning between baseline and post-treatment as well as between baseline and follow-up. The findings suggest that CBT might benefit patients diagnosed with somatization disorder and should be subjected to a controlled treatment trial.

Personal identity and the schizophrenic process: an integration.

In this paper we explore the relation between theories of self, particularly identity theory, and the schizophrenic process. A fundamental assumption in identity theory is that a person's self includes a hierarchically organized set of identities. When an individual's set of identities is limited in range and/or diffusely organized he/she is thought to be at risk for schizophrenia. The onset and relapse of schizophrenic episodes are assumed to occur when important identities are negated. Implications of identity theory for integrating extant conceptions of schizophrenia are discussed. Also discussed are the effects of medication in establishing a patient identity and the role of the patient identity in preventing psychotic relapse.

The abused child as parent.

Free-response memories and current descriptions of self, parents, babies, and significant others generated by 55 mothers who were physically abused as children were compared with memories and descriptions by 46 mothers who were not physically abused. The two groups of mothers were matched for age of baby, race, and socioeconomic status. It was found that clusters of negative attributes pervaded the memories and perceptions that abused mothers had of others, particularly parents. Moreover, the degree of negative elaboration (i.e., the number of negative clusters attributed to others) discriminated the abused and control groups almost perfectly. It was also found for both groups that the more elaborated the positive view of self and others, the more secure the attachment of infant to mother. In addition, patterns of identification and description were dramatically different between the two groups: Unlike the comparison mothers, abused mothers tended to disidentify with their own mothers and to be inconsistent in their characterization of them.

The abused child as parent: the structure and content of physically abused mothers' perceptions of their babies.

OBJECTIVE: The major aim of the study was to provide an empirical answer to the following question: Does a mother's history of being physically abused as a child have a discernible impact on the structure and content of her perceptions and beliefs concerning her own child? METHOD: Free-response memories and current descriptions of babies, self, and significant others such as parents were compared longitudinally in two groups of mothers when their babies were 6 months, 1 year, and 2 years old. One group of mothers consisted of individuals who reported being physically abused as children; the control group consisted of mothers who were not physically abused. The two groups were comparable with respect to age of baby, race, and socioeconomic status. RESULTS: Abused mothers were found to differ significantly from control mothers in the structure and content of their free-response perceptions of their own babies. More specifically, abused mothers lagged behind controls in how well-differentiated were their negative perceptions of their babies. Differentiation in this study is operationally defined as the number of unique clusters that underlie a mother's perceptions of her baby, when social perception data is analyzed using cluster analysis (HICLAS). The greater the number of clusters observed, the greater is the differentiation. On the other hand, abused mothers were comparable to controls with respect to differentiation of positive perceptions of babies. CONCLUSIONS: The findings constitute a discovery about the structural organization of social cognition in mothers at-risk for child abuse. Implications of the findings for theory and future research are briefly discussed, as are limitations of the current study.

Hemifacial microsomia. Etiology, diagnosis and treatment.

BACKGROUND: Three percent of all newborns have significant structural anomalies. Hemifacial microsomia, or HFM, is the second most common facial anomaly, second only to cleft lip and palate. New therapeutic and clinical management techniques offer promising interventions that can allow many patients to have more normal childhoods at earlier ages. DESCRIPTION: Due to a unilateral deficiency of the mandible and lower face, patients who have HFM have specific dental needs that require restorative, orthodontic and surgical correction. CLINICAL IMPLICATIONS: Oral and maxillofacial malformations present diagnostic and treatment challenges unique to the dental profession. The etiology, diagnosis and treatment modalities discussed in this article can be used to help effectively rehabilitate patients who have HFM.