Many-body interaction analysis: Algorithm development and application to large molecular clusters

A completely automated algorithm for performing many-body interaction energy analysis of clusters (MBAC) [M. J. Elrodt and R. J. Saykally, Chem. Rev. 94, 1975 (1994); S. S. Xantheas, J. Chem. Phys. 104, 8821 (1996)] at restricted Hartree-Fock (RHF)/MA Plesset 2nd order perturbation theory (MP2)/density functional theory (DFT) level of theory is reported. Use of superior guess density matrices (DM's) for smaller fragments generated from DM of the parent system and elimination of energetically insignificant higher-body combinations, leads to a more efficient performance (speed-up up to 2) compared to the conventional procedure. MBAC approach has been tested out on several large-sized weakly bound molecular clusters such as (H(2)O)(n), n=8, 12, 16, 20 and hydrated clusters of amides and aldehydes. The MBAC results indicate that the amides interact more strongly with water than aldehydes in these clusters. It also reconfirms minimization of the basis set superposition error for large cluster on using superior quality basis set. In case of larger weakly bound clusters, the contributions higher than four body are found to be repulsive in nature and smaller in magnitude. The reason for this may be attributed to the increased random orientations of the interacting molecules separated from each other by large distances.

Radioimmuno targetting (99m)technetium labeled anti-epidermal growth factor receptor monoclonal antibodies in experimental tumor models

AIM

Monoclonal antibodies (MAb) directed at the extra cellular domain (ECD) of epidermal growth factor receptor (EGFR) offer a promising strategy for diagnosis and therapy of cancers that over-express EGFR. Radiolabelled MAbs against cell surface antigens have improved in vivo tumor diagnosis and treatment. EGFR over-expression has been reported in a wide range of carcinomas especially of the head and neck, breast, etc., and is associated with poor prognosis and resistance to therapy. CIBCNSH3 is a murine MAb generated to the ECD of EGFR in our laboratory and has been extensively characterized and has proven antitumor activity. The tumor targeting potential of (99m)Tc labelled CIBCNSH3 in an experimental tumor model is discussed in this paper.

METHODS

A431, an epidermoid carcinoma cell line with overexpression of EGFR, SUDHLH, a lymphoma cell line was used to induce xenografts in inbred adult female BALB/C mice and used for the study. A reduction mediated method of (99m)Tc labelling was adopted to label the MAb. Scintiscan pictures were taken at different time intervals after i.v. administration of the (99m)Tc labelled MAb using a gamma camera and results were correlated with those of biodistribution studies.

RESULTS

Immunoscan pictures taken at different time periods showed high uptake of the radioimmunoconjugate by the tumor providing clear tumor images and no uptake in control animals with lymphoma xenografts. Results of scan pictures correlated well with the biodistribution studies.

CONCLUSION

The radioimmunoconjugate (99m)Tc-CIBCNSH3 appears to be a promising tool in identifying any early recurrence and micro-metastasis of lesions that overexpress EGFR.

Immunofluorescent localization of C-erbB-2 oncoprotein in breast cancer: a preliminary study

Monoclonal antibody CIBCgp185 of IgG2a isotype has been generated against C-erbB-2 oncoprotein using BT474 breast carcinoma cell line as immunogen. Earlier studies have revealed that this MAb has potential application as diagnostic tool in the detection of breast cancers overexpressing C-erbB-2. In the present study, the reactivity pattern of this MAb was studied on frozen sections of 28 malignant and 15 normal breast tissues and on cultured mammary tumor cell lines by indirect immunofluorescent staining. Results indicated that gp185C-erbB-2 was overexpressed in 6 malignant specimens, indicating correlation with immunohistochemical analysis studied previously. These results indicate that immunofluorescence might also be used to study C-erbB-2 overexpression in breast cancers and could serve as a confirmatory test for IHC. However, further studies with large number of cases are needed to confirm these results.

A novel form of pontocerebellar hypoplasia maps to chromosome 7q11-21

OBJECTIVE

To describe a novel form of pontocerebellar hypoplasia (PCH) and map its genetic locus.

BACKGROUND

PCH is a heterogeneous group of disorders that are characterized by abnormally small cerebellum and brainstem. Autosomal recessive inheritance has been implied in many cases, but no genetic loci have been mapped to date.

METHODS

The authors studied a consanguineous family from the Sultanate of Oman with three siblings with a novel form of PCH. The authors performed clinical studies and linkage analysis of this pedigree.

RESULTS

The clinical features of the affected children include developmental delay, progressive microcephaly with brachycephaly, seizures during the first year of life, hypotonia with hyperreflexia, short stature, and optic atrophy. Imaging studies showed a small pons and cerebellum, prominent sulci and lateral ventricles, and decreased cerebral white matter volume. A lack of dyskinesias distinguishes this pedigree from PCH type 2. Genetic studies of this family revealed evidence of significant linkage to chromosome 7q11-21 (maximum multipoint lod score 3.23).

CONCLUSIONS

This pedigree represents a novel form of autosomal recessive PCH, which the authors propose to call cerebellar atrophy with progressive microcephaly (CLAM). This disorder maps to chromosome 7q11-21, and this locus was named CLAM. This report represents the first identification of a genetic locus for PCH.

Immunohistochemical assay (IHC) to study C-erbB-2 status of breast cancer using monoclonal antibody CIBCgp185

The C-erbB-2 proto-oncogene encodes a 185KD glycoprotein with tyrosine kinase activity. Overexpression of this gene either due to gene amplification and/or increased transcription has been observed in a variety of cancers and has been associated with more aggressive disease and a poor clinical prognosis in 20-30% of patients with breast cancer. Besides several prognostic factors like tumor size, histologic grade, steroid hormone receptor status, DNA ploidy, lymph node status etc which are significant in the management of breast cancer, C-erbB-2 status might also serve as an additional parameter. Immunohistochemistry is the most widely used method to study the expression of C-erbB-2 in breast cancer. The very low levels of expression of C-erbB-2 by normal tissues makes this receptor, a potential target for diagnosis and therapy with monoclonal antibodies raised against its extracellular domain. One such monoclonal antibody designated as CIBCgp185 of IgG2a isotype has been generated in our laboratory and extensively characterized. In the present study, an indirect immunohistochemical assay was carried out on frozen tumor tissue sections of 127 malignant breast tumor specimens of various histological types using monoclonal antibody CIBCgp185, which revealed intense staining of tumor cell membrane in 32 specimens, indicating overexpression of C-erbB-2. In the case of 53 benign breast tissues and 24 normal breast tissues studied, this MAb did not exhibit any reactivity. These results suggest that MAb CIBCgp185 might prove useful to identify tumors with overexpression of C-erbB-2 which are often associated with poor prognosis and early recurrence and might have future therapeutic application in the treatment of these cancers.

Brenner tumor of the ovary with extensive stromal luteinization presenting in pregnancy: report of a case and review of the literature

Brenner tumor in pregnancy is rare, with only two reported cases in association with intrauterine pregnancy. A 30-year-old woman, G1P0, was found to have an adnexal mass at 15 weeks of gestation. The mass was resected at Cesarean section and found to be a Brenner tumor with areas of stromal luteinization. Brenner tumor should be considered in the differential diagnosis of adnexal masses presenting during pregnancy. The stromal luteinization was probably related to the hormonal environment of the pregnancy.

Pregnancy complicated by autoimmune polyglandular syndrome type II: a case report

Autoimmune polyglandular syndrome may complicate pregnancy and be confused with hyperemesis gravidarum as a cause of hypoglycemia and electrolyte imbalance in the first trimester of pregnancy. Autoimmune polyglandular syndromes are uncommon disorders characterized by the development and presentation of multiple endocrine and organ dysfunction. To our knowledge, we present the first case of an autoimmune polyglandular syndrome complicating pregnancy. A 26-year-old woman, gravida 5 para 3 at 12 weeks gestation, presented with hyperemesis and signs and symptoms consistent with adrenal insufficiency and hypothyroidism. Evaluation revealed autoimmune polyglandular syndrome type II. Autoimmune polyglandular syndromes are a myriad group of diseases characterized by polyglandular dysfunction. These syndromes should be kept in mind when dealing with pregnant patients presenting with hyperemesis and an electrolyte imbalance who do not improve with the usual treatment for hyperemesis. An endocrine dysfunction such as polyglandular syndrome may exist.

Postpartum intracranial haemorrhage in normotensive users of bromocriptine for ablactation

The authors describe three cases of severe intracranial haemorrhage, associated with marked blood pressure elevation, which occurred between the 6th and 10th days postpartum in women taking bromocriptine for ablactation. All of these patients were young, normotensive and apparently healthy during the pregnancy. These incidents probably present the 10-12th reported cases of gross intracranial bleeding among users of bromocriptine in the puerperium. The results suggest that early diagnosis and prompt surgical intervention may improve the outcome for this rare but potentially catastrophic postpartum complication.

Clinical amnionitis and endometritis in patients with premature rupture of membranes: endocervical prostaglandin E2 gel versus oxytocin for induction of labor

OBJECTIVE

To compare the rates of clinical amnionitis and endometritis in patients with premature rupture of membranes (PROM), using endocervical prostaglandin E2 (PGE2) gel for induction of labor versus immediate oxytocin induction of labor.

METHODS

We randomized 118 patients to receive either endocervical 0.5 mg of PGE2 gel (study group) or immediate oxytocin induction of labor (control group). If labor was not established in the group receiving PGE2 gel in 24 hours, intravenous oxytocin was given in incremental doses. The rates of clinical amnionitis and endometritis in the two groups were analyzed. Also compared were hours of labor, duration of rupture of membranes and number of vaginal examinations. Student t test, chi 2, or Wilcoxon rank-sum test were used for statistical analysis, as appropriate. P < .05 was considered significant.

RESULTS

The rates of clinical amnionitis were 5.3% in the PGE2 group and 8% in the control group. Endometritis developed in 1.7% of PGE2 patients and 3.2% of controls. These differences in maternal infection rates were not statistically significant. The two groups were comparable with respect to age, parity, and antepartum group B streptococcal colonization. No significant differences in hours of labor, duration of ruptured membranes, or vaginal examinations were observed. Neonatal outcome data (mean birth weight, Apgar scores at 1 and 5 minutes, Apgar score less than 7 at 5 minutes) were not statistically significant.

CONCLUSION

Endocervical placement of 0.5 mg of PGE2 gel does not increase the incidence of clinical amnionitis and endometritis in patients with PROM at term when compared with immediate induction of labor with oxytocin.

Severe cerebral accidents postpartum in patients taking bromocriptine for milk suppression

We report three recent cases of severe acute cerebral accident which occurred in the puerperium in women who received bromocriptine for milk suppression. Two patients experienced mild pregnancy-induced hypertension antepartum. Marked blood pressure elevation, above that which had prevailed previously, occurred postpartum in each case. The cerebral accidents manifested between the 6th and 14th days of the puerperium, the typical time for the occurrence of severe side effects from bromocriptine. These complications entailed lasting neurological sequelae in the three mothers who, based on their age, medical history and general state of health, were not significantly predisposed to cerebral accidents.

Comparison of the structures of the cyclotheonamide A complexes of human alpha-thrombin and bovine beta-trypsin

Thrombin, a trypsin-like serine protease present in blood, plays a central role in the regulation of thrombosis and hemostasis. A cyclic pentapeptide, cyclotheonamide A (CtA), isolated from sponges of the genus Theonella, inhibits thrombin, trypsin, and certain other serine proteases. Enzyme inhibition data for CtA indicate that it is a moderate inhibitor of alpha-thrombin (K(i) = 1.0 nM), but substantially more potent toward trypsin (K(i) = 0.2 nM). The comparative study of the crystal structures of the CtA complexes of alpha-thrombin and beta-trypsin reported here focuses on structure-function relationships in general and the enhanced specificity of trypsin, in particular. The crystal structures of the CtA complexes of thrombin and trypsin were solved and refined at 1.7 and 2.0 A resolution, respectively. The structures show that CtA occupies the active site with the Pro-Arg motif positioned in the S2 and S1 binding sites. The alpha-keto group of CtA is involved in a tetrahedral intermediate hemiketal structure with Ser 195 OG of the catalytic triad and is positioned within bonding distance from, and orthogonal to, the re-face of the carbonyl of the arginine of CtA. As in other productive binding modes of serine proteases, the Ser 214-Gly 216 segment runs in a twisted antiparallel beta-strand manner with respect to the diaminopropionic acid (Dpr)-Arg segment of CtA. The Tyr 60A-Thr 60I insertion loop of thrombin makes a weak aromatic stacking interaction with the v-Tyr of CtA through Trp 60D. The Glu 39 Tyr and Leu 41 Phe substitutions in trypsin produce an enhanced aromatic interaction with D-Phe of CtA, which also leads to different orientations of the side chains of D-Phe and the v-Tyr. The comparison of the CtA complexes of thrombin and trypsin shows that the gross structural features of both in the active site region are the same, whereas the differences observed are mainly due to minor insertions and substitutions. In trypsin, the substitution of Ile 174-Arg 175 by Gly 174-Gln 175 makes the S3 aryl site more polar because the Arg 175 side chain is directed away from thrombin and into the solvent, whereas Gln 175 is not. Because the site is occupied by the Dpr group of CtA, the occupancy of the S3 site is better in trypsin than in thrombin. In trypsin, the D-Phe side chain of CtA fits between Tyr 39 and Phe 41 in a favorable manner, whereas in thrombin, these residues are Glu 39 and Leu 41. The higher degree of specificity for trypsin is most likely the result of these substitutions and the absence of the fairly rigid Tyr 60A-Thr 60I insertion loop of thrombin, which narrows access to the active site and forces less favorable orientations for the D-Phe and v-Tyr residues.

Bromocriptine related atypical vascular accidents postpartum identified through medicolegal reviews

Recent literary case reports indicate that bromocriptine mesylate, when used for the suppression of lactation in the puerperium, can cause serious and even lethal side effects. The untoward sequelae are attributed to generalized or focal vasospasm affecting the cardiac and/or cerebral bold vessels. Apart from pre-existing hypertension and use in association with other ergot derivatives, the factors predisposing to such complications have not been elucidated, The authors present three atypical bromocriptine related postpartum accidents which may expand the understanding both of the predisposing factors and the potential consequences of bromocriptine related severe side effects. One of the cases raises the suspicion that the manifestations of hyperthyroidism may be aggravated by this method of pharmacologic ablactation. Another observation appears to imply that the drug may trigger the onset of chronic hypertension in women so predisposed. The development of cerebral infarcts, identified by MRI, in a clinically asymptomatic woman, exemplifies the threat of recurrent seizure activity in cases of bromocriptine related stroke.

Intracerebral hemorrhage in normotensive mothers using bromocriptine postpartum

Three cases of cerebral hemorrhage that occurred in the puerperium in normotensive women who used bromocriptine for milk suppression postpartum are described. Unlike in some other instances reported in the past, the extent of the bleeding was limited in these patients and the long range outcome was relatively benign. All episodes were associated with the development of hypertension. These incidents occurred between the 10th and 17th days postpartum; somewhat later than the usually observed peak time period (6th to 8th day) for the development of severe bromocriptine related side effects.

Fetal renal artery and umbilical artery Doppler flow and fetal urine output

The object of this study was to determine if a correlation exists between the resistance index (RI) of the umbilical artery, the RI of the fetal renal artery, and hourly urine output by fetuses of normal pregnancies. Doppler flow study of the fetal renal artery and the umbilical artery was performed in 110 fetuses between 19 and 40 weeks' gestation. Color and pulse wave Doppler was used to obtain the flow velocity waveforms. The RI of the flow velocity waveforms was calculated. Fetal bladder volume was calculated by transverse, anteroposterior, and longitudinal diameters obtained from coronal and transverse sonographic images of the fetal urinary bladder. The difference in bladder volume at 30-minute intervals was used to determine hourly urine output. Gestational age has a positive linear association with fetal urine output (P < 0.01). The RI of the fetal renal artery has a negative linear association with gestational age (P < 0.05). The RI of the umbilical artery decreased with an increase in gestation age (P < 0.01). There was a significant correlation between the RI of the umbilical artery (P < 0.01) and the fetal renal artery (P < 0.05) and hourly urine output by the fetus. The RI of the fetal renal artery decreased with gestational age. Hourly urine output of the fetus increased with gestational age. The RI of the umbilical artery and the fetal renal artery had a significant correlation with fetal urine output.

Effect of maternal cocaine abuse on renal arterial flow and urine output of the fetus

OBJECTIVE

Our purpose was to study the short-term effect of maternal cocaine abuse on blood flow of the fetal kidney and the fetal hourly urine output.

STUDY DESIGN

Thirty-three pregnant patients of various gestational ages with a history of cocaine abuse were studied. Patients were included if the urine specimen was positive for cocaine on the day of study. Patients were excluded if the urine specimen was positive for any other vasoactive substances or medications. Color and pulsed wave Doppler studies were used to obtain the flow velocity waveform of the fetal renal artery. The resistance index was calculated from systolic and diastolic values of flow velocity waveforms, Longitudinal, transverse, and anteroposterior diameters of the fetal urinary bladder were measured from transverse and coronal images at their maximum diameters, and the bladder volume was calculated. The hourly urine output of the fetus was measured from the difference in the bladder volume at half-hour intervals. As controls, 110 normal pregnancies between 19 and 40 weeks were similarly studied for normal values. The resistance index of the fetal renal artery and the hourly fetal urine output of the two groups were compared.

RESULTS

The resistance index of the fetal renal artery of normal pregnancies had a negative association with gestational age (p < 0.05). Cocaine-exposed fetuses had a significantly higher resistance index of the renal artery (p < 0.01) than did normal fetuses of corresponding gestational ages. A decrease in the hourly urine output of cocaine-exposed fetuses was observed, compared with normal controls of corresponding gestational ages (p < 0.001).

CONCLUSION

The resistance index values of fetal renal artery and fetal urine output were affected by maternal cocaine abuse.

Crystallographic structures of thrombin complexed with thrombin receptor peptides: existence of expected and novel binding modes

Many of the vital actions of thrombin on platelets and other cells appear to be mediated by the recently cloned seven-transmembrane-domain thrombin receptor. Thrombin activates this receptor by a novel proteolytic mechanism. The amino-terminal exodomain of the receptor contains the sequence LDPRSFLLRNPNDKYEPF. Structure-activity studies with mutant receptors and receptor peptides suggest that this sequence binds to thrombin at two sites: LDPR with the active center of thrombin and KYEPF with the fibrinogen recognition exosite of thrombin. Thrombin then cleaves the Arg41-Ser42 bond to unmask a new amino terminus, which functions as a tethered peptide ligand binding to as yet undefined sites within the body of the receptor to effect receptor activation. We have determined eight crystal structures of thrombin complexed with receptor-based peptides. Each of the two components of the bidentate docking model was captured in individual cocrystals. In one crystal type, the LDPR sequence docked in the active center of thrombin in a manner analogous to d-PheProArg chloromethyl ketone. In other crystals, the KYEPF sequence bound in the fibrinogen anion binding exosite of thrombin in a manner analogous to the DFEEI sequence of the carboxylate-terminal peptide of hirudin. Strikingly, however, generation of a single crystal that includes both components of the anticipated bidentate binding mode was not achieved, apparently because the peptides have a dominant solution S-like conformation that does not bind in a productive way at the active center. This peptide structure apparently favored a novel alternative mode of receptor peptide-thrombin interaction in which the receptor peptides formed an intermolecular bridge between neighboring thrombin molecules, resulting in an infinite peptide thrombin chain in crystals. In this structure, the KYEPF sequence docked in the expected manner at the exosite of one thrombin molecule, but the LDPR sequence docked in an unusual nonproductive mode with the active center of a neighboring molecule. Mutations that removed important determinants of the S-like receptor peptide structure underlying the bridging mode in the receptor itself did not significantly alter thrombin signaling. Additionally, a comparison of receptor density to the responsiveness of a cell did not support a role for receptor oligomerization in signaling. The physiological role for this unexpected intermolecular binding mode, if any, remains to be identified.(ABSTRACT TRUNCATED AT 400 WORDS)

Rates of cesarean section and perinatal outcome. Perinatal mortality

A comparison of relevant statistics from National Maternity Hospital, Dublin, Ireland and University Hospital, Newark, New Jersey, USA, for the years 1983-1989, revealed that after removal of major confounding factors, such as a fourfold difference in < 2500 gram births and an about tenfold discrepancy in the frequency of lethal congenital defects, the perinatal survival rates in all weight categories were significantly higher in the American center. The findings suggest that optimum perinatal results could not be achieved in an American high risk center with the approximately 6% abdominal delivery rate favored in Dublin. The same data also suggest, however, that the 17.5% rate of abdominal deliveries in Newark was unnecessarily high. The favorable impact of the relatively liberal use of cesarean section might have been derived in this study from a marked reduction of in utero losses, in the absence of an identifiable effect upon the rate of neonatal mortality.

Crystal structure of peanut lectin, a protein with an unusual quaternary structure

The x-ray crystal structure of the tetrameric T-antigen-binding lectin from peanut, M(r) 110,000, has been determined by using the multiple isomorphous replacement method and refined to an R value of 0.218 for 22,155 reflections within the 10- to 2.95-A resolution range. Each subunit has essentially the same characteristic tertiary fold that is found in other legume lectins. The structure, however, exhibits an unusual quaternary arrangement of subunits. Unlike other well-characterized tetrameric proteins with identical subunits, peanut lectin has neither 222 (D2) nor fourfold (C4) symmetry. A noncrystallographic twofold axis relates two halves of the molecule. The two monomers in each half are related by a local twofold axis. The mutual disposition of the axes is such that they do not lead to a closed point group. Furthermore, the structure of peanut lectin demonstrates that differences in subunit arrangement in legume lectins could be due to factors intrinsic to the protein molecule and, contrary to earlier suggestions, are not necessarily caused by interactions involving covalently linked sugar. The structure provides a useful framework for exploring the structural basis and the functional implications of the variability in the subunit arrangement in legume lectins despite all of them having nearly the same subunit structure, and also for investigating the general problem of "open" quaternary assembly in oligomeric proteins.