MR imaging, MR angiography, and MR spectroscopy of the brain in eclampsia

PURPOSE

To compare the MR imaging and MR angiographic changes with in vivo proton MR spectroscopic findings and to determine the spectral differences between edema and ischemia in patients with eclampsia.

METHODS

Spin-echo MR imaging, MR angiography, and single-voxel proton MR spectroscopy were performed in 10 patients with eclampsia. MR studies were obtained within 3 to 5 days of diagnosis and repeated after 2 weeks with identical parameters.

RESULTS

Multifocal subcortical/cortical hyperintensities were noted in all 10 patients on T2-weighted images; in two patients, hyperintensities were seen in both cerebral hemispheres. In nine patients, MR angiograms showed narrowing of the major vessels constituting the circle of Willis that resolved after 2 weeks. In one patient with subtle imaging changes, MR angiography showed mild bilateral narrowing of the proximal middle and posterior cerebral arteries that did not change after 2 weeks, whereas imaging abnormalities worsened. Findings at single-voxel MR spectroscopy of the reversible T2 hyperintense lesions were significantly different from findings in the control group for N-acetylaspartate (NAA)/creatine ratios. One patient with mild abnormalities at MR imaging and MR angiography had lactate and decreased creatine and NAA, and on a follow-up study had a further decrease of NAA and creatine as well as a decrease in lactate.

CONCLUSION

In vivo proton MR spectroscopy may help to differentiate cerebral edema from ischemia in patients with eclampsia and thus may help to determine the prognosis for these patients.

Identification and analysis of mutations in the Wilson disease gene (ATP7B): population frequencies, genotype-phenotype correlation, and functional analyses

Wilson disease (WD) is an autosomal recessive disorder characterized by toxic accumulation of copper in the liver and subsequently in the brain and other organs. On the basis of sequence homology to known genes, the WD gene (ATP7B) appears to be a copper-transporting P-type ATPase. A search for ATP7B mutations in WD patients from five population samples, including 109 North American patients, revealed 27 distinct mutations, 18 of which are novel. A composite of published findings shows missense mutations in all exons-except in exons 1-5, which encode the six copper-binding motifs, and in exon 21, which spans the carboxy-terminus and the poly(A) tail. Over one-half of all WD mutations occur only rarely in any population sample. A splice-site mutation in exon 12 accounts for 3% of the WD mutations in our sample and produces an in-frame, 39-bp insertion in mRNA of patients homozygous, but not heterozygous, for the mutation. The most common WD mutation (His1069Glu) was represented in approximately 38% of all the WD chromosomes from the North American, Russian, and Swedish samples. In several population cohorts, this mutation deviated from Hardy-Weinberg equilibrium, with an overrepresentation of homozygotes. We did not find a significant correlation between His1069Glu homozygosity and several clinical indices, including age of onset, clinical manifestation, ceruloplasmin activity, hepatic copper levels, and the presence of Kayser-Fleischer rings. Finally, lymphoblast cell lines from individuals homozygous for His1069Glu and 4 other mutations all demonstrated significantly decreased copper-stimulated ATPase activity.

Extensive DNA deletion associated with severe disease alleles on spinal muscular atrophy homologues

Spinal muscular atrophy (SMA) is a motor neuron disease presenting with a wide spectrum of phenotypic variations. The primary cause of most, if not all, forms of childhood-onset spinal muscular atrophy appears to be the homozygous loss of the telomeric copy of the survival motor neuron (SMNT) gene. It is interesting that approximately half of all affected patients are likewise homozygous nulls for the neuronal apoptosis inhibitory protein (NAIP) gene and a somewhat lesser fraction for the basal transcription factor, p44 subunit (BTF2p44) gene. It has been proposed that homozygous loss of SMNT is the primary cause of spinal muscular atrophy while the loss of NAIP and perhaps other genes primarily affects the severity of disease manifestation. We explored this hypothesis by evaluating the extent of gene deletions in three multigenerational families with spinal muscular atrophy exhibiting dramatic intrafamilial phenotypic variation. Using somatic cell hybrid lines to sequester individual spinal muscular atrophy homologues, we show that homologues missing several contiguous genes correlate with "severe" disease alleles and homologues missing only SMNT correlate with "mild" disease alleles. These observations support the hypothesis that phenotypic severity among the childhood-onset spinal muscular atrophies is directly correlated with the extent of disease-specific deletions.

Ultrastructure of intermediate trophoblast cells during morphogenesis of syncytiotrophoblast in early human pregnancy

During human embryonic development the process of differentiation begins in the cells covering the blastocyst, resulting in the formation of outer syncytial and inner cytotrophoblastic cell layers. Although the outer syncytial layer is known to be derived from the underlying layer of mononuclear cytotrophoblasts, the cellular mechanism involved in its morphogenesis is not clear. Furthermore, there is another type of cells, designated as intermediate trophoblasts, which play a vital role in syncytium formation. Using early first-trimester (6-10 weeks' gestation) human chorionic villi, a study was carried out to illustrate the ultrastructural features of these cells. It was observed that while there was a large number of coated vesicles, vacuoles, lysosomes and dense granules in the syncytiotrophoblast, in cytotrophoblasts there was a relatively smaller number. In intermediate cells, however, these organelles were more abundant. Moreover, a discontinuity in the plasma membrane along with gap junctions was frequently observed in these cells. Since these features represent the transitional stage of a differentiating cell, it is possible that the syncytiotrophoblast is in fact formed by the differentiation of intermediate trophoblasts.

An evaluation of a chest pain diagnostic protocol to exclude acute cardiac ischemia in the emergency department

BACKGROUND

Although accelerated diagnostic protocols are being increasingly used in emergency departments to diagnose acute cardiac ischemia, there have been no prospective evaluations of a chest pain diagnostic protocol with serial determinations of creatine kinase MB isoenzyme and mandatory exercise electrocardiography (ExECG).

METHODS

Prospective cross-sectional study in which chest pain protocol results were compared with final (reference) diagnoses of acute cardiac ischemia (including acute myocardial infarction and unstable angina). Patients in need of hospital admission but at low probability (by a validated algorithm) for acute myocardial infarction were examined for exclusions: known coronary artery disease, cardiac complications, severe comorbidities, or inability to perform exercise testing. A 12-hour diagnostic protocol included serial measurements of creatine kinase MB, ECG, and clinical assessments followed by ExECG for those with negative initial serial testing. Reference diagnoses were established during hospitalization and diagnostic accuracy was assessed.

RESULTS

The study group of 317 patients was 54% male and 65% black, and had a mean age of 46.6 years; 9.5% had a final diagnosis of acute cardiac ischemia. For this diagnosis, the protocol had a sensitivity of 90.0% (95% confidence interval, 72.3%-97.4%); specificity, 50.5% (95% confidence interval, 44.6%-56.4%); positive predictive value, 16.0%; and negative predictive value, 98.0%. Creatine kinase MB, serial ECGs, and ExECG each made a contribution to improved sensitivity and accuracy, whereas clinical reassessments were less discriminating, as indicated by protocol's receiver operating characteristic curve.

CONCLUSIONS

A chest pain diagnostic protocol achieved high sensitivity and improved specificity over the standard emergency department workup. There were no adverse advents associated with early ExECG.

Perinodular hydropic degeneration of a uterine leiomyoma: a diagnostic challenge

Perinodular hydropic degeneration of a uterine leiomyoma is a rare form of the more common hydropic change observed in leiomyomas. With minimal discussion in the surgical pathology literature, appropriate evaluation may be challenging because the differential diagnosis includes other uncommon uterine disorders such as intravenous leiomyomatosis, diffuse leiomyomatosis, myxoid leiomyosarcoma, endometrial stromal sarcoma, angiofibroma, and angiomyxoma. We describe such a diagnostic challenge in a 42-year-old woman with a left adnexal mass discovered during an annual examination. With only three cases of perinodular hydropic degeneration previously reported, this case is the first with extrauterine extension and was initially concerning for a more aggressive process.

Metallic ion concentration during menstrual cycle in normally menstruating women

Plasma concentration of metallic ions levels during menstrual cycle of twenty normally menstruating women were observed in four phases i.e. menses, follicular, ovulatory and luteal. The concentration of magnesium, zinc, selenium and manganese was highest during menses and lowest at ovulatory phase. There was rise in ionic levels of magnesium and selenium, while fall in zinc and manganese during luteal phase. Findings demonstrate changes in metallic ions (Magnesium, zinc, selenium and manganese) level in relation to hormonal status during menstrual cycle in women.

Feasibility of a rapid diagnostic protocol for an emergency department chest pain unit

STUDY OBJECTIVE

To evaluate the applicability of a short-stay protocol for exclusion of acute ischemic heart disease without hospital admission and to analyze these results in the context of a conceptual model.

METHODS

An observational study of patients who presented with chest pain to the emergency department of an 886-bed inner-city municipal hospital and who needed hospital admission to rule out acute myocardial infarction (AMI). Patients were assessed by ED attending physicians to determine eligibility for an alternative, 12-hour protocol in an ED chest pain observation unit (CPOU) followed by immediate exercise testing. Outcome measures were proportion of patients eligible for the short-stay protocol, risk factor profile, and reasons for exclusion.

RESULTS

Of 500 patients screened, 446 had sufficient data points to determine protocol eligibility. Of these, 238 (53.3%; 95% confidence interval [CI], 48.7% to 57.9%) were found to have low probability for AMI. After study exclusion criteria were applied to the patient cohort, 63 patients (14.1%; 95% CI, 10.9% to 17.3%) were eligible for the protocol. The most common reasons for exclusion were history of coronary artery disease (46%) and inability to perform an interpretable exercise tolerance test (42%).

CONCLUSION

Although most admitted patients with chest pain (53%) were at low probability for AMI, only a minority (14%) were eligible for a short-stay protocol that required patients to be free of known coronary artery disease and able to perform an exercise tolerance test. Factors affecting the operations and efficiency of a CPOU include clinical characteristics of the target patient population, protocol tests used, and hospital occupancy and reimbursement patterns.

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

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

Population structure and genetic differentiation among 16 tribal populations of central India

Genetic polymorphisms for six blood groups, three red cell enzymes, three serum proteins, and hemoglobin were examined in sixteen central Indian tribal populations. Nine of the tribes belonged to Orissa, five to Madhya Pradesh, and two to Maharashtra. Eleven tribes spoke the Dravidian language, three Indo-Ayran, and two the language of the Austro-Asiatic families. The population structure of these tribal populations was analyzed at the inter- and intrastate and linguistic levels, using data for 13 genetic systems (38 alleles or haplotypes). Nine of the 13 loci showed significant heterogeneity in the 16 tribes, and the pattern of heterogeneity was also discernible in the different states and in the Dravidian-speaking tribes. As expected, the extent of genetic differentiation or gene diversity was the highest so far reported from central India. The mean FIS and HS for each locus in the different state, linguistic, and total tribal groups were consistently higher than the FST and GST values, respectively, showing that the genetic structure of each tribe is highly influenced by inbreeding. In a genetic affinity analysis by genetic distance the Indo-Aryan and Austro-Asiatic language groups showed little affinity with each other, although there was some tendency toward geographic affinity. The present analysis indicates that, in addition to genetic drift, gene flow, and selection, the genetic structure of the populations of central India is also highly influenced by sociocultural adaptation and inbreeding.

Structure of unliganded HIV-1 reverse transcriptase at 2.7 A resolution: implications of conformational changes for polymerization and inhibition mechanisms

BACKGROUND

HIV-1 reverse transcriptase (RT) is a major target for anti-HIV drugs. A considerable amount of information about the structure of RT is available, both unliganded and in complex with template-primer or non-nucleoside RT inhibitors (NNRTIs). But significant conformational differences in the p66 polymerase domain among the unliganded structures have complicated the interpretation of these data, leading to different proposals for the mechanisms of polymerization and inhibition.

RESULTS

We report the structure of an unliganded RT at 2.7 A resolution, crystallized in space group C2 with a crystal packing similar to that of the RT-NNRTI complexes. The p66 thumb subdomain is folded into the DNA-binding cleft. Comparison of the unliganded RT structures with the DNA-bound RT and the NNRTI-bound RT structures reveals that the p66 thumb subdomain can exhibit two different upright conformations. In the DNA-bound RT, the p66 thumb subdomain adopts an upright position that can be described as resulting from a rigid-body rotation of the p66 thumb along the "thumb's knuckle' located near residues Trp239 (in strand beta 14) and Val317 (in beta 15) compared with the thumb position in the unliganded RT structure. NNRTI binding induces an additional hinge movement of the p66 thumb near the thumb's knuckle, causing the p66 thumb to adopt a configuration that is even more extended than in the DNA-bound RT structure.

CONCLUSIONS

The p66 thumb subdomain is extremely flexible. NNRTI binding induces both short-range and long-range structural distortions in several domains of RT, which are expected to alter the position and conformation of the template-primer. These changes may account for the inhibition of polymerization and the alteration of the cleavage specificity of RNase H by NNRTI binding.

Characterization of multiple mRNAs that encode mammalian translation initiation factor 5 (eIF-5)

Eukaryotic translation initiation factor 5 (eIF-5) interacts with the 40 S initiation complex (40S.mRNA.MettRNAf.eIF-2.GTP) to promote the hydrolysis of bound GTP with the concomitant joining of the 60 S ribosomal subunit to the 40 S initiation complex to form a functional 80 S initiation complex. In this paper, the multiple mRNAs that encode mammalian eIF-5 have been characterized. In rat tissues, three major eIF-5 mRNAs of 3.5, 2.8, and 2.2 kilobases in length are detected. All major eIF-5 mRNAs are initiated from a single transcription initiation site, contain identical 5'-untranslated and coding regions, but differ from one another only in the length of their 3'-untranslated regions. The different lengths of the 3'-untranslated region of eIF-5 mRNAs are generated by the use of alternative polyadenylation signals. Additionally, we demonstrate tissue-specific variations in eIF-5 mRNA expression as well as preference for polyadenylation sites. These results should lead to increased understanding of the regulation of eIF-5 gene expression.

Conformation, protein-carbohydrate interactions and a novel subunit association in the refined structure of peanut lectin-lactose complex

The structure of the complex of the tetrameric peanut lectin with lactose has been refined to an R-value of 16.4% using 2.25 angstroms resolution X-ray diffraction data. The subunit conformation in the structure is similar to that in other legume lectins except in the loops. It has been shown that in the tertiary structure of legume lectins, the short five-stranded sheet plays a major role in connecting the larger flat six-stranded and curved seven-stranded sheets. Furthermore, the loops that connect the strands at the two ends of the seven-stranded sheet curve toward and interact with each other to produce a second hydrophobic core in addition to the one between the two large sheets. The protein-lactose interactions involve the invariant features observed in other legume lectins in addition to those characteristic of peanut lectin. The "open" quaternary association in peanut lectin is stabilised by hydrophobic, hydrogen-bonded and water-mediated interactions. Contrary to the earlier belief, the structure of peanut lectin demonstrates that the variability in quaternary association in legume lectins, despite all of them having nearly the same tertiary structure, is not necessarily caused by covalently bound carbohydrate. An attempt has been made to provide a structural rationale for this variability, on the basis of buried surface areas during dimerisation. A total of 45 water molecules remain invariant when the hydration shells of the four subunits are compared. A majority of them appear to be involved in stabilising loops.

Primary sclerosing cholangitis: an experience from India

Primary sclerosing cholangitis (PSC) is considered to be rare in India. The aim of the present study was to investigate the incidence, clinical profile and outcome of PSC seen in a tertiary care centre. Over a period of 10 years (July, 1984-June, 1994) 18 patients of PSC were diagnosed at cholangiography (14 patients by endoscopic retrograde cholangiopancreatography, two patients by percutaneous transhepatic cholangiography and two patients by both methods). The presence of secondary causes, such as choledocholithiasis, biliary tract surgery, congenital biliary tract anomalies, cholangiocarcinoma and pancreatic diseases, were excluded. These patients were evaluated retrospectively with respect to their clinical presentation, radiological findings, presence of associated idiopathic ulcerative colitis (IUC), treatment instituted and outcome. The mean (+/- s.d.) age at diagnosis of PSC was 39.0 (+/- 16.1) years with a male:female ratio of 1.57:1. Nine (50%) patients had associated IUC. The diagnosis of the IUC preceded that of PSC in all but one case. Fifteen (83.3%) patients had cholestatic jaundice at presentation, while three (16.7%) patients had asymptomatic rise of alkaline phosphatase. Three (16.7%) patients had recurrent cholangitis and five (27.8%) patients developed portal hypertension during the course of the disease. At cholangiography, intrahepatic radicles were involved in all and extrahepatic radicles in 12 (66.6%) cases. Patients were managed with steroids (n = 7), colchicine (n = 3), ursodeoxycholic acid (UDCA; n = 2) and methotrexate (n = 1), along with symptomatic measures. Mean duration of follow up available in 11 (61%) patients was 20.1 months (range: 1 month-8 years). Four (36.4%) patients died. Steroids and colchicine did not have any effect while the one patient on UDCA and one on methotrexate showed improvement. In conclusion, in India PSC does not seem to be a rare entity. Its clinical profile and outcome are somewhat similar to those seen in Western countries.