Inhibitors of branched-chain amino acid biosynthesis as potential antituberculosis agents

Previous studies have shown that rheumatoid arthritis aggregates within families. However, no formal genetic analysis of rheumatoid arthritis in pedigrees together with other autoimmune diseases has been reported. We hypothesized that there are genetic factors in common in rheumatoid arthritis and other autoimmune diseases. Results of odds-ratio regression and complex segregation analysis in a sample of 43 Caucasian pedigrees ascertained through a rheumatoid arthritis proband or matched control proband, revealed a very strong genetic influence on the occurrence of both rheumatoid arthritis and other autoimmune diseases. In an analysis of rheumatoid arthritis alone, only one inter-class measure, parent-sibling, resulted in positive evidence of aggregation. However, three inter-class measures (parent-sibling, sibling-offspring, and parent-offspring pairs) showed significant evidence of familial aggregation with odds-ratio regression analysis of rheumatoid arthritis together with all other autoimmune diseases. Segregation analysis of rheumatoid arthritis alone revealed that the mixed model, including both polygenic and major gene components, was the most parsimonious. Similarly, segregation analysis of rheumatoid arthritis together with other autoimmune diseases revealed that a mixed model fitted the data significantly better than either major gene or polygenic models. These results were consistent with a previous study which concluded that several genes, including one with a major effect, is responsible for rheumatoid arthritis in families. Our data showed that this conclusion also held when the phenotype was defined as rheumatoid arthritis and/or other autoimmune diseases, suggesting that several major autoimmune diseases result from pleiotropic effects of a single major gene on a polygenic background.     

NT-3, but not BDNF, prevents atrophy and death of axotomized spinal cord projection neurons

Following spinal cord injury, projection neurons are frequently axotomized and many of the cells subsequently die. One goal in spinal injury research is to preserve damaged neurons so that ultimately they are accessible to regeneration-promoting strategies. Here we ask if neurotrophin treatment can prevent atrophy and death of axotomized sensory projection neurons. In adult rats, a hemisection was made in the thoracic spinal cord and axotomized neurons were retrogradely labelled with Fluoro-Gold. Four distinct populations of cells were identified in the lumbar spinal cord, and both numbers and sizes of labelled cells were assessed at different time points postlesion. A progressive and significant degeneration was observed over time with severe atrophy apparent in all cell populations and significant cell loss evident by 4 weeks postlesion. This time point was used to assess neurotrophin effects. Hemisected rats were treated with either neurotrophin 3 (NT-3) or brain-derived neurotrophic factor (BDNF, 12 microg/day for each), or a vehicle solution, delivered continuously to the lesion site via an osmotic minipump. Treatment with NT-3, but not BDNF, completely reversed cell atrophy in three of the four cell populations and also induced a significant increase in the number of surviving cells. In situ hybridization experiments showed trkB and trkC mRNA to be expressed in the majority of ascending spinal projection neurons, suggesting that these cells should be responsive to both BDNF and NT-3. However, only NT-3 treatment was neuroprotective, indicating that BDNF may not have reached the cell bodies of injured neurons. These results demonstrate that NT-3 may be of benefit in preventing the secondary cell loss that occurs following spinal injury.     

The role of apoptosis in the pathogenesis of canine keratoconjunctivitis sicca: the effect of topical Cyclosporin A therapy

PURPOSE: The exact etiology of dry eye is unknown but is believed to be multifactorial. Apoptosis has been implicated in the pathogenesis of autoimmune diseases such as Sj?gren's syndrome (SS). This study attempted to gain a better understanding of the role of apoptosis and its regulation in the patho-physiology of dry eye. The therapeutic effect of immunomodulatory agents such as cyclosporin A (CsA) in the treatment of dry eye, particularly its impact on the level of apoptosis in the target tissues, is also investigated. METHODS: A colony of dogs with spontaneous chronic idiopathic keratoconjunctivitis sicca (KCS) was maintained. Nictitans lacrimal gland (NLG), an accessory lacrimal gland, and conjunctival biopsies of the KCS and normal dogs were obtained before and after 12 weeks of treatment with 0.2% topical CsA ophthalmic emulsion b.i.d. (Allergan, Inc., Irvine, CA, U.S.A.). Tissues were prepared for the terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling (TUNEL) apoptosis assay and immunohistochemical analysis for various apoptosis mediators. RESULTS: The TUNEL assay demonstrated that (i) the normal NLG and conjunctival epithelial cells exhibited a limited level of apoptosis; (ii) in KCS dogs, lacrimal acinar and conjunctival epithelial cells underwent an increased apoptosis, whereas the lymphocytes had a significantly lower level of apoptosis compared to those of the normal dogs; (iii) after topical CsA, apoptosis was induced in the lymphocytes and suppressed in the acinar and conjunctival epithelial cells in KCS dogs. Immunohistochemistry revealed that p53, fas, and fasL, but not bcl-2 were highly expressed in the target tissues of KCS dogs. The immunoreactivity of p53 was significantly decreased, whereas the bcl-2 level was increased after CsA administration. CONCLUSIONS: The induction of epithelial cell apoptosis and the suppression of lymphocytic apoptosis in the NLG and ocular-surface tissues, such as conjunctiva of KCS dogs, indicates the important role of this phenomenon in the etiology of dry eye. Topical CsA appears to facilitate lymphocytic apoptosis and suppress epithelial cell apoptosis in the KCS dog. The differential expression of various apoptotic mediators after topical treatment implicates CsA in facilitating the reestablishment of the normal apoptotic balance, suggesting additional mechanisms by which CsA is therapeutic for dry-eye syndrome.     

Head injuries in Papua New Guinea

Human calcitonin (hCT) has been reported to have a less hypocalcemizing effect on rats and to have a lower binding affinity for the receptor of mouse osteoclasts than salmon CT(sCT). In this study we comparatively examined the effect of hCT and sCT on osteoclastic bone-resorbing activity of unfractionated cells obtained from human giant cell tumor of bone and from rabbit and mouse long bones. We found that hCT had the same inhibitory effect as sCT on the bone-resorbing activity of human and rabbit osteoclastic cells, but a different one on that of mouse cells. These results indicate that the activity of drugs should be assayed using human cells if possible.     

The molecular genetics of endocrine tumours

The molecular genetics of endocrine tumours is an area of great interest, due to the heterogeneity of endocrine tumour types, the association of hormone over-production in some cases, and the wide variation in tumour behaviour. Genes implicated fall into functional categories such as oncogenes, in which mutations tend to cause activation, and tumour suppressor genes, in which mutations lead to loss of function. Oncogenes include the receptor tyrosine kinases such as RET, signal transduction proteins and other molecules such as cell cycle regulators and nuclear proteins. Tumour suppressor genes include cell cycle regulators such as p53 and other molecules such as the MEN 1 gene. Loss of heterozygosity studies help in the initial localisation of the latter. Endocrine tumours, as with other tumours, develop as a result of a combination of genetic events, and in the paediatric age group they often occur in the setting of familial cancer syndromes. In this review we analyse the main genetic lesions which have been described in endocrine tumours. There has been an explosion of knowledge in the last 5 years including the identification of the causative genes for MEN 2 and most recently for MEN 1. Characterisation of such genes also aids in the study of somatic mutations in sporadic versions of the same tumour types as occur in the familial syndromes. Identification of a genetic predisposition to a certain tumour has management implications that are still to be clarified in most cases, although in the case of MEN 2 the guidelines for prophylactic thyroidectomy are generally well accepted.     

Effects of the antimigraine compound zolmitriptan (''Zomig'') on psychomotor performance alone and in combination with diazepam in healthy volunteers

Posterior lenticonus is a protrusion of the posterior capsule and cortex into the vitreous. The etiology is widely debated because of the rare nature of the condition. Lenticonus can present with concurrent ocular conditions, which can disrupt normal visual development. Currently, the only treatment option for posterior lenticonus is lensectomy, which may still have a reduced chance of visual success secondary to the associated disease. Although strabismus and amblyopia are commonly associated, keratoconus has not previously been reported with unilateral posterior lenticonus. Considering treatment of the associated condition may allow the patient to delay or forego surgical intervention.     

Hepatocellular carcinoma in primary biliary cirrhosis and its impact on outcomes

In this study we have determined the incidence of hepatocellular carcinoma (HCC) development in primary biliary cirrhosis (PBC) and its effects on patient survival. Six hundred and sixty seven patients with liver histology compatible with or diagnostic of PBC were seen over a 20-year period. Two hundred and seventy three patients who had stage III or IV disease on their last biopsy and who had been followed up for at least 1 year following that biopsy (total follow-up with advanced disease 2,010 patient years) were identified (243 female, 30 male). Patients who developed HCC were identified and their confounding risk factors were excluded. Mayo risk scores were calculated for each clinic attendance and expected survival for each time point was compared with subsequent actual survival. Sixteen cases of HCC were seen in the patients with stage III or IV disease on last biopsy, providing an overall incidence of 5.9% in this group. Fourteen of these patients had died of HCC related causes, and 2 patients were alive at the census point. The incidence of HCC was significantly higher in males with stage III/IV disease than in females (20% vs. 4.1%, P < .005). Nine of one hundred and eight (8.3%) total female deaths in this group was attributable to HCC compared with 5 of 11 (45.5%, P < .05) male deaths. HCC was not seen in any of the 394 patients with stage I and II PBC followed-up over the same time period. Throughout the disease course of all PBC patients with HCC, the Mayo prognostic model over-predicted survival. Whereas it is a relatively rare complication of cirrhotic PBC in women, HCC is a relatively common cause of death in male PBC patients with cirrhosis. HCC typically develops several years after the onset of cirrhosis, and is poorly predicted by prognostic models. In view of these findings, consideration should be given to careful screening for HCC in male PBC patients with cirrhosis. The risk of HCC development may be an additional reason to consider earlier transplantation in these patients.     

Hydrogen-bonded trimers of DNA bases and their interaction with metal cations: ab initio quantum-chemical and empirical potential study

Neutral (G.GC, A.AT, G.AT, T.AT, and C(imino).GC) and protonated (CH+.GC and AH+.GC) hydrogen-bonded trimers of nucleic acid bases were characterized by ab initio methods with the inclusion of electron correlation. In addition, the influence of metal cations on the third-strand binding in Purine-Purine-Pyrimidine (Pu.PuPy) reverse-Hoogsteen triplets has been studied. The ab initio calculations were compared with those from recently introduced force fields (AMBER4.1, CHARMM23, and CFF95). The three-body term in neutral trimers is mostly negligible, and the use of empirical potentials is justified. The only exception is the neutral G.GC Hoogsteen trimer with a three-body term of -4 kcal/mol. Protonated trimers are stabilized by molecular ion-molecular dipole attraction and the interaction within the complex is nonadditive, with the three-body term on the order of -3 kcal/mol. There is a significant induction interaction between the third-strand protonated base and guanine. The calculations indicate an enhancement of the third-strand binding in the G.GC reverse-Hoogsteen trimer due to-metal cation coordination to the N7/O6 position of the third-strand guanine. Interactions between metal cations and complexes of DNA bases are in general highly non-additive; the three-body term is above-10 kcal/mol in a complex of a divalent cation (Ca2+) with the GG reverse-Hoogsteen pair. The pairwise additive empirical potentials qualitatively underestimate the binding energy between cation and base.     

Assessing the outcomes of coronary artery bypass graft surgery: how many risk factors are enough? Steering Committee of the Cardiac Care Network of Ontario

OBJECTIVES: We sought to determine whether more comprehensive risk-adjustment models have a significant impact on hospital risk-adjusted mortality rates after coronary artery bypass graft surgery (CABG) in Ontario, Canada. BACKGROUND: The Working Group Panel on the Collaborative CABG Database Project has categorized 44 clinical variables into 7 core, 13 level 1 and 24 level 2 variables, to reflect their relative importance in determining short-term mortality after CABG. METHODS: Using clinical data for all 5,517 patients undergoing isolated CABG in Ontario in 1993, we developed 12 increasingly comprehensive risk-adjustment models using logistic regression analysis of 6 of the Panel's core variables and 6 of the Panel's level 1 variables. We studied how the risk-adjusted mortality rates of the nine cardiac surgery hospitals in Ontario changed as more variables were included in these models. RESULTS: Incorporating six of the core variables in a risk-adjustment model led to a model with an area under the receiver operating characteristic (ROC) curve of 0.77. The ROC curve area slightly improved to 0.79 with the inclusion of six additional level 1 variables (p = 0.063). Hospital risk-adjusted mortality rates and relative rankings stabilized after adjusting for six core variables. Adding an additional six level 1 variables to a risk-adjustment model had minimal impact on overall results. CONCLUSIONS: A small number of core variables appear to be sufficient for fairly comparing risk-adjusted mortality rates after CABG across hospitals in Ontario. For efficient interprovider comparisons, risk-adjustment models for CABG could be simplified so that only essential variables are included in these models.     

Adrenal gland incidentaloma in the oncologic patient: is its histologic study obligatory?

We evaluated the performance of an automatic polymerase chain reaction (PCR) detection system for identification of Mycobacterium tuberculosis in respiratory specimens. Six hundred and two respiratory specimens, including 557 sputa and 45 bronchial washing samples, were analyzed using the COBAS AMPLICOR Mycobacterium tuberculosis (MTB) test. The results were compared with those obtained from acid-fast microscopy, conventional culture, and clinical history. In cases of discrepancy between the results of the COBAS AMPLICOR MTB test and culture, the medical history of the patient was reviewed, the COBAS AMPLICOR MTB test was repeated, and the gene encoding M. tuberculosis superoxide dismutase was screened using PCR (SOD-PCR). Fourteen samples were excluded because the internal control test result was negative. Of 57 specimens that were culture positive for Mycobacterium species, 40 appeared to have growth of M. tuberculosis and 21 were smear positive for acid-fast bacteria. The sensitivity, specificity, and positive and negative predictive values for the COBAS AMPLICOR MTB test evaluated at our laboratory were 85.0% (34/40), 99.3% (544/548), 89.5% (34/38), and 98.9% (544/550), respectively. Three specimens that were culture positive for M. tuberculosis but negative by COBAS AMPLICOR MTB test were positive when rechecked by both COBAS AMPLICOR MTB test and SOD-PCR. Among the four specimens with positive reactions on both COBAS AMPLICOR MTB test and SOD-PCR that were culture negative, two were from patients who had been receiving antituberculosis treatment, one was from a patient who had been treated for tuberculosis for 1 year, and the other was from a patient who died of sepsis with adult respiratory distress syndrome. In more than 70% of smear-negative and culture-positive specimens and 86.4% of smear-positive specimens, M. tuberculosis was identified by the COBAS AMPLICOR MTB test within 10 hours after receipt of the specimens. Our data show that the COBAS AMPLICOR MTB test provides rapid and accurate detection of M. tuberculosis in respiratory specimens.