Radiologic evaluation of hyperacute brain infarction: a review.

Imaging cerebral infarction in first few hours after the onset of clinical symptoms is a challenge. The role of stroke imaging underwent a paradigm shift from confirmation of infarction from and exclusion of hemorrhage to the detection of the tissue at risk that may be rescued with restoration of circulation. Computed tomography (CT) is generally performed before starting the therapy in order to exclude the presence of bleeding and tumors. Although CT may show findings of infarction as early as 3-6 hours after ictus 30% of CT scans are normal in the first few hours after ischemic insult. Conventional spin-echo MR imaging is more sensitive and specific than CT in the detection of cerebral ischemia during the 1st few hours symptom onset. Lesion conspicuity can be further optimized by using an FLAIR sequence. Diffusion-weighted MR imaging is a technique that is more sensitive than conventional MR imaging for detection of hyperacute cerebral ischemia, within minutes after the onset of ischemia, a profound restriction in water diffusion occurs in affected brain tissue and DWI is sensitive to diffusion restriction. But DWI only shows areas that are already irreversibly damaged. Around this core, there is believed to be a region of ischemic penumbra where reversible cell death occurred. An imaging technique that accurately identifies this tissue at risk could have a tremendous impact on patient management by thrombolysis. Perfusion imaging allows depiction of both areas of irreversible ischemia and areas of reversible ischemia. Both MR and CT Perfusion imaging help define the tissue at risk. The introduction of intravenous thrombolysis with tPA has radically changed the role of neuroimaging for stroke evaluation. The ECASS trial prescribed for treatment with intravenous tPA with stroke symptoms of less than 6 hours in duration and who did not have identifiable infarction of greater than one- third of the middle cerebral artery (MCA) territory on CT images. The NINDS trial established that intravenous tPA treatment is efficacious if administered less than 3 hours after symptom onset. The experience of interventional cardiologists in treating acute myocardial infarction may predict the future of intervention neuro in treating ischemic stroke.

Central nervous system tuberculosis and adjuvant corticosteroid therapy.

Tuberculous involvement of central nervous system is one of the important health issues causing high mortality and morbidity. Uncertainty and doubt dominate all aspects of CNS tuberculosis. Diagnosis is mainly based on clinical features, cerebrospinal fluid changes, and imaging characteristics. Few studies have shown that corticosteroids improve the clinical outcome, although the precise mechanism of action remains tentative. All the cases were selected on strong clinical suspicion of CNS tuberculosis. They were graded according to tuberculous meningitis (TM) severity grades. In this connection, we studied 13 patients in one medicine unit over 12 month's period to see the effect of corticosteroid as part of the outcome. Nine patients (69.23%) were in grade II, three (23.08%) patients were in grade III, and one (7.69%) was in grade I. Seven patients (53.85%) had tuberculous meningitis and six (46.15%) had tuberculoma (CT or MRI). Out of 13 cases 3 patients (23%) died in the hospital and 10 patients (77%) improved, of whom 2 patients (20%) recovered completely and 8 patients (80%) had residual neurological deficit. Our study suggests that the early detection of CNS tuberculosis is the most important prognostic factor. Timely started anti-Koch's treatment with adjuvant corticosteroid therapy has a direct bearing on patient outcome.

Repression of activator-mediated transcription by herpes simplex virus ICP4 via a mechanism involving interactions with the basal transcription factors TATA-binding protein and TFIIB.

Infected-cell polypeptide 4 (ICP4) of herpes simplex virus is both a transcriptional activator and a repressor. It has been previously demonstrated that both SP1-activated transcription and USF-activated transcription are repressed by ICP4 without affecting basal transcription (B. Gu, R. Rivera-Gonzalez, C. A. Smith, and N. A. DeLuca, Proc. Natl. Acad. Sci. USA 90:9528-9532, 1993; R. Rivera-Gonzalez, A. N. Imbalzano, B. Gu, and N.A. DeLuca, Virology 202:550-564, 1994). In this study, it was found that ICP4 repressed the activation function of two other activators, VP16 and ICP4 itself, in vitro. ICP4 inhibited transcription by interfering with the formation of transcription initiation complexes without affecting transcription elongation. Repression of activator function required that an ICP4 DNA binding site was present in one orientation within approximately 45 bp 3' to the TATA box. DNA binding by ICP4 was necessary but not sufficient for repression. ICP4 has been shown to form tripartite complexes cooperatively with the TATA box-binding protein and TFIIB on DNA containing an ICP4 binding site and a TATA box (C. A. Smith, P. Bates, R. Rivera-Gonzalez, B. Gu, and N. DeLuca, J. Virol. 67:4676-4687, 1993). A region of ICP4 that enables the molecule to form tripartite complexes was also required in addition to the DNA binding domain for efficient repression. Moreover, repression was observed only when the ICP4 binding site was in a position that resulted in the formation of tripartite complexes. Together, the data suggest that ICP4 represses transcription by binding to DNA in a precise way so that it may interact with the basal transcription complex and inhibit some general step involved in the function of activators. The steps or interactions involved in transcriptional activation that are inhibited by ICP4 are discussed.

Clinical and laboratory evaluation of the safety of a bioartificial liver assist device for potential transmission of porcine endogenous retrovirus.

BACKGROUND: The potential risk of transmission of porcine endogenous retroviruses (PERV) from xenogeneic donors into humans has been widely debated. Because we were involved in a phase I/II clinical trial using a bioartificial liver support system (BLSS), we proceeded to evaluate the biosafety of this device. MATERIALS AND METHODS: The system being evaluated contains primary porcine hepatocytes freshly isolated from pathogen-free, purpose-raised herd. Isolated hepatocytes were installed in the shell, which is separated by a semipermeable membrane (100-kD nominal cutoff) from the lumen through which the patients' whole blood is circulated. Both before and at defined intervals posthemoperfusion, patients' blood was obtained for screening. Additionally, effluent collected from a clinical bioreactor was analyzed. The presence of viral particles was estimated by reverse transcriptase-polymerase chain reaction (RT-PCR) and RT assays. For the detection of pig genomic and mitochondrial DNA, sequence-specific PCR (SS-PCR) was used. Finally, the presence of infectious viral particles in the samples was ascertained by exposure to the PERV-susceptible human cell line HEK-293. RESULTS: PERV transcripts, RT activity, and infectious PERV particles were not detected in the luminal effluent of a bioreactor. Culture supernatant from untreated control or mitogen-treated porcine hepatocytes (cleared of cellular debris) also failed to infect HEK-293 cell lines. Finally, RT-PCR, SS-PCR, and PERV-specific RT assay detected no PERV infection in the blood samples obtained from five study patients both before and at various times post-hemoperfusion. CONCLUSION: Although longer patient follow-up is required and mandated to unequivocally establish the biosafety of this device and related bioartificial organ systems, these analyses support the conclusion that when used under standard operational conditions, the BLSS is safe.

Endotoxin causes up-regulation of endothelin receptors in cultured hepatic stellate cells via nitric oxide-dependent and -independent mechanisms.

Hepatic stellate cells (HSC) and their transformed phenotype found in the chronically injured liver play important roles in hepatic physiology and pathology. HSC produce and react to a potent contractile peptide endothelin-1 (ET-1) and also synthesize a vasorelaxant nitric oxide (NO) upon stimulation with endotoxin. However, whether endotoxin affects ET-1 system of HSC and if this is a mechanism of endotoxin-induced hepatic injury is not known. We characterized synthesis of ET-1 and NO and ET-1 receptors in cultured quiescent and transformed HSC subjected to endotoxin treatment. Endotoxin (1 - 1000 ng ml(-1)) stimulated synthesis of ET-1 and NO and up-regulated ET-1 receptors in both cell types. Inhibition of NO synthesis by N(G)-monomethyl-L-homoarginine strongly inhibited endotoxin-induced increase in ET-1 receptors in transformed HSC but produced small additional increase in quiescent HSC. Inhibition of soluble guanylyl cyclase by 1H-[1,2, 4]oxadiazolo[4,3-a]quinoxalin-1-one blocked the effect of endotoxin on ET-1 receptors in both cell types. Moreover, ET-1 receptors were increased in both cell types during earlier time points (1 - 4 h) of endotoxin treatment in the absence of the stimulation of NO synthesis. These results demonstrate that endotoxin up-regulates ET-1 receptors in HSC by NO-dependent and -independent mechanisms. Such effects of endotoxin can be of importance in acute endotoxemia and during chronic injury of the liver.

Endothelin stimulates transforming growth factor-beta1 and collagen synthesis in stellate cells from control but not cirrhotic rat liver.

Interactions between hepatic stellate cells and endothelin-1 are implicated in liver fibrosis. We determined endothelin-1, its receptors and its effects on the synthesis of a fibrogenic agent transforming growth factor (TGF)-beta1 and collagen in stellate cells from control and CCl(4)-induced cirrhotic rats. The basal synthesis of endothelin-1, TGF-beta1 and collagen was much higher in cirrhotic stellate cells than in control cells. Endothelin-1 stimulated TGF-beta1 and collagen synthesis via endothelin ET(A) and endothelin ET(B) receptors, respectively, in control stellate cells, but did not elicit these effects in the cirrhotic cells despite increased density of the respective receptor subtypes in them. These results indicate that the actions of endothelin-1 on stellate cells may be an important physiological mechanism in maintenance of hepatic architecture. However, inability of endothelin-1 to stimulate TGF-beta1 and collagen synthesis in cirrhotic stellate cells suggests that it does not influence fibrogenic activity by direct action on them probably because the processes are already maximally activated.

Islamic founding principles on organ transplantation and the evolution of Islamic scholarly opinions on the subject.

BACKGROUND: Muslims constitute about one-fourth of the human population, and a significant fraction of the organ recipients identify themselves as Muslims. A large fraction of the Muslim population is devout but unclear regarding the religious principles on organ donation and transplantation and is dependent on scholars' and imams' opinions. METHODS: The Qur'an, the authentic Prophetic Traditions, and expert opinions on the subject were investigated. RESULTS: The sources of the Islamic founding principles on organ donation and transplantation are the Qur'an, the Prophetic Traditions, Usulul Fiqh or expert opinions based on the Qur'an and Traditions, and Maslaha or the principles of public interest deduced by the scholars. Some Muslim scholars, mostly from the Indian subcontinent, opine that live organ donation, extraction of organs from dead persons, and transplantation are prohibited. Many Arab scholars and Muslim scholars settled in the western hemisphere opine that live organ donation, organ extraction from dead persons, and transplantation are permitted, but organ donation must be a voluntary act of charity. Of late, the Iranian imams/scholars have recognized that the national government may acquire live donor organs for a uniform compensation and equitably distribute the acquired organs to patients with failing organs. CONCLUSIONS: The current Islamic working principles on transplantation medicine are nonuniform, transitory, and somewhat detached from the bulk of the population. How such heterogeneity is affecting transplantation medicine, and organ donation in particular, among Muslim populations warrants further investigation.

Motivation for organ donation among college students in the United States.

BACKGROUND: The majority of the patients presently waiting for an organ are waiting for a kidney. Living kidney donation by about 0.1% of the adult population of a nation may completely eliminate kidney shortage. We investigated the concerns of college students toward charitable and compensated organ donation. METHODS: A 40-question survey was conducted. The respondents were students of the Biology Department of Utah Valley University, Orem, Utah, United States. The data were tabulated and analyzed. Tests of association among potentially linked attributes and the difference between two independent proportions were performed at the 0.05 level of significance and P-values were also calculated using XLSTAT software. RESULTS: The participants (n = 321) were 47% male, 53% female, 89% Caucasian, and 93% healthy, and 7% of the respondents had some health conditions. Of the respondents, 55% were ages 18 to 25 and 40% were ages 26 to 50 years; 43% were unmarried or single, 57% were married, and 85% had health insurance. About 65% of the respondents lived in small cities and the rest lived in large cities (23%) or the countryside (9%). There was no significant association between gender, level of education, location of living, and household income in relation to belief in organ donation with or without compensation, except that males favored compensated organ donation over females (P = .004). Rumors on organ theft and extraction of organ from questionable brain-dead patients had not negatively affected the decision of participants on being listed as organ donors in their driver's license (P = .0001). Those who considered organ donation ethically acceptable also believed that a person has the right to sale a kidney (P = .015) and the donor party should be somehow compensated (P = .001). CONCLUSIONS: A large percentage of college students supports compensated organ donation and considers that compensation will increase organ donation.

Effect of the non-conserved N-terminus on the DNA binding activity of the yeast TATA binding protein.

We have studied the DNA binding activity of recombinant yeast TATA Binding Protein (TBP) with particular interest in the role played by the non-conserved N-terminal domain. By comparing the DNA binding activity of wild type yeast TBP with a mutant form of TBP that lacks the non-conserved N-terminal domain (TBP delta 57), we have determined that the N-terminus of TBP alters both the shape and the stability of the TBP-DNA complex. Measurements of the DNA bending angle indicate that the N-terminus enhances the bending of the DNA that is induced by TBP binding and greatly destabilizes the TBP-DNA complex during native gel electrophoresis. In solution, the N-terminus has only a slight effect on the equilibrium dissociation constant and the dissociation rate constant. However, the N-terminal domain reduces the association rate constant in a temperature dependent manner and increases the apparent activation energy of the TBP-DNA complex formation by 3 kcal/mole. These data suggest that a conformational change involving the N-terminus of TBP may be one of the isomerization steps in the formation of a stable TBP-DNA complex.

Relationship between TATA-binding protein and herpes simplex virus type 1 ICP4 DNA-binding sites in complex formation and repression of transcription.

The herpes simplex virus (HSV) regulatory protein, infected-cell polypeptide 4 (ICP4), represses the transcription of promoters that have binding sites for ICP4 located near the transcription start site. It also been shown that ICP4 binds such promoter DNA cooperatively with the TATA-binding protein (TBP) and TFIIB to form a tripartite protein-DNA complex (C. Smith, P. Bates, R. Rivera-Gonzales, B. Gu, and N. A. DeLuca, J. Virol. 67:4676-4687, 1993). In this study, we analyzed the effects of position and orientation of the ICP4-binding site relative to the TATA box in the ICP4 promoter on transcriptional repression by ICP4 and on the ability of ICP4 to form tripartite complexes with TBP and TFIIB. The results of theis parallel study provide a strong correlation between tripartite complex formation and repression. Both tripartite-complex formation and transcriptional repression were efficient when the ICP4-binding site was downstream of the TATA box, within a short distance and in proper orientation. In addition, both tripartite-complex formation and repression were partially sensitive to the stereoaxial positioning of the ICP4-binding site relative to the TATA box. As a preliminary characterization of the tripartite complex, circular permutation analysis was performed to assess the distortion of the proximal promoter region in the tripartite complex. As previously reported, both TBP and ICP4 independently could bend DNA and the relative magnitude by which each of these proteins bent DNA in the tripartite complex was preserved. The results of this study suggest that the formation of tripartite complexes on a promoter is part of the mechanism of repression and that simple blocking as a sole result of ICP4 binding is not sufficient for full repression.

Down-regulation of endothelin receptors by transforming growth factor beta1 in hepatic stellate cells.

BACKGROUND/AIMS: Hepatic endothelin-1 (ET-1) receptor density as well as the levels of both ET-1 and transforming growth factor beta1 (TGF-beta1) increase in liver cirrhosis. Considering their potent contractile (ET-1) and fibrogenic (TGF-beta1) actions on myofibroblastic stellate cells found in the fibrotic/cirrhotic liver, we aimed to investigate the effects of TGF-beta1 on ET-1 receptors and ET-1 synthesis in these cells. METHODS: Stellate cells isolated from rat liver by enzymatic digestion were cultured and subjected to TGF-beta1 treatment. Cellular ET-1 receptors and ET-1 released in the medium were determined. RESULTS: TGF-beta1 treatment produced time- and dose-dependent decrease in ET-1 binding sites, but did not affect the affinity of the receptors for ET-1. TGF-beta1 also stimulated the release of ET-1 from stellate cells. The extent of TGF-beta1-induced inhibition of [125I]ET-1 binding was much greater for ETB subtype (73+/-18% inhibition), which comprised a major portion (78+/-12%) of the total ET-1 receptors, than for ETA subtype (35+/-11% inhibition). The mRNA expression of the ET-1 receptors also was reduced by TGF-beta1 treatment. TGF-beta1-induced reduction in ET-1 receptor density was coupled to the inhibition of ET-1-stimulated release of [3Hlarachidonic acid from the prelabeled cells. The effects of TGF-beta1 were inhibited by a TGF-beta1 neutralizing monoclonal antibody. CONCLUSIONS: These results suggest that the TGF-beta1-induced decrease in ET-1 receptor density may be an important mechanism in limiting the pathologic actions of ET-1 on stellate cells in chronic liver disease.