Olgotrelvir, a dual inhibitor of SARS-CoV-2 Mpro and cathepsin L, as a standalone antiviral oral intervention candidate for COVID-19

BACKGROUND

Oral antiviral drugs with improved antiviral potency and safety are needed to address current challenges in clinical practice for treatment of COVID-19, including the risks of rebound, drug-drug interactions, and emerging resistance.

METHODS

Olgotrelvir (STI-1558) is designed as a next-generation antiviral targeting the SARS-CoV-2 main protease (Mpro), an essential enzyme for SARS-CoV-2 replication, and human cathepsin L (CTSL), a key enzyme for SARS-CoV-2 entry into host cells.

FINDINGS

Olgotrelvir is a highly bioavailable oral prodrug that is converted in plasma to its active form, AC1115. The dual mechanism of action of olgotrelvir and AC1115 was confirmed by enzyme activity inhibition assays and co-crystal structures of AC1115 with SARS-CoV-2 Mpro and human CTSL. AC1115 displayed antiviral activity by inhibiting replication of all tested SARS-CoV-2 variants in cell culture systems. Olgotrelvir also inhibited viral entry into cells using SARS-CoV-2 Spike-mediated pseudotypes by inhibition of host CTSL. In the K18-hACE2 transgenic mouse model of SARS-CoV-2-mediated disease, olgotrelvir significantly reduced the virus load in the lungs, prevented body weight loss, and reduced cytokine release and lung pathologies. Olgotrelvir demonstrated potent activity against the nirmatrelvir-resistant Mpro E166 mutants. Olgotrelvir showed enhanced oral bioavailability in animal models and in humans with significant plasma exposure without ritonavir. In phase I studies (ClinicalTrials.gov: NCT05364840 and NCT05523739), olgotrelvir demonstrated a favorable safety profile and antiviral activity.

CONCLUSIONS

Olgotrelvir is an oral inhibitor targeting Mpro and CTSL with high antiviral activity and plasma exposure and is a standalone treatment candidate for COVID-19.

FUNDING

Funded by Sorrento Therapeutics.

Chimeric mRNA-based COVID-19 vaccine induces protective immunity against Omicron and Delta variants

The emerging SARS-CoV-2 variants of concern (VOCs) exhibit enhanced transmission and immune escape, reducing the effectiveness of currently approved mRNA vaccines. To achieve wider coverage of VOCs, we first constructed a cohort of mRNAs harboring a furin cleavage mutation in the spike (S) protein of predominant VOCs, including Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), and Delta (B.1.617.2). The mutation abolished the cleavage between the S1 and S2 subunits. Systematic evaluation in vaccinated mice discovered that individual VOC mRNAs elicited strong neutralizing activity in a VOC-specific manner. In particular, the neutralizing antibodies (nAb) produced by immunization with Beta-Furin and Washington (WA)-Furin mRNAs showed potent cross-reactivity with other VOCs. However, neither mRNA elicited strong neutralizing activity against the Omicron variant. Hence, we further developed an Omicron-specific mRNA vaccine that restored protection against the original Omicron variant and some sublineages. Finally, to broaden the protection spectrum of the new Omicron mRNA vaccine, we engineered an mRNA-based chimeric immunogen by introducing the receptor-binding domain of Delta variant into the entire S antigen of Omicron. The resultant chimeric mRNA induced potent and broadly nAbs against Omicron and Delta, which paves the way to developing new vaccine candidates to target emerging variants in the future.

Discovery and intranasal administration of a SARS-CoV-2 broadly acting neutralizing antibody with activity against multiple Omicron subvariants

BACKGROUND

The continual emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern, in particular the newly emerged Omicron (B.1.1.529) variant and its BA.X lineages, has rendered ineffective a number of previously FDA emergency use authorized SARS-CoV-2 neutralizing antibody therapies. Furthermore, those approved antibodies with neutralizing activity against Omicron BA.1 are reportedly ineffective against the subset of Omicron subvariants that contain a R346K substitution, BA.1.1, and the more recently emergent BA.2, demonstrating the continued need for discovery and characterization of candidate therapeutic antibodies with the breadth and potency of neutralizing activity required to treat newly diagnosed COVID-19 linked to recently emerged variants of concern.

METHODS

Following a campaign of antibody discovery based on the vaccination of Harbor H2L2 mice with defined SARS-CoV-2 spike domains, we have characterized the activity of a large collection of spike-binding antibodies and identified a lead neutralizing human IgG1 LALA antibody, STI-9167.

FINDINGS

STI-9167 has potent, broad-spectrum neutralizing activity against the current SARS-COV-2 variants of concern and retained activity against each of the tested Omicron subvariants in both pseudotype and live virus neutralization assays. Furthermore, STI-9167 nAb administered intranasally or intravenously provided protection against weight loss and reduced virus lung titers to levels below the limit of quantitation in Omicron-infected K18-hACE2 transgenic mice.

CONCLUSIONS

With this established activity profile, a cGMP cell line has been developed and used to produce cGMP drug product intended for intravenous or intranasal use in human clinical trials.

FUNDING

Funded by CRIPT (no. 75N93021R00014), DARPA (HR0011-19-2-0020), and NCI Seronet (U54CA260560).

Unbiased approach to identify and assess efficacy of human SARS-CoV-2 neutralizing antibodies

Coronavirus disease 2019 (COVID-19) continues to significantly impact the global population, thus countermeasure platforms that enable rapid development of therapeutics against variants of SARS-CoV-2 are essential. We report use of a phage display human antibody library approach to rapidly identify neutralizing antibodies (nAbs) against SARS-CoV-2. We demonstrate the binding and neutralization capability of two nAbs, STI-2020 and STI-5041, against the SARS-CoV-2 WA-1 strain as well as the Alpha and Beta variants. STI-2020 and STI-5041 were protective when administered intravenously or intranasally in the golden (Syrian) hamster model of COVID-19 challenged with the WA-1 strain or Beta variant. The ability to administer nAbs intravenously and intranasally may have important therapeutic implications and Phase 1 healthy subjects clinical trials are ongoing.

Dehydrated Human Amnion Chorion Membrane as Treatment for Pediatric Burns

Objective: Pediatric burns are a major source of injury and in the absence of adequate care can lead to lifelong functional loss and disfigurement. While split thickness skin autografts are the current standard of care for deep partial and full-thickness burns, this approach is associated with considerable morbidity. For this reason, alternative skin substitutes such as allografts have gained interest. Approach: In the present study, we present a case series of 30 children with various types of burns treated with dehydrated human amnion chorion membrane (dHACM). Results: We show that treatment with dHACM is associated with an excellent rate of healing comparable to split thickness skin grafts with less rate of hypertrophic scar and contracture. Innovation: Treatment with dHACM is particularly attractive as it consists of many tissue regenerative factors, such as growth factors and immune modulators, thus it will reduce the risk of scaring. Conclusion: While dHACM is associated with an increased upfront cost, treating patients with small to moderate-sized burns with dHACM in their regional centers works to decrease downstream costs such as management of prolonged pain from donor-site morbidity, revisional surgeries from scar and contractures of split thickness grafts, and avoiding the cost of transfer to higher level centers of care. Our findings challenge the current standard of care, suggesting that dHACM provides an alternative to the current use of split thickness skin grafting and is a safe, feasible, and potentially superior substitute for the management of small to moderate total body surface area partial and full-thickness pediatric burns.

Dynamic control of tumor vasculature improves antitumor responses in a regional model of melanoma

Despite advances in therapy for melanoma, heterogeneous responses with limited durability represent a major gap in treatment outcomes. The purpose of this study was to determine whether alteration in tumor blood flow could augment drug delivery and improve antitumor responses in a regional model of melanoma. This approach to altering tumor blood flow was termed "dynamic control." Dynamic control of tumor vessels in C57BL/6 mice bearing B16 melanoma was performed using volume expansion (saline bolus) followed by phenylephrine. Intravital microscopy (IVM) was used to observe changes directly in real time. Our approach restored blood flow in non-functional tumor vessels. It also resulted in increased chemotherapy (melphalan) activity, as measured by formation of DNA adducts. The combination of dynamic control and melphalan resulted in superior outcomes compared to melphalan alone (median time to event 40.0 vs 25.0 days, respectively, p = 0.041). Moreover, 25% (3/12) of the mice treated with the combination approach showed complete tumor response. Importantly, dynamic control plus melphalan did not result in increased adverse events. In summary, we showed that dynamic control was feasible, directly observable, and augmented antitumor responses in a regional model of melanoma. Early clinical trials to determine the translational feasibility of dynamic control are ongoing.

Intra-arterial Versus Intravenous Adoptive Cell Therapy in a Mouse Tumor Model

Adoptive cell transfer therapy for cancer has existed for decades and is experiencing a resurgence in popularity that has been facilitated by improved methods of production, techniques for genetic modification, and host preconditioning. The trafficking of adoptively transferred lymphocytes and infiltration into the tumor microenvironment is sine qua non for successful tumor eradication; however, the paradox of extremely poor trafficking of lymphocytes into the tumor microenvironment raises the issue of how best to deliver these cells to optimize entry into tumor tissue. We examined the route of administration as a potential modifier of both trafficking and antitumor efficacy. Femoral artery cannulation and tail vein injection for the intra-arterial (IA) and IV delivery, respectively, were utilized in the B16-OVA/OT-I mouse model system. Both IV and IA infusions showed decreased tumor growth and prolonged survival. However, although significantly increased T-cell tumor infiltration was observed in IA mice, tumor growth and survival were not improved as compared with IV mice. These studies suggest that IA administration produces increased early lymphocyte trafficking, but a discernable survival benefit was not seen in the murine model examined.

Water lavage as an adjunct to cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC)

BACKGROUND

Water lavage (WL) during gastrointestinal cancer surgery has osmotically mediated lytic effects on tumor cells. We investigated the safety and efficacy of WL with CRS-HIPEC.

METHODS

This is a retrospective review, 1/2003-7/2014, of a single institution experience with CRS-HIPEC comparing patients who had WL (WL+) to those who did not (WL-).

RESULTS

Of 157 CRS-HIPECs, 16 (10.2%) were WL+. WL+ had more PCI scores >20 compared to WL- (56.3% vs 19.4%, respectively, p = 0.003); however, the completeness of cytoreduction (CC) was similar. There were no differences in hospital length of stay or post-operative complications. The average POD 1 sodium (Na) level was statistically lower in the WL+ group (133.6 ± 2.5 vs 135.5 ± 3.2 mEq/L, p = 0.023); however, the average Na at discharge for each group was 140 mEq/L. There were no differences in 3-year OS (3WL+:0.63 vs WL-:0.68, p = 0.97) or RFS (WL+:0.32 vs WL-:0.39, p = 0.47). A subset analysis for patients with PCI >20 showed no difference between groups.

CONCLUSIONS

WL offers a low cost, safe and theoretically efficacious method of tumor cell lysis for peritoneal malignancy.

Abstract 4225: Dynamic control of tumor vasculature with direct observation using intravital microscopy

Introduction

Intravital microscopy (IVM) provides in vivo real-time imaging of tumor-associated vasculature. Our group was the first to use IVM successfully in human subjects to image melanoma associated vessels. In this preclinical study, we hypothesized that intravenous (IV) nicardipine increases observable blood flow to tumor through vasodilatation and therefore may facilitate drug delivery.

Methods

Standard window chambers for IVM were implanted into female BALB/c mice. The murine colon cancer cell line CT26HA was inoculated in the skin within the chamber. Fluorescein isothiocyanate dextran (FITC-dex) was injected IV to enhance vessel observation prior to nicardipine (8 μg/mouse). Observations were performed at 100x magnification using a modified Olympus microscope for 10 minutes. Naïve mice were used for control observations. Mice bearing CT26HA were observed on post-inoculation day 5, 12 and 20. Vessel architecture and vessel diameter in response to nicardipine were compared.

Results

In non-CT26HA bearing mice, nicardipine resulted in a greater than 10% increase in skin vessel diameters directly measured using IVM (pre-nicardipine diameter 82.4 ± 3.6 μm versus post-nicardipine diameter 93.0 ± 3.9 μm. In CT26HA bearing mice, abnormal vessels were observed as early as day 7 even in the absence of a solid tumor mass. Vessel abnormalities included haphazard areas of increased vessel density, aberrant vessel branching patterns, nonfunctional vessels, and altered flow rates. Following nicardipine injection, the diameter of larger tumor-associated vessels did not increase and remained constant (pre: 111.2 ± 2.7 μm vs post: 109.1 ± 3.3 μm). Paradoxically, for smaller vessels (< 20 μm), tumor-associated vessels vasoconstricted following nicardipine injection and returned to baseline diameter after approximately five minutes. Blood flow in these small vessels decreased or stopped during this observation.

Conclusions

Observation of dynamic vessel changes from vasoactive agents is feasible using IVM. For tumor-associated vessels, nicardipine was not shown to increase vessel diameter and counterintuitively decreased diameters of smaller vessels. Implication on drug delivery from vasoactive agents will lead to further pre-clinical study of applications for human IVM.

Citation Format: Emmanuel M. Gabriel, Daniel Fisher, Minhyung Kim, Colin Powers, Anthony Visioni, Jason Muhitch, Joseph Skitzki. Dynamic control of tumor vasculature with direct observation using intravital microscopy. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4225.

Self-sampling for community respiratory illness: a new tool for national virological surveillance

This report aims to evaluate the usefulness of self-sampling as an approach for future national surveillance of emerging respiratory infections by comparing virological data from two parallel surveillance schemes in England. Nasal swabs were obtained via self-administered sampling from consenting adults (≥ 16 years-old) with influenza symptoms who had contacted the National Pandemic Flu Service (NPFS) health line during the 2009 influenza pandemic. Equivalent samples submitted by sentinel general practitioners participating in the national influenza surveillance scheme run jointly by the Royal College of General Practitioners (RCGP) and Health Protection Agency were also obtained. When comparable samples were analysed there was no significant difference in results obtained from self-sampling and clinician-led sampling schemes. These results demonstrate that self-sampling can be applied in a responsive and flexible manner, to supplement sentinel clinician-based sampling, to achieve a wide spread and geographically representative way of assessing community transmission of a known organism.

Sub-clinical infection with Salmonella in chickens differentially affects behaviour and welfare in three inbred strains

1. Much evidence exists detailing how animals respond to pathogen challenge, yet information explaining how the various behavioural, immunological, and physiological systems in chickens interplay during such challenges remains limited. 2. To gain an understanding of this interplay while controlling for genetic variation, the current study collected a variety of behavioural, physiological and immunological measures from three inbred lines (P, O and N) of laying hens before and after a sub-clinical infection with Salmonella enterica Typhimurium at 56 d of age. For comparison, an equal number of control birds were inoculated with a Salmonella-free broth. To identify an underlying profile, which might result in reduced susceptibility to infection, data were also collected in the pre-infection period. Post-infection blood and faeces were collected at 1-d post infection (dpi) and faeces again at 8 dpi. Animals were killed 15 d after infection and faeces, caecal contents, and spleen were examined for the presence of Salmonella. 3. Statistical analysis was performed to identify pre- and post-infection differences between genetic lines, changes in bird behavioural patterns between the two periods, and associations between a positive test for Salmonella and the various response measures. 4. Tissues from Line P birds were more often negative for Salmonella than those from birds of other lines, though this was inconsistent and tissue-dependent. The P line was also characterised by relatively greater serum concentrations of immunoglobulins at 1 dpi and α(1)-acid glycoprotein at 15 dpi. In addition, P line birds were more timid and their growth was reduced during the pre-infection period suggesting the possibility of a profile with reduced susceptibility to the bacterial challenge. 5. The current work has identified correlations between attributes of chicken strains and improved clearance. Future work using hypothesis-based testing will be required to determine whether the identified correlations are causally related.

IRS1 G972R polymorphism and type 2 diabetes: a paradigm for the difficult ascertainment of the contribution to disease susceptibility of 'low-frequency-low-risk' variants

AIMS/HYPOTHESIS

The aim of the study was to determine the association between IRS1 G972R polymorphism and type 2 diabetes; published data concerning this association have been conflicting. To obtain further insight into this topic, we performed a meta-analysis of all available case-control studies.

METHODS

We performed a meta-analysis of 32 studies (12,076 cases and 11,285 controls).

RESULTS

The relatively infrequent R972 variant was not significantly associated with type 2 diabetes (OR 1.09, 95% CI 0.96-1.23, p = 0.184 under a dominant model). Some evidence of heterogeneity was observed across studies (p = 0.1). In the 14 studies (9,713 individuals) in which the mean age at type 2 diabetes diagnosis was available, this variable explained 52% of the heterogeneity (p = 0.03). When these studies were subdivided into tertiles of mean age at diagnosis, the OR for diabetes was 1.48 (95% CI 1.17-1.87), 1.22 (95% CI 0.97-1.53) and 0.88 (95% CI 0.68-1.13) in the youngest, intermediate and oldest tertile, respectively (p = 0.0022 for trend of ORs).

CONCLUSIONS/INTERPRETATION

Our findings illustrate the difficulties of ascertaining the contribution of 'low-frequency-low-risk' variants to type 2 diabetes susceptibility. In the specific context of the R972 variant, approximately 200,000 study individuals would be needed to have 80% power to identify a 9% increase in diabetes risk at a genome-wide significance level. Under these circumstances, a strategy aimed at improving outcome definition and decreasing its heterogeneity may critically enhance our ability to detect genetic effects, thereby decreasing the required sample size. Our data suggest that focusing on early-onset diabetes, which is characterised by a stronger genetic background, may be part of such a strategy.

Neurocognitive contributions to verbal fluency deficits in frontotemporal lobar degeneration

OBJECTIVE

To test the hypothesis that different neurocognitive networks underlie verbal fluency deficits in frontotemporal lobar degeneration (FTLD).

METHODS

Letter ("FAS") and semantic ("animal") fluency tests were administered to patients with a behavioral/dysexecutive disorder (bvFTLD; n = 71), semantic dementia (SemD; n = 21), and progressive nonfluent aphasia (PNFA; n = 26). Tests measuring working memory, naming/lexical retrieval, and semantic knowledge were also obtained. MRI voxel-based morphometry (VBM) studies were obtained on a subset of these patients (bvFTLD, n = 51; PNFA, n = 11; SemD, n = 10).

RESULTS

Patients with SemD were disproportionately impaired on the semantic fluency measure. Reduced output on this test was correlated with impaired performance on naming/lexical retrieval tests. VBM analyses related reduced letter and semantic fluency to anterior and inferior left temporal lobe atrophy. Patients with bvFTLD were equally impaired on both fluency tests. Poor performance on both fluency tests was correlated with low scores on working memory and naming/lexical retrieval measures. In this group, MRI-VBM analyses related letter fluency to bilateral frontal atrophy and semantic fluency to left frontal/temporal atrophy. Patients with PNFA were also equally impaired on fluency tests. Reduced semantic fluency output was correlated with reduced performance on naming/lexical retrieval tests. MRI-VBM analyses related semantic fluency to the right frontal lobe and letter fluency to left temporal atrophy.

CONCLUSIONS

Distinct neurocognitive networks underlie impaired performance on letter and semantic fluency tests in frontotemporal lobar degeneration subgroups.

Cytomegalovirus immune evasion

Human cytomegalovirus (HCMV) has become a paradigm for viral immune evasion due to its unique multitude of immune-modulatory strategies. HCMV modulates the innate as well as adaptive immune response at every step of its life cycle. It dampens the induction of antiviral interferon-induced genes by several mechanisms. Further striking is the multitude of genes and strategies devoted to modulating and escaping the cellular immune response. Several genes are independently capable of inhibiting antigen presentation to cytolytic T cells by downregulating MHC class I. Recent data revealed an astounding variety of methods in triggering or inhibiting activatory and inhibitory receptors found on NK cells, NKT cells, T cells as well as auxiliary cells of the immune system. The multitude and complexity of these mechanisms is fascinating and continues to reveal novel insights into the host-pathogen interaction and novel cell biological and immunological concepts.

Examination of PPP1R3B as a candidate gene for the type 2 diabetes and MODY loci on chromosome 8p23

The product of the PPP1R3B gene (G(L)) is the regulatory subunit of PP1 - a serine/threonine phosphatase involved in the modulation of glycogen synthesis in the liver and skeletal muscle. The PPP1R3B gene is located on chromosome 8p23 in a region that has been linked with type 2 diabetes and maturity-onset diabetes of the young (MODY). We examined whether sequence variants at the PPP1R3B locus are responsible for the linkage with diabetes observed at this location. RT-PCR analysis revealed the existence of two alternative promoters. These and the two exons of this gene were sequenced in the probands of 13 Joslin families showing the strongest evidence of linkage at 8p23. A total of 20 variants were observed: two in the 5' flanking region, one in the intron (9 bp 5' of exon 2), and 17 in the 3' UTR. The intronic variant generated a new acceptor splice site, resulting in an alternative splice variant with a longer 5' UTR. However, neither this nor other variants segregated with diabetes in the 13 'linked' families. Furthermore, allele frequencies were similar in 90 family probands from the Joslin Study and 347 unrelated controls. Thus, genetic variability in the PPP1R3B gene does not appear to contribute to diabetes in our mostly Caucasian families. However, a role cannot be excluded in other populations such as the Japanese, among whom linkage to diabetes is also observed at 8p23 and a non-synonymous mutation has been detected in the PPP1R3B gene.

Cross-reactive cellular and humoral immune responses to Salmonella enterica serovars Typhimurium and Enteritidis are associated with protection to heterologous re-challenge

Chickens infected with Salmonella enterica serovars Typhimurium (ST) and Enteritidis (SE) still represent a major source of human food poisoning via consumption of contaminated meat and eggs. Vaccination represents a sustainable approach to control Salmonella in the chicken and the serovar specificity of immunity has the potential to impact on the need for multivalent vaccines. The issue of cross-reactive immune responses and cross-serovar protection was examined in these experiments. Cellular and humoral immune responses were measured by antigen-specific ELISA and splenocyte proliferation assays during primary infections (with ST and SE) and during a second challenge with homologous or heterologous serovars. Primary infection with ST or SE induced strong lymphocyte proliferation and high levels of specific antibody (IgM, IgG and IgA) responses with substantial serovar cross-reactivity. The occurrence of high levels of splenocyte proliferation and strong antibody responses corresponded to the initiation of clearance with both ST and SE. Re-challenge of ST and SE infection-primed chickens with either serovar resulted in significant levels of protection (assessed by bacterial numbers and rate of clearance) with little difference between homologous or heterologous challenge schedules. Relatively low levels of antigen-specific splenocyte proliferation were detected during secondary infection, which may be caused by splenic T cells exiting to the gut. In contrast, the more rapid specific antibody responses (compared with primary infection controls) indicate the development of a secondary antigen-specific adaptive response. The substantial level of cross-protection between serovars and the level of antigenic cross-reactivity indicates the potential for single serovar live vaccines to protect against both group B and D salmonellae.

Rhesus cytomegalovirus contains functional homologues of US2, US3, US6, and US11

Human cytomegalovirus (HCMV) is a paradigm for mechanisms subverting antigen presentation by major histocompatibility complex (MHC) molecules. Due to its limited host range, HCMV cannot be studied in animals. Thus, the in vivo importance of inhibiting antigen presentation for the establishment and maintenance of infection with HCMV is unknown. Rhesus cytomegalovirus (RhCMV) is an emerging animal model that shares many of the features of HCMV infection. The recent completion of the genomic sequence of RhCMV revealed a significant degree of homology to HCMV. Strikingly, RhCMV contains several genes with low homology to the HCMV US6 gene family of inhibitors of the MHC I antigen presentation pathway. Here, we examine whether the RhCMV US6 homologues (open reading frames Rh182, -184, -185, -186, -187, and -189) interfere with the MHC I antigen-processing pathway. We demonstrate that Rh182 and Rh189 function similarly to HCMV US2 and US11, respectively, mediating the proteasomal degradation of newly synthesized MHC I. The US3 homologue, Rh184, delayed MHC I maturation. Unlike US3, MHC I molecules eventually escaped retention by Rh184, so that steady-state surface levels of MHC I remained unchanged. Rh185 acted similarly to US6 and inhibited peptide transport by TAP and, consequently, peptide loading of MHC I molecules. Thus, despite relatively low sequence conservation, US6 family-related genes in RhCMV are functionally closely related to the conserved structural features of HCMV immunomodulators. The conservation of these mechanisms implies their importance for immune evasion in vivo, a question that can now be addressed experimentally.

Age at primary infection with Salmonella enterica serovar Typhimurium in the chicken influences persistence of infection and subsequent immunity to re-challenge

Salmonella enterica remains one of the most important food-borne pathogens of humans and is often acquired through consumption of infected poultry meat or eggs. Control of Salmonella infections in chicken is therefore an important public health issue. Infection with S. enterica serovar Typhimurium results in a persistent enteric infection without clinical disease in chickens of more than 3 days of age, and represents a source for contamination of carcass at slaughter and entry into the human food chain. Data presented indicate a profound effect of age at initial exposure on the persistence of infection and a lesser effect on the development of effective immunity to re-challenge. The percentage of birds positive for Salmonella was high until 8-9 weeks of age, regardless of the age at which the birds were infected (1, 3 or 6 weeks). The birds infected at 3 and 6 weeks of age produced a more rapid and higher antibody response (IgY and IgA) than those infected at 1 week of age, but in all cases infection persisted for a considerable period despite the presence of high antibody levels. Following a re-challenge infection with S. Typhimurium, all three previously-infected groups had fewer bacteria in the gut, spleen and liver compared with age-matched birds receiving a parallel primary infection. However, the birds primary infected at 3 and 6 weeks of age cleared infection more rapidly than those infected at a younger age. Interestingly older-primed birds had higher specific T lymphocyte proliferative responses and specific circulating levels of IgY antibody at time of re-challenge. Although birds initially infected at 1 week of age and those that were previously uninfected produced a stronger antibody response following re-challenge, they were slower to clear Salmonella from the gut than the older-primed groups which expressed a stronger T lymphocyte response. The data presented indicate that clearance of Salmonella from the gut is age-dependent and we propose that this relates to the increased competence of the enteric T cell response. The findings that Salmonella persists beyond 8-9 weeks, irrespective of age at exposure, has implications for the broiler sector and indicates the need to remain Salmonella free throughout the rearing period. Moreover, the re-challenge data demonstrates that infection at a young age is less effective in producing protective immunity than in older chickens. This feature of the development of protective immunity needs to be considered when developing vaccines for the broiler sector of the poultry industry.

Temporal dynamics of the cellular, humoral and cytokine responses in chickens during primary and secondary infection withSalmonella entericaserovar Typhimurium

Salmonella enterica serovar Typhimurium (S. Typhimurium) infections cause systemic disease in the young chick, whereas in the older chicken the infection is mainly restricted to the intestine. Chickens infected orally with S. Typhimurium (F98) at 6 weeks of age and re-infected 10 weeks later were monitored for antibody production, T-cell proliferation and production of selected cytokines (interferon-gamma, interleukin-1beta and transforming growth factor-beta(4)). A strong coordinated antigen-specific humoral and cellular immune response was temporally linked to resolution of the primary infection. Enhanced levels of mRNA encoding the cytokines, interleukin-1beta, transforming growth factor-beta(4) and interferon-gamma were also evident during early phases of primary infection. Secondary infection was restricted to the intestine and of shorter duration than primary infection. Splenic immune responses were not further enhanced by secondary infection; indeed, antigen-specific proliferation was significantly reduced at 1 day after secondary infection, which may be interpreted as the trafficking of reactive T cells from the spleen to the gut.

Biomechanics of slips

The biomechanics of slips are an important component in the prevention of fall-related injuries. The purpose of this paper is to review the available literature on the biomechanics of gait relevant to slips. This knowledge can be used to develop slip resistance testing methodologies and to determine critical differences in human behaviour between slips leading to recovery and those resulting in falls. Ground reaction forces at the shoe-floor interface have been extensively studied and are probably the most critical biomechanical factor in slips. The ratio of the shear to normal foot forces generated during gait, known as the required coefficient of friction (RCOF) during normal locomotion on dry surfaces or 'friction used/achievable' during slips, has been one biomechanical variable most closely associated with the measured frictional properties of the shoe/floor interface (usually the coefficient of friction or COF). Other biomechanical factors that also play an important role are the kinematics of the foot at heel contact and human responses to slipping perturbations, often evident in the moments generated at the lower extremity joints and postural adaptations. In addition, it must be realized that the biomechanics are dependent upon the capabilities of the postural control system, the mental set of the individual, and the perception of the environment, particularly, the danger of slipping. The focus of this paper is to review what is known regarding the kinematics and kinetics of walking on surfaces under a variety of environmental conditions. Finally, we discuss future biomechanical research needs to help to improve walkway-friction measurements and safety.

Dynamic platelet accumulation at the site of the occluded middle cerebral artery and in downstream microvessels is associated with loss of microvascular integrity after embolic middle cerebral artery occlusion

Information is lacking regarding dynamic platelet accumulation at the site of the occluded middle cerebral artery (MCA) and the relationship between platelet aggregation in downstream cerebral microvessels and loss of perfusion and vascular integrity of these microvessels. In the present study, we employed a model of embolic MCA occlusion in the rat to simultaneously measure temporal and spatial profiles of platelet accumulation at the site of the embolus occluding the MCA and within downstream cerebral microvessels. We also measured the integrity of microvessels and matrix metalloproteinase (MMP) activity in ischemic brain. Rats (n=36) were subjected to embolic MCA occlusion. Immunohistochemistry was used to detect microvascular integrity, plasminogen activator inhibitor 1 (PAI-1) and the deposition of fibrin. SDS-PAGE zymography was used to measure MMP2 and MMP9 activities. Accumulation of platelets and increases in PAI-1 immunoreactivity at the site of the embolus occluding the MCA were detected 1 h (n=7) and 4 h (n=7) after ischemia, respectively, and numbers of GPIIb/IIIa immunoreactive downstream cerebral microvessels increased significantly (209+/-59; n=7; P<0.05) 4 h after ischemia, suggesting dynamic platelet aggregation. A significant (n=7; P<0.01) diffuse loss of type IV collagen immunoreactivity in microvessels was temporally associated with platelet GPIIb/IIIa immunoreactivity within the vessels. Triple immunostaining revealed that microvessels containing platelet aggregates exhibited loss of type IV collagen immunoreactivity and both intra- and extra-vascular fibrin deposition, suggesting that intravascular platelet aggregation is associated with decreases in the integrity of the microvascular basal lamina and blood-brain barrier leakage. A significant increase (P<0.05) in MMP9 was detected at 4 h (n=3) and 24 h (n=3) after ischemia but levels of MMP2 were not significantly changed in ischemic brain. Our data suggest that dynamic platelet aggregation in ischemic brain may contribute to time-dependent resistance to fibrinolysis. In addition, platelet deposition and increased MMP9 coincided with degradation of type IV collagen and loss of vascular integrity. These data suggest an important role for post-occlusive distal platelet deposition in the pathophysiology of stroke.

Ribozyme targeting demonstrates that the nuclear receptor coactivator AIB1 is a rate-limiting factor for estrogen-dependent growth of human MCF-7 breast cancer cells

Human breast tumorigenesis is promoted by the estrogen receptor pathway, and nuclear receptor coactivators are thought to participate in this process. Here we studied whether one of these coactivators, AIB1 (amplified in breast cancer 1), was rate-limiting for hormone-dependent growth of human MCF-7 breast cancer cells. We developed MCF-7 breast cancer cell lines in which the expression of AIB1 can be modulated by regulatable ribozymes directed against AIB1 mRNA. We found that depletion of endogenous AIB1 levels reduced steroid hormone signaling via the estrogen receptor alpha or progesterone receptor beta on transiently transfected reporter templates. Down-regulation of AIB1 levels in MCF-7 cells did not affect estrogen-stimulated cell cycle progression but reduced estrogen-mediated inhibition of apoptosis and cell growth. Finally, upon reduction of endogenous AIB1 expression, estrogen-dependent colony formation in soft agar and tumor growth of MCF-7 cells in nude mice was decreased. From these findings we conclude that, despite the presence of different estrogen receptor coactivators in breast cancer cells, AIB1 exerts a rate-limiting role for hormone-dependent human breast tumor growth.

Up-regulation of neuropilin-1 in neovasculature after focal cerebral ischemia in the adult rat

During development, neuropilin-1 is a receptor for semaphorin 3a-mediated axonal guidance and for vascular endothelial growth factor (VEGF) promotion of angiogenesis. The authors measured neuropilin-1 expression in the adult ischemic brain using Northern blot, in situ hybridization, and immunohistochemistry. Neuropilin-1 mRNA was significantly up-regulated as early as 2 hours and persisted at least 28 days after focal cerebral ischemia. Acute up-regulation of neuropilin-1 mRNA primarily localized to the ischemic neurons. A marked increase in both mRNA and protein of neuropilin-1 was detected in endothelial cells of cerebral blood vessels at the border and in the core of the ischemic lesion 7 days after ischemia, and neuropilin-1 gene expression persisted on these vessels for at least 28 days after ischemia. In these areas, neovascularization was detected using three-dimensional reconstructed images obtained from laser scanning confocal microscopy. Activated astrocytes also exhibited neuropilin-1 immunoreactivity during 7 to 28 days of ischemia. Double immunofluorescent staining showed colocalization of neuropilin-1 and VEGF to cerebral blood vessels and activated astrocytes. These data suggest that in addition to its role in axonal growth, up-regulation of neuropilin-1, in concert with VEGF and its receptors, may contribute to neovascular formation in the adult ischemic brain.

VEGF enhances angiogenesis and promotes blood-brain barrier leakage in the ischemic brain

VEGF is a secreted mitogen associated with angiogenesis and is also a potent vascular permeability factor. The biological role of VEGF in the ischemic brain remains unknown. This study was undertaken to investigate whether VEGF enhances cerebral microvascular perfusion and increases blood-brain barrier (BBB) leakage in the ischemic brain. Using magnetic resonance imaging (MRI), three-dimensional laser-scanning confocal microscope, and functional neurological tests, we measured the effects of administrating recombinant human VEGF(165) (rhVEGF(165)) on angiogenesis, functional neurological outcome, and BBB leakage in a rat model of focal cerebral embolic ischemia. Late (48 hours) administration of rhVEGF(165) to the ischemic rats enhanced angiogenesis in the ischemic penumbra and significantly improved neurological recovery. However, early postischemic (1 hour) administration of rhVEGF(165) to ischemic rats significantly increased BBB leakage, hemorrhagic transformation, and ischemic lesions. Administration of rhVEGF(165) to ischemic rats did not change BBB leakage and cerebral plasma perfusion in the contralateral hemisphere. Our results indicate that VEGF can markedly enhance angiogenesis in the ischemic brain and reduce neurological deficits during stroke recovery and that inhibition of VEGF at the acute stage of stroke may reduce the BBB permeability and the risk of hemorrhagic transformation after focal cerebral ischemia.

Evaluation of migraineurs' preferences for naratriptan over conventional first-line agents

OBJECTIVE

To assess patient satisfaction with and preference for naratriptan hydrochloride therapy over previous "nontriptan" therapy for migraines.

DESIGN AND SETTING

Open-label study conducted at 15 primary care clinics.

PATIENTS

One hundred forty-three adults meeting International Headache Society diagnostic criteria for migraine who were not using triptans as first-line therapy for migraines were enrolled; 115 completed the study. INTERVENTION AND OUTCOME ASSESSMENTS: At baseline, satisfaction with current migraine therapy was assessed. Patients were provided with naratriptan hydrochloride, 2.5 mg, to treat 3 migraines and diaries to record headache symptoms and response to treatment. After treating 3 migraines, satisfaction with naratriptan therapy and preference for either previous or naratriptan therapy were assessed.

RESULTS

Eighty-nine (62%) of 143 patients had previous exposure to triptans, with lack of prescribing (55%) as the primary reason for not continuing their use as first-line therapy. Medications used for first-line therapy included simple analgesics (59%), combination products (46%), and narcotics (13%). After treating 3 migraines with naratriptan, satisfaction with migraine therapy increased from 47% to 75%. Sixty-three percent of patients preferred naratriptan therapy over their previous nontriptan therapy, 27% preferred their previous therapy, and 10% had no preference. The main reasons for preference for naratriptan therapy were "relieves pain effectively" (86%) and "restores ability to function/perform task" (81%).

CONCLUSION

Naratriptan for first-line migraine therapy was preferred by most patients over previous nontriptan therapy.

New scoring system identifies kidney outcome with radiation therapy in acute renal allograft rejection

PURPOSE

To evaluate the role of radiation therapy for acute refractory renal rejection after failure of medical intervention, and to identify risk factors that influence graft survival following radiation therapy.

METHODS

Between June 1989 and December 1995, 53 renal transplant recipients (34 men and 19 women) were treated with localized radiation therapy for acute renal allograft rejection. Graft rejection was defined as an increase in serum creatinine with histologic evidence of rejection on renal biopsy. Ninety-one percent were cadaveric transplant recipients. The majority of patients who experienced acute graft rejection initially received corticosteroid therapy, except for 25% who were referred for radiation therapy and steroids for the first rejection. In more recent years, patients with moderate or severe steroid-resistant or recurrent rejection received OKT3, a polyclonal antilymphocyte antibody (ATGAM), tacrolimus (FK506), or mycophenolate mofetil (MMF). Patients who failed to respond to medical treatment were then referred for radiation therapy. Ultrasound was performed for kidney localization. Treatment consisted of a dose of 600 cGy given in 3 or 4 fractions using 6 MV photons, delivered AP or AP/PA.

RESULTS

The overall actuarial graft survival from the initiation of RT was 83% at 1 month, 60% at 1 year, and 36% at 5 years. The median follow-up from the date of transplant to the last follow-up was 22 months. The median time from the date of transplant to the initiation of radiotherapy was 3 months, and the median time from the initiation of radiotherapy to the last follow-up was 10 months. Variables evaluated were as follows: human leukocyte antigen matching on HLA-A, HLA-B, and HLA-DR, the transplant panel-reactive antibodies (PRA) at transplantation, number of acute rejection episodes, interval from the date of the transplant to the first rejection, serum creatinine levels at the time of the first radiation treatment, number of transplants, and concomitant immunosuppressive therapy. Independent factors examined by Cox regression modeling were: gender (p = 0.005), creatinine levels (p = 0.000), HLA-DR (p70% (p = 0.014). Each factor was scored using integral coefficients to generate four different groups. The Kaplan-Meier survival analyzed by group produces an interpretable separation of the risk factors for graft loss.

CONCLUSIONS

The outcome in patients treated with radiation therapy for acute renal graft rejection can be predicted by a novel scoring system. Patients with scores of three or less are able to achieve 100% renal graft salvage, while patients who have scores of 12 or higher are not able to be salvaged with the current radiation therapy regimen. Future studies should be directed toward identifying more effective treatment for patients who have a high score based on our criteria. The scoring system should be utilized to identify patients at risk who could benefit from radiation therapy. Further study with a randomized trial utilizing this scoring system is needed to confirm the validity of the scoring system in predicting graft survival and the efficacy of radiation in patients who receive radiation therapy for acute graft rejection.

Cerebral microvascular obstruction by fibrin is associated with upregulation of PAI-1 acutely after onset of focal embolic ischemia in rats

The mechanisms underlying cerebral microvascular perfusion deficit resulting from occlusion of the middle cerebral artery (MCA) require elucidation. We, therefore, tested the hypothesis that intravascular fibrin deposition in situ directly obstructs cerebral microcirculation and that local changes in type 1 plasminogen activator inhibitor (PAI-1) gene expression contribute to intravascular fibrin deposition after embolic MCA occlusion. Using laser-scanning confocal microscopy (LSCM) in combination with immunofluorescent staining, we simultaneously measured in three dimensions the distribution of microvascular plasma perfusion deficit and fibrin(ogen) immunoreactivity in a rat model of focal cerebral embolic ischemia (n = 12). In addition, using in situ hybridization and immunostaining, we analyzed expression of PAI-1 in ischemic brain (n = 13). A significant (p < 0.05) reduction of cerebral microvascular plasma perfusion accompanied a significant (p < 0.05) increase of intravascular and extravascular fibrin deposition in the ischemic lesion. Microvascular plasma perfusion deficit and fibrin deposition expanded concomitantly from the subcortex to the cortex during 1 and 4 hr of embolic MCA occlusion. Three-dimensional analysis revealed that intravascular fibrin deposition directly blocks microvascular plasma perfusion. Vascular plugs contained erythrocytes, polymorphonuclear leukocytes, and platelets enmeshed in fibrin. In situ hybridization demonstrated induction of PAI-1 mRNA in vascular endothelial cells in the ischemic region at 1 hr of ischemia. PAI-1 mRNA significantly increased at 4 hr of ischemia. Immunohistochemical staining showed the same pattern of increased PAI-1 antigen in the endothelial cells. These data demonstrate, for the first time, that progressive intravascular fibrin deposition directly blocks cerebral microvascular plasma perfusion in the ischemic region during acute focal cerebral embolic ischemia, and upregulation of the PAI-1 gene in the ischemic lesion may foster fibrin deposition through suppression of fibrinolysis.

Does cartilage down-regulate growth factor expression in tracheal epithelium?

BACKGROUND

Maintaining tracheal integrity and restoring normal physiologic function after injury is complex. Some of the critical events in this process are deposition of a provisional extracellular matrix, tissue remodeling, and angiogenesis. These events are coordinated with epithelial migration and proliferation to restore the mucosal barrier. The ability of respiratory epithelial cells (REC) to migrate and proliferate and restore denuded areas of the large conducting airway after injury is poor.

OBJECTIVE

To test the hypotheses that (1) the cartilaginous framework, underlying the extracellular matrix (submucosa) and epithelium, decreases the migratory ability of REC when compared with REC on the same provisional extracellular matrix (type I collagen) alone, and (2) this phenomenon is associated with a change in expression of transforming growth factor (TGF)-alpha and TGF-beta, both of which have been demonstrated in cutaneous models to be important in epithelial migration and proliferation.

DESIGN

We developed a culture system that reconstitutes the tracheal lumen in vitro, consisting of dissociated chondrocytes cultured in a manner to form cartilage, submucosa (type I collagen), and REC (termed a "composite culture"). Control cultures consisted of epithelial cells grown on type I collagen alone. Control and composite cultures were evaluated morphologically using scanning electron and light microscopy. Expression of TGF-alpha and TGF-beta was determined in day 14 cultured epithelial cells from control and composite cultures by semiquantitative polymerase chain reaction.

RESULTS

Epithelial cells from composite cultures did not spread and were less squamoid in morphological appearance than epithelial cells on type I collagen alone. Expression of both growth factors was reduced in epithelial cells from composite cultures compared with those on type I collagen.

CONCLUSIONS

Cartilage modulates TGF-alpha and TGF-beta expression in REC, and may contribute to regulation of REC proliferation and differentiation.

cDNA isolation, expression, and chromosomal localization of the mouse pcph proto-oncogene

We report here the isolation and characterization of a cDNA from mouse thymus encoding the murine homolog of the protein product of the Syrian hamster Pcph proto-oncogene. The single open reading frame identified in the cDNA sequence encoded a protein predicted to have 428 amino acids, which shared 93.7% amino acid identity with the Syrian hamster Pcph within the first 412 residues but had a shorter, highly dissimilar C-terminus. Northern and western analyses revealed that Pcph mRNA and protein were widely distributed in mouse embryo and adult tissues, with the highest expression in adults detected in kidney and liver. The mouse Pcph proto-oncogene was mapped by linkage analysis to within 3.3+/-2.3 cM of Pkch-rs1 on chromosome 12. These data should prove valuable in designing studies to define the cellular function of the Pcph proto-oncogene.

Effectiveness of exercise versus normal activity on acute low back pain: an integrative synthesis and meta-analysis

There are a variety of protocols used to treat acute low back pain in adults. Therapies currently prescribed include bed rest, normal activity, and exercise therapy. The effectiveness of each of these treatments is controversial. The purpose of this study is to compare the effectiveness of exercise therapy with normal activity in the treatment of employed adults with acute low back pain through an integrative synthesis and meta-analysis of published research. The integrative synthesis and meta-analytical results support the hypothesis that employed adults diagnosed with acute low back pain will have fewer number of days absent from work after exercise therapy when compared to number of days absent from work after normal activity. This study's weighted P is 0.0000003109. The weighted effect size D is 0.4785 and this is a strong effect of exercise on number of days absent from work. This study concluded that exercise therapy should be prescribed for the treatment of adults with acute low back pain to expedite recovery. The results of this study allow the health care provider to confidently prescribe exercise therapy for acute low back pain. This study can be used to support exercise therapy as an evidence based care protocol for health care providers.

Functional analysis of Tpr: identification of nuclear pore complex association and nuclear localization domains and a role in mRNA export

Tpr is a 270-kD coiled-coil protein localized to intranuclear filaments of the nuclear pore complex (NPC). The mechanism by which Tpr contributes to the structure and function of the nuclear pore is currently unknown. To gain insight into Tpr function, we expressed the full-length protein and several subdomains in mammalian cell lines and examined their effects on nuclear pore function. Through this analysis, we identified an NH2-terminal domain that was sufficient for association with the nucleoplasmic aspect of the NPC. In addition, we unexpectedly found that the acidic COOH terminus was efficiently transported into the nuclear interior, an event that was apparently mediated by a putative nuclear localization sequence. Ectopic expression of the full-length Tpr caused a dramatic accumulation of poly(A)+ RNA within the nucleus. Similar results were observed with domains that localized to the NPC and the nuclear interior. In contrast, expression of these proteins did not appear to affect nuclear import. These data are consistent with a model in which Tpr is tethered to intranuclear filaments of the NPC by its coiled coil domain leaving the acidic COOH terminus free to interact with soluble transport factors and mediate export of macromolecules from the nucleus.

Neuronal damage and plasticity identified by microtubule-associated protein 2, growth-associated protein 43, and cyclin D1 immunoreactivity after focal cerebral ischemia in rats

BACKGROUND AND PURPOSE

An objective of therapeutic intervention after cerebral ischemia is to promote improved functional outcome. Improved outcome may be associated with a reduction of the volume of cerebral infarction and the promotion of cerebral plasticity. In the developing brain, neuronal growth is concomitant with expression of particular proteins, including microtubule-associated protein 2 (MAP-2), growth-associated protein 43 (GAP-43), and cyclin D1. In the present study we measured the expression of select proteins associated with neurite damage and plasticity (MAP-2 and GAP-43) as well as cell cycle (cyclin D1) after induction of focal cerebral ischemia in the rat.

METHODS

Brains from rats (n=28) subjected to 2 hours of middle cerebral artery occlusion and 6 hours, 12 hours, and 2, 7, 14, 21, and 28 days (n=4 per time point) of reperfusion and control sham-operated (n=3) and normal (n=2) rats were processed by immunohistochemistry with antibodies raised against MAP-2, GAP-43, and cyclin D1. Double staining of these proteins for cellular colocalization was also performed.

RESULTS

Loss of immunoreactivity of both MAP-2 and GAP-43 was observed in most damaged neurons in the ischemic core. In contrast, MAP-2, GAP-43, and cyclin D1 were selectively increased in morphologically intact or altered neurons localized to the ischemic core at an early stage (eg, 6 hours) of reperfusion and in the boundary zone to the ischemic core (penumbra) during longer reperfusion times.

CONCLUSIONS

The selective expressions of the neuronal structural proteins (MAP-2 in dendrites and GAP-43 in axons) and the cyclin D1 cell cycle protein in neurons observed in the boundary zone to the ischemic core are suggestive of compensatory and repair mechanisms in ischemia-damaged neurons after transient focal cerebral ischemia.

Intrahepatic biliary enteric bypass provides effective palliation in selected patients with malignant obstruction at the hepatic duct confluence

BACKGROUND

Palliating the effects of biliary obstruction is a major goal of therapy in patients with cancer at the hepatic duct confluence. This study was undertaken to evaluate the effectiveness of intrahepatic biliary-enteric bypass to either the segment III duct or the right sectoral hepatic ducts in patients with unresectable hilar cholangiocarcinoma or gallbladder carcinoma.

METHODS

From December 1991 to October 1996, 55 consecutive bypass procedures were prospectively evaluated in patients with unresectable hilar cholangiocarcinoma or gallbladder cancer. Patients were divided into three groups based on the primary tumor and the type of bypass performed: group 1A, cholangiocarcinoma/segment III bypass (n = 20); group 1B, cholangiocarcinoma/right sectoral hepatic duct bypass (n = 14); group 2, gallbladder cancer/segment III bypass (n = 21).

RESULTS

Mean hospital stay (14+/-2 days) and mean blood loss (629+/-84 mL) were similar among the three groups. Perioperative death occurred in 6 patients (11%): 0 in group 1A, 3 each in groups 1B and 2. All survivors had relief of jaundice and pruritus after bypass. Complications occurred in 25 patients (45%). Preoperative transhepatic biliary drainage, performed in 14 patients prior to referral, was associated with a higher incidence of contaminated bile, greater operative blood loss, and postoperative biliary leak that was less likely to resolve spontaneously. Median survival in patients with cholangiocarcinoma (groups 1A and 1B) was 52 weeks and was unaffected by the type of bypass performed. By contrast, median survival in patients with gallbladder cancer (group 3) was 20 weeks; all but 3 died within 32 weeks of surgery. In patients with cholangiocarcinoma, the 1-year bypass patency was 80% in group 1A (segment III bypass) and 60% in group 1B (right sectoral hepatic duct bypass). Overall, there were 9 late bypass failures (18%) requiring reintervention.

CONCLUSIONS

Intrahepatic biliary-enteric bypass effectively relieves symptoms due to malignant hilar obstruction. In patients with cholangiocarcinoma, segment III bypass provides excellent palliation with relatively few late complications and can be performed with minimal morbidity and mortality. Bypass to the right sectoral hepatic ducts, on the other hand, is associated with significant procedure-related morbidity and mortality and more late complications. Patients with gallbladder cancer, because of their poor survival, are probably better palliated by percutaneous biliary stenting.

Intact, injured, necrotic and apoptotic cells after focal cerebral ischemia in the rat

Middle cerebral artery occlusion (MCAo) leads to brain cell death. However, quantitation of injured brain cells and inflammatory cells after MCAo has not been determined in the rat. Transient (2 h) MCAo was therefore induced in male Wistar rats by means of an intraluminal monofilament. Immunohistochemical and histochemical procedures performed at 46 h after MCAo were used to identify specific cellular populations in ischemic and control rats (n = 11). In the ischemic core of the lesion, approximately 24.7% of cells disappeared. Forty-four point eight percent of parenchymal cells consisted of intact (13.0%) or reversibly injured swollen (7.6%) and scalloped/shrunken dark (24.2%) cells. The percentage of irreversibly damaged cells was 55.2%, and included 49.9% necrotic cells (10.5% red and 39.4% ghost) and 5.4% apoptotic cells. In the inner boundary zone of the lesion, 15.9% of cells disappeared. Viable cells constituted 62.0% of all remaining cells. Neutrophils and macrophages were localized to this area. In the outer boundary zone of the lesion, 9.0% of cells disappeared. Viable cells constituted 91.6% of all remaining cells. The ratio of apoptotic to necrotic cells was 1:9, 1:6, 1:13 in the ischemic core, inner and outer boundary zones, respectively. Our data suggest the presence of three zones within the ischemic lesion: the core, and inner and outer boundaries. At 46 h after 2 h of MCAo the ischemic lesion is highly heterogeneous containing relatively large percentages of morphologically intact cells, suggesting the possibility of an extended window of therapeutic opportunity.