Biomedical subjects

C Powers

Publications and source records attributed to C Powers.

At least 19 recordsLinked to original sources

PubMed2006

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.

Animals↗

PubMed2006

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.

5' Untranslated Regions↗

PubMed2004

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.

Age Factors↗

PubMed2004

Temporal dynamics of the cellular, humoral and cytokine responses in chickens during primary and secondary infection with Salmonella enterica serovar 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.

Animals↗

PubMed2001

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.

Accidental Falls↗

PubMed2001

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.

Animals↗

PubMed2001

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.

Animals↗

PubMed2001

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.

Animals↗

PubMed2000

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.

Acute Disease↗

PubMed2000

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.

Adult↗

PubMed2000

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.

Animals↗

PubMed1999

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.

Animals↗

PubMed1999

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.

Journal Article↗

PubMed1999

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.

Animals↗

PubMed1999

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.

Amino Acid Sequence↗

PubMed1998

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.

Animals↗

PubMed1998

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.

Animals↗

PubMed1998

The expression of P- and E-selectins in three models of middle cerebral artery occlusion.

The expression and localization of P- and E-selectins in rat brain (n=126) were examined using immunohistochemical techniques at various time points after induction of middle cerebral artery (MCA) occlusion in the suture, thrombotic and embolic models of stroke. Expression of P- or E-selectin was not observed in brain tissue of sham operated control rats (n=9). P-selectin immunoreactivity was detected as early as 15 min and decreased to control level at 1 h after the onset of the MCA occlusion in all three models. P-selectin then slightly increased at 2 h and peaked at 6 h after MCA occlusion. E-selectin immunoreactivity was first observed at 2 h and peaked at 6 h and 12 h of after MCA occlusion in all three models. P- and E-selectin immunoreactivity was colocalized with von Willebrand factor immunoreactive microvessels. 90.4+/-2.0% of all vessels expressing P-selectin immunoreactivity were 7.5 to 30.0 micron in diameter; 3.6+/-1.4% were contained in vessels smaller than 7.5 micron, and 6.0+/-1.8% were localized in vessels greater than 30.0 micron in diameter. The percent distribution of E-selectin immunoreactive vessels were 75.9+/-2.1% in vessels 7.5 to 30.0 micron in diameter; 23.6+/-2.2% were in vessels smaller than 7.5 micron, and 0.6+/-0.4% were localized in vessels greater than 30.0 micron in diameter. These findings indicate that the temporal profiles of P- and E-selectin expression are independent of these models of MCA occlusion and are consistent with the time course of selectin mediated leukocyte infiltration after focal cerebral ischemia in the rat.

Analysis of Variance↗