Biomedical subjects

K Cain

Publications and source records attributed to K Cain.

At least 19 recordsLinked to original sources

PubMed2006

Risk factors for encephalitis and death from West Nile virus infection.

We conducted a nested case-control study to determine potential risk factors for developing encephalitis from West Nile virus (WNV) infection. Retrospective medical chart reviews were completed for 172 confirmed WNV cases hospitalized in Houston between 2002 and 2004. Of these cases, 113 had encephalitis, including 17 deaths, 47 had meningitis, and 12 were fever cases; 67% were male. Homeless patients were more likely to be hospitalized from WNV compared to the general population. A multiple logistic regression model identified age [odds ratio (OR) 1.1, P<0.001], history of hypertension, including those cases taking hypertension-inducing drugs (OR 2.9, P=0.012), and history of cardiovascular disease (OR 3.5, P=0.061) as independent risk factors for developing encephalitis from WNV infection. After adjusting for age, race/ethnicity (being black) (OR 12.0, P<0.001), chronic renal disease (OR 10.6, P<0.001), hepatitis C virus (OR 23.1, P=0.0013), and immunosuppression (OR 3.9, P=0.033) were identified as risk factors for death from WNV infection.

Adolescent↗

PubMed2001

Physiological concentrations of K+ inhibit cytochrome c-dependent formation of the apoptosome.

In many forms of apoptosis, cytochrome c released from mitochondria induces the oligomerization of Apaf-1 to form a caspase-activating apoptosome complex. Activation of lysates in vitro with dATP and cytochrome c results in the formation of an active caspase-processing approximately 700-kDa apoptosome complex, which predominates in apoptotic cells, and a relatively inactive approximately 1.4-MDa complex. We now demonstrate that assembly of the active complex is suppressed by normal intracellular concentrations of K(+). Using a defined apoptosome reconstitution system with recombinant Apaf-1 and cytochrome c, K(+) also inhibits caspase activation by abrogating Apaf-1 oligomerization and apoptosome assembly. Once assembled, the apoptosome is relatively insensitive to the effects of ionic strength and processes/activates effector caspases. The inhibitory effects of K(+) on apoptosome formation are antagonized in a concentration-dependent manner by cytochrome c. These studies support the hypothesis that the normal intracellular concentrations of K(+) act to safeguard the cell against inappropriate formation of the apoptosome complex, caused by the inadvertent release of small amounts of cytochrome c. Thus, the assembly and activation of the apoptosome complex in the cell requires the rapid and extensive release of cytochrome c to overcome the inhibitory effects of normal intracellular concentrations of K(+).

Apoptosis↗

PubMed2001

Elevated extracellular [K+] inhibits death-receptor- and chemical-mediated apoptosis prior to caspase activation and cytochrome c release.

Efflux of intracellular K(+) and cell shrinkage are features of apoptosis in many experimental systems, and a regulatory role has been proposed for cytoplasmic [K(+)] in initiating apoptosis. We have investigated this in both death-receptor-mediated and chemical-induced apoptosis. Using Jurkat T cells pre-loaded with the K(+) ion surrogate (86)Rb(+), we have demonstrated an efflux of intracellular K(+) during apoptosis that was concomitant with, but did not precede, other apoptotic changes, including phosphatidylserine externalization, mitochondrial depolarization and cell shrinkage. To further clarify the role of K(+) ions in apoptosis, cytoprotection by elevated extracellular [K(+)] was studied. Induction of apoptosis by diverse death-receptor and chemical stimuli in two cell lines was inhibited prior to phosphatidylserine externalization, mitochondrial depolarization, cytochrome c release and caspase activation. Using a cell-free system, we have demonstrated a novel mechanism by which increasing [K(+)] inhibited caspase activation. In control dATP-activated lysates, Apaf-1 oligomerized to a biologically active caspase processing approximately 700 kDa complex and an inactive approximately 1.4 MDa complex. Increasing [K(+)] inhibited caspase activation by preventing formation of the approximately 700 kDa complex, but not of the inactive complex. Thus intracellular and extracellular [K(+)] markedly affect caspase activation and the initiation of apoptosis induced by both death-receptor ligation and chemical stress.

Amino Acid Chloromethyl Ketones↗

PubMed2001

Liver toxicity and apoptosis: role of TGF-beta1, cytochrome c and the apoptosome.

Transforming growth factor-beta1 (TGF-beta1), is involved in controlling liver size, by inducing apoptotic cell death in hepatocytes. However the mechanism by which TGF-beta(1) induces caspase activation and cell death is unknown. Apoptosis can be initiated either by receptor-mediated (e.g. Fas/CD95) or non-receptor chemically mediated (stress-induced) processes. With Fas/CD95 receptor mediated cell death, a multi-protein complex (DISC) is assembled at the plasma membrane, which activates the downstream caspases and cell death. In stress-mediated apoptosis, a cytosolic DISC equivalent, the apoptosome is formed that activates the effector caspases. We have characterised this complex in THP.1 cells, and shown that this is a cytochrome c dependent process that induces the formation of an approximately 700 kDa apoptosome caspase processing complex. This is formed by oligomerisation of apoptotic protease-activating factor 1 (Apaf-1), and recruitment and processing of caspase-9. We have now shown that TGF-beta1-induced apoptosis also occurs via the release of cytochrome c and the subsequent oligomerisation of Apaf-1 into an approximately 700 kDa apoptosome complex. Our studies show that, even though TGF-beta1 induction of apoptosis is a receptor-mediated event, it operates through the mitochondrial/Apaf-1 caspase activation pathway that appears to act as a common execution pathway for many diverse apoptotic stimuli.

Animals↗

PubMed2001

Parental concerns for the child with febrile convulsion: long-term effects of educational interventions.

OBJECTIVE: To evaluate long-term effects of educational interventions on parental concerns for children with febrile convulsions (FC). SUBJECTS AND METHODS: 209 FC parents were recruited from southern Taiwan, and assigned into program or pamphlet groups by their choices. A questionnaire was used to examine the parental concerns at 4 time points: prior to the interventions, 3 months, 1 year, and 2 years after the interventions. RESULTS: The concern scores were high before the interventions. Parents concerned that their child is apt to get a fever, has further seizures in the night, that FC results in potential brain damage and is life threatening. After interventions the concern scores were significantly lower for the program group than for the pamphlet group. The educational program was the most significant factor that influenced the change in parental concerns. The recurrence of FC did not significantly influence the change in the concern trajectory in the program group but showed a significant difference in the pamphlet group. CONCLUSION: FC parental concerns decreased as time passed particularly in the program group. The educational program was the significant factor that influenced the change of concern trajectories, and the recurrent/non-recurrent factor influenced the change of concern only in pamphlet group. FC parental concerns should be assessed, and information given combined with emotional support.

Adult↗

PubMed2001

Caspase-3 cleaves Apaf-1 into an approximately 30 kDa fragment that associates with an inappropriately oligomerized and biologically inactive approximately 1.4 MDa apoptosome complex.

Cytochrome c and dATP/ATP induce oligomerization of Apaf-1 into two distinct apoptosome complexes: an approximately 700 kDa complex, which recruits and activates caspases-9, -3 and -7, and an approximately 1.4 MDa complex, which recruits and processes caspase-9, but does not efficiently activate effector caspases. While searching for potential inhibitors of the approximately 1.4 MDa apoptosome complex, we observed an approximately 30 kDa Apaf-1 immunoreactive fragment that was associated exclusively with the inactive complex. We subsequently determined that caspase-3 cleaved Apaf-1 within its CED-4 domain (SVTD(271) downward arrowS) in both dATP-activated lysates and apoptotic cells to form a prominent approximately 30 kDa (p30) N-terminal fragment. Purified recombinant Apaf-1 p30 fragment weakly inhibited dATP-dependent activation of caspase-3 in vitro. However, more importantly, prevention of endogenous formation of the p30 fragment did not stimulate latent effector caspase processing activity in the large complex. Similarly, the possibility that XIAP, an inhibitor of apoptosis protein (IAP), was responsible for the inactivity of the approximately 1.4 MDa complex was excluded as immunodepletion of this caspase inhibitor failed to relieve the inhibition. However, selective proteolytic digestion of the approximately 1.4 MDa and approximately 700 kDa complexes showed that Apaf-1 was present in conformationally distinct forms in these two complexes. Therefore, the inability of the approximately 1.4 MDa apoptosome complex to process effector caspases most likely results from inappropriately folded or oligomerized Apaf-1.

Amino Acid Sequence↗

PubMed2001

Proteasome inhibitor-induced apoptosis of B-chronic lymphocytic leukaemia cells involves cytochrome c release and caspase activation, accompanied by formation of an approximately 700 kDa Apaf-1 containing apoptosome complex.

Proteasome inhibitors, including lactacystin and MG132 (carbobenzoxyl-leucinyl-leucinyl-leucinal), potently induce apoptosis in leukaemic B cells from patients with B cell chronic lymphocytic leukaemia (B-CLL). This pro-apoptotic effect occurs in cells from patients at all stages of the disease, including those resistant to conventional chemotherapy, suggesting that proteasome inhibitors may be useful for treatment of B-CLL. Following initial inhibition of proteasomal activity, these agents induce mitochondrial cytochrome c release and caspase-dependent apoptosis, involving cleavage/activation of caspases -2, -3, -7, -8 and -9. Pre-treatment with the cell permeable caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp (OMe)fluoromethyl ketone (Z-VAD.fmk), did not prevent the release of cytochrome c or partial processing of caspase-9 but prevented activation of effector caspases and the induction of apoptosis. These results suggest that the release of cytochrome c is caspase independent and that caspase-9 is the initiator caspase in proteasome inhibitor-induced apoptosis of B-CLL cells. Activation of B-CLL lysates with dATP results in the formation of an approximately 700 kDa caspase-activating apoptosome complex containing Apaf-1. We describe for the first time the formation of a similar approximately 700 kDa caspase-activating apoptosome complex in B-CLL cells induced to undergo apoptosis by proteasome inhibitors.

Acetylcysteine↗

PubMed2001

Comprehension skill, inference-making ability, and their relation to knowledge.

In this study we investigated the relation between young children's comprehension skill and inference-making ability using a procedure that controlled individual differences in general knowledge (Barnes & Dennis, 1998; Barnes, Dennis, & Haefele-Kalvaitis, 1996). A multiepisode story was read to the children, and their ability to make two types of inference was assessed: coherence inferences, which were essential for adequate comprehension of the text, and elaborative inferences, which enhanced the text representation but which were not crucial to understanding. There was a strong relation between comprehension skill and inference-making ability even when knowledge was equally available to all participants. Subsidiary analyses of the source of inference failures revealed different underlying sources of difficulty for good and poor comprehenders.

Child↗

PubMed2000

Protein complexes activate distinct caspase cascades in death receptor and stress-induced apoptosis.

Caspases play a central role in the execution phase of apoptosis and are responsible for many of the morphological features normally associated with this form of cell death. Caspases can activate one another and consequently can initiate specific caspase cascades. Caspases-8 and -9 appear to be the apical caspases activated in death receptor- and mitochondrial stress-induced apoptosis, respectively. The role of large protein complexes in mediating these pathways is discussed.

Animals↗

PubMed2000

Apaf-1 oligomerizes into biologically active approximately 700-kDa and inactive approximately 1.4-MDa apoptosome complexes.

Apaf-1, by binding to and activating caspase-9, plays a critical role in apoptosis. Oligomerization of Apaf-1, in the presence of dATP and cytochrome c, is required for the activation of caspase-9 and produces a caspase activating apoptosome complex. Reconstitution studies with recombinant proteins have indicated that the size of this complex is very large in the order of approximately 1.4 MDa. We now demonstrate that dATP activation of cell lysates results in the formation of two large Apaf-1-containing apoptosome complexes with M(r) values of approximately 1.4 MDa and approximately 700 kDa. Kinetic analysis demonstrates that in vitro the approximately 700-kDa complex is produced more rapidly than the approximately 1.4 MDa complex and exhibits a much greater ability to activate effector caspases. Significantly, in human tumor monocytic cells undergoing apoptosis after treatment with either etoposide or N-tosyl-l-phenylalanyl chloromethyl ketone (TPCK), the approximately 700-kDa Apaf-1 containing apoptosome complex was predominately formed. This complex processed effector caspases. Thus, the approximately 700-kDa complex appears to be the correctly formed and biologically active apoptosome complex, which is assembled during apoptosis.

Apoptosis↗

PubMed2000

Heat-shock protein 70 inhibits apoptosis by preventing recruitment of procaspase-9 to the Apaf-1 apoptosome.

The cellular-stress response can mediate cellular protection through expression of heat-shock protein (Hsp) 70, which can interfere with the process of apoptotic cell death. Stress-induced apoptosis proceeds through a defined biochemical process that involves cytochrome c, Apaf-1 and caspase proteases. Here we show, using a cell-free system, that Hsp70 prevents cytochrome c/dATP-mediated caspase activation, but allows the formation of Apaf-1 oligomers. Hsp70 binds to Apaf-1 but not to procaspase-9, and prevents recruitment of caspases to the apoptosome complex. Hsp70 therefore suppresses apoptosis by directly associating with Apaf-1 and blocking the assembly of a functional apoptosome.

Apoptosis↗

PubMed2000

Transforming growth factor-beta(1) induces apoptosis in rat FaO hepatoma cells via cytochrome c release and oligomerization of Apaf-1 to form a approximately 700-kd apoptosome caspase-processing complex.

In mammalian cells, non receptor-mediated apoptosis occurs via the cytochrome c-dependent assembly of a approximately 700-kd apoptotic protease-activating factor 1 (Apaf-1)/caspase-9 containing apoptosome complex. This initiates the postmitochondrial-mediated effector caspase cascade. We now show that receptor mediated transforming growth factor beta(1) (TGF-beta(1))-induced apoptosis in rat hepatoma cells is accompanied by processing and activation of caspases-2, -3, -7, and -8. Furthermore, we show that caspase activation is mediated via the release of cytochrome c and the oligomerization of Apaf-1 into an approximately 700-kd apoptosome complex. Similarly, in vitro activation of hepatoma cell lysates with 2'-deoxyadenosine 5'-triphosphate (dATP) results in the formation of the approximately 700-kd apoptosome complex, which recruits and processes caspases-3 and -7. Z-VAD.FMK [benzyloxycarbonyl-Val-Ala-Asp (OMe) fluoromethylketone], the pan-caspase inhibitor totally inhibits dATP-stimulated caspase activation but does not block the assembly of the large Apaf-1 containing apoptosome complex. However, the recruitment and subsequent processing of caspases-3 and -7 to the apoptosome is blocked. Similarly, in intact cells, although Z-VAD.FMK blocked TGF-beta(1)-induced apoptosis, it did not prevent the oligomerization of Apaf-1 into the apoptosome. However, recruitment and processing of caspases-3 and -7 were prevented by Z-VAD.FMK. These data show that TGF-beta(1) induces apoptosis via release of cytochrome c and activation of the Apaf-1 apoptosome complex, which initiates the caspase cascade.

Animals↗

PubMed2000

Children's Difficulties in Text Comprehension: Assessing Causal Issues.

In this article we consider the difficulties of children who have a specific reading comprehension problem. Our earlier work has shown that good and poor comprehenders differ, in particular, in their ability to make inferences, integrate information in text, understand story structure, and monitor their understanding. We outline some studies that illustrate the poor comprehenders' problems and present two studies that use a comprehension-age match design to explore the direction of causality between comprehension skill and other abilities. We also present data from the first and second stages of a longitudinal study, when the children were 7 to 8 and 8 to 9 years old. Multiple regression analyses show that a number of factors predict significant variance in comprehension skill even after "general ability" factors such as IQ and vocabulary have been taken into account. These findings suggest that, not only can children have comprehension problems in the absence of word recognition problems, but that distinctly different skills predict variance in word recognition and variance in comprehension. The data support the view that single-word reading skills and the ability to build integrated text representations make independent contributions to overall reading ability. We discuss the implications of these findings for our understanding of children's problems in text comprehension, for deaf readers, and for remediation.

Journal Article↗

PubMed1999

Caspases-3 and -7 are activated in goniothalamin-induced apoptosis in human Jurkat T-cells.

Goniothalamin, a plant styrylpyrone derivative isolated from Goniothalamus andersonii, induced apoptosis in Jurkat T-cells as assessed by the externalisation of phosphatidylserine. Immunoblotting showed processing of caspases-3 and -7 with the appearance of their catalytically active large subunits of 17 and 19 kDa, respectively. Activation of these caspases was further evidenced by detection of poly(ADP-ribose) polymerase cleavage (PARP). Pre-treatment with the caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp fluoromethyl ketone (Z-VAD.FMK) blocked apoptosis and the resultant cleavage of these caspases and PARP. Our results demonstrate that activation of at least two effector caspases is a key feature of goniothalamin-induced apoptosis in Jurkat T-cells.

Amino Acid Chloromethyl Ketones↗

PubMed1999

Caspase activation involves the formation of the aposome, a large (approximately 700 kDa) caspase-activating complex.

In mammals, apoptotic protease-activating factor 1 (Apaf-1), cytochrome c, and dATP activate caspase-9, which initiates the postmitochondrial-mediated caspase cascade by proteolytic cleavage/activation of effector caspases to form active approximately 60-kDa heterotetramers. We now demonstrate that activation of caspases either in apoptotic cells or following dATP activation of cell lysates results in the formation of two large but different sized protein complexes, the "aposome" and the "microaposome". Surprisingly, most of the DEVDase activity in the lysate was present in the aposome and microaposome complexes with only small amounts of active caspase-3 present as its free approximately 60-kDa heterotetramer. The larger aposome complex (M(r) = approximately 700,000) contained Apaf-1 and processed caspase-9, -3, and -7. The smaller microaposome complex (M(r) = approximately 200,000-300,000) contained active caspase-3 and -7 but little if any Apaf-1 or active caspase-9. Lysates isolated from control THP.1 cells, prior to caspase activation, showed striking differences in the distribution of key apoptotic proteins. Apaf-1 and procaspase-7 may be functionally complexed as they eluted as an approximately 200-300-kDa complex, which did not have caspase cleavage (DEVDase) activity. Procaspase-3 and -9 were present as separate and smaller 60-90-kDa (dimer) complexes. During caspase activation, Apaf-1, caspase-9, and the effector caspases redistributed and formed the aposome. This resulted in the processing of the effector caspases, which were then released, possibly bound to other proteins, to form the microaposome complex.

Apoptosis↗

PubMed1999

A reappraisal of the role of Zn2+ in TGF-beta1-induced apoptosis in primary hepatocytes.

There is now a wealth of information regarding the apoptotic mode of cell death and its importance in toxicological studies in many mammalian organs including the liver. In this study, we investigated the modulatory effects of the heavy metal Zn2+ on transforming growth factor-beta1 (TGF-beta1)-induced apoptosis in primary rat hepatocytes. Apoptosis induced by TGF-beta1 (1 ng/ml) in hepatocytes was accompanied by nuclear condensation as assessed morphologically by staining with Hoechst 33258 and DNA cleavage as detected biochemically by in situ end-labeling, field inversion and conventional gel electrophoresis. Pretreatment with 100 micromol/L Zn2+ abrogated the nuclear condensation, in situ end-labeling, and DNA laddering in TGF-beta1-treated hepatocytes. Surprisingly, Zn2+ did not inhibit the formation of high-molecular-weight DNA fragments (30-50 kbp to 250-300 kbp). These data provide evidence that Zn2+ exerts its effects on the endonucleases that act downstream in the execution phase of TGF-beta1-induced apoptosis in hepatocytes.

Animals↗

PubMed1999

Evaluation of the Washington State Workers' Compensation Managed Care Pilot Project I: medical outcomes and patient satisfaction.

OBJECTIVES: This study examined the effect of managed care on medical outcomes and patient satisfaction as part of an evaluation of the Washington State Workers' Compensation Managed Care Pilot. METHODS: One hundred twenty firms (7,041 employees) agreed to have their injured workers treated in managed-care plans. Managed care introduced two changes from the fee-for-service (FFS) delivery system currently used by injured workers in Washington State: (1) experience-rated capitation, and (2) a primary occupational-medicine delivery model. The FFS control group included injured workers employed at 392 firms (12,000 employees). A total of 1,313 workers who experienced occupationally related injuries or illnesses between April 1995 and June 1996 were interviewed by telephone at 6 weeks after injury regarding their medical outcomes and satisfaction with care. Workers whose injuries resulted in four or more lost workdays (n = 372) were also interviewed at 6 months after injury on the same topics. The areas surveyed included functional outcomes and satisfaction with care, providers, and access to providers. RESULTS: The measures of functional outcome reflected no consistent differences between the managed care and the FFS conditions. The workers who attended the managed-care system reported lower levels of satisfaction with care, particularly with access to providers. For example, 58% of managed-care patients reported satisfaction with their attending physician as compared with 69% of FFS patients (P<0.01). CONCLUSIONS: Workers treated through managed-care arrangements were less satisfied with their care, but their medical outcomes were similar to those of workers who received traditional FFS care. The current workers' compensation system in Washington State affords injured workers great latitude in choosing providers. If provider choice is substantially restricted by managed care, worker satisfaction is likely to diminish.

Adult↗

PubMed1999

Evaluation of the Washington State Workers' Compensation Managed Care Pilot Project II: medical and disability costs.

OBJECTIVES: This study examined the effect of managed care on medical and disability costs as part of an evaluation of the Washington State Workers' Compensation Managed Care Pilot (MCP). METHODS: One hundred twenty firms (7,041 employees) agreed to have their injured workers treated in managed care plans. Managed care introduced two changes from the fee-for-service (FFS) delivery system currently used by injured workers in Washington State: experience- rated capitation and a primary occupational medicine delivery network. The FFS control group included injured workers employed at 392 firms (12,000 employees). Medical and disability costs were compared for 1,058 injuries in the managed care group and 1,159 injuries in the FFS group occurring between April 1995 and June 1996. Univariate and multivariate statistical methods were used to analyze the effects of managed care on medical and disability costs. RESULTS: The mean unadjusted medical cost per injury ($587) for the managed care group was 21.5% lower (P = 0.06) than for the FFS group ($748). Adjustment for differences in worker and firm-level characteristics through multivariate analysis had little effect on the unadjusted results, except that the difference in costs between managed care and FFS groups became statistically significant (P<0.01). The major cost differences were for outpatient surgery (cost per surgery) and ancillary services (pharmacy, x-ray, physical therapy, and all other costs). In addition, disability costs, particularly percent on time loss and time-loss cost per injury, were significantly lower (P<0.01) in the managed care group. CONCLUSIONS: The results from the MCP suggest that substantial savings in workers' compensation medical and disability costs may be realized using the type of managed care intervention designed for this study. Delivering occupational health services through managed care arrangements whose design is based on an integrated, occupational health-centered delivery model may offer a viable approach for improving delivery systems, reducing costs and encouraging greater attention to disability prevention.

Adult↗