Biomedical subjects

J Kowalski

Publications and source records attributed to J Kowalski.

At least 37 records · Page 2Linked to original sources

PubMed2001

A comparative meta-analysis on the variability in test performance among FDA-licensed enzyme immunosorbent assays for HIV antibody testing.

BACKGROUND: Although independently published studies have compared diagnostic test performance among various manufactured enzyme immunosorbent assays (EIAs) used in HIV antibody testing, none have attempted to formally synthesize such results through a comparative meta-analysis. In particular, no estimates of post-FDA approval test performance, in terms of sensitivity and specificity, and their associated variability within each manufacturer, has been reported in the literature, along with an analysis of the relative differences in manufacturer test performance in practice (after FDA approval). METHODS: Retrieval of studies was done using several searching strategies, while retrieval of manufacturer information was done through package inserts and direct contacts. Comparisons of HIV antibody test performance across manufacturers and within a single manufacturer were made based on 16 estimates (from 11 articles) and 33 estimates (from 19 articles), respectively. A generalized linear model, based upon Bayes estimates of sensitivity and specificity, was used to assess the impact of several study-level covariates on the performance of these EIAs, with overall estimates of manufacturer test performance and associated variability obtained based on generalized estimating equations. RESULTS: Estimates of test performance were obtained across studies, with a significant (P < 0.01) difference between manufacturers. The test performance of each manufacturer significantly interacted (P < 0.05) with the following study-level covariates: type of population screened, year of diagnostic testing and study quality. Among a single manufacturer, Abbott, significant improvement in estimates of test sensitivity (P < 0.01) and specificity (P < 0.01) was observed with each newly produced antibody kit. CONCLUSION: Estimates on the relative differences in test performance within each manufacturer may be used for guiding decisions on the choice of EIA test kit for HIV antibodies, given the type of population screened, as well as cost and time considerations. In addition, the results of this meta-analysis may be used in modeling HIV prevalence when used as prior information within a Bayesian framework or for standardizing test results among various manufacturers.

Bayes Theorem↗

PubMed2001

Reliability and responsiveness of three different pain assessments.

The visual analogue scale (VAS) and ordered categorical scales, i.e. numeric rating scales (NRS), are commonly used in the assessment of pain. However, these scales are bounded by fixed endpoints and thus the range of measurement is limited. The disparity in repeated assessments of perceived pain intensity with the VAS, NRS, and electrical stimulation applied as a matching stimulus was studied in 69 patients (48 women and 21 men, 19-72 years) with chronic nociceptive or neurogenic pain. Responsiveness with transcutaneous electrical nerve stimulation (TENS) using the same measurement procedures was evaluated in the same patients. Comparison of results from the three pain assessments showed that the painmatcher is at least as reliable and responsive as VAS and NRS. None of the three measurements showed evidence for systematic disagreement and had only significant random individual disagreement. They also showed evidence for responsiveness.

Adult↗

PubMed2001

A non-parametric approach to translating gene region heterogeneity associated with phenotype into location heterogeneity.

MOTIVATION: The analysis of genetic data poses statistical problems in the form of high dimensionality with small sample sizes. The construction of a composite gene region (sequence pair) heterogeneity measure is one technique for reducing the dimensionality of the problem. This approach however is not without cost, since the contribution of locations to observed gene region differences between groups becomes entangled in this summary measure. This is problematic since it is of scientific interest to identify locations that together depict phenotype. RESULTS: A method is proposed for relating observed gene region heterogeneity back to the location level. In the spirit of a factor analysis-type setting, the approach focuses on identifying a latent variable structure among locations to explain within and between group genetic differences associated with phenotype. The method is flexible for identifying either the additive contribution from individual locations or the additive contribution from a group of locations, to observed gene region heterogeneity, depending upon the weighting scheme used in constructing a gene region heterogeneity measure. The approach is illustrated with clinical trial data, where the problem of altered HIV drug susceptibility is examined through characterizing location contributions to HIV protease gene region differences associated with a phenotypic treatment response. AVAILABILITY: The Splus (MathSoft, Inc. S-Plus 2000, Seattle, WA, 1999) developed menu-driven functions for obtaining results, GENE_ S (J.Kowalski, Harvard School of Public Health, Boston, MA 2001), is available from the author upon request.

Clinical Trials, Phase II as Topic↗

PubMed2001

Increasing protein stability using a rational approach combining sequence homology and structural alignment: Stabilizing the WW domain.

This study shows that a combination of sequence homology and structural information can be used to increase the stability of the WW domain by 2.5 kcal mol(-1) and increase the T(m) by 28 degrees C. Previous homology-based protein design efforts typically investigate positions with low sequence identity, whereas this study focuses on semi-conserved core residues and proximal residues, exploring their role(s) in mediating stabilizing interactions on the basis of structural considerations. The A20R and L30Y mutations allow increased hydrophobic interactions because of complimentary surfaces and an electrostatic interaction with a third residue adjacent to the ligand-binding hydrophobic cluster, increasing stability significantly beyond what additivity would predict for the single mutations. The D34T mutation situated in a pi-turn possibly disengages Asn31, allowing it to make up to three hydrogen bonds with the backbone in strand 1 and loop 2. The synergistic mutations A20R/L30Y in combination with the remotely located mutation D34T add together to create a hYap WW domain that is significantly more stable than any of the protein structures on which the design was based (Pin and FBP28 WW domains).

Adaptor Proteins, Signal Transducing↗

PubMed2001

Levels of sICAM-1, sVCAM-1 and MCP-1 in patients with hyperlipoproteinemia IIa and -IIb.

OBJECTIVE: Hyperlipoproteinemia is one of the factors that are involved in the development of atherosclerosis. One of the mechanisms through which these high plasma lipid levels trigger the formation of atherosclerotic lesions is a change in the expression of adhesion molecules on endothelial and smooth muscle cells. The aim of this study was to evaluate the plasma levels of soluble intracellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1) and monocyte chemoattractant protein-1 (MCP-1) in patients with Type IIa (HLP-IIa) and IIb (HLP-IIb) hyperlipoproteinemias. SUBJECTS: Twenty patients with HLP-IIa, 20 patients with HLP-IIb and 23 control subjects were studied. To accurately evaluate adhesion molecule levels, we excluded those hyperlipemic patients and control subjects who had an inflammatory disease. METHODS: Plasma sICAM-1, sVCAM-1 and MCP-1 levels were measured by the ELISA method. RESULTS: sVCAM-1 levels in HLP-IIa and HLP-IIb patients (535 +/- 27 ng/ml and 545 +/- 22 ng/ml, respectively) did not differ significantly from those in the control group (558 +/- 20 ng/ml). sICAM-1 levels were significantly higher in patients with HLP-IIa and HLP-IIb (279 +/- 10 ng/ml and 322 +/- 12 ng/ml, respectively) compared to the control group (226 +/- 10 ng/ml). MCP-1 levels were significantly higher in HLP-IIa and HLP-IIb patients (151 +/- 12 pg/ml vs 154 +/- 12 pg/ml, respectively) compared to healthy controls (98 +/- 4 pg/ml). sICAM-1 levels in the HLP-IIb group were significantly higher than in the HLP-IIa group. CONCLUSION: The results of the study suggest that lipid abnormalities affect the levels of adhesion molecules and chemokines in plasma.

Adult↗

PubMed2001

Effects of fibrates on plasma prothrombotic activity in patients with type IIb dyslipidemia.

OBJECTIVE: Increased levels of fibrinogen and plasminogen activator inhibitor 1 (PAI-1) are associated with an increased risk of ischemic coronary disease and its complications. Since atherogenic dyslipidemias are well-known risk factors for coronary heart disease, this study aimed to determine whether Type IIb dyslipidemia, one of the most atherogenic dyslipidemias, is accompanied by increased PAI-1 and fibrinogen synthesis. The additional aim of this study was to evaluate the effect of micronized fibrates on the levels of PAI-1 and fibrinogen in patients with Type IIb dyslipidemia. SUBJECTS: Thirty patients with Type IIb dyslipidemia and 12 age-matched control subjects were studied. Fourteen patients were treated with fenofibrate and 16 were treated with ciprofibrate for 1 month. METHODS: Plasma PAI-1 levels were measured by the ELISA method with Diagnostica Stago kit. The level of fibrinogen was measured by the Clauss method. RESULTS: PAI-1 levels in dyslipidemic patients before treatment differed significantly in both the fenofibrate and ciprofibrate treatment groups (101.18 +/- 36.47 ng/ml, 87.64 +/- 32.06 ng/ml, respectively) from those in the control group (32.32 +/- 7.39 ng/ml, p < 0.001). Compared with the control subjects (2.91 +/- 0.35 g/l), fibrinogen levels before treatment were higher in patients with dyslipidemia treated with ciprofibrate (3.42 +/- 0.59 g/l, NS) and fenofibrate (3.65 +/- 1.10 g/l, p < 0.05). One-month ciprofibrate treatment resulted in an insignificant decrease in PAI-1 levels (76.28 21.60 ng/ml, NS) and in a significant decrease in fibrinogen levels (2.73 +/- 0.40 g/l, p < 0.01). After one-month fenofibrate treatment PAI-1 levels (81.22 +/- 25.01 ng/ml, p < 0.01) and fibrinogen levels (2.95 0.72 g/l, p < 0.01) decreased significantly. CONCLUSION: Type IIb dyslipidemic patients have increased levels of PAI-1 and fibrinogen. Micronized fibrates decreased not only lipid levels but also the levels of fibrinogen and PAI-1 in these patients.

Adult↗

PubMed2001

PET imaging of somatostatin receptors using [68GA]DOTA-D-Phe1-Tyr3-octreotide: first results in patients with meningiomas.

UNLABELLED: Imaging of somatostatin receptors (SSTRs) using [111In]diethylenetriaminepentaacetic-acid-octreotide (DTPAOC) has proven to be helpful in the differentiation of meningiomas, neurinomas or neurofibromas, and metastases as well as in the follow-up of meningiomas. A drawback of the SPECT method is its limited sensitivity in detecting small meningiomas. Because of PET's increased spatial resolution and its ability to absolutely quantify biodistribution, a PET tracer for SSTR imaging would be desirable. METHODS: 1,4,7,10-tetraazacyclododecane-N,N',N",N"'-tetraacetic-acid-D-Phe1-Tyr3-octreotide (DOTATOC) was labeled using the positron-emitting generator nuclide 68Ga. We acquired dynamic PET images over 120 min after intravenous injection of 175 MBq [68Ga]DOTATOC in 3 patients suffering from 8 meningiomas (WHO I degrees; 7- to 25-mm diameter). Patients' heads had been fixed using individually shaped fiber masks equipped with an external stereotactic localizer system to match PET, CT, and MRI datasets. RESULTS: [68Ga]DOTATOC was rapidly cleared from the blood (half-life alpha, 3.5 min; half-life beta, 63 min). Standardized uptake values (SUVs) of meningiomas increased immediately after injection and reached a plateau 60-120 min after injection (mean SUV, 10.6). No tracer could be found in the surrounding healthy brain tissue. All meningiomas (even the 3 smallest [7- to 8-mm diameter]) showed high tracer uptake and could be visualized clearly. Tracer boundaries showed a good correspondence with the matched CT and MRI images. PET provided valuable additional information regarding the extent of meningiomas located beneath osseous structures, especially at the base of the skull. CONCLUSION: According to our initial experiences, [68Ga]DOTATOC seems to be a very promising new PET tracer for imaging SSTRs even in small meningiomas, offering excellent imaging properties and a very high tumor-to-background ratio.

Gallium Radioisotopes↗

PubMed2001

[Evaluation of anti-mycobacterial antibody IgG concentration in rapid diagnosis of tuberculosis].

Tuberculosis is not always easy to diagnose. All the methods applied in diagnosis of this illness have certain limitations. In this study the value of Rapid Test TB in diagnosis of tuberculosis was evaluated. The aim of the test is to detect antibody against mycobacterial antigen 38 kDa. Material consisted of 100 persons divided into 4 groups: BK(+) tuberculosis patients, BK (0) tuberculosis patients--culture (+), lung cancer patients and patients with sarcoidosis. Positive results were obtained in 100% of culture positive patients and in 10% of patients culture (+), in 20% of lung cancer patients and in 40% of patients with sarcoidosis. Specifity of the test was 55%. The results indicate that Immunozyme Mycobacterium test is valuable tool in tuberculosis diagnosis especially in case when a technical equipment is wanting.

Antigens, Bacterial↗

PubMed2001

[Generation of reactive oxygen species by peripheral blood neutrophils in patients with pulmonary tuberculosis].

Oxygen metabolism of neutrophils was measured using chemiluminescence method in patient with pulmonary tuberculosis. Patients were included into three groups. Group I--20 patients (10 men, 10 women) aged 24-74 years (mean 48.3 years) with pulmonary tuberculosis BK(+). Group II--20 patients (15 men, 5 women) aged 19-67 years (mean 45.1 years) with pulmonary tuberculosis BK(0). The control group consisted 16 clinically healthy persons (12 men, 4 women) aged 28-59 years (mean 42.5 years). Blood samples (5 ml) were collected for examination from cubital vein early morning before breakfast. A luminometer 1251 coupled with an IBM PC AT compatible computer was used for the measurement of chemiluminescence. The chemiluminescence of non-stimulated neutrophils and those stimulated by a receptor stimulus formyl-Met-Leu-Phe (fMLP) as well as an extrareceptor stimulus phorbol myristate acete (PMA) was measured. The results of our study demonstrated that chemiluminescence of non-stimulated as well as stimulated by fMLP and PMA neutrophils was lower in comparison to the values of chemiluminescence in the control group.

Adult↗

PubMed2001

[Estimation of plasma malonyl dialdehyde concentration in patients with pulmonary tuberculosis].

Plasma malonyl dialdehyde (MDA) concentration was determined by Placer method in patients with pulmonary tuberculosis before and during treatment period with tuberculostatic drugs. Patients were divided into three groups. Group I comprised 20 patients (10 men and 10 women) aged 24-74 years (mean 48.3 years) with pulmonary tuberculosis BK(+). Group II comprised 20 patients (15 men and 5 women) aged 19-67 years (mean 45.1 years) with pulmonary tuberculosis BK(0). The control group consisted of 16 clinically healthy persons (12 men and 4 women) aged 28-59 years (mean 42.5 years). In patients blood samples (5 ml) were collected for examination from cubital vein before, after 1-month and 2-month treatment period with tuberculostatic drugs. In the control group blood samples were collected from cubital vein once. Results of our study showed that plasma MDA concentrations in patients with pulmonary tuberculosis, both before and during treatment period with tuberculostatic drugs, were significantly higher, in comparison to the control group.

Adult↗

PubMed2001

[Pulmonary lymphangioleiomyomatosis: presentation and results of treatment].

Lymphangioleiomyomatosis is a rare lung disease of unknown aetiology that affects only women. Eight premenopausal women with LAM confirmed by lung biopsy specimens were observed in 1984-2001. The most common presenting feature was exertional dyspnea (6) followed by chylous pleural effusions and pneumothoraces. In two women severe airflow obstruction was observed at presentation. HRCT revealed characteristic cysts in all cases. All women were given hormonal therapy (tamoxifen, medroxyprogesterone). The best results of treatment were achieved in cases with chylothoraces.

Adult↗

PubMed2000

Complete inhibition of rhabdomyosarcoma xenograft growth and neovascularization requires blockade of both tumor and host vascular endothelial growth factor.

Growth of the human rhabdomyosarcoma A673 cell line in nude mice is substantially reduced but not completely suppressed after systemic administration of the antihuman vascular endothelial growth factor (VEGF) monoclonal antibody (Mab) A.4.6.1. Potentially, such escape might be attributable to incomplete local penetration of the antibody because of a diffusion barrier associated with tumor growth. Alternatively, it might reflect a compensatory up-regulation of murine VEGF, produced by the stroma of the host, or of other angiogenic factor genes. To test these potential mechanisms, systemic administration of Mab A.4.6.1, was performed in conjunction with intratumoral administration of an irrelevant antibody, an antihuman VEGF Fab or mFlt(1-3)-IgG that neutralizes both human and murine VEGF. Tumor growth in the systemic-plus-intratumoral anti-VEGF group was not different from that in the systemic anti-VEGF-plus-intratumoral-control antibody group, arguing against the possibility that bioavailability is the factor that limits the antitumor efficacy of Mab A.4.6.1. However, intratumoral mFlt(l-3)-IgG administration dramatically enhanced the activity of systemic anti-VEGF Mab and resulted in complete suppression of tumor growth, which indicated that host VEGF significantly contributes to tumor growth. Systemic administration of mFlt(1-3)-IgG alone replicated these findings. Histological analysis of residual tumor tissues revealed an almost complete absence of host-derived vasculature and massive tumor-cell necrosis in the mFlt(1-3)-IgG groups. Such extensive necrotic areas were not present in the other groups. Real-time reverse transcription-PCR analysis of total RNA derived from tumor tissues indicated strong up-regulation of both human and murine VEGF as well as other genes regulated by hypoxia. Our findings emphasize the need to completely block VEGF for maximal inhibition of tumor growth.

Animals↗

PubMed2000

Analysis of biological effects and signaling properties of Flt-1 (VEGFR-1) and KDR (VEGFR-2). A reassessment using novel receptor-specific vascular endothelial growth factor mutants.

Endothelial cells express two related vascular endothelial growth factor (VEGF) receptor tyrosine kinases, KDR (kinase-insert domain containing receptor, or VEGFR-2) and Flt-1 (fms-like tyrosine kinase, or VEGFR-1). Although considerable experimental evidence links KDR activation to endothelial cell mitogenesis, there is still significant uncertainty concerning the role of individual VEGF receptors for other biological effects such as vascular permeability. VEGF mutants that bind to either KDR or Flt-1 with high selectivity were used to determine which of the two receptors serves to mediate different VEGF functions. In addition to mediating mitogenic signaling, selective KDR activation was sufficient for the activation of intracellular signaling pathways implicated in cell migration. KDR stimulation caused tyrosine phosphorylation of both phosphatidylinositol 3-kinase and phospholipase Cgamma in primary endothelial cells and stimulated cell migration. KDR-selective VEGF was also able to induce angiogenesis in the rat cornea to an extent indistinguishable from wild type VEGF. We also demonstrate that KDR, but not Flt-1, stimulation is responsible for the induction of vascular permeability by VEGF.

Capillary Permeability↗

PubMed2000

A repressor sequence in the juxtamembrane domain of Flt-1 (VEGFR-1) constitutively inhibits vascular endothelial growth factor-dependent phosphatidylinositol 3'-kinase activation and endothelial cell migration.

Vascular endothelial growth factor (VEGF) has two highly homologous tyrosine kinase receptors: Flt-1 (VEGFR-1) and KDR (VEGFR-2). KDR is strongly phosphorylated on tyrosines and can transmit mitogenic and motogenic signals following VEGF binding, while Flt-1 is markedly less effective in mediating such functions. To dissect the regions that account for the differences between the two receptors, we generated a series of chimeric Flt-1-KDR molecules. We found that the juxtamembrane region of Flt-1 prevents key signaling functions. When the juxtamembrane region of Flt-1 is replaced by that of KDR, Flt-1 becomes competent to mediate endothelial cell migration and phosphatidylinositol 3'-kinase activation in response to VEGF. Further mutational analysis shows that a short divergent sequence is responsible for such repressor function. However, mutant Flt-1 receptors lacking this sequence do not transmit effective proliferative signals, suggesting that this receptor function is regulated separately. These results define a novel functional domain that serves to repress Flt-1 activity in endothelial cells.

Amino Acid Sequence↗

PubMed2000

Activation of blood platelets after percutaneous transluminal coronary angioplasty and coronary artery bypass graft surgery.

We have evaluated the activation of platelets in blood samples taken from patients with stable angina undergoing balloon angioplasty (percutaneous transluminal coronary angioplasty [PTCA]) (n=11) or coronary artery bypass grafting (CABG) under hypothermic (n=11) or normothermic conditions (n=11). We have found that surface expression of P-selectin on platelets in whole blood from PTCA patients upon thrombin treatment was significantly reduced, as compared with control platelets from healthy subjects. This effect was partially reversed when platelets washed from the same blood sample were used, but even then P-selectin expression was significantly lower in PTCA patients than it was in control subjects. There was a significant increase in basal expression of P-selectin in blood platelets taken from patients who underwent CABG under normothermic conditions (warm blood cardioplegia) as opposed to hypothermic patients (cold crystalloid cardioplegia). These platelets retain the ability to respond to agonists, although to a much lower extent than do those from healthy control donors. The surface exposure of P-selectin on resting and thrombin-treated platelets isolated from CABG surgery patients was not different from that of the control platelets. The adhesion to fibrinogen of resting and thrombin-treated platelets from patients who underwent balloon angioplasty as well as CABG surgery under normothermic and hypothermic conditions was significantly reduced when compared with the fibrinogen of the control platelets. These results suggest that the function of platelet fibrinogen receptor is impaired in patients with stable angina pectoris and that PTCA and CABG surgery activates platelets.

Adult↗

PubMed2000

Stressful life events, bipolar disorder, and the "kindling model".

A common misconception is that bipolar disorder is an endogenous process. However, previous research suggests a role for life events in the onset of and recovery from bipolar episodes. Yet, there remains some question as to whether the relationship between life events and onset changes over the course of the disorder as a result of the number of episodes an individual has experienced. Using a rigorous interview measure of stressful life events, the current study tested the kindling model (R. M. Post, 1992), which theorizes that major life events play a diminishing role over the course of illness in bipolar patients. Analyses revealed that the number of episodes experienced does not appear to have a significant effect on bipolar 1 patients' reactivity to external stressors. In addition, the results suggest that a more complex relationship exists among age, stress, and onset of new episodes than can be adequately explained by the kindling model.

Adult↗

PubMed2000

Pain management: an organizational commitment.

Although much has been done to promote pain assessment and management, pain remains a major, yet largely preventable, public health problem in the United States. A strategy that has been proposed to assure optimal pain management is the development of formal means within institutions to evaluate pain management practices and foster improved outcomes. In response to a pain-related patient care problem, South Nassau Communities Hospital recognized the need to undertake more formal methods for managing patients with acute, chronic, and cancer pain. A Pain Management Task Force was charged with the development of a comprehensive pain management program. Its efforts to date and plans for the future position this institution as ready for the Joint Commission for the Accreditation of Healthcare Organizations' pain assessment and management standards that were introduced in 2000.

Hospitals, Community↗

PubMed2000

Elevated levels of lipoprotein(a) in familial bone marrow edema syndrome of the hip.

There is controversy whether bone marrow edema syndrome represents a distinct transient disease or reflects an early reversible phase of spontaneous osteonecrosis of the hip. Hypofibrinolysis on the basis of elevated plasma levels of plasminogen activator inhibitor or lipoprotein(a) or both has been reported to favor the development of bone marrow edema syndrome and nontraumatic avascular necrosis. The current authors report on the familial occurrence of transient bone marrow edema syndrome of the hip in three female family members. Plasma concentrations of lipoprotein(a) were elevated in all three patients, whereas serum levels of plasminogen activator inhibitor were within normal ranges. This first familial description of transient bone marrow edema syndrome of the hip strongly suggests that a genetically determined elevation of lipoprotein(a) may be an important predisposing factor in these patients.

Adult↗