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Biomedical subjects

A Kaplan

Publications and source records attributed to A Kaplan.

At least 55 records · Page 3Linked to original sources
PubMed2000

Venlafaxine in children, adolescents, and young adults with autism spectrum disorders: an open retrospective clinical report.

Autism is characterized by social deficits, communication and language impairments, narrow restricted interests, repetitive behaviors, inattention, and hyperactivity. While selective serotonin reuptake inhibitors have demonstrated efficacy in treating core symptoms of autism, norepinephrine reuptake inhibitors have demonstrated efficacy in symptoms of attention-deficit hyperactivity disorder (ADHD). An open, retrospective clinical study with venlafaxine evaluated its effect on core symptoms of autism as well as associated features of ADHD. Ten consecutive subjects meeting Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV), criteria for an autism spectrum disorder were treated with venlafaxine, initiated at 12.5 mg per day and adjusted on a flexible basis. Six of 10 completers were judged to be sustained treatment responders, by scoring 1 (very much improved) or 2 (much improved) on the Clinical Global Impressions improvement scale. Venlafaxine was effective in low dosages (mean, 24.37 mg/day; range, 6.25 to 50 mg/day) and was well tolerated. Improvement was noted in repetitive behaviors and restricted interests, social deficits, communication and language function, inattention, and hyperactivity. Controlled treatment trials with venlafaxine are warranted in autism spectrum disorders.

Adult↗
PubMed2000

Ticlopidine, Alka-Seltzer, or a combination of citric acid with aspirin: effects on platelet aggregation in individuals with an insufficient response to aspirin alone.

Aspirin (ASA) does not effectively lower platelet aggregation in all people. The platelet aggregation (PA) score is an easily used clinical method for measuring the effect in individuals of antiplatelet medications. Fifteen apparently healthy subjects (2 men and 13 women), selected for their resistance to ASA's antiaggregation effect, completed a sequential trial of ticlopidine, Alka-Seltzer, and ASA + citric acid (CTA). Ticlopidine was the strongest aggregation inhibitor and the ASA + CTA combination was more inhibitory than Alka-Seltzer. It was determined that measuring antiaggregation effects of a particular agent in an individual prior to usage would optimize treatment. The PA score methodology provides a means for testing patients prior to antiplatelet therapy for prevention and treatment of the thrombotic complications of vascular disease.

Adult↗
PubMed2000

EEG analysis with nonlinear deterministic and stochastic methods: a combined strategy.

We describe nonlinear deterministic versus stochastic methodology, their applications to EEG research and the neurophysiological background underlying both approaches. Nonlinear methods are based on the concept of attractors in phase space. This concept on the one hand incorporates the idea of an autonomous (stationary) system, on the other hand implicates the investigation of a long time evolution. It is an unresolved problem in nonlinear EEG research that nonlinear methods per se give no feedback about the stationarity aspect. Hence, we introduce a combined strategy utilizing both stochastic and nonlinear deterministic methods. We propose, in a first step to segment the EEG time series into piecewise quasi-stationary epochs by means of nonparametric change point analysis. Subsequently, nonlinear measures can be estimated with higher confidence for the segmented epochs fulfilling the stationarity condition.

Algorithms↗
PubMed1999

Eight centuries of north atlantic ocean atmosphere variability

Climate in the tropical North Atlantic is controlled largely by variations in the strength of the trade winds, the position of the Intertropical Convergence Zone, and sea surface temperatures. A high-resolution study of Caribbean sediments provides a subdecadally resolved record of tropical upwelling and trade wind variability spanning the past 825 years. These results confirm the importance of a decadal (12- to 13-year) mode of Atlantic variability believed to be driven by coupled tropical ocean-atmosphere dynamics. Although a well-defined interdecadal mode of variability does not appear to be characteristic of the tropical Atlantic, there is evidence that century-scale variability is substantial. The tropical Atlantic may also have been involved in a major shift in Northern Hemisphere climate variability that took place about 700 years ago.

Journal Article↗
PubMed1999

Programmed cell death of the dinoflagellate Peridinium gatunense is mediated by CO(2) limitation and oxidative stress.

The phytoplankton assemblage in Lake Kinneret is dominated in spring by a bloom of the dinoflagellate Peridinium gatunense, which terminates sharply in summer [1]. The pH in Peridinium patches rises during the bloom to values higher than pH9 [2] and results in CO(2) limitation. Here we show that depletion of dissolved CO(2) (CO(2(dis))) stimulated formation of reactive oxygen species (ROS) and induced cell death in both natural and cultured Peridinium populations. In contrast, addition of CO(2) prevented ROS formation. Catalase inhibited cell death in culture, implicating hydrogen peroxide (H(2)O(2)) as the active ROS. Cell death was also blocked by a cysteine protease inhibitor, E-64, a treatment which stimulated cyst formation. Intracellular ROS accumulation induced protoplast shrinkage and DNA fragmentation prior to cell death. We propose that CO(2) limitation resulted in the generation of ROS to a level that induced programmed cell death, which resembles apoptosis in animal and plant cells. Our results also indicate that cysteine protease(s) are involved in processes that determine whether a cell is destined to die or to form a cyst.

Animals↗
PubMed1999

Atypical processing of amyloid precursor fusion protein by proteolytic activity in Pichia pastoris.

Secretases catalyze the production of important proteolytic products of the amyloid precursor protein. We expressed a fusion protein that contained horseradish peroxidase, fragment 590-695 of amyloid precursor protein, and c-myc and polyhistidine tags in Pichia pastoris. It secreted a 50-kDa N-terminal fragment; a 15-kDa C-terminal fragment accumulated in cells. The N-terminal fragment exhibited peroxidase activity and reacted with antibodies specific for peptides within the sequences -2 to 15 and 21-37 of beta-amyloid peptide. The C-terminal fragment reacted with antibodies that recognize the sequences 649-664 and 676-695 of amyloid precursor protein and the C-terminal c-myc tag. To locate the cut site, the C-terminal fragment was metabolically labeled with either [(35)S]Met or [(3)H]Lys and radiosequenced. A major component, derived from a cleavage at Gly(25)-Ser(26) of beta-amyloid, was detected. Results suggest a predominant atypical cleavage, like that observed in Down Syndrome fibroblasts, occurs between the alpha- and gamma-sites.

Amino Acid Sequence↗
PubMed1999

Achievement Goals and Student Well-Being.

This study is concerned with the role that achievement goals may play in facilitating the psychological well-being of students. Specifically, we build on "goal theory" analysis of adaptive behavior in examining the relationship between task and ego goals, perceptions of school emphases on task and ego goals, and indices of well-being and disruptive behavior. Generally, task goals and perception of the school as emphasizing task goals were related to positive psychological well-being, and ego goals and perceiving the school as emphasizing ego goals were related to negative psychological well-being. This pattern was found for both African American and Euro-American students. However, path analyses pointed to possible different processes as operating for the African Americans and the Euro-Americans in the sample. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Patterns of late corneal scarring after photorefractive keratectomy in high and severe myopia.

OBJECTIVE: To study the correlation between scarring 1 year after photorefractive keratectomy (PRK), final refraction, and degree of myopia. DESIGN: A retrospective, noncomparative case series. PARTICIPANTS: One hundred twenty eyes of 78 patients underwent PRK for high and severe myopia. Thirty-nine eyes had a pre-PRK spherical equivalent (SE) between -9.5 and -18.25 diopters (D) (severe myopia). Eighty-one eyes had a pre-PRK SE between -6.25 and -9.25 D (high myopia). Follow-up time ranged between 12 and 37 months with a mean of 18.2 months. INTERVENTION: Multizone PRK with the VISX 20/20 excimer laser. MAIN OUTCOME MEASURES: Corneal scarring, final best-corrected visual acuity (BCVA), and refraction. RESULTS: There were 71.7% of eyes with severe myopia and 60.5% of eyes with high myopia found to have any pattern of stromal scarring, which was classified as focal, semiannular, annular, and discoid. Discoid scars were rare (6.6%) and found in 12.8% of severe myopic eyes compared to 3.7% of high myopic eyes. Only 50% of the eyes with a discoid scar achieved final BCVA between 6/6 and 6/9 compared to 81.6% of the eyes with a clear cornea. The severe myopic eyes with a discoid scar had the highest level of final undercorrection (-5.0 D) compared to a maximum of -1.5 D in the high myopia group. The severe myopic eyes with a discoid scar had a higher number of retreatments (4 of 5) compared to the high myopia group (1 of 3). Other types of scars were less clinically significant. CONCLUSIONS: Photorefractive keratectomy was efficient in the correction of high myopia but less so in severe myopia, in which discoid scarring was more frequent and more clinically significant, being associated with significant regression. Other types of scarring were less clinically significant.

Adolescent↗
PubMed1999

Metastatic renal cell carcinoma with concurrent inferior vena caval invasion: long-term survival after combination therapy with radical nephrectomy, vena caval thrombectomy and postoperative immunotherapy.

PURPOSE: We report our experience using aggressive multimodal therapy in a high risk group of patients with metastatic renal cell carcinoma and concurrent inferior vena caval extension. MATERIALS AND METHODS: We retrospectively reviewed the records of all patients in our kidney cancer database who had metastatic renal cell carcinoma and tumor thrombus extension into the inferior vena cava at the initial diagnosis. Patients were included in the study if they underwent radical nephrectomy and inferior venal caval thombectomy, and immunotherapy was planned for the postoperative period. Tumor size and grade, metastatic sites, level of vena caval extension, surgical complications and overall survival were obtained from the medical records. The primary end point analyzed was overall survival. RESULTS: We identified 31 cases of metastatic renal cell cancer with extensive disease and vena caval extension. Of the patients 23% had an isolated lung metastasis, and 53% had metastasis in the lung and at other sites. The remaining patients had involvement primarily at nonpulmonary metastatic sites, including lymph node in 38%, soft tissue in 13%, liver in 29% and bone in 10%. Average blood loss during nephrectomy was 3,200 cc (median 2,100) and the rate of major complications was 12%. Of the patients 80% underwent the full course of surgery and postoperative immunotherapy. At a mean followup of 18 months (34 for survivors) 26% of the patients are alive. Actuarial overall 5-year survival of the group was 17%. Tumor thrombus level did not correlate with overall survival, while immunotherapy, tumor grade and metastatic site provided significant prognostic information. In patients with an isolated pulmonary metastasis the 5-year survival rate was 43%, while in those with low grade tumors it was 52%. CONCLUSIONS: In contrast to the poor results of surgery only in patients with renal cell carcinoma and concurrent inferior venal caval invasion, reasonable 5-year survival may be achieved after combined aggressive surgery and immunotherapy. Patients in whom metastasis was limited to the lungs and those with grade 1 to 2 tumors had a better prognosis. With careful planning and experienced immunotherapists therapy may be completed in the majority of this high risk group of patients.

Adult↗
PubMed1999

Memory self-appraisal in middle-aged and older adults with the apolipoprotein E-4 allele.

OBJECTIVE: Because subjective memory complaints may indicate subtle functional brain abnormalities, the authors studied the influence of the major genetic risk for Alzheimer's disease, the apolipoprotein E-4 (APOE-4) allele, on self-reports of memory performance in middle-aged and older adults. METHOD: Subjective and objective assessments of memory performance were compared in relation to the presence or absence of the APOE-4 allele in 39 cognitively intact persons with mild memory complaints. RESULTS: Subjects with the APOE-4 allele had lower scores on objective verbal memory and on the subjective memory measure for retrospective functioning. Among the subjects in the age range where APOE-4 has its greatest influence on the risk of Alzheimer's disease (55-74 years), the APOE-4 group had lower scores on the subjective memory measure for frequency of forgetting. Moreover, the standardized difference in retrospective functioning scores between the two genetic risk groups increased when the mid-age-range group was examined rather than the whole study group. CONCLUSIONS: The APOE-4 allele is associated with increased subjective memory impairment in middle-aged and older adults. Longitudinal studies of age-related memory loss should include genetic risk and subjective memory measures as potential predictors of decline.

Adult↗
PubMed1998

A putative HCO3- transporter in the cyanobacterium Synechococcus sp. strain PCC 7942.

Cyanobacteria possess an inducible mechanism which enables them to concentrate inorganic carbon (Ci) within the cells. An inactivation library was used to raise the high-CO2-requiring mutant of Synechococcus PCC 7942, IL-2, impaired in HCO3- transport. Analysis of the relevant genomic DNA detected several modifications, probably due to the single crossover recombination, leading to inactivation of ORF467 (designated ictB) in IL-2. IctB contains 10 trans-membrane regions and is homologous to several transport-related proteins from various organisms. Kinetic analyses of HCO3- uptake in the wild type and IL-2 suggested the presence of two or three HCO3- carriers exhibiting different affinities to HCO3-.

Bicarbonates↗
PubMed1998

A mutant of Synechococcus PCC 7942 impaired in HCO3- uptake.

An inactivation library was used to isolate high-CO2-requiring mutants of Synechococcus PCC 7942. One of them, mutant IL-7, is composed of elongated cells, some 5-15 times longer than the wild-type. IL-7 is impaired in the ability to accumulate inorganic carbon within the cells due to a lesion in HCO3- transport. Consequently, the apparent photosynthetic affinity for external inorganic carbon was about 50-100-fold lower than in the wild-type. Analysis of the genomic region modified in IL-7 demonstrated that the inactivating fragment was composed of two genomically unrelated fragments which were ligated together during the formation of the inactivation library. One of the fragments originated from a known genomic region, rbcLS, encoding ribulose 1,5-bisphosphate carboxylase/oxygenase and the other showed high homology to mutS encoding a DNA mismatch repair protein. We suggest that the primary lesion in IL-7 was in mutS and not in rbcLS, and that the phenotype of IL-7 resulted from secondary random mutations. We were unable to identify the spontaneous mutation(s) due to low transformability of IL-7. Our finding that two unrelated fragments ligated together points to possible mistakes in the identification of the function of putative genes with the aid of an inactivation library.

Amino Acid Sequence↗
PubMed1998

Modification of topA in Synechococcus sp. PCC 7942 resulted in mutants capable of growing under low but not high concentration of CO2.

Insertion of a cartridge encoding kanamycin resistance within an open reading frame, ORF839, in the cyanobacterium Synechococcus sp. PCC 7942 resulted in merodiploids bearing both the normal and the modified ORF839, suggesting that its gene product is essential for growth. In the absence of kanamycin the mutants were able to grow like the wild type, but in its presence the mutants grew under 0.015% CO2 in air but not under 5% CO2 in air. ORF839, identified in this study, is highly homologous to topA encoding topoisomerase I in several organisms, but it does not contain the zinc-binding motif identified in the C-terminal region of the enzyme from Escherichia coli.

Carbon Dioxide↗
PubMed1998

The Development and Validation of Scales Assessing Students' Achievement Goal Orientations

Achievement goal theory has emerged as a major new direction in motivational research. A distinction is made among conceptually different achievement goal orientations including the goal to develop ability (task goal orientation), the goal to demonstrate ability (ability-approach goal orientation), and the goal to avoid the demonstration of lack of ability (ability-avoid goal orientation). Scales assessing each of these goal orientations were developed over an eight year period by a group of researchers at the University of Michigan. The results of studies conducted with seven different samples of elementary and middle school students are used to describe the internal consistency, stability, and construct validity of the scales. Comparisons of these scales with those developed by Nicholls and his colleagues provide evidence of convergent validity. Confirmatory factor analysis attests to the discriminant validity of the scales. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

Changes in cytokine production of breast cancer patients treated with interferons.

A clinical randomized study was performed on advanced breast cancer patients who were treated by interferons (IFN) beta and gamma in combination with hormonotherapy (Megace or Tamoxifen). Cytokine levels (IL-1beta, IL-2, IL-6, TNF-alpha, IFN-gamma) and sIL-2R of individual patients before, during (3 months) and after (6 months) therapy were evaluated and correlated to clinical response according to UICC criteria (responder patients-partial or Complete Response versus non-responder patients-Stable/Progression). Decreases in IL-1beta, IL-6 and sIL-2R were associated with clinical response to therapy versus increases in their levels which corresponded to progression of disease. A significant and dramatic increase in IFN-gamma levels was associated with a favourable response to therapy in the IFNs-treated patients, mainly in the group of Tamoxifen. Baseline levels of sIL-2R and of IFN-gamma were prognostic of clinical response and were found to be the most sensitive cytokine parameters for defining the clinical utility of the combination of IFNs and hormonotherapy in breast cancer patients.

Antineoplastic Agents, Hormonal↗
PubMed1998

VEGF administration in chronic myocardial ischemia in pigs.

OBJECTIVE: Previous investigations have shown the effectiveness of sustained intra- or extravascular administration of vascular endothelial growth factor (VEGF) in chronic myocardial ischemia in improvement of left ventricular function. The present investigations were undertaken in order to evaluate efficacy of a single bolus or local intracoronary delivery. METHODS: Yorkshire pigs underwent placement of a left circumflex artery ameroid occluder. Three weeks later the animals were randomized to treatment with VEGF (20 micrograms) accomplished by local intracoronary delivery system (InfusaSleeve, n = 10), intracoronary bolus infusion (n = 7) or by epicardial implantation of an osmotic delivery system (n = 7). An additional group of animals received intracoronary administration of saline and served as a control (n = 9). Three weeks after initiation of therapy, the animals were evaluated with regard to myocardial perfusion and global as well as regional ventricular function. RESULTS: All three VEGF treatment groups but not the control animals demonstrated a significant increase in the left-to-left (but not right-to-left) collateral index, myocardial blood flow (pre-therapy LCX vs. LAD (average of all groups): 0.76 +/- 0.35 vs. 0.96 +/- 0.38 ml*min-1*g-1, p = 0.03; post-therapy: LCX vs. LAD: 1.16 +/- 0.39 vs. 1.15 +/- 0.28 ml*min-1*g-1, p = NS) and coronary vasodilatory reserve 3 weeks after growth factor administration. The observed increase in VEGF-induced perfusion correlated with improvement in regional ventricular function in all VEGF-treated groups (pre-therapy vs. post-therapy: i.c. VEGF 20 +/- 5.1 vs. 33 +/- 4.8; local VEGF 16 +/- 2.8 vs. 33.6; pump VEGF 17 +/- 3.8 vs. 34 +/- 4.9 p < 0.05 for all) but not control animals (21 +/- 3.3 vs. 27 +/- 5.8, p = NS). CONCLUSION: Single intracoronary delivery (intravascular bolus or local delivery) of VEGF is effective in stimulating physiologically significant angiogenesis in porcine model of chronic myocardial ischemia.

Animals↗