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Biomedical subjects

A Leaf

Publications and source records attributed to A Leaf.

At least 73 records · Page 4Linked to original sources
PubMed1994

Effects of long-chain polyunsaturated fatty acids on the contraction of neonatal rat cardiac myocytes.

Because of the ability of certain long-chain polyunsaturated fatty acids (PUFAs) to prevent lethal cardiac arrhythmias, we have examined the effects of various long-chain fatty acids on the contraction of spontaneously beating, isolated, neonatal rat cardiac myocytes. The omega 3 PUFA from fish oils, eicosapentaenoic acid [EPA; C20:5 (n-3)] and docosahexaenoic acid [DHA; C22:6 (n-3)], at 2-10 microM profoundly reduced the contraction rate of the cells without a significant change in the amplitude of the contractions. The fatty acid-induced reduction in the beating rate could be readily reversed by cell perfusion with fatty acid-free bovine serum albumin. Addition of either oxygenase inhibitors or antioxidants did not alter the effect of the fatty acids. Arachidonic acid [AA; C20:4 (n-6)] produced two different effects on the beating rate, an increase or a decrease, or it produced no change. In the case of the increased or unchanged beating rate in the presence of AA, addition of AA oxygenase inhibitors subsequently reduced the contraction rate. The nonmetabolizable AA analog eicosatetraynoic acid (ETYA) always reduced the beating rate, as did EPA or DHA. Two other PUFAs, linoleic acid [C18:2 (n-6)] and linolenic acid [C18:3 (n-3)] also exhibited similar but less potent effects compared with EPA or ETYA. In contrast, neither the monounsaturated fatty acid oleic acid [C18:1 (n-9)] nor the saturated fatty acids stearic acid (C18:0), myristic acid (C14:0), and lauric acid (C12:0) affected the contraction rate. The inhibitory effect of these PUFAs on the contraction rate was similar to that produced by the class I antiarrhythmic drug lidocaine. The fatty acids that are able to reduce the beating rate, particularly EPA and DHA, could effectively prevent and terminate lethal tachyarrhythmias (contracture/fibrillation) induced by high extracellular calcium concentrations or ouabain. These results suggest that free PUFAs can suppress the automaticity of cardiac contraction and thereby exert their antiarrhythmic effects.

5,8,11,14-Eicosatetraynoic Acid↗
PubMed1994

Omega 3 polyunsaturated fatty acid modulates dihydropyridine effects on L-type Ca2+ channels, cytosolic Ca2+, and contraction in adult rat cardiac myocytes.

The effect of docosahexaenoic acid (DHA; C22:6) on dihydropyridine (DHP) interaction with L-type Ca2+ channel current (ICa), cytosolic Ca2+ (Cai), and cell contraction in isolated adult rat cardiac myocytes was studied. The DHP L-type Ca(2+)-channel blocker nitrendipine (10 nM) reduced peak ICa (measured by whole-cell voltage clamp from -45 to 0 mV) and reduced the amplitude of the Ca2+ transient (measured as the transient in indo-1 fluorescence, 410/490 nm) and the twitch amplitude (measured via photodiode array) during steady-state electrical stimulation (0.5 Hz). The DHP L-type Ca2+ channel agonist BAY K 8644 (10 nM) significantly increased ICa, the amplitude of the Cai transient, and contraction. When cells were exposed to DHA (5 microM) simultaneously with either BAY K 8644 or nitrendipine, the drug effects were abolished. Arachidonic acid (C20:4) at 5 microM did not block the inhibitory effects of nitrendipine nor did it prevent the potentiating effects of BAY K 8644. DHA modulation of DHP action could be reversed by cell perfusion with fatty acid-free bovine serum albumin at 1 mg/ml. Neither DHA nor arachidonic acid alone (5 microM) had any apparent effect on the parameters measured. DHA (5 microM) had no influence over beta-adrenergic receptor stimulation (isoproterenol, 0.01-1 microM)-induced increases in ICa, Cai, or contraction. The findings that DHA inhibits the effect of DHP agonists and antagonists on Ca(2+)-channel current but has no effect alone or on beta-adrenergic-induced increases in ICa suggests that DHA specifically binds to Ca2+ channels at or near DHP binding sites and interferes with ICa modulation.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1994

Prevention of ischemia-induced ventricular fibrillation by omega 3 fatty acids.

A specially prepared dog model of myocardial infarction was used to test the efficacy of the long-chain polyunsaturated fish oil omega 3 fatty acids eicosapentaenoic (20:5 n-3) and docosahexaenoic (22:6 n-3) acids to prevent ischemia-induced malignant cardiac arrhythmias. The dogs had sustained a prior experimental myocardial infarction from ligation of the left anterior descending coronary artery, and a hydraulic cuff was implanted around the left circumflex artery at that operation. After recovery from that procedure the animals were tested during a treadmill exercise test. With compression of the left circumflex artery sensitive animals will predictably develop ventricular fibrillation (VF). In such prepared dogs an emulsion of fish oil fatty acids was infused i.v. over a 50- to 60-min period just before the exercise-plus-ischemia test, and the effect on development of VF was recorded. The infusion was 100 ml of a 10% (vol/vol) emulsion of a fish oil concentrate containing 70% omega 3 fatty acids with free eicosapentaenoic acid and docosahexaenoic acid composing 33.9% and 25.0% of that total, respectively. Alternatively, some animals similarly received an emulsion containing 5 ml of the free fatty acid concentrate plus 5 ml of a triacylglyerol concentrate containing 65% omega 3 fatty acids with eicosapentaenoic acid and docosahexaenoic acid composing 34.0% and 23.6% of that total, respectively. In seven of eight animals the infusion of the fish oil emulsion completely prevented the acute occurrence of VF in the susceptible animals (P < 0.005). In five of five of these animals the subsequent exercise-plus-ischemia test after a similar infusion of an emulsion in which soy bean oil replaced the fish oil fatty acid concentrates resulted in prompt development of VF. Possible mechanisms for this protective effect of omega 3 fatty acids against exercise and ischemia-induced malignant arrhythmias are considered.

Animals↗
PubMed1994

The Krüppel-associated box-A (KRAB-A) domain of zinc finger proteins mediates transcriptional repression.

We have previously reported the cloning, sequencing, and partial characterization of Kid-1, a zinc finger-encoding cDNA from the rat kidney. The Kid-1 protein and approximately one-third of all other zinc finger proteins contain a highly conserved region of approximately 75 amino acids at their NH2 terminus named Krüppel-associated box (KRAB), which is subdivided into A and B domains. The evolutionary conservation, wide distribution, and genomic organization of the KRAB domains suggest an important role of this region in the transcriptional regulatory function of zinc finger proteins. The functional significance of the KRAB domain was evaluated by studying transcriptional activities of yeast GAL4-rat Kid-1 fusion proteins containing various regions of the non-zinc-finger domain of Kid-1. Transcriptional repressor activity of GAL4-Kid-1 fusion proteins maps to the KRAB-A domain. The KRAB-A domain of another zinc finger protein, ZNF2, also has repressor activity. Site-directed mutagenesis of conserved amino acids in this motif results in decreased repressor activity. Thus, we have established a functional significance for the KRAB-A domain, a consensus sequence common in zinc finger proteins.

Amino Acid Sequence↗
PubMed1994

Do fish oils prevent restenosis after coronary angioplasty?

BACKGROUND: The omega-3 polyunsaturated fatty acids derived from fish oils have been shown to modulate many factors believed to affect the pathogenesis of atherosclerosis. Because certain features of restenosis following angioplasty mimic some of the early changes of atherogenesis, some researchers have suggested that fish oil might prevent restenosis following angioplasty. We report the effects of omega-3 fatty acids on the rate of restenosis following percutaneous intraluminal coronary angioplasty (PTCA). METHODS AND RESULTS: From August 1989 through September 1992, 551 patients were randomized to start receiving a daily dietary supplement of ten 1.0-g capsules containing 80.6% ethyl esters of omega-3 fatty acids providing 4.1 g eicosapentaenoic acid (EPA) and 2.8 g docosahexaenoic acid (DHA) for 6 months or an equal amount of an ethyl ester of corn oil. Four hundred seventy subjects who were well matched for risk factors completed successful angioplasty of one or multiple lesions in native coronary vessels and constituted the study cohort, of whom 447 were evaluable at 6 months after PTCA. The criteria for restenosis were that the quantitative coronary angiography at 6 months show a > 30% increase in narrowing at the stenosis site or loss of at least half of the gain achieved at the time of PTCA and final restenosis with < 50% luminal diameter remaining. In 93% of the patients, the end point was determined by angiography and in all except 1% of these by quantitative coronary angiography. Compliance with the fish oil supplement was good as judged by incorporation of EPA and DHA in plasma and red blood cell phospholipids. The restenosis rate among analyzable patients was 46% for corn oil and 52% for fish oil (P = .37). The addition of 200 mg alpha-tocopherol for all subjects during the study had no effect on restenosis rates. CONCLUSIONS: This was the largest of such trials to date, and a supplement of 8 g/d of omega-3 fatty acids failed to prevent the usual high rate of restenosis after PTCA. No adverse effects were attributable to this large daily supplement of omega-3 fatty acids.

Adult↗
PubMed1994

Infusional cyclophosphamide, doxorubicin and etoposide in HIV-related non-Hodgkin's lymphoma: a follow-up report of a highly active regimen.

Based on our prior data suggesting a therapeutic advantage for infusional administration of cyclophosphamide (C), doxorubicin (D), and etoposide (E) in patients with relapsed and resistant non-Hodgkin's lymphoma (NHL), we administered C (750 mg/m2), D (50 mg/m2), and E (240 mg/m2) via continuous intravenous infusion over 96 hours as first line therapy for 21 patients with intermediate- or high-grade non-Hodgkin's lymphoma associated with human immunodeficiency virus (HIV) infection. Treatment was repeated every 28 or more days. The median CD4 count of the study group was 87/ul, and the median serum lactate dehydrogenase was 383 IU/L. Extranodal disease, lymphomatous marrow involvement, and lymphomatous meningitis were present at diagnosis in 90%, 33%, and 10% of patients, respectively. Complete response (CR) occurred in 13 patients (62%, 95% confidence intervals 41%, 81%) and partial response occurred in five patients (24%). The estimated median survival of the study group was 18.0 months. Hematologic toxicity required dose reduction for 47% of cycles and for 79% of patients who received at least two cycles. The mean dose intensity for C, D, and E were 73%, 70%, and 73% of the intended dose intensity, respectively. Opportunistic infection included oral/esophageal candidiasis (N = 7), herpes labialis (N = 3), pulmonary Mycobacterium avium-intracellulare (N = 1), candidemia (N = 1), pneumonitis (N = 1), and disseminated aspergillosis than resulted in a single treatment-related death (5%). Treatment resulted in a significant decrease in the CD4+ lymphocytes, as well as total lymphocytes, T lymphocytes, and CD8+ lymphocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Mycobacterium marinum infection in a patient with the acquired immunodeficiency syndrome.

A variety of mycobacterial organisms may infect patients with acquired immunodeficiency syndrome. A patient with acquired immunodeficiency syndrome, lymphoma, and sporotrichoid Mycobacterium marinum is described. The patient responded completely to antimycobacterial therapy but relapsed when he discontinued his medications six months into his course. Disease persistence in spite of therapy had been noted in other immunocompromised states but not previously in acquired immunodeficiency syndrome. Patients with acquired immunodeficiency syndrome may require prolonged treatment or suppressive therapy for Mycobacterium marinum infections.

AIDS-Related Opportunistic Infections↗
PubMed1993

Infusional cyclophosphamide, doxorubicin, and etoposide in human immunodeficiency virus- and human T-cell leukemia virus type I-related non-Hodgkin's lymphoma: a highly active regimen.

Fourteen patients with poor-prognosis intermediate- to high-grade non-Hodgkin's lymphoma (NHL) associated with human immunodeficiency virus (HIV) infection (12 patients) or human T-cell leukemia virus type I (HTLV-I) infection (two patients) received cyclophosphamide 750 mg/m2, doxorubicin 50 mg/m2, and etoposide 240 mg/m2 administered as a continuous intravenous (IV) infusion over 4 days (infusional CDE); treatment was repeated every 28 or more days for up to six cycles. All HIV-positive patients had at least one poor prognostic feature, which included either extranodal disease (10 patients), Karnofsky performance status less than 70% (six patients), a CD4 count less than 100/microL (six patients), or a prior history of acquired immunodeficiency syndrome (AIDS; one patient). Both HTLV-I-positive patients had an elevated serum lactate dehydrogenase (LDH) level, a poor prognostic feature in that setting. Complete response (CR) occurred in 10 patients (71%; 95% confidence interval, 48% to 95%) and partial response (PR) occurred in three patients (21%), yielding an overall objective response rate of approximately 93%. The estimated Kaplan-Meier median survival was 17.4 months; seven of 12 HIV-positive patients are alive and disease-free with a median follow-up of 15 months (range, 7 to 24 months). Hospitalization was required after 19% of treatment cycles due to fever associated with granulocytopenia. Documented or suspected opportunistic infection occurred in five patients (36%), bacteremia occurred in three patients (21%), and candidemia occurred in one patient (7%). There was one treatment-related death attributable to disseminated aspergillosis. This pilot study suggests that infusional CDE may be a highly active regimen capable of producing durable remissions in a high proportion of patients with HIV-related NHL. Further study is required to confirm this observation.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Role of leuCAM integrins and complement in platelet-monocyte rosette formation induced by immune complexes of human immunodeficiency virus-type 1-immune thrombocytopenic purpura patients.

Patients with human immunodeficiency virus-type 1-immune thrombocytopenic purpura (HIV-1-ITP) have elevated polyethylene glycol (PEG)-precipitable immune complexes (ICs) composed of IgG, IgM, and complement that are threefold to sevenfold higher than in healthy control subjects. These complexes contain anti-F (ab')2 as well as anti-idiotype antibodies versus anti-HIV-1gp120. Because anti-F (ab')2 and anti-idiotype antibodies correlate with thrombocytopenia (r = .83 [J Clin Invest 77:1756, 1986] and r = .90 [J Clin Invest 89:356, 1992], respectively) we studied the binding of ICs to platelets and monocytes as well as their role in platelet-monocyte rosette formation. ICs bind to platelets in a saturation-dependent manner (optimum at 10 micrograms/mL; 0.5% of serum conc). Binding to platelets could not be inhibited with platelet saturating concentrations of aggregated IgG or with monoclonal antibody (MoAb) IV.3 versus FcR gamma II. Platelet binding could be inhibited with Fab anti-C3, anti-Clq, or anti-C4 by 57%, 40%, and 46% respectively, not with control Fab (P < .001). Monocytes from HIV-1-ITP patients form rosettes with normal platelets 16.8 +/- 5.2 rosettes/100 monocytes compared with 4.8 +/- 0.8 control monocytes plus normal platelets (P = .009). Gel-washed HIV-1-ITP platelets formed 19 +/- 2.0 rosettes with U937 cells compared to 6.3 +/- 1.0 for normal platelets (P = 0.001). Arming of U937 cells with HIV-1-ITP ICs (5 micrograms/mL) formed 36.7 +/- 2.5 rosettes compared with 10.6 +/- 1.2 for control ICs (P < .01). Rosetting of armed U937 cells could be inhibited with MoAbs versus the alpha chains of CD11a (LFA-1), 11b (Mac-1), or 11c (p150,95) by 67%, 70%, and 61%, respectively (P < .007), whereas binding of ICs to U937 cells was unaffected. Isotype-matched control as well as MoAbs versus antigens on U937 cells (CD13, CD33) or the anti-FcR gamma II receptor had no effect. However, Fab fragments of polyclonal anti-C3 inhibited rosette formation by 78% (P < .01); control Fab had no effect. Thus, platelet-monocyte rosette formation is not Fc dependent. It is complement receptor dependent and requires the cooperation of all three leuCAM integrins.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Nutrition and neurodevelopmental disorders.

Since the 1960s the structural requirements for the growth, development and function of the brain have become better understood due to the recognition of the prodigious energy needs for brain development and its structural requirements for lipids. The most vulnerable period of neural development is during embryonic and fetal growth. There is now both retrospective and prospective evidence that maternal nutrition prior to conception is most important to pregnancy outcome. Our studies on maternal nutrition in pregnancy again illustrate the relationship of maternal nutrition to birthweight and head circumference. In a study of 513 pregnancies we found that nutrient intakes in mothers of low birthweight babies were well below those of mothers whose babies were in the 3.5-4.5 Kg range at which morbidity is at its lowest. Nutrient intakes tracked with birthweight, independent of smoking and alcohol up to, but not above 3,270 g. The closest correlations were obtained with the diet of the mother at or about the time of conception rather than later in the pregnancy. Our studies also reveal that premature and intrauterine growth retarded babies were born with deficits of the types of essential fatty acids (arachidonic AA, docosahexaenoic DHA acids) known to be required for brain development. Deficits of brain DHA have been found experimentally to impair visual and cognitive development and also to cause haemorrhage, not unlike peri-ventricular haemorrhage in low birthweight babies, the above evidence is suggestive of a route to test the prevention and treatment of these types of membrane related disorders.

Cephalometry↗
PubMed1993

Infusional cyclophosphamide, doxorubicin, and etoposide in relapsed and resistant non-Hodgkin's lymphoma: evidence for a schedule-dependent effect favoring infusional administration of chemotherapy.

PURPOSE: This study attempted to determine the efficacy of cyclophosphamide (C), doxorubicin (D), and etoposide (E) administered as a continuous intravenous (IV) infusion (infusional CDE) over 4 days in patients with relapsed or resistant non-Hodgkin's lymphoma (rNHL) and in patients with previously untreated (uNHL) who had poor prognostic features. PATIENTS AND METHODS: Fifty-eight patients with rNHL and 10 patients with uNHL received infusional CDE every 28 or more days; all but one had intermediate- to high-grade histology. The cumulative doses of C, D, and E administered per treatment cycle were 750 mg/m2, 50 mg/m2, and 240 mg/m2, respectively. In the rNHL group, all patients had previously received C, most (81%) had received D, and a minority (16%) had received E. RESULTS: Objective response occurred in 30 patients with rNHL (52%; 95% confidence interval, 39% to 65%); 10 patients had a complete response (CR) (17%; 95% confidence interval, 7% to 27%). Eleven patients (19%) remain progression-free (median follow-up, 22 months; range, 10+ to 38+), and six patients (10%) are disease-free (median follow-up, 25 months; range, 10+ to 38+). Among 10 patients with uNHL, eight (80%) had a CR, and none have relapsed (median follow-up, 11 months; range, 9+ to 24+). Toxicity was primarily hematologic. Two treatment-related deaths (3%) occurred, both attributable to infection in the relapsed or resistant group. CONCLUSION: Infusional CDE produced a CR in substantial proportion of patients who had previously been exposed to at least two of the agents administered as an IV bolus, suggesting a schedule-dependent effect in favor of the infusional administration of certain cytotoxic agents in patients with lymphoid neoplasms. In addition, infusional CDE was effective and tolerable in patients with poor-prognosis NHL when used as initial therapy, and merits further study in that setting.

Adult↗
PubMed1992

Psychological, behavioral and biochemical risk factors for coronary artery disease among American and Italian male corporate managers.

Differences in psychological, behavioral and biochemical risk factors for coronary artery disease (CAD) among male corporate managers of 2 countries (United States and Italy), with very different age-specific rates of mortality for CAD were evaluated. In all, 129 American (mean age 43 +/- 7 years) and 80 Italian (mean age 45 +/- 7 years) managers volunteered to participate in this study. Each subject was administered several questionnaires assessing various psychological and behavioral risk factors for CAD, and all 129 Americans and 55 of 80 Italians had their blood drawn between 8:00 and 9:30 AM after overnight fasting for the measurement of plasma levels of dehydroepiandrosterone-sulfate (DHEA-S), total cholesterol, triglycerides, and apolipoproteins A-I and B. Italian managers reported significantly more cynicism and hostility, and less enjoyment in leisure activities than did American ones. Furthermore, 40 Italian (51%) and only 18 American (14%) managers were smokers (this difference being statistically significant). Although no significant differences were found in factors positively related with CAD (cholesterol, triglycerides and apolipoprotein B), there were clear differences in parameters inversely correlated with the incidence of CAD. Italian managers had significantly lower levels of plasma DHEA-S and apolipoprotein A-I than did American ones. In conclusion, this study found that Italian managers had a significantly more unhealthy psychological and behavioral profile than did American ones, and had lower levels of those biochemical parameters (apolipoprotein A-I and DHEA-S) thought to have a protective role against development of CAD.

Administrative Personnel↗
PubMed1992

Evidence of growth retardation in neonates of apparently normal weight.

The aim of this study was to examine the relationship of ponderal index (PI) and the ratio of mid-arm circumference to occipito-frontal circumference (MAC/OFC) to the delivered weight of the child. Measurements were made on 160 singleton neonates with birthweight greater than 2500 g and delivery at 37 weeks or more. Surprisingly, there was a highly significant correlation between PI and birthweight and MAC/OFC and birthweight. We conclude that: (1) values of PI must be evaluated in relation to birthweight, and not against a single absolute standard for the whole normal population; (2) measurement of PI and MAC/OFC may reveal a group of growth-retarded infants amongst infants of apparently 'normal' birthweight; and (3) this group of infants might be a target for the extra care normally accorded to the low birthweight infant.

Anthropometry↗