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Biomedical subjects

J Kutti

Publications and source records attributed to J Kutti.

At least 19 recordsLinked to original sources
PubMed1992

Cigarette smoking increases thromboxane A2 formation without affecting platelet survival in young healthy females.

Smoking is a risk factor for the development of atherosclerotic cardiovascular disease, in men as well as in women. An increased urinary excretion of the thromboxane metabolite 2,3-dinorthromboxane B2 (Tx-M) has been observed in smokers of both genders, suggesting that cigarette smoking may facilitate cardiovascular disease via an action on the platelets. The present study addressed the hypothesis that the increased Tx-M excretion in female smokers reflects a true facilitation of platelet reactivity in vivo, rather than an increased destruction of the platelets. In healthy female volunteers (aged 20-46 years, 18 smokers and 17 non-smokers) platelet life-span and indices of platelet activity were determined, together with plasma levels of plasminogen activator inhibitor-1 (PAI-1), fibrinogen, peripheral blood cell counts and hematocrit. The urinary excretion of Tx-M was higher in smokers than in non-smokers (361 vs. 204 pg/mg creatinine, respectively, p < 0.05), while plasma and urinary beta-thromboglobulin, plasma platelet factor 4, platelet mean life-span and platelet production rate did not differ between the groups. PAI-1 activity, white blood cell count and hematocrit were higher in smokers than in non-smokers (p < 0.05). These data indicate that smoking facilitates platelet formation of thromboxane A2 without affecting platelet survival; i.e. it increases the activity of platelets without affecting their viability to a measurable extent. Such an increase in platelet activity, operating in parallel to a reduced fibrinolytic activity and a higher hematocrit and white blood cell count, may play an etiological role in smoking-induced cardiovascular disease in women.

Adult↗
PubMed1992

Some storage characteristics of buffy coats used for preparation of platelet concentrates.

The present study examined biochemical storage lesions in 58 buffy coats (BCs) intended as the raw material for platelet concentrates. The work was conducted in three series; the aims were to investigate: (a) the storage quality of BCs obtained from the routine production (series I), (b) whether improvement in platelet quality could be achieved by continuous agitation during storage (series II), and (c) whether macroscopic aggregate formation indicates platelet damage (series III). Series I and II consisted of 20 BCs each. Series III compared ten BCs with visible clumping with eight BCs not demonstrating macroscopic aggregates. In series I and II platelet counts and platelet factor 4 (PF4) release were determined after 1, 3, 5, and 24 h; lactate dehydrogenase (LDH) extracellular activity was measured after 1 and 24 h. In addition, in series I elastase concentrations were analyzed after 3, 5, and 24 h. Finally, in series III extracellular beta-thromboglobulin (beta-TG) levels were determined after 18-24 h. Low platelet counts, most likely reflecting the presence of aggregate formation, were found in 20% of the BCs (series I); in this series a total of 25% demonstrated increasing platelet counts, together with elevated PF4 and elastase, over the study period. Significant biochemical storage lesions were found after 5 and 24 h of storage. The study also demonstrated that continuous agitation during storage does not improve platelet quality (series II) and that BCs demonstrating visible clumping (series III) had augmented levels of extracellular beta-TG (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Platelets↗
PubMed1992

Dysplastic megakaryopoiesis with thrombocytopenia and chromosomal aberration.

A case of isolated thrombocytopenia with decreased platelet production and abnormal megakaryopoiesis is described. In the bone marrow, a chromosomally aberrant clone, 45,XX,-11,-18,+der (11;18)(11q13;18p11), was found. These findings indicate a myelodysplastic nature of the abnormal thrombocytopoiesis. The described case demonstrates the value of a bone marrow examination including histopathology with immunologic techniques to evaluate the megakaryopoiesis in thrombocytopenia and the interest of cytogenetic studies not only in instances with overt hematologic malignancies or complete myelodysplastic syndromes, but also when morphologic abnormalities occur in a single cell line.

Biopsy↗
PubMed1992

Investigation of how different filters affect some biochemical properties of stored platelet concentrates.

The aim of the present study was to investigate how four different filters, i.e. Imugard IG500 (Terumo, Japan), Miropore (Miramed, Italy), Pall P1-100 (Pall, USA) and Sepacell P1-10A (Asahi, Japan) affect some biochemical properties of platelet concentrates. The work was conducted using 42 pairs of platelet concentrates. After 2 days of storage, one of the preparations was filtered and the other served as an unfiltered control. Immediately after filtration, determination of the platelet count, desarginated activated complement factor 3 (C3a des arg) and the extracellular and total concentrations of platelet factor 4 (PF4) and lactate dehydrogenase (LDH) were carried out on both these platelet concentrates. After an additional storage period of 3 d, extracellular concentrations of PF4 and LDH were determined on both concentrates. A significant decrease of extracellular PF4 concentration was found immediately after filtration when Pall P1-100 and Imugard IG500 were used. During the 3-d storage after filtration, the concentrates filtered with Imugard IG500 and Pall P1-100 demonstrated significantly higher platelet lysis as compared to the unfiltered controls. It is concluded that the present work demonstrates storage instability after filtration with Imugard IG500 and Pall P1-100. Therefore, platelet concentrates filtered with these filters would not appear to be suitable for storage.

Blood Platelets↗
PubMed1991

The effect of alpha-interferon on bone marrow megakaryocytes and platelet production rate in essential thrombocythemia.

In 10 patients with previously untreated essential thrombocythemia (ET), by using 111In-labeled platelets and megakaryocyte morphometry, the relation between platelet production rate and bone marrow megakaryocytes was evaluated before and during alpha-2b-interferon (IFN) therapy. A highly significant decrease in platelet count occurred during IFN therapy; the platelet counts, at baseline and after 2 and 6 months of IFN therapy, were 1,102 +/- 345 x 10(9)/L, 524 +/- 169 x 10(9)/L (P less than .0001), and 476 +/- 139 x 10(9)/L (P less than .0001), respectively. The decrement in platelet count was mainly a result of diminished platelet production rate, which at baseline and after 2 and 6 months of IFN therapy was 89 +/- 30 x 10(10) platelets/d, 53 +/- 18 x 10(10) platelets/d (P = .0033), and 45 +/- 20 x 10(10) platelets/d (P less than .0001), respectively. Also, a slight shortening of platelet mean life-span (MLS) was observed in response to IFN treatment; platelet MLS was 7.96 +/- 0.69 days at baseline and 6.68 +/- 1.30 days (P = .012) after 6 months of IFN therapy. IFN induced a significant decrease in bone marrow megakaryocyte volume; both megakaryocyte nuclear and cytoplasmatic volumes were affected. The mean megakaryocyte volume was 372 +/- 126 x 10(2) pL/microL at baseline and 278 +/- 147 x 10(2) pL/microL (P = .049) after 6 months of IFN therapy. However, the number of megakaryocytes did not show any significant change in response to IFN. It is concluded that alpha-IFN reduces platelet production rate and the peripheral platelet count in ET mainly through an anti-proliferative action on the megakaryocytes and to a considerably lesser degree by a shortening of platelet MLS.

Adult↗
PubMed1991

The in vivo kinetics of 111In- and 51Cr-labelled platelets: a comparative study using both stored and fresh platelets.

The in vivo kinetics of simultaneously injected 51Cr- and 111In-labelled platelets was investigated in 20 healthy male volunteers. The studies were carried out using both fresh platelets and platelets stored for 5 d at 22 degrees C; the disappearance of platelet-bound radioactivity was measured on whole blood samples as well as platelet pellets. Compared to 111In, the labelling efficiency was notably lower for 51Cr, and a higher amount of 51Cr was bound to contaminating red cells. As regards the fresh platelets, only small dissimilarities were observed in the in vivo kinetics obtained with the two labels. 51Cr yielded a slightly higher platelet recovery and longer T1/2 than 111In, when whole blood samples were used for calculations; no differences were seen when using platelet pellets. When stored platelets were studied, 51Cr gave significantly longer T1/2 and mean life-span (MLS) than did 111In. This difference was present for all mathematical models used for the calculation of MLS, and when whole blood samples as well as platelet pellets were employed. It was demonstrated that the estimation of MLS was also highly dependent upon techniques of blood sampling and curve fitting. Calculation, in which the initial data points were excluded, gave consistently longer MLS (P less than 0.0001), as compared to when all data points were included. Furthermore, when all survival studies were grouped together, calculations using platelet pellets gave a significantly (P less than 0.001) shorter platelet MLS than calculations using whole blood samples. It is concluded that both 51Cr and 111In are acceptable as radiolabels for both fresh and stored platelets. However, it appears that the viability of stored platelets may be influenced by the choice of label, and caution must be taken when these isotopes are used together in dual tracer experiments. Also, our results show that a meticulously standardized processing of blood samples and experimental data is required to enable interlaboratory comparisons of the results.

Adult↗
PubMed1991

Leukocyte removal filtration of platelet concentrates. A study of platelet loss using 111In-labelled platelets and dynamic gamma camera scintigraphy.

111In labelled platelets and gamma camera scintigraphy were used for the study of the platelet loss during leukocyte removal filtration of stored platelets. Two different filters were examined, Imugard IG500 and Pall PL100, and platelet pools containing varying number of platelet concentrates were filtered. It was found that a sizeable amount of the platelets was trapped within the filter. Some of the trapped platelets could be recovered by rinsing the filters with normal saline. The most appropriate rinsing volume to recover lost platelets seemed to match with the "dead space" volume within the filter. It is concluded that radiolabelled platelets and gamma camera scintigraphy appears to be an excellent method to investigate the dynamic events of platelet loss during leukocyte removal filtration. This technique should be well applicable for the study of technological advances in filter construction.

Blood Platelets↗
PubMed1990

DNA content and nuclear size of megakaryocytes in thrombocythaemia.

Total nuclear DNA content and nuclear size of megakaryocytes were studied in biopsies of the iliac bone marrow of individuals with normal or increased platelet counts. The DNA content was determined using Feulgen cytophotometry of bone marrow smears and the nuclear area by morphometric analysis of megakaryocytes of bone marrow sections. The mean DNA content and the mean nuclear area were both significantly larger in megakaryocytes of patients with thrombocytosis as a result of myeloproliferative disease than in patients with secondary thrombocytosis as well as in two control groups of individuals with normal platelets counts, one comprising healthy volunteers, the other with various non-haematological disorders. There was a statistically significant correlation between the DNA content and nuclear area of the megakaryocytes (r = 0.92) in the entire group of bone marrows studied.

Adolescent↗
PubMed1990

Endothelial cell seeding reduces thrombogenicity of Dacron grafts in humans.

Vascular prostheses in humans do not endothelialize spontaneously. In the present study we explored the feasibility of seeding autologous endothelial cells into prostheses implanted in patients undergoing reconstruction of the infrarenal aorta. In 22 patients one limb of an aortic Dacron bifurcation prosthesis was seeded with autologous endothelial cells harvested from the distal portion of the saphenous vein. The other limb was sham-seeded with culture medium only. The effect of seeding was studied by use of indium 111 radiolabeled platelets and external gamma camera scanning at 1, 4, and 12 months after surgery. No complications ascribable to the seeding procedure were seen. During the first year after surgery a gradual decrease in platelet accumulation occurred over the whole vascular prosthesis. At all time points studied the seeded graft limbs exhibited significantly less deposition of radiolabeled platelets than did control limbs. The observed difference in platelet accumulation on autologous endothelial seeding-treated graft segments merits further investigation of this technique in humans.

Aged↗
PubMed1989

ADP-induced platelet aggregation as a function of age in healthy humans.

In 120 healthy humans (58 males and 62 females) possible differences in platelet aggregability were investigated with respect to age and sex. By using a narrow range of final ADP concentrations (0.2-1.0 microM) primary and secondary aggregation were evaluated. The rate of primary aggregation was shown to be significantly related to increasing age and this was true for both sexes. As regards secondary aggregation the same pattern was seen in the group of male subjects. Thus, among the youngest (less than 34 years) the frequency of secondary waves was only one third of that encountered among the oldest (greater than 50 years). No similar association was detectable among the female subjects. The present study calls attention to some important issues which should be considered in platelet aggregation studies; the interpretation of data obtained from such studies invariably requires a careful selection of appropriate age- as well as sex-matched control groups.

Adenosine Diphosphate↗
PubMed1988

Splenic platelet kinetics and platelet production after major reconstructive vascular surgery.

By using 111In-labelled platelets and dynamic gamma camera scintigraphy, platelet production rate and intrasplenic platelet kinetics were determined in 13 patients at 1 and 4 months after aortic reconstructive vascular surgery with implantation of dacron prostheses. A significant decrease in platelet production rate and venous platelet count was recorded over time after surgery. Irrespective of whether the exchangeable splenic platelet pool was estimated from initial recovery of platelet-bound radioactivity or from compartmental analysis, the size of this pool was significantly lower at the first study; a change in intrasplenic platelet transit time accounted for the observed difference. Platelet mean life-span increased over time after surgery but the difference between the duplicate studies was not statistically significant. It can be concluded that there is a reduction of platelet production rate and venous platelet count over time after major reconstructive vascular surgery. The early postoperative elevation in the platelet count is mainly the result of an increased platelet production and to a lesser degree due to redistribution of platelets between the splenic platelet pool and general circulation.

Aged↗
PubMed1988

In vitro platelet function in infantile autism.

It has previously been demonstrated that patients with infantile autism demonstrate impaired in vivo platelet behaviour. Therefore, in 14 children (13 boys and 1 girl) with infantile autism (aged 2-14, mean 6 years) and 12 healthy control boys (aged 6-15, mean 11 years) we studied in vitro platelet reactivity using ADP- and collagen-induced platelet aggregation. In each child a total of 7 different final concentrations of ADP and 4 different concentrations of collagen were employed. At all concentrations of ADP and collagen used the autistic children consistently exhibited diminished platelet aggregability; the differences, however, did not reach statistical significance. Therefore a wider panel of in vitro tests is apparently required and a larger group of patients be studied to help elucidate the functional/metabolic platelet defect met in infantile autism.

Adolescent↗