PubMed Health⌕ Search

Biomedical subjects

R Calabrese

Publications and source records attributed to R Calabrese.

32 records · Page 2Linked to original sources
PubMed1993

Mouse antithrombotic assay. Inhibition of platelet thromboembolism by disintegrins.

The mouse antithrombotic assay represents a model of fatal pulmonary thromboembolism induced by intravenous injection of collagen and epinephrine. Mice were protected by low doses of two disintegrins, albolabrin (10 micrograms/mouse) and eristostatin (0.6 micrograms/mouse), whereas high doses of a thrombin inhibitor and an inhibitor of von Willebrand Factor binding to glycoprotein Ib were not effective. Injection of collagen and epinephrine resulted in the drop of platelet count and accumulation of platelet aggregates in the lung that appears to be the immediate cause of death. Albolabrin or eristostatin administration did not prevent the decrease of platelet count. Injection of albolabrin resulted in the formation of smaller and reversible platelet aggregates in the lungs and decreased accumulation of 51Cr-labeled platelets in the lung suggesting that this disintegrin decreases formation of platelet aggregates in vivo. We compared the effects of albolabrin and erisostatin on platelet aggregation, tail bleeding time, and survival of challenged animals. Eristostatin was about 5 times more potent in inhibiting platelet aggregation in vitro than albolabrin and 38 times more potent than albolabrin in protecting animals from sudden death. Both disintegrins, at the same doses (0.6-5 micrograms/mouse), caused similar dose-dependent prolongation of the bleeding time; however, only eristostatin exerted a protective effect. In conclusion, a) the mouse antithrombotic assay is a suitable model to screen and to evaluate the potency of platelet fibrinogen receptor antagonists in vivo; b) the results of the antithrombotic assay correlate better with the inhibition of platelet aggregation in vitro than with the prolongation of bleeding time.

Amino Acid Chloromethyl Ketones↗
PubMed1987

A comparative analysis of the effects of alienation on public and private school females.

The levels of alienation of American female school students (N = 431; 256 public, 175 private) were assessed to determine the extent of the influence of the school environment on the student's level of alienation and the dimensions of isolation, normlessness, and powerlessness. It was hypothesized that substantially different school settings would have no significant effects because student alienation is influenced by a series of complex environmental factors. The Dean Alienation Scale (1961) was used to assess levels of alienation. There were no significant differences in terms of total alienation and powerlessness. Private school students, however, were more isolated (p less than .001) and public school students had higher levels of normlessness (p less than .05).

Adolescent↗
PubMed1984

Changes in plasma progesterone concentrations around the time of the luteinizing hormone surge in women superovulated for in vitro fertilization.

The purpose of the present study was to examine plasma progesterone (P4) changes around the time of the onset of the LH surge in women superovulated with clomiphene citrate and human Menopausal Gonadotrophin for in vitro fertilization (IVF). It was considered that changes in P4 levels which should be closely associated with the onset of the LH surge may be an accurate indicator for the time of oocyte recovery for IVF and that premature P4 secretion may prevent the establishment of pregnancy after embryo replacement. The plasma P4 concentrations determined at 0800, 1400, and 2100 h during the period 36 h before to 16 h after the onset of the LH surge in 72 women showed a significant diurnal variation with the nadir at 0800 h. The onset of the LH surge was detected in 51%, 32%, and 17% of patients at 0800, 1400, and 2100 h, respectively. The first significant increase in mean P4 concentrations was coincident with the onset of the LH surge at 1400 and 2100 h but because of the diurnal nadir of P4 at 0800 h, the increase in mean P4 levels was delayed until 1400 h when the LH surge began at 0800 h. Elevation of P4 concentrations from 2 to 8 nmol/liter in individual patients at 1400 and 2100 h before the onset of the LH surge did not prevent the establishment of pregnancy after embryo transfer. P4 concentrations before and after the onset of the LH surge were higher with increasing numbers of mature follicles. We conclude that changes in plasma P4 concentrations may be used to determine the time of ovulation or oocyte recovery for IVF because of their close association with the timing of the onset of the LH surge.

Circadian Rhythm↗
PubMed1980

Inhibition of mechanosensory interneurons in the crayfish. I. Presynaptic inhibition from giant fibers.

1. Sucrose-gap and intracellular recordings were used to study the primary afferent depolarization (PAD) produced in mechanosensory afferents by impulses in lateral and medial giant axons, which are the command cells for the tail flip escape response in the crayfish. 2. The lateral and medial giant axons produce PAD through a polysynaptic interneuronal pathway. The response has a relatively long intraganglionic latency (7--11 ms), and command-evoked PAD can be recorded in ganglia from which the giant axons have been experimentally disconnected. 3. The final neurons of the pathway that delivers inhibition are few in number and extensive in distribution; most appear to be common to lateral and medial giant pathways. 4. At least some of the inhibitory interneurons have axons in the interganglionic connectives and probably produce both presynaptic and postsynaptic inhibition. 5. Stimulation of the lateral, but not the medial, giant axons causes a small, short-latency deplorization that is stable at high repetition rates. This small potential can be accounted for by transmission across known electrical synapses between mechanosensory afferents and the lateral giants in each abdominal ganglion. 6. Repetitive stimulation of the lateral giant axons causes substantial augmentation of PAD, apparently through recruitment of additional interneurons. PAD evoked by a single medial giant (MG) stimulus is generally much larger than that elicited by a single lateral giant (LG) spike. However, MG-PAD summates little and so the maximum PAD deltaV reached during repetitive firing is equivalent for the two types of giant axons. 7. Iontophoresis of gamma-aminobutyric acid (GABA) into the ganglionic neuropil depolarizes the primary afferents and blocks activity in neurons that have axons in the interganglionic connective. 8. The extrapolated PAD reversal potential and pharmacological studies suggest that a GABA-mediated chloride conductance increase is involved in the production of PAD.

Animals↗
PubMedDate not supplied

[Status epilepticus in chronically dialyzed patients treated with erythropoietin].

This paper describes the clinical features of two patients with chronic renal failure and uremic anaemia treated with recombinant human erythropoietin (9000 I.U. subcutaneously subdivided in 3 times weekly at the end of haemodialysis treatment) who developed seizures and status epilepticus. This treatment has unequivocal benefits but in some patients has been accompanied by elevated blood pressure leading to hypertensive encephalopathy with seizures. In fact, the correction of the anaemia results in a rise in packed cell volume with a consequent increase in blood viscosity, predisposing to increased vascular resistance and the development of hypertension.

Adult↗
PubMedDate not supplied

Interpersonal communication skills and the radiologic technologist.

Studies done in the behavioral sciences suggest that the quality of the communication skills of persons in "helping" professions is related directly to the credibility, respect, and cooperation they receive from their clients. In his article, Dr. Calabrese discusses some specific communication skills that could strengthen the relationship between the radiologic technologist and his/her patients.

Communication↗
PubMedDate not supplied

Serum erythropoietin and circulating transferrin receptor in thalassemia intermedia patients with heterogeneous genotypes.

BACKGROUND: Thalassemia intermedia patients usually do not require blood transfusions; however, all show variable degrees of erythropoietic marrow expansion to compensate for more or less marked anemia, and this represents the major cause of complications in untransfused individuals. MATERIALS AND METHODS: To assess the degree of erythropoietic expansion in thalassemia intermedia, serum erythropoietin (sEpo) and serum transferrin receptor (sTfr) were determined in thirty Italian patient's characterized by their beta-globin genotype. RESULTS: Six patients showed inappropriately low sEpo levels (O/P ratio < 0.85). Even excluding these cases, no clear relationship was observed between Hb levels and sEpo or sTfr. Two groups of patients were compared: the first with low HbF (< 40%) that included the majority of beta(+) genotypes, and the second with high HbF (> 40%) that contained a prevalence of beta(0) genotypes. Hb levels were similar in the two groups: 8.09 +/- 1.15 g/dL in low HbF and 8.82 +/- 1.28 g/dL in high HbF patients. Mean sEpo was 112 +/- 78.02 mU/mL (O/P ratio = 0.98 +/- 0.22) in the first and 246.62 +/- 184.30 mU/mL (O/P ratio = 1.25 +/- 0.30) in the second group, with a statistically significant difference, as expected, because of HbF oxygen hyperaffinity. No significant difference in sTfr levels was observed, indicating a comparable erythropoietic response in the two groups. CONCLUSIONS: The relationships between anemia, HbF and total erythropoiesis in thalassemia are more complex than expected. Further studies of subjects with high HbF and benign conditions, such as HPFH, could be of help in clarifying this point, to the aim of safely increasing HbF in thalassemia intermedia.

Adult↗