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Biomedical subjects

M A Pascual

Publications and source records attributed to M A Pascual.

13 recordsLinked to original sources
PubMed2006

Learning by operant conditioning as a nonlinear self-organized process.

Responses of individuals have been rewarded in fixed ratio operant conditioning experiments throughout the last 5 years. The long numerical series of performance rates so obtained have been analyzed by using Fourier spectra, obtaining 1/f noise, and wavelet techniques for the analysis of local variability. These techniques reveal that the evolution of data in each individual is nonlinear but it fluctuates showing self-organized patterns in successive time scales, which leads to a long term logarithmic growth. Based on these observations a model has been developed. It can simulate with a great accuracy the rate of response exhibited by our subjects in all time scales.

Conditioning, Operant↗
PubMed2003

Myometrial trophoblastic implant as a complication of surgically induced first-trimester termination of pregnancy.

Persistent trophoblastic tissue has been described in the abdominal cavity after surgical treatment of tubal ectopic pregnancy. More infrequently the cause of the ectopic trophoblast is linked to uterine perforation due to surgically induced termination of pregnancy (TOP). Ultrasonographic images may suggest an ectopic pregnancy. A case of myometrial trophoblastic tissue implantation following surgically induced first-trimester TOP is described.

Abortion, Therapeutic↗
PubMed2001

Cervical ectopic twin pregnancy: diagnosis and conservative treatment: case report.

A case of cervical ectopic twin pregnancy with cardiac activity in both embryos is presented. It was diagnosed in the eighth week of gestation by ultrasonography, and treated conservatively with intra-amniotic administration of methotrexate under ultrasonographic guidance followed by curettage. This procedure allows subsequent gestations.

Abortifacient Agents, Nonsteroidal↗
PubMed2000

Role of color Doppler ultrasonography in the diagnosis of endometriotic cyst.

We studied the role of color Doppler ultrasonography in the distinction between endometriomas and other adnexal masses. Three hundred and fifty-two ovarian lesions were studied, comparing sonographic diagnosis with pathologic findings. On color Doppler sonography, an endometriotic cyst usually appeared as a cystic lesion with diffuse internal echoes and low vascularization. The sensitivity and specificity of color Doppler transvaginal sonography in detecting endometriotic cysts were 91.8% and 95.3%, respectively. The positive and negative predictive values were 95.5% and 91.5%, respectively. In our experience, transvaginal sonography with color Doppler interrogation is a useful technique in the diagnosis of pathologic ovarian conditions, including cystic endometriosis.

Adult↗
PubMed1999

Morphological changes in hysterectomies after endometrial ablation.

Electrosurgical ablation of the endometrium is a therapeutic choice for those patients having abnormal uterine bleeding. When ablation is followed by a hysterectomy, tissue damage due to thermal effect can be seen. From a total of 350 women with endometrial ablation, 12 required subsequent hysterectomy. The histological features found in these specimens are described and related to the elapsed time between the two surgical procedures. The mean elapsed time between ablation and hysterectomy was 19 +/- 17.3 months. Scarring with formation of additional endometrial cavities was seen in five cases, and endocervical stenosis in two cases. In seven patients, endometrial regrowth was seen at hysterectomy. Necrosis, granulomatous and foreign-body giant cell reaction, eosinophilic infiltrate and pigment-containing macrophages in the myometrium were seen in the long-term post-ablation hysterectomies. Necrosis was seen in short period post-ablation hysterectomies. Six of the seven patients with endometrial regeneration had adenomyosis in the hysterectomy specimen. Endometrial ablation induces thermal effects in the endometrium and granulomatous reaction with foreign-body giant cell reaction, fibrosis and deposition of pigment within macrophages in the myometrium. Adenomyosis is a possible explanation for endometrial regeneration in cases of ablation failure.

Adult↗
PubMed1999

Complement activation in acute humoral renal allograft rejection: diagnostic significance of C4d deposits in peritubular capillaries.

The distinction between acute humoral rejection (AHR) and acute cellular rejection (ACR) in renal allografts is therapeutically important, but pathologically difficult. Since AHR is probably mediated by antibodies to the donor endothelium that activate the classical complement pathway, it was hypothesized that peritubular capillary C4d deposition might distinguish this group. Renal biopsies (n = 16) from 10 patients with AHR who had acute graft dysfunction, neutrophils in peritubular capillaries, and a concurrent positive cross-match were stained for C4d by immunofluorescence. Control biopsies for comparison showed ACR (n = 14), cyclosporin A toxicity (n = 6), or no abnormality (n = 4). Peribiopsy sera were tested for anti-donor HLA antibody. C4d deposited prominently and diffusely in the peritubular capillaries in all AHR biopsies (16 of 16). IgM and/or C3 were also present in 19 and 44%, respectively. With two-color immunofluorescence, C4d was localized in basement membranes (type IV collagen+) and in the endothelium (Ulex europaeus agglutinin-I+). In ACR, no more than trace C4d was found in peritubular capillaries (P < 0.0001 versus AHR), and no patient had anti-donor HLA antibodies (0 of 8); 27% had neutrophils in peritubular capillaries. One of six biopsies with cyclosporin A toxicity had similar C4d deposits, and circulating anti-donor class I antibody was detected. Grafts with AHR were lost (40%) more often than those with ACR (0%; P < 0.02). C4d in peritubular capillary walls distinguishes AHR from ACR, is more specific and sensitive than traditional criteria, and is a potentially valuable adjunct in the diagnosis of graft dysfunction.

Acute Disease↗
PubMed1997

Transvaginal sonographic appearance of functional ovarian cysts.

Knowledge of the nature of ovarian lesions is important in order to establish the correct treatment and, especially, to detect ovarian cysts that do not require surgical treatment. With the purpose of demonstrating the utility of transvaginal sonography with colour Doppler of ovarian functional ovarian cysts, 378 ovarian tumours were studied, comparing sonographic diagnosis with pathological findings. Sensitivity and specificity of colour Doppler transvaginal sonography to detect functional ovarian cysts were 84.6 and 99.2% respectively. Positive and negative predictive values were 98 and 93.5% respectively. In our experience, transvaginal sonography with colour Doppler is a useful technique in the diagnosis of ovarian pathology.

Adult↗
PubMed1989

[Pericardial mesothelioma: apropos of a case].

We report a case of primary pericardial malignant mesothelioma in a 53-year old male with no asbestos previous exposure. The first clinical sign was a massive pericardial effusion causing hemodynamic disturbances. CT confirmed the initial ecochardiographic diagnosis. The patient underwent pericardiocentesis which improved his hemodynamic status as well as showed malignant cellularity in the liquid examination. Surgical treatment, including pericardiectomy and tumor resection, together with chemotherapy restored normal hemodynamics, the patient being now asymptomatic. We want to emphasize the rarity of this tumor and its insidious clinical presentation even leading to hemodynamic impairment, as well as the great value of echocardiography and CT in its diagnosis, although, in some cases, thoracotomy has been the only valid diagnostic procedure.

Heart Neoplasms↗
PubMedDate not supplied

Progress in understanding humoral rejection in kidney transplantation: implications for patient management.

After more than 40 years of clinical renal transplantation, the contribution of humoral immunity to the pathogenesis of allograft rejection is progressively being clarified. With the advent of a new generation of immunosuppressive agents, the production and consequences of anti-donor alloantibodies can now be controlled. In the upcoming years, immunosuppressive regimens that will specifically control both T- and B-cell responses may further improve long-term allograft survival, if the immunosuppressive efficacy of such regimens is not hampered by an increase in infectious, neoplastic or cardio-vascular complications.

ABO Blood-Group System↗