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Biomedical subjects

J M Rivera

Publications and source records attributed to J M Rivera.

At least 55 records · Page 3Linked to original sources
PubMed1991

[The cardioprotective action of nifedipine during short-term transient ischemia].

To determine the therapeutic activity on regional myocardial function of nifedipine intravenous administration (0.16 mg/kg) during short term myocardial induced ischemia, we used 6 mongrel dogs anesthetized and intubated those who we have implanted 3 pairs of ultrasonic crystals in the subendocardial layer. Utilizing an open chest canine model we performed total 1 minute and partial 2 minutes 30 seconds alternative obstructions, controlled with electromagnetic flowmeters in the anterior descending (AD) and circumflex (Cx) coronary arteries before and after drug administration. During the 70-80% obstructions we have shown a significant improvement in segment shortening, reduced by ischemia, in the ischemic and peri-ischemic zone. The ischemic markers, per cent increment of end diastolic length (% IEDL) and per cent increment of end systolic length (% IESL), have shown significant improvement during partial obstructions in the ischemic and peri-ischemic zone. After total obstructions the improvement on regional myocardial function is less marked and limited to ischemic zone.

Animals↗
PubMed1991

[Malherbe's calcifying epithelioma (pilomatrixoma) of the head and neck].

Calcifying Epitheliomas of Malherbe (Pilomatrixomas) are benign tumors that have their origin in the hair matrix and clinically resemble a hard subcutaneous swelling. Most of these tumors are placed in the head and neck region, in our sample the Pilomatrixomas of this location were 49.6% of the total. The middle age of presentation of this tumor were 32.2 years, with two main peaks of incidence below 20 years and under 50. The most frequent locations were the auricular, cervical, ciliar, frontal, and temporal regions, with one case of multiple location. The middle size of the tumor in our sample was 1.2 cm. In this paper we review the main pathologic, clinic and therapeutic features of this lesion in the head and neck region.

Adolescent↗
PubMed1990

[Neuroleptic malignant syndrome. Analysis of 9 cases].

The malignant neuroleptic syndrome (MNS) is an idiosyncratic reaction to neuroleptic drugs. Although it was described in the sixties, it is still a poorly known condition. Controversy still exists about its conceptual frame, and its true incidence is still unknown. We have evaluated 9 cases of MNS seen in a 37 month period. There were 5 females, with a mean age of 50 years. Haloperidol, either single or in association, was the most commonly implicated drug. The estimated frequency of MNS in our population at risk was 1.5%. Eight patients had complications and 5 died from them (55%). We discuss the pathogenetic mechanisms, the conceptual characterization and the current diagnostic criteria. We evaluate the causes of the high mortality in our series. We think that a higher suspicion index of this condition would be desirable, and we recommend early treatment with vigorous supportive measures and drug therapy. We think that prospective studies are required to assess the true incidence of MNS.

Adult↗
PubMed1989

[Regional differences in the contractile function of the subendocardium and subepicardium of the left ventricle in the dog].

With the objective to study the regional differences in myocardial function of different left ventricular (LV) segments, twelve pairs of ultrasound crystals were implanted in six open-chest dogs. Six pairs in the subendocardium and six in the subepicardium in three zones of the left ventricle (4 in the apex, 4 in the left anterior descending region and 4 in the circumflex region). In each zone of subendocardium one pair was placed parallel to the epicardial fibers (long axis) and the other following the circumferential plane of the left ventricle (short axis); the same orientation was followed in the subepicardium. Left ventricular pressure, coronary flow (electromagnetic flow-meters), peripheral ECG leads, dp/dt, and segmental shortening were measured. The extent of shortening and the fraction of shortening were considered. The extent of shortening is always higher in the long axis than in the short axis crystals. Similarly, the shortening in the subendocardium is higher than in the subepicardium. The greater extent of shortening and fraction of shortening appeared in the apex, above all in the subendocardium. There are differences in the time-course of fibrillar shortening between subepicardium and subendocardium; the subendocardial contraction was simultaneous with a lengthening of the subepicardial segments. In conclusion, there are differences in myocardial contraction depending on the myocardial region and the layer. Also the shortening of the subendocardium is not synchronous with the subepicardium.

Animals↗
PubMed1984

Clinical and pathologic evaluation of 342 benign ovarian tumors.

A series of 289 patients who were diagnosed with 342 benign ovarian tumors (BOT) at laparotomy have been reviewed. Mean age was 36.7 years (S.D. +/- 13.9), mean parity was 1.5 (S.D. +/- 1.6); 236 (81.7%) patients had a single unilateral ovarian tumor; 29 (10%) patients had bilateral ovarian tumors. Benign cyst teratoma was diagnosed in 89 (26%) tumors, and it was the most frequent histological type. In eight patients (2.8%) the post-operative pathologic report was compatible with malignancy, despite the lack of suspicion at laparotomy. Mean maximal diameter of BOT was 9.1 cm, and almost 60% of the mucinous cystoadenomas were larger than 16 cm. Benign cyst teratoma and serous cytoadenoma had a medium size, about 6-10 cm. Lower abdominal-pelvic pain was the symptom most frequently reported by patients with BOT. Calcifications were most frequently seen in benign cyst teratoma. Tumors of 11-15 cm in size were the tumors most frequently torsioned. Twenty four (8.3%) patients had their surgical operation done during pregnancy; benign cyst teratoma was the tumor most frequently associated with pregnancy.

Adolescent↗
PubMed1982

[Idiopathic pulmonary hemosiderosis: anatomoclinical study of 2 cases].

Two children with idiopathic pulmonary hemosiderosis are described. Both of them presented initially a clinical picture of recurring iron deficiency anemia, before pulmonary symptoms and signs made it possible to establish correct diagnosis. In one case diagnosis was considered only when an overwhelming pulmonary hemorrhage occurred, leading to the patient's death. At necropsy, areas of fresh alveolar hemorrhage and hemosiderin loaded macrophages were found, as well as moderate to severe interstitial fibrosis and hyperplastic alveolar cells. There was not disruption of the basal alveolocapillary membrane.

Anemia, Hypochromic↗
PubMed1978

Proximal renal tubular acidosis in metachromatic leukodystrophy.

A 2-year-old girl affected with the late infantile form of metachromatic leukodystrophy had a persistent and moderate metabolic acidosis. Renal functional studies demonstrated the presence of decreased tubular reabsorption of sodium, bicarbonate and some amino acids. Other tubular functions, including distal urinary acidification and concentrating mechanism were normal. Glomerular filtration rate was moderately decreased. Metachromatic inclusions were demonstrated along the nephron by histochemistry and electron microscopy. Tubular dysfunction in metachromatic leukodystrophy could have been overlooked until now given the severity of the neurological picture.

Acidosis, Renal Tubular↗
PubMed1977

[Fucosidosis type 2. A new case (author's transl)].

We have studied a child 10 years old with a defficit of alpha-fucosidase demonstrated in the urine, serum, tears and fibroblasts culture. The clinical evolution and the presence of a "angiokeratom corporis diffusum" permits one to diagnose the patient in the type 2 fucosidosis. We have revised the clinical features, the exigible criteria for biochemical diagnosis, the histopathological findings, ultrastructural alterations and the genetic aspects; specially the behaviour of the H substance and Lewis in the red cell and saliva.

Biopsy↗
PubMedDate not supplied

Visual assessment of valvular regurgitation: comparison with quantitative Doppler measurements.

To investigate which factors influence visual evaluation and how accurate it is in patients with valvular insufficiency, 83 patients were studied. All were in sinus rhythm, 43 with mitral and 40 with tricuspid regurgitation. Categoric visual grading (mild, moderate, and severe) was compared with jet area method and regurgitant fraction and the factors that influenced the assigned rank were identified. With jet area method (mean of areas in three planes), the correlation with regurgitant fraction was r = 0.61 for free jets and r = 0.32 for wall jets (overall r = 0.47) in patients with mitral regurgitation, and r = 0.81 and r = 0.46 for free and wall jets, respectively, in patients with tricuspid regurgitation (overall, r = 0.65). With visual grading, the correlation was for free and wall jets, respectively, rho = 0.80 and rho = 0.74 (overall rho = 0.76) in patients with mitral regurgitation, and rho = 0.79 and rho = 0.49 for free and wall jets, respectively (overall rho = 0.62), in patients with tricuspid regurgitation. The jet area parameter found to have the most influence on visual grading was the average area in three planes divided by atrial area, with rho = 0.80 and rho = 0.51 in patients with mitral regurgitation (free and impinging jets respectively) and rho = 0.60 and rho = 0.46 in tricuspid regurgitation. We conclude that visual grading of valvular regurgitant jets correlates well with quantitative measures of valvular incompetence and better than any simple jet area method.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗