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Biomedical subjects

J R Pena

Publications and source records attributed to J R Pena.

At least 19 recordsLinked to original sources
PubMed2000

Altered hemodynamics in transgenic mice harboring mutant tropomyosin linked to hypertrophic cardiomyopathy.

We used transgenic (TG) mice overexpressing mutant alpha-tropomyosin [alpha-Tm(Asp175Asn)], linked to familial hypertrophic cardiomyopathy (FHC), to test the hypothesis that this mutation impairs cardiac function by altering the sensitivity of myofilaments to Ca(2+). Left ventricular (LV) pressure was measured in anesthetized nontransgenic (NTG) and TG mice. In control conditions, LV relaxation was 6,970 +/- 297 mmHg/s in NTG and 5,624 +/- 392 mmHg/s in TG mice (P < 0.05). During beta-adrenergic stimulation, the rate of relaxation increased to 8,411 +/- 323 mmHg/s in NTG and to 6,080 +/- 413 mmHg/s in TG mice (P < 0.05). We measured the pCa-force relationship (pCa = -log [Ca(2+)]) in skinned fiber bundles from LV papillary muscles of NTG and TG hearts. In control conditions, the Ca(2+) concentration producing 50% maximal force (pCa(50)) was 5.77 +/- 0.02 in NTG and 5.84 +/- 0.01 in TG myofilament bundles (P < 0.05). After protein kinase A-dependent phosphorylation, the pCa(50) was 5.71 +/- 0.01 in NTG and 5.77 +/- 0. 02 in TG myofilament bundles (P < 0.05). Our results indicate that mutant alpha-Tm(Asp175Asn) increases myofilament Ca(2+)-sensitivity, which results in decreased relaxation rate and blunted response to beta-adrenergic stimulation.

Actin Cytoskeleton↗
PubMed1989

[Kidney transplantation: the current situation in Portugal, 1989].

The modern treatment of renal failure has been one of the most exciting developments of modern medicine. Within this field the portuguese doctors had a performance that compares with the average developed countries. The number of patients that need haemodialysis and renal transplantation is still increasing. These treatments are very expensive. As the patients would die if not treated, this whole issue is a political concern and a public health problem. We give the demographic outline of this CRF patients group. Dialysis and transplantation should be in balance, with a particular stress on transplantation because it is much less expensive. Shortness of organ supply has been like elsewhere the most important limiting factor of renal transplantation. Some public controversy concerning brain death, permission, and commercial profit from organ donation, has been sometimes deleterious. We review the results of renal transplantation. In 1987 and 1988, 92% of transplanted kidneys had still function after one year. We conclude that our programs in Portugal can expand, on the condition that people keep their acceptance and give their support to transplanting teams.

Brain Death↗
PubMed1989

[Kidney transplant: the current situation in Portugal, 1989].

The modern treatment of renal failure has been one of the most exciting developments of modern medicine. Within this field the portuguese doctors had a performance that compares with the average developed countries. The number of patients that need haemodialysis and renal transplantation is still increasing. These treatments are very expensive. As the patients would die if not treated, this whole issue is a political concern and a public health problem. We give the demographic outline of this CRF patients group. Dialysis and transplantation should be in balance, with a particular stress on transplantation because it is much less expensive. Shortness of organ supply has been like elsewhere the most important limiting factor of renal transplantation. Some public controversy concerning brain death, permission, and commercial profit from organ donation, has been sometimes deleterious. We review the results of renal transplantation. In 1987 and 1988, 92% of transplanted kidneys had still function after one year. We conclude that our programs in Portugal can expand, on the condition that people keep their acceptance and give their support to transplanting teams.

Brain Death↗
PubMed1988

Hepatic extraction of somatostatin in conscious dogs.

Fractional hepatic extraction of endogenous somatostatin immunoreactivity was examined in conscious dogs with Doppler flow probes on the portal vein and hepatic artery and catheters in the portal and hepatic veins and carotid artery before and after induction of hypoglycemia by infusion of insulin. Insulin infusion (1 and 2 mU.kg-1.min-1) decreased arterial plasma glucose from 76 +/- 4 mg/dl to a nadir of 41 +/- 2 mg/dl. Basal portal vein somatostatin was 117 +/- 11 pg/ml, which was significantly greater than the 97 +/- 12 pg/ml in the hepatic vein (P less than 0.05) and 79 +/- 8 pg/ml in the carotid artery (P less than 0.05). Hypoglycemia significantly augmented portal vein somatostatin to 206 +/- 32 pg/ml with parallel increases in the hepatic vein and carotid artery. The mean basal fractional hepatic extraction of total somatostatin immunoreactivity was 9 +/- 6% and was unchanged during hypoglycemia (14 +/- 4%). Column chromatography of the portal vein somatostatin immunoreactivity in the basal period yielded three peaks with most of the material eluting with somatostatin-14 and the void volume. Very little somatostatin-28 was detected. There was very little hepatic extraction of the void volume material while approximately 50% of somatostatin-14 was removed by that organ. After insulin-induced hypoglycemia, there was the greatest percent increase in somatostatin-28 and a doubling of somatostatin-14 and the void volume material. Most of the somatostatins-14 and -28 were removed by the liver, while extraction of the void volume material was negligible.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1969

Liver transplantation in man--3, Studies of liver function, histology, and immunosuppressive therapy.

The experience gained from 13 hepatic transplant operations is described, with particular reference to the findings in nine patients who survived the immediate operative period. A major problem was found to be infection. Fulminant pneumonia caused death in two adults, at a time when liver function was virtually normal. Infection related to bile fistula and sepsis may be overcome by an improved method of biliary drainage by cholecyst-dochostomy, which was carried out in the last two patients. Jaundice in the second week due to rejection was observed in several patients. The striking histological change was centrilobular cholestasis. The jaundice, which was not prevented by administration of antilymphocyte globulin, was rapidly controlled by temporarily increasing die dose of prednisone. One patient who survived for four and a half months and who had a poor tissue match subsequently developed chronic rejection with progressive cholestatic jaundice. Five of the patients were able to go home and at time of publication two are alive and well 14 and 20 weeks after treatment.

Adolescent↗