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Biomedical subjects

G Ponce

Publications and source records attributed to G Ponce.

At least 37 records · Page 2Linked to original sources
PubMed2000

Endovascular repair of abdominal aortic aneurysm in a renal transplant patient.

A 65-year-old man presented with an asymptomatic infrarenal abdominal aortic aneurysm of 6 cm in transverse diameter. Five years before he received a cadaveric renal transplant. The patient also had the following risk factors and associated diseases: arterial hypertension, coronary artery disease, previous myocardial infarction, coronary angioplasty and stent, ileal resection secondary to Chron disease, hepatopathy, hyperlipidemia and hepato-renal cystic disease. The ASA classification was III, IV. Considering previous abdominal operations and risk factors, we decided to repair the aneurysm with a minimal aggression. The aneurysm was successfully approached by an endovascular route implanting a 22x10 bifurcated aorto-iliac endovascular prosthesis. The patient died 13 months later after being diagnosed of enterocolitis by cytomegalovirus complicated with sepsis and lung infection. We consider this less invasive modality of treatment a valid and useful alternative in this high-risk group of patients.

Aged↗
PubMed1998

In vivo and in vitro induction of sister-chromatid exchanges by nordihydroguaiaretic acid.

Nordihydroguaiaretic acid (NDGA) is a phenolic lignan previously used as an antioxidant in commercial products, and with a number of properties potentially useful to man. As its genotoxic capacity has been poorly evaluated, in this investigation we determined its effect on the production of sister-chromatid exchanges (SCEs), and on the level of mitotic index (MI) in cultured human lymphocytes and in mouse bone marrow cells in vivo. The proliferative index (PI), and the average generation time (AGT) were also determined for human lymphocytes and in mouse bone marrow cells respectively. The in vitro study was made in two donors using NDGA doses of 1.1, 3.6, 6.7, 13.5, and 27.0 microM; and for the in vivo study the tested doses were 8.8, 17.6, 35.3, and 70.7 mg/kg of body weight. The results concerning SCE induction in human lymphocytes showed a dose-dependent response with a maximum mean increase of 5.52 SCE in relation to the control level, and with respect to MI and PI a decrement of more than 50% and a cell cycle delay was detected only with the high dose. In the study with bone marrow cells, a statistically significant difference was determined with the high two doses (an increase of 1.06 SCEs with 70.7 mg/kg in relation to the control level). The MI decreased only with the high dose and no modification was observed with respect to AGT. In conclusion, in both used models the study demonstrated that NDGA produced genotoxic and cytotoxic effects.

Adult↗
PubMed1997

Effect of physical protection on the mesothelial integrity of the pericardium.

BACKGROUND: Mesothelial integrity is essential for the prevention of pericardial adhesions. This study was performed to determine the effect of physical protection of the pericardium on mesothelial integrity. METHODS: A pericardial biopsy specimen was obtained at the time of pericardiotomy (0 minutes) in 10 patients undergoing a cardiac operation for the first time. The left free edge of the pericardiotomy was plicated inward to protect the mesothelium. Biopsy specimens were obtained from the protected and unprotected pericardium at 45 and 90 minutes after the start of extracorporeal circulation. Mesothelial integrity and the local inflammatory response were then assessed and graded histologically. RESULTS: The mesothelium was found to be present in the protected specimens at 0, 45, and 90 minutes, but it was found to be denuded in the unprotected specimens (p = 0.003 at 45 minutes; p = 0.004 at 90 minutes). Local inflammation was totally established in both the protected and unprotected specimens at 45 minutes. CONCLUSIONS: Physical agents appear to be the main factor that is damaging to the pericardial mesothelium, and this is an important concept to be taken into consideration when designing a method to prevent pericardial adhesions.

Adult↗
PubMed1997

Long-term clinical performance of Sorin tilting-disc mechanical prostheses in the mitral and aortic position.

OBJECTIVE: Analyzing the long term performance of sorin tilting-disc mechanical prostheses. EXPERIMENTAL DESIGN: Retrospective patient-oriented study. The total follow-up was 460.2 patient-years. Follow-up data was obtained from the patients themselves or from their relatives. SETTING: Department of Cardiovascular Surgery in a general community hospital. PATIENTS: Seventy four patients undergoing valve replacement with Sorin tilting-disc mechanical prostheses between May, 1982 and July 1991. INTERVENTIONS: Thirty one of those patients underwent isolated mitral valve replacement (MVR) and 43 isolated aortic valve replacement (AVR). MEASURES: The incidence of the different complications is expressed as linearized rates. Actuarial analysis was performed with the Kaplan-Meier method. RESULTS: Linearized rates for MVR and AVR for the different complications (events per 100 patient-years) were, respectively: Late mortality: 4.5 +/- 1.6 and 1.8 +/- 0.8; Thromboembolism: 3.4 +/- 1.4 and 1.1 +/- 0.6; Anticoagulant-related hemorrhage: 2.8 +/- 1.3 and 0.3 +/- 0.3; Prosthetic endocarditis: 1.1 +/- 0.8 and 0.7 +/- 0.5; Non-structural dysfunction: 0.5 +/- 0.5 and 1.1 +/- 0.6; Reoperation: 1.1 +/- 0.8 and 0.3 +/- 0.3. Actuarial probabilities of freedom from the different complications were, respectively, at 13 years follow-up for MVR and 12 years follow-up for AVR, the following: Late mortality: 45.7 +/- 12.4% and 70.3 +/- 7.9%; Thromboembolism: 74.6 +/- 10.8% and 90.7 +/- 5.1%; Anticoagulant-related hemorrhage: 79.4 +/- 11.6% and 97.3 +/- 2.7%; Prosthetic endocarditis: 92.7 +/- 4.9% and 91.2 +/- 6.4%; Non-structural dysfunction: 95.6 +/- 4.3% and 88.2 +/- 6.6%; Reoperation: 83.6 +/- 11.8% and 97.3 +/- 2.7%. All valve-related mortality and morbidity: 42.2 +/- 11.0% and 56.7 +/- 8.6%. There was no instances of prosthetic structural failure. CONCLUSIONS: The Sorin mechanical prosthesis presents a good durability and its performance in the long term is comparable to other tilting-disc devices of the same generation.

Actuarial Analysis↗
PubMed1997

[Cardiac tamponade as first clinical manifestation of small cell carcinoma].

A 69 year old man was diagnosed of cardiac tamponade. At surgery a large hemopericardias was evacuated, cardiac and pericardial metastasis of an oat cell carcinoma was demonstrated. The patient died 4 weeks later. A review of the literature is done about patients with cardiac tamponade as the first manifestation of a neoplastic process.

Carcinoma, Small Cell↗
PubMed1996

[Is illegal abortion a secure procedure? A case report].

Woman with illegal abortion presenting bleeding and shock secondary to hypovolemia and sepsis. In the laparotomy there is no uterine perforation and the patient develops disseminated coagulation. The patient is taken to the operating room and bleeding stops. She receives more fluids than necessary and develops pulmonary edema. 48 hours after she develops shock secondary to tamponade and disappears with pericardiocentesis. A month and a half later she goes to the hospital because of ileus secondary to blood in peritoneo of an ovary cyst. Many pathologies and iatrogenesis characterized this case report.

Abortion, Illegal↗
PubMed1994

Influence of thyroid status on TRH metabolism in rat olfactory bulb.

The effect of thyroid hormones (TH) on the metabolism of thyrotropin-releasing hormone (TRH) in the olfactory bulb (OB) was compared with the hypothalamic response to TRH. Two methods were used to induce hypothyroidism: propylthiouracyl-methimazole (PTU-M) or 131I treatment. Hyperthyroidism was produced by 3,3',5-triiodo-L-thyronine (T3) injections to the hypothyroid animals. With PTU-M treatment, paraventricular TRH mRNA levels increased 57% and returned to the euthyroid level with T3 treatment. In OB, TRH mRNA was not altered. The TRH content was unaffected in the mediobasal hypothalamus of PTU-M-treated animals whereas it was reduced in OB (31%) with no further response upon T3 treatment. 131I-induced hypothyroidism did not modify the OB TRH content but it was decreased (31%) in hyperthyroids. In the median eminence, TRH increased 26% in hypothyroids, and the response was reversed with T3. Our results demonstrate that treatments that change thyroid status can alter TRH levels in the OB, probably at a translational or postranslational level, though the effects may be pharmacological.

Animals↗
PubMed1994

Disposition of nifurtimox and metabolite activity against Trypanosoma cruzi using rat isolated perfused liver.

Nifurtimox disposition was investigated using the rat isolated perfused-liver method after administration of 25 micrograms mL-1 nifurtimox, and its disappearance was monitored by analysing the perfusate sample at various times. Biliary excretion was also measured. The drug concentration profile underwent a biexponential decline over the 2-h study period, with a terminal half-life of 62.76 +/- 17.56 min. Nifurtimox is a high clearance compound (15.23 +/- 5.53 mL min-1). The extraction ratio was 0.621 +/- 0.159. Biliary excretion accounted for 0.05% of the dose, the remainder consisting of highly polar metabolites. By 2 h, a minimal fraction of unchanged nifurtimox was recovered from the perfusate. Nifurtimox activity against Trypanosoma cruzi (clone CA-1) during the perfusion was also determined. Epimastigotes isolated from continuous culture were exposed to the samples of perfusate at different perfusion times in a microtitre plate. After an incubation time of 72 h at 27 degrees C, the parasite number in each well was counted under a microscope. From 0 to 75 min after the perfusion, the anti-trypanosomal activity decreased, but an increase in activity was observed at the later times. These findings show that active metabolites are formed during the perfusion.

Animals↗
PubMed1993

The disposition of nifurtimox in the rat isolated perfused liver: effect of dose size.

The disposition of nifurtimox was studied in the rat isolated perfused liver using a recirculating system. The drug was administered as a bolus (5.0, 15.0 or 30.0 micrograms mL-1), and its disappearance was monitored by analysing perfusate samples. In all experiments perfusate disappearance was monoexponential, and no significant difference was found between the three doses for the elimination constant (0.016, 0.011 and 0.012 min-1, respectively), half-life (46.6, 65.8 and 66.8 min, respectively), extraction rate (0.128, 0.091 and 0.099, respectively) and distribution volume (41.1, 47.3 and 30.7 mL g-1, respectively). At 30 micrograms mL-1 the hepatic clearance was lower than the other concentrations of nifurtimox (0.66, 0.51 and 0.34 mL min-1 g-1, respectively). Relatively little parent drug was recovered from the liver at the end of the perfusions. In summary, nifurtimox is cleared slowly from the rat isolated perfused liver, is poorly extracted by hepatocyte cells and is completely metabolized from 2 to 4 h after perfusion.

Animals↗
PubMed1993

[Endoscopic papillotomy and extraction of bile duct calculi in patients with gallbladder in situ and cholelithiasis].

Cholecystectomy with surgical papillotomy is a prolonged procedure with significant morbidity and mortality. In patient stay is usually extended. Occasionally the bad general conditions and the advanced age of the patients contraindicate surgical procedures. Eventually, the drainage of the biliary ducts is inevitable. For this reason, since 1983, we are performing the endoscopic papillotomy and extraction of stones from the bile duct in patients with choledocholithiasis and cholelithiasis. Cholecystectomy was performed only in cases with real necessity. Ninety one patients, 26 men and 65 women, between 25 and 82 years, have been submitted to this procedure in our department. Cholecystectomy was performed in 52 cases after 24 to 72 hours post-papillotomy. Due to acute cholecystitis 12 patients had to be operated after a period of 2 months to 2 years. No cholecystectomy was performed in 27 patients, they are still asymptomatic. Then were no mortality related to the method.

Adult↗
PubMed1993

Steroid receptors and heat-shock proteins in patients with primary biliary cirrhosis.

Primary biliary cirrhosis has a definite female preponderance. Increased estrogen levels have been found in patients with this disease; however no studies indicate the status of sex hormone steroid receptors in primary biliary cirrhosis patients. In this study the occurrence and distribution of estrogen receptors, progesterone receptors and androgen receptors in liver biopsy specimens from patients with primary biliary cirrhosis were examined and compared with these receptors in the normal liver. In addition, three heat-shock proteins associated with steroid receptors (90 kD, 70 kD and 27 kD) were examined. All of the receptor proteins were detected on immunocytochemical study using specific receptor antibodies; monoclonal and polyclonal antibodies were also used to detect the heat-shock proteins. Normal bile duct epithelial cells displayed low-to-moderate amount of estrogen receptors and abundant 90- kD, 70- kD and 27-kD heat-shock protein expression, whereas normal hepatocytes showed moderate estrogen receptor and 90-kD heat-shock protein and high 70-kD heat-shock protein expression. Expression of 70-kD heat-shock protein was due mainly to the constitutive form of this protein (hsc72). In patients with primary biliary cirrhosis, significant increases in estrogen receptor and 90-kD heat-shock protein content were seen in bile duct cells and in hepatocytes. Levels of 27-kD heat-shock protein were also increased in some of the primary biliary cirrhosis biopsy specimens. The expression of progesterone receptor and androgen receptor was very low in normal and primary biliary cirrhosis bile duct cells and hepatocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

A second endogenous molecular form of mammalian hypothalamic luteinizing hormone-releasing hormone (LHRH), (hydroxyproline9)LHRH, releases luteinizing hormone and follicle-stimulating hormone in vitro and in vivo.

In vitro and in vivo release of pituitary hormones were studied in the presence of (hydroxyproline9)LHRH ((Hyp)LHRH), a newly characterized endogenous molecular form of LHRH. Results were compared to those obtained with LHRH itself. (Hyp)LHRH, as LHRH, stimulated both luteinizing hormone (LH) and follicle-stimulating hormone (FSH) release in a homothetic manner. The hydroxylated compound was, however, 24 times (in vitro) and 5 times (in vivo) less potent than LHRH. The lower activity of (Hyp)LHRH than of LHRH in the in vitro assay correlated well with a 28-fold lesser potency in a binding test using pituitary membrane preparations. The higher relative potency and the prolonged effect of (Hyp)LHRH in the in vivo test were related to a lesser susceptibility of the hydroxylated form to proteolytic degradation. Effects of LHRH and of (Hyp)LHRH were not additive, both peptides were equally able to desensitize gonadotrophs to a subsequent challenge by the other. Taken together, these observations suggest that both forms of LHRH act at the same receptor site. The lesser affinity of the hydroxylated compound is compensated to a certain extent by its higher resistance to enzymatic degradation. It is concluded that in spite of its lesser potency, (Hyp)LHRH may participate in the regulation of gonadotropins.

Animals↗
PubMed1991

Some events of thyrotropin-releasing hormone metabolism are regulated in lactating and cycling rats.

Levels of thyrotropin-releasing hormone (TRH), TRH mRNA and pyroglutamyl peptidase II were analyzed in the hypothalamus-adenohypophyseal axis during lactation and estrous cycle. Mediobasal hypothalamic levels of TRH dropped 41% (p less than 0.01) from pregnancy levels (taken as 100%) on the first day of lactation, recovering until day 15 to the values observed at pregnancy. A sharp decrease was also observed during weaning (36%, p less than 0.01 compared to last day of lactation). TRH levels in the neurohypophysis increased during lactation and dropped at weaning. Highest TRH mRNA levels in the paraventricular nucleus were found at the end of pregnancy and beginning of lactation; they decreased 37% (p less than 0.05) at day 5 of lactation and stayed constant thereafter. Pyroglutamyl peptidase II adenohypophyseal activity was not modified during lactation but changed during estrous cycle. Relative to estrous values, activity diminished 58% (p less than 0.05) at 10.00 h (57% at 14.00 h) during diestrus 2 and 27% at 10.00 h (37% at 14.00 h) during proestrus. Hypothalamic TRH mRNA levels fluctuated in an opposite manner to adenohypophyseal pyroglutamyl peptidase II during the estrous cycle with a peak at diestrus 2: 183% of the estrous value (p less than 0.05). These data point to a regulation of TRH metabolism in conditions where prolactin (PRL) secretion fluctuates. They also suggest a sharp release of TRH between the end of pregnancy and the first day of lactation and that translational efficiency or post-translational processing of TRH precursor in the paraventricular neurons (projecting to the median eminence) increases during lactation and drops at weaning, concomitantly with PRL secretion.

Aminopeptidases↗
PubMed1990

[Endoscopic treatment of acute pancreatitis of biliary etiology].

23 patients with acute biliary pancreatitis were treated with endoscopic papillotomy and extraction of bile duct stones. 12 suffered on an acute moderate and 11 on an severe pancreatitis in the classification of Glasgow. The patients were between 45 and 92 years old. 19 had an evolution without complications, 2, who also had an acute cholangitis, had a slow but good evolution. 2 died due to a septic shock and cardio-respiratory failure.

Aged↗
PubMed1988

Tissue-specific regulation of pyroglutamate aminopeptidase II activity by thyroid hormones.

Among the enzymes capable of degrading thyrotropin-releasing hormone (TRH) in vitro, two pyroglutamate aminopeptidases (PGA) are specific for TRH: thyroliberinase, a seric enzyme and PGAII, a membrane-bound peptidase. The effect of thyroid hormone status on the activity of these enzymes was evaluated in serum and various tissues. Only in adenohypophysis, triiodothyronine treatment increased PGAII to 376% of control; hypothyroidism produced the reverse effect (decrease to 23% of control). As previously reported, similar changes were observed for thyroliberinase. TRH degradation at the adenohypophysis level may participate in the negative feedback control of thyroid hormones.

Aminopeptidases↗
PubMed1984

Accumulation of thyrotropin releasing hormone by rat hypothalamic slices.

It has been postulated that thyrotropin releasing hormone (TRH) may play an active role in synaptic transmission. If such is the case, an inactivation mechanism must exist, in analogy to other neuroactive substances. In these studies we have considered the possibility that TRH may be taken up by rat hypothalamic slices. We observed that in the presence of bacitracin TRH was stable in the medium up to 90 min. We detected intact [3H]Pro-TRH associated with the slices as evidenced by TLC and paper electrophoresis; the association was time-dependent up to 60 min, and the maximum tissue-to-medium ratio was 1.3 at this time. At 5 min incubation, 30-50% of the TRH was not extracellular, and the plot of TRH-associated tissue versus the total amount of tissue was linear up to two hypothalami per flask. The association was saturable (Km 1.07 microM) and temperature-dependent, and the saturable part of the accumulation was inhibited by ouabain, dinitrophenol, and the absence of glucose. These results suggest that an uptake mechanism for TRH exists in the hypothalamus; its physiological relevance remains to be elucidated.

Animals↗