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Biomedical subjects

R Montenegro

Publications and source records attributed to R Montenegro.

At least 19 recordsLinked to original sources
PubMed2005

Mathematical modelling of prolactin-receptor interaction and the corollary for prolactin receptor gene expression in skin.

A mathematical model of prolactin regulating its own receptors was developed, and compared with experimental data on a qualitative level. The model incorporates the kinetics of prolactin-receptor interactions and subsequent signalling by prolactin-receptor dimers to regulate the production of receptor mRNA and hence the receptor population. The model relates changes in plasma prolactin concentration to prolactin receptor (PRLR) gene expression, and can be used for predictive purposes. The cell signalling that leads to the activation of target genes, and the mechanisms for regulation of transcription, were treated empirically in the model. The model's parameters were adjusted so that model simulations agreed with experimentally observed responses to administration of prolactin in sheep. In particular, the model correctly predicts insensitivity of receptor mRNA regulation to a series of subcutaneous injections of prolactin, versus sensitivity to prolonged infusion of prolactin. In the latter case, response was an acute down-regulation followed by a prolonged up-regulation of mRNA, with the magnitude of the up-regulation increasing with the duration of infusion period. The model demonstrates the feasibility of predicting the in vivo response of prolactin target genes to external manipulation of plasma prolactin, and could provide a useful tool for identifying optimal prolactin treatments for desirable outcomes.

Animals↗
PubMed2003

Cushing's disease and sphenoidal aspergilloma.

A rare case of isolated sphenoid sinus aspergillosis in a 51-year-old patient, with the clinical and laboratory diagnosis of Cushing's disease but no radiologically confirmed tumor is presented. The patient made a complete recovery after treatment. The radiologic findings and the management of this potential disease are discussed.

Aspergillosis↗
PubMed2002

Quality of RCTs in periodontology--a systematic review.

Randomization, concealment of treatment allocation, blinding, and patient follow-up are key quality components of randomized controlled trials (RCTs). The objective of this study was to assess the quality of RCTs in periodontology using these evidence-based components. Following a detailed search, screening and quality assessments of RCTs were conducted in duplicate and independently. The results showed that although 91% of trials were described as randomised, adequate methods for randomization and allocation concealment were found in 17% and 7% of studies, respectively. Blinding was adequate for the caregiver in 17% and for the examiner in 55% of studies. A clear accounting of all participants was present in 56% of reports. This rigorous systematic review revealed that the quality of RCTs in periodontology, judged by their publications, frequently does not meet recommended standards. If this quality is reflected in actual study conduct, fundamental errors could have a significant impact on the outcomes of these trials.

Dental Research↗
PubMed2001

Development and optimization of polymerase chain reaction-based malaria diagnostic methods and their comparison with quantitative buffy coat assay.

Polymerase chain reaction (PCR)-based assays targeting the small-subunit rRNA were developed and evaluated, allowing for the simultaneous diagnosis of Plasmodium falciparum and Plasmodium vivax DNA in human blood samples. The PCR methods and quantitative buffy coat (QBC) were compared in 402 patients. The heminested PCR method showed a sensitivity of 97.4%, which was superior to the sensitivity of the QBC method (91.7%, P < 0.05), to simple PCR (84.6%, P < 0.001), and to PCR with digoxigenin labeling (PCR-DIG) (88.5%, P < 0.001). The PCR-DIG and QBC analyses were more sensitive than simple PCR (P < 0.003 and P < 0.05, respectively). There was no significant difference between the sensitivities of the QBC assay and the PCR-DIG assay. The specificity for the 3 PCR-based methods was 100%, superior to the specificity calculated for the QBC assay (88.95%, P < 0.009). The frequency of a positive result in groups from endemic areas but without detectable parasitemia increased, in order, from simple PCR, QBC test, PCR-DIG, to heminested PCR. An association between a positive PCR result and a history of malaria was also found. Taken together, these data suggest that this technology could be further developed to screen people with oligoparasitemia and to monitor malaria treatment.

Adolescent↗
PubMed2000

Social functioning in depression: a review.

OBJECTIVE: This article reviews the available data on social functioning in depression and provides clinical guidelines and opinion on this important and expanding field. DATA SOURCES: A MEDLINE search was conducted to identify all English-language articles (1988-1999) using the search terms depression and social functioning, depression and social adjustment, depression and psychosocial functioning, and social functioning and antidepressant. Further articles were obtained from the bibliographies of relevant articles. DATA SYNTHESIS: Depressive disorders are frequently associated with significant and pervasive impairments in social functioning, often substantially worse than those experienced by patients with other chronic medical conditions. The enormous personal, social, and economic impact of depression, due in no small part to the associated impairments in social functioning, is often underappreciated. Both pharmacologic and psychotherapeutic approaches can improve social impairments, although there is a lack of extended, randomized controlled trials in this area using consistent assessment criteria. CONCLUSION: Despite this lack, it is becoming clear that not all treatments are equally effective in relieving the impaired social functioning associated with depressive disorders. Furthermore, efficacy in relieving the core symptoms of depression does not necessarily guarantee efficacy in relieving impaired social functioning.

Adaptation, Psychological↗
PubMed1990

The value of early third-trimester maternal serum alpha-fetoprotein determination.

The value of determination of maternal serum of alpha-fetoprotein (MSAFP) concentration in the second trimester is well established. In addition to open neural tube defects, pregnancies associated with elevated second-trimester MSAFP have been shown to be at increased risk for a variety of problems, including low birth weight, preterm delivery, and pregnancy-induced hypertension (PIH). We evaluated the potential usefulness of MSAFP in the early third trimester. MSAFP concentration was determined in over 200 women at the time of glucose screening. Results were analysed with regard to gestational age at sampling, maternal weight, race, diabetes, and presence of twins. MSAFP was twice as high in twin gestation, but not affected by race or the presence of diabetes. In contrast to levels in early gestation, third-trimester MSAFP does not appear to be predictive of preterm delivery, low birth weight, or PIH.

Female↗
PubMed1989

[Initial results of restoration of bile flow in liver transplant].

The initial results of biliary reconstruction in 72 liver transplants realized in 62 patients, 50 adults and 12 children, are presented. Three reconstruction techniques were used: end-to-end choledocho-choledochostomy on a Kehr tube in 44 transplants (61.1%); choledocho-jejunostomy on a Roux-en-Y loop in 24 transplants (33.3%); double derivation cholecysto-choledocho-jejunostomy in 2 transplants (2.7%). The number of early complications related to biliary reconstruction was 5 (7.14%): 3 fistulas in the choledocho-choledochostomy series (6.8%) and 2 fistulas among the choledocho-jejunostomies (8.3%). All complications required reoperation and mortality was nil. Thirty-two months after the onset of the program, no late complications of the biliary anastomosis have been registered.

Adolescent↗
PubMed1985

The effect of serotonergic blockade in postpartum preeclamptic patients.

Thirty postpartum preeclamptic patients from the University of South Florida Obstetrical Service were enrolled in a placebo-controlled, randomized, double-blind study to test the effectiveness of ketanserin in lowering the blood pressure. An intravenous bolus of ketanserin resulted in a significant drop in the mean arterial blood pressure. The decrease in the blood pressure could be maintained by a continuous infusion of ketanserin. Hypertension returned after the medication was discontinued. These observations suggest that ketanserin, a selective blocker of type II serotonin receptors, may be effective in acutely reducing elevated postpartum blood pressure in preeclamptic patients, and that serotonin may play a role in the pathogenesis of preeclampsia, but not be important as a mediator in the severity of the disease.

Adult↗
PubMed1984

Results and complications with the Omniscience prosthesis.

A clinical trial with the Omniscience heart valve was conducted from June, 1980, until May, 1981. In this period 166 patients underwent heart valve replacement: mitral valve replacement (MVR) 70 patients, aortic valve replacement (AVR) 37, and combined mitral-aortic valve replacement (M/AVR) 59 patients. There were 20 hospital deaths, for a mortality of 12%. Total follow-up was 226 patient-years (range 6 to 28 months, mean 18 months). There were eight late deaths (MVR 4.6%, AVR 3.1%, and M/AVR 8.1%). All patients were taking oral anticoagulants. The incidence of valve-related complications (expressed as events per 100 patient-years) was as follows: Systemic embolism--MVR 2, AVR 4.7, and M/AVR 2.5; and anticoagulant complications--MVR 1.9, AVR 2.3, and M/AVR 0. The incidence of valvular dysfunction (expressed as events per 100 patient-years) was as follows: valvular thrombosis--MVR 4.8, AVR 0, and M/AVR 1.2; perivalvular leakage--MVR 1.9, AVR 2.3, and M/AVR 2.5; and infective endocarditis--MVR 0.96, AVR 0, and M/AVR 1.2. The actuarial probability of being free of valvular dysfunction 30 months postoperatively is 73% for the MVR group, 90% for the AVR group, and 71% for the M/AVR group. Despite a short follow-up, the incidence of valvular dysfunction has been significant. For this reason, we have discontinued using these prostheses for heart valve replacement.

Aortic Valve↗
PubMed1983

Early surgical results of the Medtronic-Hall valve.

A clinical trial with the Medtronic-Hall (M-H) valve was started in November 1981. From then until December 1982, 157 patients underwent heart valve replacement: Mitral valve replacement (MVR) 63 patients, isolated aortic valve replacement (MVR) 41 patients, and 53 underwent combined mitral-aortic valve replacement (MVR + AVR). Hospital mortality was 2.5% overall (4/157). The total follow-up was 147 patient-years (range 1 to 12 months). Late mortality was 3.2% for MVR, 2.5% for AVR and 1.9% for double MVR + AVR. Oral anticoagulation therapy (Dicumarol) was administered to all patients included in this study. There were no anticoagulant complications and no prosthetic bacterial endocarditis registered in this series of patients up to date. The incidence of systemic embolism was 2.5 events per 100 patient-years in the AVR group. No embolic episodes have been registered in the other 2 groups. The incidence of valvular dysfunction (expressed as events per 100 patient-years) were: --Perivalvular leak (0 MVR, 0 AVR and 2 MVR + AVR) --Valve thrombosis (1.7 MVR, 0 AVR and 0 MVR + AVR) --Mechanical dysfunction (1.7 MVR, 0 AVR and 0 MVR + AVR) Despite a short follow-up, the results with the Medtronic-Hall valve are encouraging and compare favorably with other mechanical prostheses.

Adult↗