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Biomedical subjects

C Fernandez

Publications and source records attributed to C Fernandez.

At least 127 records · Page 7Linked to original sources

Total Laparoscopic Hysterectomy

We analyzed our experience with laparoscopic hysterectomy and determined the most important factors that made it safe and reproducible. From January 1, 1994, to March 30, 1996, 68 laparoscopic hysterectomies were performed. The most frequent indication was uterine myomas. Average operating time decreased over the years from 6 hours in 1994 to 1.5 hours in 1996. The most important reasons for the long surgery time were surgeons' skills, uterine size, posterior wall leiomyomata, presence of adhesions, history of cesarean section, presence of deep infiltrating endometriosis with obliteration of the cul-de-sac, and equipment failure. We had no major intraoperative complications, except for a bladder injury in a woman who had had two cesarean sections, which was diagnosed and immediately repaired laparoscopically. Continuous training in endoscopic surgery, especially learning how to dissect the pelvic organs, the development of a trained team, adequate equipment, and appropriate patient selection were among the most important factors that allowed us to reach a safe level in performing this procedure.

Journal Article↗

Hysteroscopic Correction of Cesarean Section Scars in Women with Abnormal Uterine Bleeding

Abnormal postmenstrual uterine bleeding may occur in women with history of cesarean section. To study the etiology of this anomaly, transvaginal ultrasound (TVU) was performed during follicular phase in 20 such patients, and hysteroscopy in 7. The TVU revealed the presence of fluid in the isthmus in relation to the cesarean section scar, where a kind of pouch or bursa was observed. Cervical introduction of a catheter showed that the fluid was blood. The TVU observation was confirmed in women in whom hysteroscopy was performed. Resection of ring-shaped fibrotic tissue on the inferior part of the scar stopped abnormal bleeding. Four women were infertile and two conceived, probably because stopping postmenstrual bleeding could interfere with the quality of cervical mucus. These findings suggest that abnormal uterine bleeding in women with an abnormal uterine scar could be resolved by minimally invasive endoscopic surgery, and TVU is a valuable diagnostic tool.

Journal Article↗

Second-Look Microlaparoscopy

Second-look laparoscopy performed a short time after corrective surgery to determine reproductive function has always been controversial. The need for general anesthesia and additional abdominal wall trauma make it unpopular. However, postponing pelvic evaluation after the original surgery results in a large proportion of women attempting pregnancy with deformed anatomy as the result of reformation of pelvic adhesions. Since November 1995 we performed microlaparoscopy for a second look in 20 patients. Original procedures were performed for endometriosis, salpingo-oophorolysis, tubal repair, and complicated ectopic pregnancy. Six of the women had adhesions that interfered with fertility and were referred to an assisted reproduction technology (ART) program. Procedures lasted 14 minutes (range 10-17 min). We encountered no complications. Patients were discharged after 2 hours of recovery and resumed normal activity. Second-look microlaparoscopy can be an important tool in assessing the efficacy of reconstructive reproductive surgery, and in accelerating referral to ART programs in women with poor results.

Journal Article↗

Topical beta-blockade with intrinsic sympathomimetic activity offers no advantage for the respiratory and cardiovascular function of elderly people.

Topical therapy with beta-antagonists, such as timolol, may cause unrecognized impairment of respiratory and cardiovascular function in elderly people. Beta-antagonists with intrinsic sympathomimetic or cardioselective properties, such as carteolol or betaxolol, may cause less impairment. In a randomized, double-masked study of glaucoma patients, over 60 years of age, without history of bronchospasm and who were using timolol (0.5%), 60 patients were allocated to betaxolol (0.5%) or carteolol (2%) or continued timolol (0.5%) treatment. Spirometry, pulse and blood pressure were measured on enrollment and after 4 weeks. In the timolol and carteolol groups there were no significant changes in mean spirometric values. Changing to betaxolol improved mean peak flow (PF) by 9.1%, from 310 to 3411/min (p < 0.05) and forced expiratory volume in 1 second (FEV1) by 9.4%, from 1.74 to 1.861 (p < 0.05). Differences in the changes in PF and FEV1 between betaxolol and timolol as well as betaxolol and carteolol groups were statistically significant (p < 0.05). Twenty-one per cent of those allocated to betaxolol showed clinically significant improvement in FEV1. There was no change in pulse or blood pressure when carteolol was substituted for timolol but an increase of 10 beats per minute (p < 0.05) in mean resting pulse in the betaxolol group. Therapy with cardioselective beta-blockade may offer significant advantages in respiratory function for elderly people with glaucoma over non-selective drugs, even if they have sympathomimetic activity.

Adrenergic beta-Antagonists↗

Effects of captopril related to increased levels of prostacyclin and angiotensin-(1-7) in essential hypertension.

OBJECTIVE: To evaluate the contribution of angiotensin-(1-7) [Ang-(1-7)] and prostaglandins to the acute and long-term antihypertensive actions of captopril in mild-to-moderate essential hypertensive patients. DESIGN AND METHODS: Blood pressure, cardiac rate and the plasma concentrations of angiotensin I (Ang I), angiotensin II (Ang II), Ang-(1-7), prostaglandin E2 and 6-keto prostaglandin F1 alpha (the breakdown product of prostacyclin) were determined in the peripheral venous blood of 24 essential hypertensive subjects before and 3 h after administration of 50 mg captopril. Eleven of 24 patients completed a 6-month treatment period with captopril monotherapy (50 mg twice a day). The hemodynamic and hormonal response produced by a last 50 mg dose of captopril was determined once again in the 11 subjects who maintained blood pressure control with captopril monotherapy for 6 months. RESULTS: The fall in blood pressure produced 3 h after drug intake was comparable for the first and the last 50 mg captopril dose. Although the first response to captopril increased plasma levels of Ang I only, the response to the last dose of the drug (6 months after) caused significantly higher levels of Ang I and Ang-(1-7). Neither acute nor chronic therapy with captopril had a significant effect on plasma concentrations of Ang II. Although plasma levels of prostaglandin E2 and 6-keto prostaglandin F1 alpha were not modified by a first exposure to captopril, the concentrations of 6-keto prostaglandin F1 alpha but not prostaglandin E2 rose significantly in subjects treated with the inhibitor for 6 months. A negative correlation was also demonstrated between diastolic blood pressure and plasma Ang-(1-7) levels in the 11 essential hypertensive subjects in whom blood pressure was controlled with captopril monotherapy. CONCLUSIONS: Inhibition of angiotensin converting enzyme with captopril had a significant effect on blood pressure that was not directly accounted for by a suppression of plasma Ang II levels. Continuous therapy with captopril unmasked a contribution of Ang-(1-7) and prostacyclin to the antihypertensive actions of this drug.

Adolescent↗

Safety and efficacy of total parenteral nutrition delivered via a peripherally inserted central venous catheter.

Central venous catheters for total parenteral nutrition (TPN) have traditionally been inserted via direct cannulation of the subclavian vein, but this technique requires physician participation and is associated with well-described complications. We report the single largest institutional experience with peripherally inserted central venous catheters (PICC lines) used exclusively for TPN in non-intensive care unit patients. From July 1991 to March 1994, 135 PICC lines were placed in 126 patients via the antecubital vein, advanced into the central venous system, and used only for TPN. Complication rates were determined and compared with those for TPN administered through a subclavian vein-inserted central catheter. Patient demographics were similar in each group with respect to age, type of disease process, acuity of illness, and indications for nutrition support. A cumulative number of 1381 TPN days (mean = 11 days per patient) comprised the PICC line experience. Comparison was made with 135 successive standard (subclavian) central lines inserted in 105 patients for TPN administration (1056 TPN days, mean = 10 days per patient). There was no difference in the overall rate of complications between the two groups. There were no major complications that prolonged hospitalization (eg, catheter-related sepsis or pneumothorax) in the PICC group compared with three such complications in the standard group. PICC lines can be used safely and effectively for TPN and are associated with an acceptable rate of complications.

Adult↗

[Genomic heterogeneity of hepatitis B virus, genotype A circulating in the metropolitan area of Buenos Aires, Argentina].

HVB DNA was extracted from highly purified Dane particles, from sera of HBV viremic patients, collected in the metropolitan area of Buenos Aires (Argentina). HBV DNA was cloned in pUC18 vector, amplified in Escherichia coli DH5 F'. Plasmids were recovered and analyzed for HBV DNA inserts. Three recombinant plasmids, pHB4, pHB7 and pHB20 were selected, and HBVDNA inserts sequenced. The resulted sequences were incorporated at the GenBank, with the following accession numbers: PHB4P3=U33188; PHB4P5=U33189; PHB7P3=U33190; PHB7P5=U33191 and PHB20=U33190; PHB7P5=U33191 and PHB20=U33187. All belongs to the genotype A, pHB4 and pHB20 have a very close relation in between each other and with L13994 sequence, from North America origin. pHB7 have a significant distance from pHB4 and pHB20 and have a discrete homology with m57633 detected in Philippines. pHB4 shows a mutation at the T 3182-Leu in the preS1 region that change Pro for Leu, this mutation is absent in 125 sequences selected (having a 65% or more of homology) from NCBI by Blast algortm. The sequence of the pre C regions of all three inserts do not show any evidence to belong to the e-or scape mutants. Type A genotypes shows to be common in the area, but a hight degree of divergence have been demonstrate between two circulating strains.

Amino Acid Sequence↗

Evaluation of the significance of polyamines and their oxidases in the aetiology of human cervical carcinoma.

The risk of cancer of the cervix is linked with sexual behaviour. Although infectious agents such as human papillomaviruses (HPVs) are implicated, these alone may be insufficient to induce the disease. We have investigated the potential role of oxidation products of the polyamines spermine and spermidine and the diamine putrescine in seminal plasma (SP) as co-factors in the development of cervical cancer. These amines are oxidised by polyamine oxidase (PAO) and diamine oxidase (DAO) to generate oxygen radicals and hydrogen peroxide, reactive aldehydes and acrolein, which are likely to exert local mutagenic, cytotoxic and immunosuppressive effects in vivo. Using a chemiluminescence assay, we determined the levels of these amines in 187 samples of SP. Spermine plus spermidine, as substrates for PAO, were present in a range equivalent to 0-4.8 mg ml-1 spermine. Putrescine, as a substrate for DAO, was detectable in only 4 of 40 samples assayed (range 0-168 micrograms ml-1) and constitutes a minor component of the oxidisable content of SP. Cervical mucus (126 samples) was assayed for the presence of PAO and DAO. Both enzymes were present in 14.3% of the samples, PAO only in 21.4%, DAO only in 15.1% and neither enzyme in 49.2%. PAO levels ranged from 0 to 0.828 pmol peroxide generated min-1 mg-1 mucus and DAO levels ranged from 0 to 7.0 pmol peroxide generated min-1 mg-1 mucus. These results suggest that sexual activity in the absence of physical barrier contraception may lead to the generation of mutagenic and immunosuppressive polyamine oxidation products within the female genital tract. We thus propose that women with high levels of PAO and/or DAO in their cervical mucus may be at increased risk of cervical cancer, especially if the male partner's SP shows high polyamine levels. HPV infection may synergise with the effects of polyamine oxidation by suppressing apoptosis in keratinocytes carrying potentially oncogenic mutations, leading to the survival and proliferation of transformed cells in the cervix.

Adolescent↗

Mortality associated with nosocomial bacteremia due to methicillin-resistant Staphylococcus aureus.

We prospectively studied all cases of Staphylococcus aureus bacteremia that occurred during an extensive outbreak of methicillin-resistant S. aureus (MRSA) in our hospital over a 4-year period (January 1990 through September 1993). We report the results of a comparative analysis of the clinical characteristics and mortality rates among patients with nosocomial bacteremia caused by MRSA (84 cases) or methicillin-susceptible S. aureus (MSSA; 100 cases). The patients with MRSA bacteremia were older than those with MSSA bacteremia (69 years vs. 54 years, respectively; P < .01) and were more likely than those with MSSA bacteremia to have the following predisposing factors: a prolonged hospitalization (32 days vs. 14 days, respectively; P < .01); prior antimicrobial therapy (61% vs. 34%, respectively; P < .01); urinary catheterization (58% vs. 27%, respectively; P < .01); nasogastric tube placement (31% vs. 13%, respectively; P < .01); and prior surgery (45% vs. 31%, respectively; P = .05). Multivariate analysis with use of the stepwise logistic regression method showed a relationship between mortality and the following variables: methicillin resistance (odds ratio [OR], 3), meningitis (OR, 13), and inadequate treatment (OR, 11).

Aged↗

A double-blind, randomized, placebo-controlled clinical trial to evaluate the safety and efficacy of mupirocin calcium ointment for eliminating nasal carriage of Staphylococcus aureus among hospital personnel.

Sixty-eight health care workers were enrolled in a double-blind clinical trial and randomized to receive either mupirocin calcium ointment or placebo, intranasally bid for 5 days. Nasal cultures were taken immediately before starting treatment, 1 and 2 during treatment, at the end of treatment, 3 days later, weekly for 1-5 weeks and then monthly for 2-6 months after treatment. Mupirocin eliminated nasal carriage with Staphylococcus aureus in 58% of subjects within two days and 86.7% subjects by the end of therapy compared to 9.4% subjects at the end of treatment with placebo (P < 0.001). Post-treatment colonization rates of 43%, 56% and 67% were attained after 1 month, 2-4 and 6 months treatment with mupirocin respectively and recolonisation with the same strain of S. aureus that had been isolated before treatment was noted in 32%, 40% and 48%. No resistance to mupirocin developed and the drug was well tolerated. Mupirocin is safe and effective in suppressing nasal carriage of S. aureus.

Administration, Intranasal↗

Clinical pharmacokinetics of zopiclone.

Zopiclone is a cyclopyrrolone hypnotic agent. It possesses a chiral centre and is commercially available as a racemic mixture. Methods involving high performance liquid chromatography (HPLC), gas chromatography, capillary electrophoresis (CE) and high performance thin layer chromatography have been developed for the quantitation of zopiclone and its 2 main metabolites in biological samples. For the chiral determination of the enantiomers of zopiclone and its metabolites, HPLC and CE methods are available. After oral administration, zopiclone is rapidly absorbed, with a bioavailability of approximately 80%. The plasma protein binding of zopiclone has been reported to be between 45 and 80%. Zopiclone is rapidly and widely distributed to body tissues including the brain, and is excreted in urine, saliva and breast milk. Zopiclone is partly metabolised in the liver to form an inactive N-demethylated derivative and an active N-oxide metabolite. In addition, approximately 50% of the administered dose is decarboxylated and excreted via the lungs. Less than 7% of the administered dose is renally excreted as unchanged zopiclone. In urine, the N-demethyl and N-oxide metabolites account for 30% of the initial dose. The terminal elimination half-life (t1/2z) of zopiclone ranges from 3.5 to 6.5 hours. The pharmacokinetics of zopiclone in humans are stereoselective. After oral administration of the racemic mixture, Cmax (time to maximum plasma concentration), AUC (area under the plasma time-concentration curve) and t1/2z values are higher for the dextrorotatory enantiomer owing to the slower total clearance and smaller volume of distribution (corrected by the bioavailability), compared with the levorotatory enantiomer. In urine, the concentrations of the dextrorotatory enantiomers of the N-demethyl and N-oxide metabolites are higher than those of the respective antipodes. The pharmacokinetics of zopiclone are altered by aging and are influenced by renal and hepatic functions. Drug interactions have been observed with erythromycin, trimipramine and carbamazepine.

Azabicyclo Compounds↗

Immune responses to bacterial polysaccharides: terminal epitopes are more immunogenic than internal structures.

Two types of dextran-protein conjugates can be produced depending on the size of dextran and the method chosen for coupling. Dextran of 4 x 10(4) molecular weight, randomly coupled to keyhole limpet hemocyanin evoked "incomplete" T cell-dependent (TD) immune responses. This atypical response only affected the dextran epitope since the response to the protein carrier was as expected for TD secondary immune responses. A second type of TD conjugates can be derived by coupling dextran (Dx) of 10(3) Da to the protein chicken serum albumin (CSA) via the reducing end (CSA-Dx-1). Immunization with CSA-Dx-1 induced the classical pattern of TD immune responses. Interestingly, immunization with CSA-Dx-1 favored the production of antibodies directed against terminal structures of the dextran molecule. These results were also confirmed at the hybridoma cell level. In contrast to other protein-dextran conjugates, CSA-Dx-1 was able to induce anti-dextran antibodies in CBA/N mice and in neonatal animals. We have interpreted these results to mean that conjugates exposing carbohydrate terminal nonreducing end structures could be more "physiological" and able to be recognized by helper T cells. This opens a new possibility for the production of vaccines against bacterial polysaccharides.

Animals↗

Anti-IgM-Ficoll conjugates activate B cells from CBA but not CBA/N mice.

We have compared the stimulating effects of an anti-IgM-Ficoll conjugate on B cells from the two mouse strains CBA and CBA/N. CBA/N mice have a recessive defect on their X chromosome which make them unable to respond to T1-2 antigens and B cells from these mice are supposed to be in an immature state. We found that the anti-IgM-Ficoll conjugate stimulated B cells of the CBA strain to proliferate even without the addition of interleukins, but was not able to stimulate B cells from the CBA/N strain. To rule out that the unresponsiveness of CBA/N mice to anti-IgM-Ficoll was due to the immaturity of their B cells, we cultured B cells from both strains in the presence of an anti-IgM-Sepharose conjugate. This conjugate stimulated B cells from both mouse strains to proliferate in the presence of IL-4. These results agree with the hypothesis that the T1-2 antigen Ficoll is able to deliver activating signals to B cells and therefore cannot be considered as an inert carrier.

Animals↗

Refinement of solid-state MAS NMR spectra of quadrupolar nuclei: application to the analysis of some 51V compounds.

Magic angle solid-state 51V NMR spectra of several vanadium powder compounds have been recorded. A refinement of these spectra using theoretical simulations of the powder spectra have been performed assuming the simultaneous anisotropic effects of electric field gradients (EFG) and of electronic shielding. It is shown that the relative orientation of the principal axes of the two tensors have to be considered.

Anisotropy↗

Determination of 51V quadrupole and chemical shift tensor orientations in V2O5 by analysis of magic-angle spinning nuclear magnetic resonance spectra.

Magic-angle spinning (MAS) 51V nuclear magnetic resonance (NMR) spectra of V2O5 have been recorded at various fields to evidence the relative effects of the quadrupole interaction and electronic shielding at the nucleus. A refinement of the spectra using theoretical simulations has been performed assuming a simultaneous existence of these two anisotropic interactions. The relative orientation of the principal axes for both tensors has been obtained. The results agree with previous single-crystal studies. Reliability of the results is discussed. A fundamental indetermination of the actual relative tensor orientations remains, owing to the powder nature of the sample.

Anisotropy↗

Identical VHD and DJH junctions in monoclonal antibodies derived in response to dextran B512 could be the result of developmental selection.

We describe here the CDR3s of a collection of monoclonal antibodies (MoAb) with specificity for the carbohydrate dextran B512 produced in the mouse strain C57BL/6. In spite of the postulated mechanisms for variability in this region, a high proportion of these monoclonals displayed identical VHD (24/30) and DJH (21/30) junctions and 21 of them were identical in the whole CDR3. These 21 independently generated identical CDR3s could be ordered in eight groups indicating that not a particular CDR3, but instead the mechanism for generating identical junctions was preserved. Two of the CDR3s in this study were found to be identical to the CDR3 of the monoclonal B1-8 produced in C57BL/6 in response to proteins bearing the hapten (4-hydroxy-3-nitrophenyl)acetyl (NP). This and other parameters support the notion that the generation of identical junctions could be independent of antigenic selection. We also report here the association between JH usage and amino acid (aa) residues at the VHD and DJH junctions. Since these MoAb were generated in response to dextran B512, immunoglobulin conformation has to be compatible with antigen binding. Nevertheless, no aa residue of CDR3 could be directly related to antigen binding. We postulate therefore, that the observed selection of CDR3s could be directed to the production of variable regions with protein configuration most suitable with immunoglobulin folding and may occur prior to antigenic selection. Selection for junctional residues in relation to JH usage and the generation of identical CDR3s are probably different events. Possible genetic mechanisms operating for CDR3 construction and/or selection by cellular ligands are discussed.

Amino Acid Sequence↗