Biomedical subjects

C Peña

Publications and source records attributed to C Peña.

At least 73 records · Page 4Linked to original sources

PubMed1997

Synthetic peptides derived from the central loop of fasciculin: structural analysis and evaluation as inhibitors of acetylcholinesterase.

Fasciculins are peptides present in the venom of green and black mamba snakes, with potent inhibitory activity towards acetylcholinesterase. In order to determine the role of fasciculin loop II in the acetylcholinesterase inhibition, two fasciculin fragments were synthesized by the solid phase procedure using N-alpha-Boc protected amino acids. The two peptides, Fas-A and Fas-B, span the 26-32 and 22-35 sequences of fasciculin and a disulfide bridge links each peptide end, thus ensuring the formation of a looped structure. Both peptides were characterized chemically, structurally and functionally. Circular dichroism indicated the existence of 19.4 and 24.9% of beta-sheet for Fas-A and Fas-B, respectively; SDS-PAGE patterns and mass spectrometry disclosed the intramolecular disulfide formation in both peptides. An inhibitory effect on eel acetylcholinesterase was observed with the longer peptide (Ki = 15.1 microM), without reaching the affinity level of the parent native toxin (Ki = 0.3 nM). This study confirms that fasciculin central loop residues strongly contribute to toxin interaction with acetylcholinesterase.

Acetylcholinesterase↗

PubMed1997

Risk factors for faecal carriage of Klebsiella pneumoniae producing extended spectrum beta-lactamase (ESBL-KP) in the intensive care unit.

In the course of an outbreak of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae (ESBL-KP) in an intensive care unit (ICU), we conducted active surveillance to determine the risk factors for ESBL-KP faecal colonization of patients. We used weekly rectal samples during a four-month period. ESBL-KP was found in the faeces of 72 of 188 (38%) patients, and 42 (58%) of them were colonized within the first week of admission to the ICU. The probability of remaining free of faecal colonization was less than 20% at 30 days of ICU admission. The risk factors associated with ESBL-KP faecal colonization were clinical severity score at admission (P = 0.004), arterial catheterization (P = 0.002), total parenteral nutrition (P = 0.04), urinary catheterization (P = 0.01), mechanical ventilation (P < 0.001), and previous antibiotic therapy (P = 0.04). A logistic regression analysis identified duration of urinary catheterization (OR:3.5; 95% CI 1.2-10.3) and mechanical ventilation (OR:4.6; 95% CI 1.1-19.3) as independent risk factors for ESBL-KP faecal colonization. Our results suggest that in an ESBL-KP prevalent environment, manipulations that facilitate cross-infection are the most relevant in the acquisition of the micro-organism and risk increases throughout hospitalization.

Adult↗

PubMed1997

Involvement of histidine 134 in the binding of alpha-bungarotoxin to the nicotinic acetylcholine receptor.

Peptides corresponding to the sequence alpha 124-147 of the Torpedo californica and Homo sapiens nicotinic cholinergic receptors were synthesized. The His residue at position 134 was ethoxyformylated or substituted by Ala. Effects of such modifications were studied by: (a) a toxin blot assay and (b) a competition assay between each peptide and the Discopyge Ischudii receptor for 125I alpha-bungarotoxin, in solution. Apparent Kd values were 0.1 and 0.8 microM for Torpedo californica and Homo sapiens native peptides, respectively, and no binding was observed when the His residue was modified or substituted by Ala. ic50 values for the Torpedo californica and Homo sapiens fragments were 1.0 and 0.8 microM, respectively, and no significant displacement occurred when His 134 was ethoxyformylated or substituted by Ala. Hydroxylamine treatment restored 80-100% of their binding ability. Results strongly support the involvement of His 134 in the binding of alpha-bungarotoxin either to the Torpedo californica or the Homo sapiens receptor.

Alanine↗

PubMed1997

Differential properties between an endogenous brain Na+, K(+)-ATPase inhibitor and ouabain.

By means of a Sephadex G-50 column and anionic exchange HPLC a cerebral cortex soluble fraction (II-E) which highly inhibits neuronal Na(+)-K(+)-ATPase activity has been previously obtained. Herein, II-E properties are compared with those of the cardenolide ouabain, the selective and specific Na+, K(+)-ATPase inhibitor. It was observed that alkali treatment destroyed II-E but not ouabain inhibitory activity. II-E presented a maximal absorbance at 265 nm both at pH 7 and pH 2 which diminished at pH 10. Ouabain showed a maximum at 220 nm which was not altered by alkalinization. II-E was not retained in a C-18 column, indicating its hydrophilic nature, whereas ouabain presented a 26-min retention time in reverse phase HPLC. Therefore, it is concluded that the inhibitory factor present in II-E is structurally different to ouabain.

4-Nitrophenylphosphatase↗

PubMed1997

Adrenal masses: characterization with delayed contrast-enhanced CT.

PURPOSE: To evaluate the use of attenuation measurements from early delayed computed tomographic (CT) scans to differentiate benign from malignant lesions of the adrenal glands. MATERIALS AND METHODS: Forty-four patients (19 men, 25 women; age range, 21-88 years; mean age, 63 years) with 46 adrenal masses underwent dynamic contrast material-enhanced CT and early delayed CT (range, 12-18 minutes; mean delay, 14 minutes) with similar scanning parameters. Each patient also underwent non-contrast-enhanced CT within 3 months of the contrast-enhanced examination. Attenuation of adrenal masses on each type of scan was measured, and receiver operating characteristic analysis was performed. RESULTS: An attenuation threshold of 24 HU was selected; thus, all lesions with attenuation values of 24 HU or less were considered benign. When this threshold was applied to the results, the sensitivity of characterization of adrenal masses on early delayed scans was 96%, and the specificity was 96%. CONCLUSION: Adrenal masses detected with contrast-enhanced CT can be characterized as benign or malignant on early delayed scans of the adrenal glands.

Adrenal Gland Neoplasms↗

PubMed1997

[Endocarditis caused by group B streptococci in adults].

OBJECTIVE: To evaluate clinical characteristics, treatment and outcome of group B streptococcal endocarditis in nonpregnant adults. METHODS: We included all cases of Streptococcus agalactiae endocarditis diagnosed according to the Duke criteria between 1980 and 1994 in a 1000-bed university hospital, where a prospective surveillance of all cases of bacteremia is regularly performed. RESULTS: There were 9 episodes of S. agalactiae endocarditis, that account for the 10.5% of 85 bacteremia caused by this organism and 2.6% of 336 infectious endocarditis (in non-drug abusers) during the study period. They occurred in 6 males and 3 females with an average age of 60 years (44-86 years). Three patients had underlying disease and three had been previously diagnosed of having valvulopathy. There were no cases of prosthetic valve endocarditis. The valves most frequently involved were the aortic and mitral valves. Only one patient had large vessel embolization. All isolates were penicillin-susceptible (MIC < 0.12 microgram/ml). Most of the patients were treated with penicillin plus an aminoglycoside and 6 patients also underwent surgery combined with the medical therapy after an average of 40 days (13-60 days). The overall mortality was 11%. CONCLUSIONS: S. agalactiae is a rare cause of infectious endocarditis. Combination of surgery with the antibiotic therapy might decrease mortality rates of this infection.

Adult↗

PubMed1996

[Estimation of costs attributable to nosocomial infection: prolongation of hospitalization and calculation of alternative costs].

BACKGROUND: Nosocomial infection represents a prolongation of hospital stay and an increase of costs. The aim of the study was to estimate attributable costs by means of two methods: calculation of costs resulting from an increase of hospital stay and calculation of costs attributed to services. METHODS: A matched case-control study was carried out with a cohort population. An appropriate control was found for 63 patients with surgical site infection, for 30 patients with respiratory infection and for 55 with urinary infection. The estimation of costs attributable to services includes the case-control pairs with surgical site infection and was performed of the sum of costs of diagnostic and therapeutic services rendered in the care of the surgical site infection. RESULTS: The median of postoperative stay was 21 days for cases with surgical site infection vs 10 days for controls (p < 0.001); the median length of stay was 21.5 days for cases with respiratory infection vs 11.5 days for controls (p < 0.01); and for urinary infection the median length of stay was 21 days for cases vs 15 days for controls (p < 0.01). The surgical site infection cost attributed to extra days was 310,310 pesetas and the surgical site infection cost attributed to service cost was 220,546 pesetas. CONCLUSIONS: Nosocomial infection produces a increase median hospital stay of 7-10 days. In absence of a precise accounting system, the prolongation of hospital stay was considered as the more objective date to estimate the costs.

Adolescent↗

PubMed1996

Alcohol consumption in a rural area of Cantabria.

A two-stage cross-sectional survey was performed in a representative rural sample of the autonomous community of Cantabria, to investigate the social, medical and psychopathological factors associated with alcohol consumption. Alcohol consumption was investigated by means of a specific questionnaire. Mental and physical health was evaluated in the first-stage sample using: (1) the General Health Questionnaire, (2) the Cornell Medical Index. In the second stage all members of the sample were interviewed at home using the 140-item version of the Present State Examination (PSE-9). We found that 25.4% of males and 0.6% of females were consuming more than 63 alcohol units per week. Alcohol consumption was significantly associated with different social variables. Although it was possible to detect an increase in weekend drinking, especially in the heavy alcohol users, daily alcohol consumption, mainly around meals, was the predominant drinking pattern. We also found a significant inverse association between excessive alcohol consumption and the presence of physical or mental illness. Excessive alcohol use tended to be associated in males with depression and in females, with anxiety.

Adolescent↗

PubMed1996

Nosocomial Staphylococcus aureus bacteremia among nasal carriers of methicillin-resistant and methicillin-susceptible strains.

OBJECTIVES: To determine the relevance of nasal carriage of Staphylococcus aureus, either methicillin-sensitive (MSSA) or methicillin-resistant (MRSA), as a risk factor for the development of nosocomial S aureus bacteremia during an MRSA outbreak. PATIENTS AND METHODS: In this prospective cohort study, 488 patients admitted to an intensive care unit (ICU) during a 1-year period were screened with nasal swabs within 48 hours of admission and weekly thereafter in order to identify nasal S aureus carriage. Nasal staphylococcal carriers were observed until development of S aureus bacteremia, ICU discharge, or death. RESULTS: One hundred forty-seven (30.1%) of 488 patients were nasal S aureus carriers; 84 patients (17.2%) harbored methicillin-sensitive S aureus; and 63 patients (12.9%) methicillin-resistant S aureus. Nosocomial S aureus bacteremia was diagnosed in 38 (7.7%) of 488 patients. Rates of bacteremia were 24 (38%) of the MRSA carriers, eight (9.5%) of the MSSA carriers, and six (1.7%) of noncarriers. After adjusting for other predictors of bacteremia by means of a Cox proportional hazard regression model, the relative risk for S aureus bacteremia was 3.9 (95% confidence interval, 1.6-9.8; P = 0.002) for MRSA carriers compared with MSSA carriers. CONCLUSIONS: Among ICU patients, nasal carriers of S aureus are at higher risk for S aureus bacteremia than are noncarriers; in the setting of an MRSA outbreak, colonization by methicillin-resistant strains represents a greater risk than does colonization by MSSA and strongly predicts the occurrence of MRSA bacteremia.

Adult↗

PubMed1996

The public health impact of Lyme disease in Maryland.

The purpose of this study was to estimate the health burden imposed by Lyme disease (LD) in Maryland during 1992 and 1993. A cross-sectional 1-in-15 survey of physicians (total, 1200) in Maryland was conducted to estimate the incidence of diagnosed LD, presumptive cases of LD, patients with tick bites, and diagnostic tests ordered for LD. Results show that LD is underreported by 10- to 12-fold in Maryland, that 80% of cases are managed by primary care physicians, and that there is discordance between the actual clinical treatment of patients and the recommended approach. In addition, the much greater numbers of patients treated for presumptive LD, seen and given prophylaxis for tick bites, and having diagnostic tests indicate that real and perceived LD is a far greater public health problem and uses more medical resources than official surveillance data suggest.

Animals↗

PubMed1996

Conformational comparison in the snake toxin family.

A theoretical method was applied to consensus sequences of several members of the snake toxin family as a further approach to examining their conformational homology. Some secondary-structure predictions as well as hydropathy profiles were also examined. A comparison of long neurotoxins themselves reveals a high homology degree. However, their C-terminal fragments show poor homology and the N-terminal fragments appear as the region of maximum variability. Moreover, when the matrix includes the consensus sequence of the genus Laticauda (LNTX1), lacking the disulfide bridge 31-35, the method detects a lower conformational homology in a molecular region centered at position 31. Unlike long neurotoxins, the N-terminal segments of short neurotoxins show a high homology degree, but when comparing short with long neurotoxins, a poor correlation is found in this zone of the molecule. Cytotoxins studied exhibit an excellent conformational homology except when the consensus sequence of cytotoxin homologues CTXE is one of the proteins in the matrix. A comparison between cytotoxins and short neurotoxins reveals homology only in two segments belonging to a beta-sheet structure. A considerable degree of homology is found between the short neurotoxin group and calciseptin and fasciculin as well as between the long neurotoxin group and kappa-neurotoxins.

Amino Acid Sequence↗

PubMed1996

Environmental health and hazardous waste issues related to the U.S.-Mexico border.

Environmental health and environmental quality issues along the U.S.-Mexico border have been of concern for several years. The enactment of the North American Free Trade Agreement and the presence of the maquiladoras (foreign-owned industries using imported raw materials) have intensified those concerns recently. Efforts to assess these issues are complicated by the fact that many of the issues affecting the border region are within federal jurisdiction, but the problems are regional and local in nature. Thus, state and local governments become involved with public concerns about real and potential problems. One major problem is that environmental health data from this region are lacking, particularly from Mexico. Some new agencies such as the Border Environment Cooperation Commission, the United States-Mexico Border Health Commission, and the North American Commission on Environmental Cooperation have joined several existing agencies at the federal and state level to address environmental quality and health. Several studies have been initiated to determine air and water quality, but little is being done in the areas of hazardous waste and health assessment. Several problems are anticipated in the generation of such data, such as its format and accessibility. Data gaps and research needs are discussed.

Environmental Health↗

PubMed1995

Relationship between quinolone use and emergence of ciprofloxacin-resistant Escherichia coli in bloodstream infections.

From 1988 to 1992, 27 of 855 cases of Escherichia coli bacteremia in nonneutropenic adult patients observed at our hospital were due to ciprofloxacin-resistant (CIPRO-R) strains. Eighteen episodes (67%) were community acquired, and nine (33%) were nosocomially acquired. Overall, the rates of E. coli bacteremia caused by CIPRO-R strains increased steadily from 0% in 1988 to 7.5% in 1992 (P < 0.01). There was a statistically significant correlation between the incidence of CIPRO-R E. coli bacteremia and the upward trend in fluoroquinolone (norfloxacin and ciprofloxacin) use in the community (r = 0.974; P = 0.005) as well as in the hospital (r = 0.975; P = 0.005). When we compared the 27 case patients with 54 simultaneous control patients who had ciprofloxacin-susceptible E. coli bacteremia, the case patients more frequently had chronic underlying diseases (71 versus 37%; P = 0.004), urinary tract infection (74 versus 50%; P = 0.03), prior surgery (22 versus 6%; P = 0.02), and prior fluoroquinolone use (63 versus 4%; P < 0.001). A logistic regression analysis identified prior quinolone use as the only independent risk factor for CIPRO-R E. coli bacteremia. In conclusion, our study shows a significant correlation between ciprofloxacin resistance and fluoroquinolone use and indicates that prior fluoroquinolone use seems to be the most important risk factor for CIPRO-R E. coli bacteremia.

Adult↗

PubMed1994

Risk factors for nosocomial bacteremia due to methicillin-resistant Staphylococcus aureus.

In a prospective surveillance study (February 1990-December 1991) performed at a 1000-bed teaching hospital to identify risk factors for nosocomial methicillin-resistant Staphylococcus aureus (MRSA) bacteremia, 309 patients were found to be colonized (n = 103; 33%) or infected (n = 206; 67%) by MRSA. Sixty-three of them developed bacteremia. Compared with 114 patients who had nosocomial bacteremia caused by methicillin-sensitive Staphylococcus aureus during the same period of time, MRSA bacteremic patients had more severe underlying diseases (p < 0.01), were more often in intensive care units (p < 0.01) and had received prior antibiotic therapy more frequently (p < 0.01). To further identify risk factors for MRSA bacteremia, univariate and multivariate analyses of this series of 309 patients were performed using the occurrence of MRSA bacteremia as the dependent variable. Among 14 variables analyzed, intravascular catheterization, defined as one or more intravascular catheters in place for more than 48 h, was the only variable selected by a logistic regression model as an independent risk factor (OR = 2.7, CI = 1.1-6.6). The results of this study reinforce the concept that recent antibiotic therapy may predispose patients to MRSA infection and suggest that among patients colonized or infected by MRSA, those with intravascular catheters are at high risk of developing MRSA bacteremia.

Adult↗

PubMed1994

Isolation of pharmacologically active benzodiazepine receptor ligands from Tilia tomentosa (Tiliaceae).

Tilia species are traditional medicinal plants widely used in Latin America as sedatives and tranquilizers. For this purpose, the infusion of their inflorescences is used to prepare a tea. In this study extracts of inflorescences from Tilia tomentosa Moench, one of the species found in the market, were purified using a benzodiazepine (BZD) binding assay to detect BZD receptor ligands in the different fractions. One of the ligands was identified as kaempferol, but it had low affinity (Ki = 93 microM) for this receptor, and did not produce sedative or anxiolytic effects in mice. On the other hand, a complex fraction, containing as yet unidentified constituents, but probably of a flavonoid nature, when administered intraperitoneally in mice, had a clear anxiolytic effect in both the elevated plus-maze and holeboard tests, two well validated pharmacological tests to measure anxiolytic and sedative compounds. This active fraction had no effect on total and ambulatory locomotor activity. In conclusion, our results demonstrate the occurrence of active principle(s) in, at least, one species of Tilia that may explain its ethnopharmacological use as an anxiolytic.

Animals↗

PubMed1994

Effects of angiotensin II and angiotensin-(1-7) on the release of [3H]norepinephrine from rat atria.

We examined the effects of angiotensin II (Ang II) and Ang-(1-7) on the release of [3H]norepinephrine elicited by nerve stimulation (2 Hz, 0.5 millisecond, for 2 minutes) in rat atria isolated with their cardioaccelerans nerves. The stimulation-induced release of [3H]norepinephrine was increased 50% by 3 x 10(-8) mol/L of either peptide. No further increase in [3H]norepinephrine release was observed with peptide concentrations up to 3 x 10(-7) mol/L. This effect was completely blocked by the nonselective angiotensin receptor antagonist saralasin (1 x 10(-7) mol/L). The type 1 angiotensin receptor antagonist DuP 753 (1 x 10(-6) mol/L) entirely prevented the increases in [3H]norepinephrine caused by Ang II and Ang-(1-7). On the other hand, the type 2 angiotensin receptor antagonist PD 123319 (1 x 10(-6) mol/L) prevented the increase in [3H]norepinephrine release elicited by Ang-(1-7) but not by Ang II. These results suggest that Ang-(1-7), like Ang II, could have a neuromodulatory function in rat atria via activation of specific angiotensin receptor subtypes, which could be the subtype 1 angiotensin receptor for Ang II and subtypes 1 and 2 for Ang-(1-7).

Angiotensin I↗

PubMed1993

Stimulation of Trypanosoma cruzi adenylyl cyclase by an alpha D-globin fragment from Triatoma hindgut: effect on differentiation of epimastigote to trypomastigote forms.

A peptide from hindguts of the Triatoma hematophagous Chagas insect vector activates adenylyl cyclase activity in Trypanosoma cruzi epimastigote membranes and stimulates the in vitro differentiation of epimastigotes to metacyclic trypomastigotes. Hindguts were obtained from insects fed 2 days earlier with chicken blood. Purification was performed by gel filtration and HPLC on C18 and C4 columns. SDS/PAGE of the purified peptide showed a single band of about 10 kDa. The following sequence was determined for the 20 amino-terminal residues of this peptide: H2N-Met-Leu-Thr-Ala-Glu-Asp-Lys-Lys-Leu-Ile-Gln- Gln-Ala-Trp-Glu-Lys-Ala-Ala-Ser-His. This sequence is identical to the amino terminus of chicken alpha D-globin. On a Western blot, the peptide immunoreacted with a polyclonal antibody against chicken globin D. A synthetic peptide corresponding to residues 1-40 of the alpha D-globin amino terminus also stimulated adenylyl cyclase activity and promoted differentiation. This 125I-labeled synthetic peptide bound specifically to T. cruzi epimastigote cells. Activation of epimastigote adenylyl cyclase by the hemoglobin-derived peptide may play an important role in T. cruzi differentiation and consequently in the transmission of Chagas disease.

Adenylyl Cyclases↗

PubMed1993

Cephalosporins as risk factor for nosocomial Enterococcus faecalis bacteremia. A matched case-control study.

BACKGROUND: Nosocomial enterococcal infections have increased in various institutions, and patients with these infections had often been treated with cephalosporins during the previous weeks. The objective of this study was to determine whether the use of second- and third-generation cephalosporins is a risk factor for nosocomial enterococcal bacteremia (NEB), by means of a matched case-control study design. METHODS: Two hundred seven cases of NEB were studied. A control was matched to each case by sex, age (+/- 10 years), date of admission (+/- 2 years), hospital service, days of hospitalization, primary diagnosis, and operative procedures. RESULTS: One hundred fifty-six cases had an appropriate matched control. The univariate analysis of unmatched variables showed that the presence of a urinary catheter (odds ratio [OR], 3.8), mechanical ventilation (OR = 2.6), and cephalosporin use (OR = 5.1) were associated with NEB. Using a conditional logistic regression model, cephalosporin use (adjusted OR = 4.8, 95% confidence interval, 2.3 to 9.8) and urinary catheter use (adjusted OR = 3.6, 95% confidence interval, 1.7 to 7.4) remained significantly associated with NEB after controlling for other unmatched variables. CONCLUSIONS: These data show that the use of second- and third-generation cephalosporins may be a major risk factor for NEB. It may explain, at least partially, the steadily increasing number of enterococcal infections observed in some hospitals.

Adult↗