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Biomedical subjects

A Perez

Publications and source records attributed to A Perez.

At least 73 records · Page 4Linked to original sources
PubMed1999

Eating pathology before and after bariatric surgery: a prospective study.

OBJECTIVE: The objectives of the study were (1) to determine the prevalence of eating pathology in patients before bariatric surgery and at follow-up; (2) to assess the relationship of presurgical eating pathology to various measures of psychopathology; and (3) to assess the relationship between presurgical eating pathology and outcome. METHOD: One hundred sixteen patients were evaluated prior to surgery and at follow-up an average of 5.5 years after surgery. RESULTS: Preoperative binge eating occurred in 52% of patients, 16% met criteria for binge eating disorder, and 10% had the night eating syndrome. All three forms of presurgical eating pathology were statistically associated with cognitive distortions. At follow-up, 33% of patients were vomiting at least weekly. There was no relationship between presurgical eating pathology and weight outcome or presence of vomiting at follow-up. DISCUSSION: Although postoperative vomiting usually does not represent purge behavior, it may represent failed attempts to binge.

Adult↗
PubMed1999

A vital stain for studying membrane dynamics in bacteria: a novel mechanism controlling septation during Bacillus subtilis sporulation.

At the onset of sporulation in Bacillus subtilis, two potential division sites are assembled at each pole, one of which will be used to synthesize the asymmetrically positioned sporulation septum. Using the vital stain FM 4-64 to label the plasma membrane of living cells, we examined the fate of these potential division sites in wild-type cells and found that, immediately after the formation of the sporulation septum, a partial septum was frequently synthesized within the mother cell at the second potential division site. Using time-lapse deconvolution microscopy, we were able to watch these partial septa first appear and then disappear during sporulation. Septal dissolution was dependent on sigma E activity and was partially inhibited in mutants lacking the sigma E-controlled proteins SpoIID, SpoIIM and SpoIIP, which may play a role in mediating the degradation of septal peptidoglycan. Our results support a model in which sigma E inhibits division at the second potential division site by two distinct mechanisms: inhibition of septal biogenesis and the degradation of partial septa formed before sigma E activation.

Bacillus subtilis↗
PubMed1999

Renal function in compensated hepatic cirrhosis: effects of an amino acid infusion and relationship with nitric acid.

AIMS: In order to assess the possible participation of nitric oxide (NO) in renal function during compensated hepatic cirrhosis, we studied renal function, the plasma and urinary levels of cGMP and the concentration of nitrates and nitrites, as markers of NO synthesis in blood and urine, in 10 patients with Child A hepatic cirrhosis as compared with 10 control subjects, both under basal conditions and during stimulation (amino acid-induced glomerular hyperfiltration). METHODS: To study renal function, the glomerular filtration rate (GFR), effective renal plasma flow (ERPF), renal functional reserve (RFR), renal venous resistance (RVR) and the filtration fraction (FF) were measured. Renin and aldosterone levels were determined to assess the possible involvement of these compounds in the renin-angiotensin-aldosterone axis. RESULTS: GFR and ERPF were significantly lower in the patients with cirrhosis than in the controls (mean GFR: 82+/-12.3 vs. 105+/-15 ml/min, p = 0. 01; ERPF 452+/-86 vs. 543+/-56 ml/min, p = 0.002). The RFR value was similar in both groups. In the basal situation cGMP levels were higher in plasma and urine in patients with cirrhosis than in the controls (plasma cGMP in cirrhosis 8.4+/-2.4 vs. 4.2+/-3.5 pmol/ml; urine cGMP in cirrhosis 1.2+/-2.1 vs. 0.68+/-0.1 pmol/ml). The NO levels were also higher in plasma and urine in patients with cirrhosis vs. controls (plasma NO in cirrhosis 45.5+/-9.2 vs. 30. 3+/-1.2 micromol/l; urinary NO in cirrhosis 6.2+/-1.3 vs. 3.1+/-2.3 micromol/ml). In both groups the amino acid perfusion increased GFR, ERPF, cGMP and NO levels in plasma and urine. In the patients with cirrhosis the RVR decreased significantly during perfusion and no noteworthy changes in FF were observed. The GFR values observed during amino acid perfusion were similar in patients with cirrhosis and portal hypertension to those observed in the controls (27.2+/-12 vs. 25.3+/-16%). However, the changes induced the ERPF were more marked in patients with cirrhosis (cirrhosis 35.3+/-15 vs. 22. 2+/-13%, p = 0.02). CONCLUSIONS: The present findings point to certain alterations in renal function in patients with hepatic cirrhosis and portal hypertension without ascitis, a clear difference being visible between the ERPF and GFR following amino acid-induced stimulation. The significant elevation in cGMP and NO levels in plasma and urine implies a maintained vasodilatory action that may at least partly compensate the vasoconstrictor effects of angiotensin II.

Adult↗
PubMed1999

Monitoring oral anticoagulant treatment from plasma stored for up to 48 hours and frozen plasma.

BACKGROUND AND OBJECTIVE: The number of patients being referred for lifelong anticoagulant treatment has increased markedly in the last years. The prothrombin time test is sometimes difficult to perform the same day as sample collection. The aim of this study is to determine International Normalized Ratio (INR) and vitamin-K dependent factor levels of frozen plasma and plasma stored for up 48 hours. DESIGN AND METHODS: The INR of 84 patients receiving acenocoumarol were determined fresh (0 hours), on samples stored between 2 degrees C and 8 degrees C for 24 hours and 48 hours, and on frozen samples (-40 degrees C) using 4 different thromboplastin reagents (Thromboplastin IS; Thromborel; Simplastin; and Thromboplastin D+G). In addition, factors II, VII, IX, X were determined in 34 of these patients in all these situations. We used the interclass correlation coefficient to compare the results obtained at 0 hours and the results obtained in the subsequent measurements. Both measurement and proportional errors were also estimated by linear regression analysis. RESULTS: The correlation coefficient of the INR between fresh and frozen plasma was 0.98, 0.98, 0.92 and 0.97 for IS, Thromborel, Simplastin and D+G respectively. The correlation between 0 and 24 hours was 0. 98, 0.91, 0.95 and 0.85 for IS, Thromborel, Simplastin and D+G respectively. By 48 hours although IS still had r=0.94, Thromborel, Simplastin, and D+G had r=0.55, r=0.50 and r=0.81, respectively. By 24 hours in stored plasma and in frozen plasma the activity of vitamin-K dependent factors was slightly reduced (r=0.97 at 24h/r=0. 94 with frozen plasma for factor II, r=0.92/0.96 for factor VII, r=0. 83/0.98 for factor IX, and r=0.98/0.95 for factor X). By 48 hours however, significant reductions were noted in the activity of these factors (r=0.94 for factor II, r=0.88 for factor VII, r=0.70 for factor IX, and r=0.98 for factor X). INTERPRETATION AND CONCLUSIONS: The INR can be reliable determined in frozen plasma and in plasma stored at 2-8 degrees C for up to 24 hours.

Administration, Oral↗
PubMed1999

Effects of systemically administered dynorphin A(1-17) in rhesus monkeys.

The effects of i.v. dynorphin A(1-17) and its main nonopioid biotransformation fragment, dynorphin A(2-17), were compared in rhesus monkeys with those of the selective kappa-opioid agonist, U69, 593, in assays of operant behavior, thermal antinociception, and neuroendocrine function (prolactin release). Dynorphin A(1-17) (0. 1-3.2 mg/kg i.v.) and U69,593 (0.001-0.032 mg/kg s.c.) decreased rates of schedule-controlled (fixed ratio 20) food-reinforced responding, whereas dynorphin A(2-17) (1-3.2 mg/kg i.v.) was ineffective. Pretreatment studies with the opioid antagonist quadazocine (0.32 mg/kg s.c.) revealed that the operant effects of dynorphin A(1-17) were not mediated by kappa- or micro-opioid receptors. A different profile was observed in the warm water tail withdrawal assay of thermal antinociception, where both dynorphin A(1-17) and A(2-17) (0.032-3.2 mg/kg i.v., n = 4) were modestly effective in 50 degrees C water, and both were ineffective in 55 degrees C water. By comparison, U69,593 (0.032-0.18 mg/kg s.c.) was maximally effective in 50 degrees C water and partially effective in 55 degrees C. kappa-opioid agonists increase serum levels of prolactin in animals and humans. Dynorphin A(1-17) (ED(50) = 0.0011 mg/kg i.v.), similar to U69,593 (ED(50) = 0.0030 mg/kg i.v.), was very potent in increasing serum prolactin levels in follicular phase female rhesus monkeys, whereas dynorphin A(2-17) (0.32 mg/kg i.v.) was ineffective. The effects of dynorphin A(1-17) and U69,593 on serum prolactin were both antagonized by quadazocine (0.32 mg/kg s.c.) in a surmountable manner, consistent with opioid receptor mediation. The present studies show that serum prolactin levels are a sensitive quantitative endpoint to study the systemic effects of the endogenous opioid peptide, dynorphin A(1-17), in primates.

Analgesics, Opioid↗
PubMed1998

Stage-specific effects of sonic hedgehog expression in the epidermis.

Sonic hedgehog (Shh) is expressed in the ectoderm of the forming hair follicle and feather bud during normal development. However, inappropriate activation of the Shh signal transduction cascade in human epidermis can cause basal cell carcinoma. Here we show that during normal development of avian skin, Shh is first expressed only after the responsiveness to this protein has been suppressed in most of the surrounding ectodermal cells. Forced expression of Shh in avian skin prior to this time causes a disorganized ectodermal proliferation. However, as skin begins to differentiate, the forced expression of Shh causes feather bud formation. Subsequently, expression of Shh in interfollicular epidermis has little or no morphological effect. Restricted responsiveness to Shh in developing skin has functional consequences for morphogenesis and may have important implications for cutaneous pathologies as well.

Animals↗
PubMed1998

Interlaboratory study of the analysis of benzylpenicillin by liquid chromatography.

A liquid chromatography method for analysis of benzylpenicillin was examined in a collaborative study involving seven laboratories. The method comprised an isocratic part, which is used in the assay. The isocratic part corresponds to the assay method for benzylpenicillin used by a manufacturer. When the isocratic part is combined with gradient elution, the method is suitable for purity control. Five samples of benzylpenicillin (sodium and potassium salts) were analysed. The main component and the impurities were determined. An analysis of variance proved the absence of consistent laboratory bias. The laboratory-sample interaction was not significant. Estimates for the repeatability and reproducibility of the method, expressed as standard deviations (S.D.) of the result of the determination of benzylpenicillin, were calculated to be 0.71 and 0.80, respectively.

Analysis of Variance↗
PubMed1998

Periodate oxidation of R36A pneumococci greatly enhances production of hybridomas secreting anti-protein antibodies.

Most hybridomas derived from mice immunized with non-capsulated Streptococcus pneumoniae strains secrete antibodies to C-polysaccharide epitopes and very rarely against cell wall proteins. Mild periodate oxidation of the non-capsulated R36A pneumococcal strain destroys C-polysaccharide antigenicity without a noticeable loss in the immunizing capacity for proteins. Following immunization of BALB/c mice with periodate-treated R36A cells, most hybridomas obtained (87.5%) secreted anti-pneumococcal protein antibodies. This strategy can be exploited for the development of MAb to pneumococcal polypeptides which, in turn, will be of use in the analysis of pneumococcal cell wall protein antigens.

Animals↗
PubMed1998

Antioxidant transport by the human placenta.

We investigated the transfer of three antioxidants - melatonin, S-adenosyl methionine (SAM) and various forms of vitamin E - across the term, normal human placenta. The transport technique involved the single, isolated placental cotyledon system in vitro. Melatonin crossed the placental rapidly, equally to the freely diffusible marker, antipyrine. There was no biotransformation of the agent. SAM was transferred slowly, similarly to passively transported L-glucose as a marker. There was a breakdown of SAM to at least one other derivative; the process appeared to be nonenzymatic. Vitamin E was transferred slowly, at a rate only 10% of L-glucose. The natural RRR (nonracemic) form of vitamin E was transported best. Free vitamin, rather than the acetate seems to be transferred best, a finding that will require further study.

Antioxidants↗
PubMed1998

High levels of soluble IFN gamma receptor alpha chain in the plasma of rheumatoid arthritis patients.

Soluble receptors for hormones and cytokines have been described. They can serve as natural blockers of their respective ligands. The natural soluble interferon gamma receptor (sIFN gamma R) has been isolated and characterized only in urine. Chromatography of human (hu) plasma from rheumatoid arthritis (RA) patients and controls on immobilized hu IFN gamma or antibodies against IFN gamma R alpha chain permitted us to isolate the sIFN gamma R. The receptor isolated from one control is a protein with a molecular weight between 60-67 kDa depending on the presence of reducing agents. We detected a significantly higher level of plasma sIFN gamma R in patients with rheumatoid arthritis than in apparently healthy subjects.

Arthritis, Rheumatoid↗
PubMed1998

Sex ratio associated with timing of insemination and length of the follicular phase in planned and unplanned pregnancies during use of natural family planning.

This was a multicentred, prospective study of pregnancies among women using natural family planning. The women maintained natural family planning charts of the conception cycle, recording acts of intercourse and signs of ovulation (cervical mucus changes, including peak day and basal body temperature). Charts were used to assess the most probable day of insemination relative to the day of ovulation and length of the follicular phase of the cycle. The sex ratio (males per 100 females) for 947 singleton births was 101.5, not significantly different from the expected value of 105. The sex ratio did not vary consistently or significantly with the estimated timing of insemination relative to the day of ovulation, with the estimated length of the follicular phase or with the planned or unplanned status of the pregnancy. Although these findings may be affected by imprecision of the data, the study suggests that manipulation of the timing of insemination during the cycle cannot be used to affect the sex of offspring.

Family Planning Services↗
PubMed1998

Microbiology of acute otitis media in Costa Rican children.

BACKGROUND: Because of the increasing number of resistant middle ear pathogens reported from different centers worldwide, an active surveillance of the microbiology and susceptibility pattern of middle ear pathogens is required for proper antimicrobial recommendations among different regions of the world. OBJECTIVE: To study the microbiology and susceptibility pattern of middle ear pathogens obtained from Costa Rican children with acute otitis media. METHODS: Between 1992 and 1997 a diagnostic tympanocentesis was performed in 398 Costa Rican patients with acute otitis media. Middle ear fluid was obtained for culture and minimal inhibitory concentrations were determined by the E-test technique in those isolates obtained between October, 1995, and January, 1997. RESULTS: The most common pathogens cultured were Streptococcus pneumoniae (30%), Haemophilus influenzae (14%), Staphylococcus aureus (4%) and Streptococcus pyogenes (4%). Moraxella catarrhalis was uncommon. Beta-lactamase production was low (3.7%) among the H. influenzae isolates but frequent among the Staphylococcus aureus (57.1%) and M. catarrhalis (100%) strains. Overall 9 of 46 S. pneumoniae isolates (19.6%) exhibited decreased susceptibility to penicillin of which 8 isolates (17.4%) showed intermediate and one strain (2.2%) high level resistance. Among the penicillin-susceptible S. pneumoniae isolates, susceptibility to the following antimicrobials was: 81%, azithromycin; 89%, clarithromycin; and 100%, ceftriaxone and trimethoprim-sulfamethoxazole (TMP-SMX). Among the penicillin-resistant S. pneumoniae isolates the percentage of susceptible strains was 89% for azithromycin, clarithromycin and ceftriaxone and 67% for TMP-SMX. CONCLUSIONS: Based on this microbiologic information the agents considered first line drugs in the treatment of acute otitis media in Costa Rica remain amoxicillin or TMP-SMX.

Acute Disease↗
PubMed1998

Overproduction of the CFTR R domain leads to increased levels of asialoGM1 and increased Pseudomonas aeruginosa binding by epithelial cells.

Mutations in cystic fibrosis transmembrane conductance regulator (CFTR), particularly the common DeltaF508 mutation, have been associated with alterations in glycolipid sialylation and the availability of receptors for Pseudomonas aeruginosa binding. The surface properties of 9HTEo- tracheal epithelial cell lines transfected with plasmids that overproduce the regulatory (R) domain of CFTR (pCEP-R) and lack cyclic adenosine monophosphate-stimulated Cl- conductance were compared with control cell lines with normal CFTR function. There was increased bacterial adherence to the mutant cell lines with abnormal CFTR activity. Cell lines with overexpression of the R domain had surface properties similar to cells expressing the common DeltaF508 mutation in CF. P. aeruginosa adherence correlated with the increased numbers of asialoGM1 residues available on the surface of the epithelial cells with altered CFTR function; and antibody to asialoGM1, a P. aeruginosa pilin receptor, was able to compete with piliated bacteria for epithelial binding sites. The pCEP-R cell lines with increased bacterial binding were also associated with increased production of interleukin-8 in response to adherent P. aeruginosa compared with cells transfected with the empty vector pCEP. P. aeruginosa pil mutants that lack the adhesin specific for the asialoGM1 receptor did not discriminate between epithelial cells with normal or deficient CFTR function. These results confirm a direct relationship between aberrant CFTR function and increased levels of apical asialoGM1, and support the role of these asialylated glycolipids as P. aeruginosa receptors that initiate an epithelial proinflammatory response in response to bacterial ligands.

Bacterial Adhesion↗
PubMed1998

Anti-idiotype guinea pig antibodies as response to insulin immunization.

The study was done using 39 guinea pigs grouped as followed; 18 were injected with 0.5 mg of porcine insulin emulsified in complete Freund's adjuvant; 12 were injected with saline and 9 were used as control of cardiac bleeding during the assay. Intraperitoneal glucose tolerance tests (IGTT) were carried out on days 0, 11, 32 and 38. Seven of the thirteen guinea pigs immunized with insulin which survived after the study, showed glucose intolerance on day 32 at 90 and 120 min (p < 0.01 and p < 0.001) and on day 38 at 120 min (p < 0.05). Anti-idiotypic IgG partially purified from a sera pool from these animals inhibited 125-Insulin binding to rat hepatocytes, immunoprecipitated 125I-rat insulin receptors and recognized the alpha-subunit of insulin receptor in immunoblotting. We conclude that insulin anti-idiotypes in guinea pigs offer a simple way to produce antibodies against insulin receptor binding site. The methodology for anti-idiotype identification can be applied to patients with insulin resistance.

Animals↗
PubMed1997

Immune response to a combined hepatitis B, diphtheria, tetanus and whole-cell pertussis vaccine administered to infants at 2, 4 and 6 months of age.

The objective of this study was to evaluate the immune response and reactogenicity of a combined hepatitis B, diphtheria, tetanus and whole-cell Bordetella pertussis (DTPw-HBV) vaccine administered to healthy infants at 2, 4 and 6 months of age. A total of 179 infants (6-12 weeks of age) received three doses of DTPw-HBV vaccine. Blood samples for antibody determinations were taken before vaccination, 2 months after the second dose and 1 month after the third dose. Solicited and unsolicited symptoms were recorded by parents in a diary card. All vaccinees had protective levels of anti-HBs [geometric mean titre (GMT): 1526 mIU.ml-1], anti-diphtheria and anti-tetanus antibodies, 1 month after the third dose. Ninety-two percent of the subjects exhibited a response to the B. pertussis component. Most (99.4%) solicited reactions occurred within the first 48 h and the majority were mild or moderate. The safety, immunogenicity of this tetravalent vaccine was demonstrated when it was administered in infants following the 0, 2, 4-month dosing schedule.

Antibodies, Viral↗
PubMed1997

Familial complex chromosome rearrangement ascertained by in situ hybridisation.

A complex familial chromosome translocation has been ascertained by combining classical cytogenetics and CISS (chromosomal in situ suppression). Cytogenetic analysis of a chorionic villus sample with G banding showed a 47,XX,-2, +der(2)t(2;22),+der(22)t(2;22) karyotype. Analysis of peripheral blood lymphocytes from the parents by G banding and CISS showed a more complex translocation in the father: 46,XY,-2,-11,-22, +der(2) t(2;11)(q13;q23), +der(11) t(11;22) (q23;q11.2), +der(22) t(2;22) (q13;q11.2). Definitive analysis of cultured amniotic fluid cells showed a double partial trisomy of chromosomes 11 and 22. The couple decided to continue the pregnancy. The fetal karyotype was confirmed at birth. Clinical abnormalities present in our patient were typical of an unbalanced 11;22 translocation. Our findings confirm that chromosome painting techniques allow a better characterisation of complex chromosome rearrangements which may be difficult to detect in G banded karyotypes.

Abnormalities, Multiple↗
PubMed1997

Nutrition risk classification: a reproducible and valid tool for nurses.

BACKGROUND: Incorporating the nursing staff to assist with the screening process on admission will allow patients who are at nutritional risk to be assessed by registered dietitians earlier in their hospital stay. The goal of this study was to develop an objective, valid, reproducible nutrition screen for use by registered nurses (RNs) to allow for nutrition classifications of hospitalized patients. METHODS: The current nursing admission assessment form was modified to contain questions on weight loss history, percentage of ideal body weight, and alterations in dietary intake and gastrointestinal function. Assessments were completed within 48 hours of admission. On the basis of the answers to these questions, patients were classified as "at nutritional risk" or "low nutritional risk." In phase 1, to assess reproducibility of the form, a prospective study between staff RNs and a nutritionist was undertaken on 186 consecutive adult admissions. Nutrition screening and classification was done independently by both practitioners. In phase 2 of the study, prospective validation of the form contrasting prealbumin (PAB) levels with RN nutritional risk classification (n = 56) was investigated. RESULTS: Interobserver agreement of nutrition classification between RN and nutritionist was 97.3% (p = .95). Twenty-nine patients were classified at low nutritional risk (27 normal PAB and 2 low PAB); 27 patients were classified as at nutritional risk (16 normal PAB and 11 low PAB) (chi 2 = 8.9, p < .003, power 0.8). The sensitivity of the tool was 84.6%. CONCLUSION: To our knowledge, this is the first nutrition screening tool designed for staff RNs that has been tested for both validity and reproducibility.

Adult↗