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Biomedical subjects

H Hernández

Publications and source records attributed to H Hernández.

At least 19 recordsLinked to original sources
PubMed2006

Monthly variation of fertility and oestrus frequency in crossbred dual-purpose cows in three agroecological areas of the South American tropics.

The aim of this study was to examine the monthly variation of the first service conception (FSC) and oestrus frequency (OF) from 8308 artificial inseminations (AI) of 2960 crossbred dual-purpose cows on three commercial farms with improved management located in the Maracaibo Lake Basin, Venezuela. The effects of month of the year, agroecological area (from dry tropical forest to sub-humid tropical forest on the three farms), predominant breed (BT, Bos taurus; BI, Bos indicus), and season (December-April; May-August; and September-November) were considered. Data were analysed using logistic regression (FSC) and GLM (OF) from SAS. The mean FSC was 55.4% overall and 48.7%, 57.0% and 58.3% for farms A, B and C, respectively (p < 0.01). Within the three agroecological areas (farms A, B and C), the FSC was highest during the cooler and drier months of the year (season 1), while the lowest FSC was obtained during the months of highest rainfall and humidity (season 3) (53.3% vs. 37.4%; 58.5% vs. 49.0% and 63.0% vs. 52.3% on farms A, B, C, respectively; p < 0.01). In the three studied farms, OF was higher during the first 4 months of the year; with a diminishing trend towards the end of the year (p < 0.05). In general, BI cows had a higher FSC than BT cows, especially during the second half of the year, when environmental conditions were characterized by higher rainfall and humidity with lower wind velocity (58.8%a, 55.5%b and 46.4%c in season 1, 2 and 3 respectively; a,b,c p < 0.01).

Animals↗
PubMed2004

Open versus closed day-case haemorrhoidectomy: is there any difference? Results of a prospective randomised study.

BACKGROUND AND AIMS: Nowadays there is still controversy as to whether open or closed haemorrhoidectomy is the surgical treatment of choice for haemorrhoidal pathology. PATIENTS AND METHODS: We carried out a randomised prospective study in the Day Surgery Unit comparing 100 patients undergoing Milligan-Morgan haemorrhoidectomy (group A) versus 100 patients undergoing Ferguson haemorrhoidectomy (group B) for symptomatic haemorrhoids, in whom medical treatment or rubber band ligation had failed. RESULTS: Characteristics of the population were: mean age 43.5 years, with predominance of males, 123 vs. 77; 88% ASA I-II. CLINICAL PRESENTATION: 95% rectal bleeding; 87.5% third-fourth degree. The anaesthetic technique of choice was local anaesthesia plus sedation in 180 patients (90%). Length of surgery: 24 min (group A) and 30 min (group B) (p=n.s.). Resection of three haemorrhoidal cushions was done in 87.5% of cases. There were no re-operations or re-admissions after discharge. Symptomatic recurrence, stenosis and incontinence were not found during the follow-up of the first year. Postoperative pain during the first postoperative week was greater in the open haemorrhoidectomy group, but the difference was statistically significant (p<0.05) only during bowel movements. There was complete healing in 40% of the patients in group A and 90% of those in group B (p<0.05) after 1 month. After 1 year, the results and complications were similar in both groups (p=n.s.). CONCLUSIONS: Closed haemorrhoidectomy gives better results in terms of pain and healing than open haemorrhoidectomy, whereas recurrence and complications are similar after 1 year.

Adult↗
PubMed2004

Monoclonal antibodies against a 62 kDa proteinase of Trichomonas vaginalis decrease parasite cytoadherence to epithelial cells and confer protection in mice.

Trichomonas vaginalis infects the epithelium of the genital tract. The mechanism by which it invades the tissue leading to the disease is not thoroughly understood. However, results of several studies seem to agree that parasite adhesion to epithelium cells is the initial step leading to infection in women. T. vaginalis is associated with high levels of proteolytic activity. The role of some of these proteinases in the development of infection has been demonstrated. The current study establishes the role of a 62 kDa excretion-secretion proteinase in parasite cytoadherence. Monoclonal antibodies (MAbs) against this enzyme were tested for their ability to inhibit this process. Three stable hybrid producers of IgG(1)class MAbs (4D8, 1A8, 3C11) against the 62 kDa proteinase were obtained. Two of them (4D8 and 1A8) showed parasite recognition by immunofluorescence. Parasite cytoadherence to a monolayer of HeLa cells was inhibited by the 4D8, 1A8 and 3C11 antibodies. MAb 4D8 administered 24 h before a challenge with T. vaginalis by the intraperitoneal route was able to protect the majority of mice. Nitric oxide levels in the serum of animals inoculated with MAb 4D8 and challenged with the parasite were significantly different from those recorded in mice treated with an unrelated MAb. These studies show that an appropriate antibody against 62 kDa proteinase can help the host resist a challenge by the intraperitoneal route with T. vaginalis.

Animals↗
PubMed2001

[Analysis of a programme of direct referral between primary and specialist care in potential surgery patients].

OBJECTIVE: To describe the results of a programme of direct referral of potential surgery patients between primary and specialist care, designed to lessen waiting-times.Design. Prospective, longitudinal and descriptive study. SETTING: Health Area N. masculine 19 (Valencian Health Service): Surgery Service of Elche Hospital and 6 Health Centres. PARTICIPANTS: Patients with pathologies that do not need special techniques for diagnosis except examination and who have a clear irrefutable indication of surgery without risk factors (ASA I-II).Intervention. The referral protocol consists of: a) diagnosis of pathology and pre-operative study in primary care (PC); b) appointment made by phone for the surgery clinic at the hospital, where diagnosis and pre-operative study are confirmed; c) referral and operation in the unit of non-hospital major surgery (UCMA); d) monitoring post-operation by the home hospitalisation unit (HHU) or preferably by the health centre, and e) check-up at the surgery clinic. Main measurements. The degree of agreement between PC and the specialist, assessment of the pre-operative study, and waiting time. RESULTS: 86 patients were referred (average age, 35; 76% male) by 28 doctors. The most common pathologies were hernia (36%), pilonidal sinus (23.2%) and miscellaneous (32.5%). There was general agreement in diagnosis in 90.7% of cases. 89.5% of patients brought the proper pre-operative study. Mean waiting time between the primary care consultation in the different procedures and the first hospital consultation was 19 days; with 44 more days elapsing till the surgical operation. CONCLUSIONS: This new programme is effective and economic, in that there is < > of patients, waiting time is reduced by over 7 months for pilonidal sinus and by over 2 years for hernia pathology, and the procedure can be used for a large number of patients, as the pathologies involved are very common.

Adolescent↗
PubMed2001

Observation of the iron-sulfur cluster in Escherichia coli biotin synthase by nanoflow electrospray mass spectrometry.

Biotin synthase from Escherichia coli was analyzed by nanoflow electrospray ionization mass spectrometry. From solution conditions in which the protein is in its native state, a distribution of monomeric, dimeric, and tetrameric species was observed. The distribution of these species was sensitive to changes in ionic strength: in the positive ion spectrum, biotin synthase at low ionic strength (pH 7.0-8.5) yielded less than 10% dimer. The masses of the monomeric species were consistent with the presence of a [2Fe-2S] cluster with a mass difference of 175.3 Da from the apomonomer with one disulfide bond. Despite the molecular mass of the noncovalent dimer (77 kDa), it was possible to observe a dimeric species containing one iron-sulfur cluster in both positive and negative ion spectra. Additionally, observation of a series of charge states assigned to the apodimer indicated that binding of the iron-sulfur cluster was not required to maintain the dimer. Binding of Cu2+ to biotin synthase was also observed; in the presence of excess chelating agent, free metals were removed and the iron-sulfur cluster remained intact. Evidence for the coordination of the iron-sulfur cluster in biotin synthase was obtained in a tandem mass spectrometry experiment. A single charge state containing the cluster at m/z 2416.9 was isolated, and collision-induced dissociation resulted in sequential loss of sulfur and retention of Fe3+.

Buffers↗
PubMed2001

MitoTracker labeling in primary neuronal and astrocytic cultures: influence of mitochondrial membrane potential and oxidants.

MitoTracker dyes are fluorescent mitochondrial markers that covalently bind free sulfhydryls. The impact of alterations in mitochondrial membrane potential (Delta Psi(m)) and oxidant stress on MitoTracker staining in mitochondria in cultured neurons and astrocytes has been investigated. p-(Trifluoromethoxy) phenyl-hydrazone (FCCP) significantly decreased MitoTracker loading, except with MitoTracker Green in neurons and MitoTracker Red in astrocytes. Treatment with FCCP after loading increased fluorescence intensity and caused a relocalization of the dyes. The magnitude of these effects was contingent on which MitoTracker, cell type and dye concentration were used. H(2)O(2) pretreatment led to a consistent increase in neuronal MitoTracker Orange and Red and astrocytic MitoTracker Green and Orange fluorescence intensity. H(2)O(2) exposure following loading increased MitoTracker Red fluorescence in astrocytes. In rat brain mitochondria, high concentrations of MitoTracker dyes uncoupled respiration in state 4 and inhibited maximal respiration. Thus, loading and mitochondrial localization of the MitoTracker dyes can be influenced by loss of Delta Psi(m) and increased oxidant burden. These dyes can also directly inhibit respiration. Care must be taken in interpreting data collected using MitoTrackers dyes as these dyes have several potential limitations. Although MitoTrackers may have some value in identifying the location of mitochondria within cultured neurons and astrocytes, their sensitivity to Delta Psi(m) and oxidation negates their use as markers of mitochondrial dynamics in healthy cultures.

Aldehydes↗
PubMed2001

Origin and differentiation of dendritic cells.

Despite extensive, recent research on the development of dendritic cells (DCs), their origin is a controversial issue in immunology, with important implications regarding their use in cancer immunotherapy. Although, under defined experimental conditions, DCs can be generated from myeloid or lymphoid precursors, the differentiation pathways that generate DCs in vivo remain unknown largely. Indeed, experimental results suggest that the in vivo differentiation of a particular DC subpopulation could be unrelated to its possible experimental generation. Nevertheless, the analysis of DC differentiation by in vivo and in vitro experimental systems could provide important insights into the control of the physiological development of DCs and constitutes the basis of a model of common DC differentiation that we propose.

Animals↗
PubMed2001

Immune response to measles vaccine in Peruvian children.

OBJECTIVE: To evaluate the immune response in Peruvian children following measles vaccination. METHODS: Fifty-five Peruvian children received Schwarz measles vaccine (about 10(3) plaque forming units) at about 9 months of age. Blood samples were taken before vaccination, then twice after vaccination: one sample at between 1 and 4 weeks after vaccination and the final sample 3 months post vaccination for evaluation of immune cell phenotype and lymphoproliferative responses to measles and non-measles antigens. Measles-specific antibodies were measured by plaque reduction neutralization. FINDINGS: The humoral response developed rapidly after vaccination; only 4 of the 55 children (7%) had plaque reduction neutralization titres <200 mlU/ml 3 months after vaccination. However, only 8 out of 35 children tested (23%) had lymphoproliferative responses to measles antigens 3-4 weeks after vaccination. Children with poor lymphoproliferative responses to measles antigens had readily detectable lymphoproliferative responses to other antigens. Flow cytometric analysis of peripheral blood mononuclear cells revealed diffuse immune system activation at the time of vaccination in most children. The capacity to mount a lymphoproliferative response to measles antigens was associated with expression of CD45RO on CD4+ T-cells. CONCLUSION: The 55 Peruvian children had excellent antibody responses after measles vaccination, but only 23% (8 out of 35) generated detectable lymphoproliferative responses to measles antigens (compared with 55-67% in children in the industrialized world). This difference may contribute to the less than uniform success of measles vaccination programmes in the developing world.

Antibodies, Viral↗
PubMed2000

High accuracy isotope dilution analysis for the determination of ethanol using gas chromatography-combustion-isotope ratio mass spectrometry.

A procedure was established for the determination of ethanol in water samples by isotope dilution analysis. After spiking the sample with labelled [13C2]ethanol, it was analysed by gas chromatography-combustion-isotope ratio mass spectrometry. Results are reported for two certified reference materials and also ethanol solutions prepared for a CITAC (Co-operation on International Traceability in Analytical Chemistry) interlaboratory comparison. The certified reference materials were certified using the dichromate titration method at nominal levels of 80 and 200 mg per 100 mL. The CITAC solutions were prepared gravimetrically at nominal levels of 50, 80 and 200 mg per 100 mL. The results of the analysis agree well to within 0.5% of the gravimetric values of the different samples. The relative expanded standard uncertainties (with a coverage factor equal to 2) associated with the results varied between 0.18 and 0.37%, a range that encompassed the gravimetric values for the different samples. A complete uncertainty budget was also drawn up so that the different contributions could be identified and quantified. The main contributions were due to variations in the measured isotope amount ratios and a 'between' blend component introduced to quantify the contribution of factors such as the degree of matching of the isotope amount ratios between standards and samples used in the isotope dilution analysis.

Journal Article↗
PubMed2000

Removal of the N-terminal hexapeptide from human beta2-microglobulin facilitates protein aggregation and fibril formation.

The solution structure and stability of N-terminally truncated beta2-microglobulin (deltaN6beta2-m), the major modification in ex vivo fibrils, have been investigated by a variety of biophysical techniques. The results show that deltaN6beta2-m has a free energy of stabilization that is reduced by 2.5 kcal/mol compared to the intact protein. Hydrogen exchange of a mixture of the truncated and full-length proteins at microM concentrations at pH 6.5 monitored by electrospray mass spectrometry reveals that deltaN6beta2-m is significantly less protected than its wild-type counterpart. Analysis of deltaN6beta2-m by NMR shows that this loss of protection occurs in beta strands I, III, and part of II. At mM concentration gel filtration analysis shows that deltaN6beta2-m forms a series of oligomers, including trimers and tetramers, and NMR analysis indicates that strand V is involved in intermolecular interactions that stabilize this association. The truncated species of beta2-microglobulin was found to have a higher tendency to self-associate than the intact molecule, and unlike wild-type protein, is able to form amyloid fibrils at physiological pH. Limited proteolysis experiments and analysis by mass spectrometry support the conformational modifications identified by NMR and suggest that deltaN6beta2-m could be a key intermediate of a proteolytic pathway of beta2-microglobulin. Overall, the data suggest that removal of the six residues from the N-terminus of beta2-microglobulin has a major effect on the stability of the overall fold. Part of the tertiary structure is preserved substantially by the disulfide bridge between Cys25 and Cys80, but the pairing between beta-strands far removed from this constrain is greatly perturbed.

Amino Acid Sequence↗
PubMed2000

Clinical and programmatic mismanagement rather than community outbreak as the cause of chronic, drug-resistant tuberculosis in Buenaventura, Colombia, 1998.

SETTING: Buenaventura, Colombia. OBJECTIVE: To assess whether antituberculosis drug resistance was generated by poor management or community transmission. DESIGN: Treatment-failure and new tuberculosis (TB) patients identified between May 1997 and June 1998 were interviewed and their treatment histories reviewed. Bacteriologic testing, including drug susceptibility profiles (DSP) and DNA fingerprinting by restriction fragment length polymorphism (RFLP), was performed and human immunodeficiency virus (HIV) testing was offered. RESULTS: DSP and RFLP fingerprints were obtained for isolates from 34 of 64 treatment-failure patients; 25 (74%) were resistant to > or = one drug. Fifteen of the 25 patients consented to HIV testing; none were positive. An average of 2.8 major treatment errors per patient was identified. RFLP from the treatment-failure patients revealed 20 unique isolates and six clusters (isolates with identical RFLP); 4/6 clusters contained isolates with different DSP. Analysis of the RFLP from both treatment-failure and new patients revealed that 44/111 (40%) isolates formed 18 clusters. Four of 47 (9%) new patients had multidrug-resistant TB (MDR-TB). Eleven isolates belonged to the Beijing family, related to the MDR strain W. CONCLUSION: Drug resistance in Buenaventura results from both poor management and community transmission. Dependence on DSP to identify TB transmission is inadequate when programmatic mismanagement is common.

AIDS-Related Opportunistic Infections↗
PubMed1998

Detection and typing of human papillomavirus DNA in benign and malignant tumours of laryngeal epithelium.

The role of human papillomaviruses (HPV) in laryngeal squamous cell carcinoma has not yet been established. Thirty-three cases of laryngeal squamous cell carcinoma were analysed for the presence of HPV DNA and compared with 25 cases of normal larynx and 29 cases of laryngeal squamous papilloma in their positivity index. The presence of HPV DNA was analysed by using L1 consensus primers and also by primers specific for the E7 gene of HPV types 16 and 18. Four normal laryngeal samples (16%) were positive for HPV DNA against the 24 samples (82%) (p < 0.001) found for laryngeal papilloma and 16 (48.5%) (p < 0.05) found for laryngeal squamous cell carcinoma. HPV 16 was the type most frequently found in laryngeal carcinoma samples. Our results support an etiologic role for this type of HPV in the pathogenesis of laryngeal carcinoma.

Adult↗
PubMed1998

Microcomputer decision support system for intensive care.

This article describes a computer system to support decisions in Intensive Medicine developed for a multipurpose Intensive Care Unit (13 beds and about 700 yearly patients). The system is used in a microcomputer (486DX4). Works done in this area are mentioned; and the different programs which integrate the system, the advantages of its use and the results accomplished are described. Some of the most important results are the quality increment of the medical care given, physicians' possibilities of dedicating more time to their patients, cost reductions, and improvements in the development of teaching and in the conditions to carry out research work in the Intensive Care Unit (ICU). An analysis is made of the system requirements that guarantee its integration to the Unit work, and the easy and safe use of it by the physicians and nurses.

Critical Care↗
PubMed1997

Determination of cis-thymine glycol in DNA by gas chromatography-mass spectrometry with selected ion recording and multiple reaction monitoring.

A novel method for the determination of cis-thymine glycol in DNA has been developed, using gas chromatography-mass spectrometry with selected ion recording or multiple reaction monitoring. The procedure involves acidic hydrolysis of DNA in the presence of the internal standard cis-[2H3]thymine glycol, followed by derivatisation with N-methyl-N-(tert.-butyldimethylsilyl)trifluoroacetamide. The method was validated on DNA that had been oxidatively modified in vitro by radiation treatment, and was then applied to determine cis-thymine glycol in human placental DNA. Background levels of 5.45+/-2.98 ng cis-thymine glycol/mg DNA were observed in the human samples.

Acetamides↗