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Biomedical subjects

J Herrera

Publications and source records attributed to J Herrera.

At least 163 records · Page 9Linked to original sources
PubMed1971

Role of molybdenum in nitrate reduction by chlorella.

Molybdenum is absolutely required for the nitrate-reducing activity of the nicotinamide adenine dinucleotide nitrate reductase complex isolated from Chlorella fusca. The whole enzyme nicotinamide adenine dinucleotide nitrate reductase is formed by cells grown in the absence of added molybdate, but only its first activity (nicotinamide adenine dinucleotide diaphorase) is functional. The second activity of the complex, which subsequently participates also in the enzymatic transfer of electrons from nicotinamide adenine dinucleotide to nitrate (FNH(2)-nitrate reductase), depends on the presence of molybdenum. Neither molybdate nor nitrate is required for nitrate reductase synthesis de novo, but ammonia acts as a nutritional repressor of the complete enzyme complex. Under conditions which exclude de novo synthesis of nitrate reductase, the addition of molybdate to molybdenum-deficient cells clearly increases the activity level of this enzyme, thus suggesting in vivo incorporation of the trace metal into the pre-existing inactive apoenzyme.Competition studies with tungstate corroborate these conclusions and indicate that the only role played by molybdenum in Chlorella is connected with the reduction of nitrate to nitrite. Tungsten seems to act by replacing molybdenum in the nitrate reductase complex, thus rendering inactive the FNH(2)-nitrate reductase portion of the nicotinamide adenine dinucleotide nitrate reductase complex.

Journal Article↗
PubMedDate not supplied

Regional distribution of pyroglutamyl peptidase II in rabbit brain, spinal cord, and organs.

Pyroglutamyl peptidase II (PPII) is a narrow specificity ectoenzyme that degrades thyrotropin-releasing hormone (TRH). We detected the enzyme in the brain of various mammals, with highest specific activity in rabbit brain. In this species, activity was heterogeneously distributed in the central nervous system. There was a 28-fold difference between regions of highest and lowest PPII activity. Enzyme activity was highest in the olfactory bulb and posterior cortex. In the spinal cord, activity was low but unevenly distributed, with highest values detected in the thoracic (T) region. Segments T1 and T2 activities were particularly high. Other organs contained low or undetectable levels of activity. The levels of TRH-like immunoreactivity (TRH-LI) in spinal cord segments were greatest in T3-T4 and lumbar L2-L6. Low concentrations were found in T1 and T9-T12. There was a partial correlation between the distribution of PPII activity and TRH receptors but not with TRH-LI levels. These results demonstrate that PPII is predominantly a central nervous system enzyme, and they support the hypothesis that PPII is responsible for degrading TRH released into the synaptic cleft.

Animals↗
PubMedDate not supplied

The responsiveness of the Hamilton Depression Rating Scale.

In clinical studies of antidepressants, the Hamilton Depression Rating Scale (HAMD) total score has been the gold standard instrument for establishing and comparing the efficacy of new treatments. However, the HAMD is a multidimensional measure, which may reduce its ability to detect differences between treatments, in particular, changes in core symptoms of depression. Two meta-analyses were conducted to compare the responsiveness of the HAMD total score with several published unidimensional subscale scores based upon core symptoms of depression. The first compared the above instrument's ability to detect differences between fluoxetine and placebo across eight studies involving over 1600 patients. The second analysis involved four studies and over 1200 patients randomized to tricyclic antidepressants and placebo. In both meta-analyses, the unidimensional core subscales outperformed the HAMD total score at detecting treatment differences. The implications of this on sample sizes and power for clinical studies will be discussed. In fact, studies based on the observed effect sizes from the core subscales would require approximately one-third less patients than studies based on the HAMD total score. Effect sizes from each individual HAMD item will also be presented to help explain the differences in responsiveness between the scales.

Antidepressive Agents↗
PubMedDate not supplied

Efficacy and safety of dipyrone versus tramadol in the management of pain after hysterectomy: a randomized, double-blind, multicenter study.

BACKGROUND AND OBJECTIVES: We assessed the efficacy and safety of dipyrone in comparison with tramadol in the relief of early postoperative pain following abdominal hysterectomy. METHODS: A total of 151 women between 18 and 60 years of age undergoing abdominal hysterectomy during general anesthesia participated in a randomized, double-blind, controlled, multicenter study. Seventy-three patients received dipyrone and 78 received tramadol. Patients received an intravenous loading dose of the study drug immediately after operation followed by intravenous (IV) maintenance infusion and IV on-demand boluses up to a maximum number of predetermined doses/day of 8 g dipyrone and 500 mg tramadol. The duration of the study was 24 hours. RESULTS: The mean (SD) number of boluses in the dipyrone group was 3.8 (2.4) and 3.5 (2.5) in the tramadol group (95% confidence interval, -0.455 to 1.175), and the percentage of patients requiring rescue IV morphine (dipyrone 26.9%, tramadol 26.8%) was not statistically significant. Other analgesic efficacy parameters, such as pain intensity differences, sum of pain intensity differences, pain relief assessed by the patient, or patients who required the maximum number of demand doses, were not different between treatment groups. A significantly higher percentage of adverse gastrointestinal effects was found in patients given tramadol (42.1%) than in patients given dipyrone (20.2%) (P <.05). Also, a significantly higher number of tramadol-treated patients required ondansetron to control nausea and vomiting at 1 hour (19% v 7%), 2 hours (26% v 11%), and 24 hours (46% v 29%) (P <.05) after surgery. Patients and the investigators reported similar tolerability for both study arms. CONCLUSIONS: Dipyrone and tramadol showed similar efficacy for early pain relief after abdominal hysterectomy. Nausea and vomiting, possibly caused by the tramadol, occurred more frequently in those patients. In this group, the need of the antiemetic drug ondansetron was also higher.

Adolescent↗
PubMedDate not supplied

Acrosome reaction in fertile and subfertile boar sperm.

The main purpose of sperm evaluation is to predict its fertilizing ability. However, basic sperm test results show a low correlation with fertilizing ability. The purpose of this study was to determine whether there is an association between acrosome reaction (AR) and the incidence of subfertility of normal sperm boar. The production records of 22 farms were analyzed to identify boars with low fertility and/or prolificity, classified as subfertile. Twenty-two subfertile boar semen samples were analyzed and compared with 51 samples of fertile boars. Sperm were capacitated during 4 h at 39 degrees C. viability was determined by bisbenzimide (Hoechst-33258) staining. Acrosome reaction was assessed with fluorescein isothiocyanate conjugated Pisum sativum agglutinin. The percentage of spontaneous acrosome reaction (SAR) was not significantly different in fertile (4.5%) and subfertile boars (4.75%) (p > .05). Nevertheless, the percentage of progesterone-induced acrosome reaction (IAR) was significantly lower in subfertile boars (5.75%) as compared with fertile boars (10%) (p < .01). These results suggest that assessment of IAR in vitro may be a useful parameter to identify subfertility in boars.

Acrosome Reaction↗
PubMedDate not supplied

Expression of lectin receptors on the membrane surface of sperm of fertile and subfertile boars by flow cytometry.

Studies suggest that carbohydrates are important in different stages of fertilization. Plasma membrane changes accompanying in vitro capacitation and acrosome reaction (AR), such as removal or appearance of specific glycoproteins, have been studied using lectins that bind specifically to carbohydrate residues. In specialized artificial insemination farms and semen production centers, identification of boars with decreased fertilization ability (subfertility) is a newborn necessity. This investigation is a sequential study to determine the kinetics of surface carbohydrates turnover during in vitro capacitation and AR in fertile and subfertile boar sperm. Flow cytometry determinations of the binding of three FITC-labeled lectins were assessed. WGA binding was significantly lower in fresh, capacitated, and acrosome-reacted sperm of subfertile boars than in fertile boars. Con-A binding was not significantly different in fresh sperm of fertile and subfertile boars. However. Con-A labeling in capacitated, and acrosome-reacted sperm differed significantly in both groups. UEA binding increased only in capacitated sperm of subfertile boars. These findings could be used as indicators of capacitation and AR and may also be a good indicator of sperm fertilizing ability in boars.

Acrosome Reaction↗
PubMedDate not supplied

[Utilisation of organs proceeding from donors with heart failure: review of the pathogenesis of organic damage and the possible mechanisms of prevention].

There is an evident imbalance between the number of patients awaiting a kidney transplant and the availability of organs proceeding from donors with brain death. A high number of patients die each day from heart failure, whose organs could be used for transplants if specific care is employed. Although centres do exist where these methods of extraction are established, the problems of organic damage have yet to be resolved, since one third of the organs are still lost, besides the increase in the need for early dialysis, and the number of dysfunctioning grafts two years after the transplant, when this type or organ is employed. There is increasingly detailed knowledge of the pathogenesis of organic damage following heart failure and reanimation, as well as of the damage following the conservation and reimplantation of the kidney. Knowledge of the maximum time of hot ischemic that an organ can withstand is of crucial importance if organs are not to be unduly discarded. Besides, the increasing understanding of the physiopathology of oxidative stress could make it possible for us, through the use of antioxidants, to attempt to improve the utilisation of the organs and diminish the incidence of dysfunctions and rejections.

English Abstract↗
PubMedDate not supplied

[Acute cholecystitis: analysis of the different therapeutic approaches in a General Surgery Service during the years 1994-1996].

INTRODUCTION: The commonly accepted approach in the treatment of acute cholecystitis is urgent cholecystectomy. Laparoscopy has renewed interest in the option of "cooling" the inflammatory process, in order to subsequently carry out a programmed cholecystectomy through the technique mentioned. We present an analysis of the data collected on hospital stay and medico-surgical complications in both therapeutic options. The aim of this work is to reflect on the results obtained in the treatment of acute cholecystitis and to evaluate the results of the application of laparoscopic cholecystectomy in the emergency area. MATERIAL AND METHODS: 152 patients diagnosed with acute cholecystitis are studied. They are distributed in 3 groups, analysing the simple and accumulated hospital stay, the index of medical and surgical complications and mortality. RESULTS: Of the 152 patients with a diagnosis of acute cholecystitis, 91 (59.8%) were operated on in their first admission, 47 (30.9%) were treated using "cooling" of the process to be operated on in a second admission and 14 (9.3%) by means of percutaneous cholecystostomy. A total of 29 patients were readmitted, 4 for relapse of acute cholecystitis and 25 for programmed operations. Urgent conventional cholecystectomy shows a greater rate of infections. The cholecystectomy on second admission supposes a moderate increase of the accumulated average stay. 17% of these patients were operated on using open surgery. CONCLUSIONS: Urgent surgery seems the most suitable approach in acute cholecystitis. The employment of laparoscopic surgery in these cases probably reduces the rate of the medical and surgical complications due to laparotomy in infectious acute pathology, and increases the comfort of the patient

English Abstract↗
PubMedDate not supplied

[Present state of the surgical treatment of hepatic metastasis of colorectal origin: a practical view].

Hepatic resection is the only real possibility of cure for a selected group of patients with hepatic metastasis of colorectal cancer. Survival obtained in these patients is of some 30-40% after 5 years and some 20-25% after ten years following surgery; no other treatment approaches these results. The key for obtaining these results is the treatment of these patients by a multidisciplinary team, a team that must include the participation of surgeons specially trained in the techniques of hepatic resection. The present review describes: the pre-operational staging of hepatic metastasis of colorectal origin by diagnostic imaging techniques, the selection criteria for surgery, the standards of the surgical technique and the adjuvant treatment that forms part of the Protocol of the Hepatobiliary Surgery Section of the Hospital of Navarra, based on our experience in 150 hepatectomies and on the best scientifically available evidence.

English Abstract↗