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Biomedical subjects

J Hernandez

Publications and source records attributed to J Hernandez.

At least 91 records · Page 5Linked to original sources
PubMed1996

Interactions between metallothionein inducers in rat liver and primary cultures of rat hepatocytes.

The interaction of Zn, stress and endotoxin on liver metallothionein (MT) regulation has been studied in the rat. Zn, stress and endotoxin increased liver MT levels significantly, by 12-, 5- and 8-fold, respectively. The previous administration of Zn to stress or endotoxin treatments increased MT levels by 35- and 42-fold, respectively, indicating a synergistic effect in both cases. In contrast, when liver MT was preinduced by stress, MT levels were further increased by endotoxin only in an additive manner. In another experiment where liver MT induction by stress was studied in control rats and in rats with preinduced MT by Zn, endotoxin or stress, it was found that Zn pretreated animals had higher MT-I mRNA levels than endotoxin- or stress-pretreated ones. No synergisms between dexamethasone, Zn, TNF and IFN were observed in primary culture of hepatocytes. These results suggest that the observed synergisms between Zn and other MT inducers in vivo in the liver is a consequence of increased Zn levels in the body and mobilization capacity, with concomitant MT synthesis.

Animals↗
PubMed1996

Prognostic value of BHCG and local tumor invasion in stage I seminoma of the testis.

Approximately 10-15% of patients with stage 1 pure seminoma of the testis have an elevated preorchiectomy serum beta human chorionic gonadotropin level [1-4]. The prognostic significance of this elevation is unknown. We performed a multi-institutional retrospective review of 332 men with stage I pure seminoma of the testis and evaluated the prognostic significance of this elevation and the prognostic value of local invasion of the primary tumor. Twenty-five of 191 evaluable patients (13%) had elevated preorchiectomy beta human chorionic gonadotropin. All normalized postoperatively and are alive without evidence of disease with a median follow-up of 50 months (range 1-124 mo). Of 191 patients, 190 (99.5%) are alive and free of disease. One patient underwent salvage chemotherapy for a chest recurrence, and he is alive and free of disease at 72 months. We conclude that elevated preorchiectomy serum beta human chorionic gonadotropin level and local invasion of the primary tumor do not portend a poor prognosis in patients with clinical stage I pure seminoma of the testis.

Chorionic Gonadotropin, beta Subunit, Human↗
PubMed1996

Vav: function and regulation in hematopoietic cell signaling.

Vav, a 95 kDa proto-oncogene product expressed specifically in hematopoietic cells, was originally isolated as a transforming human oncogene. Vav contains an array of functional domains that are involved in interactions with other proteins and, possibly, with lipids. These include, among others, a putative guanine nucleotide exchange domain, a cysteine-rich region similar to the phorbol ester/diacylglycerol-binding domain of protein kinase C, a pleckstrin-homology domain, and Src-homology 2 and 3 (SH2 and SH3, respectively) domains. The presence of these domains, the transforming activity of the vav oncogene, and the rapid increase in tyrosine phosphorylation of Vav induced by triggering of diverse receptors indicate that it plays an important role in hematopoietic cell signaling pathways. Such a role is supported by recent studies using "knockout" mice and transiently transfected T cells, in which Vav deletion or overexpression, respectively, had marked effects on lymphocyte development or activation. The presence of a putative guanine nucleotide exchange domain, the prototype of which is found in the dbl oncogene product, implies that Vav functions as a guanine nucleotide exchange factor (GEF) for one (or more) members of the Ras-like family of small GTP-binding proteins. In support of such a role, Vav preparations were found in some (but not other) studies to mediate in vitro-specific GEF activity for Ras. Additional studies are required to identify the physiological regulators and targets of Vav, and its exact role in hematopoietic cell development and signaling.

Amino Acid Sequence↗
PubMed1996

Acute renal failure due to sulphadiazine crystalluria in AIDS patients.

We report two AIDS patients who developed acute renal failure while receiving sulphadiazine for cerebral toxoplasmosis. Renal ultrasound revealed diffuse bilateral echogenic shadowing material. 'Sheaves of wheat' crystals, typical of sulphadiazine crystalluria, were present in the urine. One patient required a percutaneous nephrostomy. Hydration and urine alkalinisation resulted in rapid improvement of renal function and ultrasonographic findings. Sulphadiazine-induced crystalluria and acute renal failure is increasingly frequent. Awareness of its existence may lead to prevention and early conservative treatment.

AIDS-Related Opportunistic Infections↗
PubMed1996

Effect of stress on mouse and rat brain metallothionein I and III mRNA levels.

The effect of immobilization stress on brain and liver metallothionein (MT) mRNA levels has been studied in mice and rats. Stress increased brain and liver MT-I mRNA levels in mice in a time-dependent manner, in agreement with the MT-I+II protein levels, suggesting an increased gene transcription during stress. In contrast, the brain-specific isoform, MT-III, tended to decrease during stress. In selected brain areas of rats, the overall tendency for both MT-I and MT-III mRNA levels was to be transiently decreased by stress in hippocampus, and increased in hypothalamus, cerebellum and the remaining brain tissues; adrenalectomy significantly affected MT mRNA levels either in basal conditions or during stress, with very different temporal patterns of response depending on the brain area studied. These results suggest that glucocorticoids could be involved in MT-I but also MT-III regulation. In both rats and mice, the subtle response to stress observed in the brain contrasts with the robust response in the liver, suggesting that the factors involved in MT regulation in both tissues differ substantially. In primary cultures enriched in astrocytes or neurons, MT-III mRNA was clearly detected by Northern blotting in both cases, suggesting that it is expressed in both types of cells. Dexamethasone appeared to decrease MT-III mRNA levels in cultured neurons and to increase them in astrocytes, which indicates that glucocorticoids have a different role in MT-III regulation in both cell types.

Animals↗
PubMed1995

Cytogenetic profile of minimally differentiated (FAB M0) acute myeloid leukemia: correlation with clinicobiologic findings.

Cytogenetic data were studied in 26 patients with de novo acute myeloid leukemia (AML) with minimal myeloid differentiation, corresponding to the M0 subtype of the French-American-British classification, in correlation with cytoimmunologic and clinical findings. Clonal abnormalities were detected in 21 cases (80.7%), 12 of which had a complex karyotype. Partial or total monosomy 5q and/or 7q was found, either as the sole aberration or in all abnormal metaphases, in 11 patients; in 8 cases, additional chromosome changes were present, including rearrangements involving 12p12-13 and 2p12-15 seen in 3 cases each. Five patients had trisomy 13 as a possible primary chromosome change; in 5 cases, nonrecurrent chromsome abnormalities were observed. Comparison of these findings with chromosome data from 42 patients with AML-M1 shows that abnormal karyotypes, complex karyotypes, unbalanced chromosome changes (-5/5q- and/or -7/7q- and +13) were observed much more frequently in AML-M0 than in AML-M1. Patients with abnormalities of chromosome 5 and/or 7 frequently showed trilineage myelodysplasia and low white blood cell count. Despite their relatively young age, complete remission was achieved in 4 of 11 patients only. Patients with +13 were elderly males with frequent professional exposure to myelotoxic agents. Unlike patients with clonal abnormalities, most AML-M0 patients with normal karyotype showed 1% to 2% peroxidase-positive blast cells at light microscopy and frequently achieved CR. It is concluded that (1) AML-M0 shows a distinct cytogenetic profile, partially recalling that of therapy-related AML, (2) different cytogenetic groups of AML-M0 can be identified showing characteristic clinicobiologic features, and (3) chromosome rearrangements may partially account for the unfavorable outcome frequently observed in these patients.

Adult↗
PubMed1995

Development of a PCR assay combined with a short enrichment culture for detection of Campylobacter jejuni in estuarine surface waters.

Two extraction procedures were examined, and it was found that DNA recovered from Campylobacter jejuni lysed by the cetyltrimethylammonium bromide (CTAB) method was more suitable for use as a PCR template than DNA released by the boiling method. The region targeted for PCR amplification was a 1.73-kb portion of the flagellin A gene of C. jejuni. The detection limit was lower than 30 cells per 100 ml in artificially contaminated waters. PCR assay and conventional culturing method had the same sensitivity, but results of the PCR technique were available within 48 h and so shortened the time necessary for detection by 48 h.

Bacteriological Techniques↗
PubMed1995

Valvuloplasty in traumatic aortic insufficiency due to subtotal tear of the intima.

Aortic regurgitation is one of the usual pathologic findings necessitating valve replacement in cardiac surgery. Several diseases may result in leaflet incompetence. Circumferential intimal tear of the aortic root with prolapse of the aortic valve commissures is a rare cause of aortic incompetence. We report the repair of the aortic wall and valve in 1 patient with such a tear 6 months after an important thoracic trauma. Three months after the aortic valve reconstruction the patient is in good condition and fully asymptomatic.

Aged↗
PubMed1995

In vitro autonomous proliferation in ANLL: clinical and biological significance.

In acute non-lymphoblastic leukemia (ANLL) progenitor cells frequently display a certain degree of autonomous growth. The aim of the present work was to analyze the autonomous proliferative capacity of leukemic progenitors in both de novo and secondary to myeloproliferative disorders (MPD) and myelodysplastic syndromes (MDS), acute myeloid leukemias and to correlate with clinical and biological characteristics of the disease. Clonogenic assays with and without leukocyte conditioned medium with PHA (LCM-PHA) were performed and the autonomous proliferation index (API) calculated in a series of 50 patients (34 de novo ANLL, eight secondary to MPD and eight secondary to MDS). Patients were divided into two groups according to their API, low (< or = 0.4) or high (> 0.4). Autonomous growth was observed in 84% of cases studied (82% in de novo ANLL, 75% secondary to MDS and 100% secondary to MPD). The group with the highest API (29 patients) had increased levels of hemoglobin (P = 0.006) and platelets (P = 0.01). A high API was also associated with an immature phenotype of blast cells (P = 0.02). Upon analyzing the de novo ANLL separately we observed that a high API correlated with high Hb values (P = 0.02), a lower rate of complete remission (42% vs 61%) and a lower survival rate (medium of 3 vs 10 months). These findings suggest that the capacity for autonomous proliferation can condition the clinical and biological profile of the disease.

Adult↗
PubMed1995

Lignan models as inhibitors of Phanerochaete chrysosporium lignin peroxidase.

The lignan 8,8'-bis-(methylenedioxy)cinnamic acid (BMDCA) is a powerful competitive inhibitor (K1 = 2.0 microM) of the lignin peroxidase (LiP) from Phanerochaete chrysosporium and of the extracellular peroxidase of Phlebia radiata (I0.5 = 10 microM). BMDCA derivatives with the same double bond system also inhibited these enzymes to some extent. If the double bonds were hydrogenated, the inhibitory effect was lost. HRP-VIII and HRP-XI were slightly inhibited by BMDCA (I0.5 > 50 microM) and two plant peroxidases described as efficient lignan synthesizers were unaffected. Liquid cultures of P chrysosporium did not discolour the dve Poly R478 when 250 microM of BMDCA was present.

Anthraquinones↗
PubMed1995

Diazoxide blocks the morphine induced lengthening of action potential duration on guinea-pig papillary muscle.

1. Intracellular microelectrodes were used to evaluate the possible involvement of potassium currents in the action potential prolongation induced by morphine. To this purpose we investigated the electrophysiological effect of morphine on the isolated guinea pig right ventricular papillary muscle in the presence of the potassium channel opener and inhibitor diazoxide and glibenclamide respectively. 2. Diazoxide (1 microM), which is devoid of effect on its own, blocks the lengthening of action potential duration (APD) induced by morphine (5 mM). 3. However, in the presence of glibenclamide (1 microM), morphine (5 mM) prolonged APD in approximately the same proportion as that observed when used alone. 4. These results suggest that diazoxide but not glibenclamide sensitive potassium channels could mediate the APD prolongation induced by morphine.

Action Potentials↗
PubMed1995

Random amplified polymorphic DNA fingerprinting of Campylobacter jejuni and C. coli isolated from human faeces, seawater and poultry products.

The polymerase chain reaction (PCR) technique was used to obtain randomly amplified polymorphic DNA (RAPD) profiles from 64 type and serotype reference strains and 114 isolates of Campylobacter jejuni and C. coli from food, seawater and human faeces. Genetic diversity was detected among the strains as a total of 118 different RAPD profiles were obtained, each one containing from 4 to 11 bands between 0.30 and 1.50 kb. The discriminatory power of a random 10-mer primer (sequence 5'-CAATCGCCGT-3') was assessed. In general, no profiles were common to strains of the same Penner serogroup, but occasional strains from different Penner serotypes shared identical band profiles. RAPD analysis also differentiated between the species, and after numerical analysis, five main clusters were defined at the 40% similarity level, corresponding to C. jejuni, C. coli and C. lari with some exceptions. RAPD profiling of Campylobacter is highly discriminatory and is a valuable new alternative to traditional typing in epidemiological studies.

Campylobacter↗
PubMed1995

Looking forward: using a sociocultural perspective to reframe the study of learning disabilities. VODD group.

The purpose of this series has been to invite educators involved with individuals with learning disabilities to look through other lenses and listen to other voices. In this article, the authors use a sociocultural perspective of teaching and learning, based on cultural-historical and activity theory, to synthesize the articles of this series and to project where inquiry in the field of learning disabilities might be headed. A model is used to organize the discussion and help illuminate the sociocultural nature of the pathways of ideas, expectations, and activities that either foster or hinder students' school experiences. This final article invites readers to refocus and reframe their conversations about learning disabilities based on the "new visions" that have been presented in this series.

Child↗
PubMed1995

Reliability of in-bed weighing procedures for critically ill infants.

The purpose of this study was to describe the intra- and interexaminer reliability of weight measurements obtained from critically ill infants on an in-bed electronic scale. Weight measurements were obtained using the in-bed scale (Smart Model 35, Olympic Medical, Seattle, Washington) for 32 infants; 16 were in an incubator, and 16 were under a radiant warmer. Two nurses each obtained two weight measurements for each infant for three consecutive days, for a total of 96 data collection sessions. The nurses were blinded to their own and to the other nurse's weight measurements. The average mean absolute difference for individual nurses' weight measurements (interexaminer reliability) was 12.58 gm for weights obtained in the incubator and 19.19 gm for weights obtained under the radiant warmer. The average mean absolute difference for pairs of nurses' weight measurements (interexaminer reliability) was 14.29 gm for weights obtained in the incubator and 24.42 gm for weights obtained under the radiant warmer. The average mean absolute differences for weights obtained in the two bed types differed significantly for both intra- (Z = -2.46, p = .0141) and interexaminer (Z = -3.11, p = .0019) reliability. The number of pieces of equipment that had to be held during the weight measurement was weakly correlated with both the intra- (rs = .1878, p = .0091) and interexaminer (rs = .1600, p = .0266) mean absolute differences. These findings suggest that weight measurements of critically ill infants obtained using the Smart Model 35 in-bed electronic scale are sufficiently reliable for calculation of medication, parenteral fluid, blood replacement, and nutritional requirements.(ABSTRACT TRUNCATED AT 250 WORDS)

Anthropometry↗
PubMed1994

The substrate specificity of Saccharomyces cerevisiae myristoyl-CoA: protein N-myristoyltransferase. Polar probes of the enzyme's myristoyl-CoA recognition site.

Saccharomyces cerevisiae myristoyl-CoA:protein N-myristoyltransferase (Nmt1p) is a monomeric enzyme that is essential for vegetative growth. Nmt1p catalyzes the co-translational transfer of myristate from CoA to the amino-terminal Gly of cellular proteins in an ordered Bi Bi reaction mechanism that initially involves binding of myristoyl-CoA to the apoenzyme. Forty one fatty acid analogs were synthesized to define features in the acyl chain of myristoyl-CoA which are important determinants of its recognition by Nmt1p's acyl-CoA binding site as well as to help us deduce the structure of the binding site itself. These analogs included dicarboxylic acids, omega-nitrocarboxylic acids, analogs equivalent in length to C13:0-C15:0 which contain electronegative halogens at their omega-termini, hydroxytetradecanoic acids with hydrogen replaced by OH from C3 to C13, and azidophenyl-containing fatty acids with the linear azide unit attached either meta or para to phenyl and with variations in the length of their methylene chains. These compounds were converted to their CoA derivatives using Pseudomonas acyl-CoA synthetase and then surveyed as substrates for purified Nmt1p in an in vitro assay system that included an octapeptide derived from residues 1-8 of the human immunodeficiency virus Pr55gag polyprotein precursor. The results suggest that the myristoyl-CoA binding site contains a conical-shaped "receptor" that interacts with the omega-terminus of the bound acyl chain of acyl-CoAs. The acuteness of this cone determines the enzyme's capacity to accommodate steric bulk at the omega-terminus as well as Nmt1p's sensitivity to the distance between the eclipsed C5-C6 bond of a bound acyl chain and its omega-terminus. The activity profile of the various analog-CoAs also indicates that the enzyme's myristoyl-CoA binding site can accommodate fatty acid analogs with marked increases in polarity at their omega-terminus (compared to C14:0) as long as their chain length is equivalent to that of myristate.

Acyl Coenzyme A↗