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Biomedical subjects

S Lopez

Publications and source records attributed to S Lopez.

At least 73 records · Page 4Linked to original sources
PubMed1997

Depression in Latina mothers of children with mental retardation: a neglected concern.

Depression among 148 Latina women who have children with mental retardation was examined. Results showed that their depressive symptomatology was elevated, with almost half reporting negative experiences in excess of a commonly used cut-off for the Center for Epidemiologic Studies Scale (CES-D). Depression scores related to variables pertaining to the child, mother's health and level of acculturation, and aspects of stress and coping. When mothers were categorized in three groups by CES-D scores, discriminant analysis correctly classified 84% of the low and high group mothers. High CES-D membership was predicted by mothers' reporting more family problems, worse health, fewer interactions with English-speaking persons in their daily lives, and more negative feelings about parenting their child with mental retardation.

Adaptation, Psychological↗
PubMed1997

[Secondary hyperparathyroidism and multiple vertebral brown tumors: cure after parathyroidectomy].

A 46 year old man was referred for severe left cruralgia and multiple vertebral cystic defects on CT-scan. He was treated by hemodialysis since 1987 for chronic renal failure secondary to focal and segmental glomerulosclerosis, diagnosed in 1960 on renal biopsy. Dialysis schedule consisted of 3 x 4 h/week with a polysulfone dialyser and 1.75 mMol Ca containing bicarbonate dialysate. On early 1995, the patient complained of back pain and cruralgia, which gradually worsened. Vertebral column CT-scan and MRI showed multiple lytic lesions expanding into the medullary canal. Biological hyperparathyroidism was present. To differentiate between hyperparathyroidism with brown tumors, malignancy and amyloid deposition, an iliac biopsy and a biopsy of a corporeal vertebral cyst were done. They showed florid hyperparathyroidism and brown tumors. The patient was submitted to surgical parathyroidectomy. Six months after surgery, cruralgia resumed, CT-scan and MRI showed refilling of the cysts by calcic material.

Glomerulosclerosis, Focal Segmental↗
PubMed1996

Identification of distal silencing elements in the murine interferon-A11 gene promoter.

The murine interferon-A11 (Mu IFN-A11) gene is a member of the IFN-A multigenic family. In mouse L929 cells, the weak response of the gene's promoter to viral induction is due to a combination of both a point mutation in the virus responsive element (VRE) and the presence of negatively regulating sequences surrounding the VRE. In the distal part of the promoter, the negatively acting E1E2 sequence was delimited. This sequence displays an inhibitory effect in either orientation or position on the inducibility of a virus-responsive heterologous promoter. It selectively represses VRE-dependent transcription but is not able to reduce the transcriptional activity of a VRE-lacking promoter. In a transient transfection assay, an E1E2-containing DNA competitor was able to derepress the native Mu IFN-A11 promoter. Specific nuclear factors bind to this sequence; thus the binding of trans-regulators participates in the repression of the Mu IFN-A11 gene. The E1E2 sequence contains an IFN regulatory factor (IRF)-binding site. Recombinant IRF2 binds this sequence and anti-IRF2 antibodies supershift a major complex formed with nuclear extracts. The protein composing the complex is 50 kDa in size, indicating the presence of IRF2 or antigenically related proteins in the complex. The Mu IFN-A11 gene is the first example within the murine IFN-A family, in which a distal promoter element has been identified that can negatively modulate the transcriptional response to viral induction.

Animals↗
PubMed1995

Bimodal distribution of proteinase 3 (PR3) surface expression reflects a constitutive heterogeneity in the polymorphonuclear neutrophil pool.

Proteinase 3, which is known as an intracellular serine protease of neutrophils, was detected at the surface of a subpopulation of freshly isolated PMN. The proportion of PR3-positive and -negative PMN, observed by flow cytometry with anti-PR3 mAbs or ANCA autoantibodies, varies among individuals but is extremely stable for each individual over prolonged time periods. After PMN degranulation by FMLP with cyt. B, membrane PR3 expression increases but the proportion of low and high PR3-expressing cells remains stable. The existence of a subset of PMN which spontaneously expresses PR3 and varies among individuals, may be relevant to the pathogenesis of anti-PR3 ANCA autoantibody-related vasculitis.

Animals↗
PubMed1995

Identification and functional characterization of an erythroid-specific enhancer in the L-type pyruvate kinase gene.

The rat L-type pyruvate kinase gene is transcribed either from promoter L in the liver or promoter L' in erythroid cells. We have now cloned and functionally characterized an erythroid-specific enhancer, mapped in the fetal liver as hypersensitive site B (HSSB) at 3.7 kilobases upstream from the promoter L'. Protein-DNA interactions were examined in the 200-base pair core of the site by in vivo footprinting experiments. In the fetal liver, footprints were revealed at multiple GATA and CACC/GT motifs, whose association is the hallmark of erythroid-specific regulatory sequences. Functional analysis of the HSSB element in transgenic mice revealed properties of a cell-restricted enhancer. Indeed, this element was able to activate the linked ubiquitous herpes simplex virus thymidine kinase promoter in erythroid tissues. The activation was also observed in a variety of nonerythroid tissues known to synthesize GATA-binding factors. In the context of L'-PK transgenes, HSSB was not needed for an erythroid-specific activation of the L' promoter, while it was required to stimulate the L' promoter activity to a proper level. Finally, HSSB cannot be replaced by strong ubiquitous viral or cellular enhancers, suggesting a preferential interaction of the HSSB region with the L' promoter.

Animals↗
PubMed1995

Neutrophil expression of tumour necrosis factor receptors (TNF-R) and of activation markers (CD11b, CD43, CD63) in rheumatoid arthritis.

In vitro analysis of polymorphonuclear neutrophils (PMN) has allowed various stages of cell activation to be distinguished, characterized by the expression level of specific membrane markers and of functional receptors. Among those, TNF-alpha receptors (TNF-R) are modulated by various PMN activators, a mechanism which may be important to control cell responses to TNF in inflammatory reactions such as rheumatoid arthritis (RA). PMN, isolated from the blood of 36 RA patients and from the synovial fluid of 23 of them, were analysed for membrane expression of the two TNF-R (p55 and p75). Soluble p55 and p75 (sTNF-R) and TNF concentrations were measured in the plasma and synovial fluid by specific ELISA assays. Our results show that PMN from the blood of RA patients bear a normal number of TNF-R, with a normal p55/p75 ratio, compared with PMN from normal controls. Soluble TNF-R levels were similar in patients and normal plasma. In spite of high endogenous TNF concentration, patients' circulating PMN were not activated, as shown by a CD11b/CD18 expression similar to that of control resting cells. In contrast with blood neutrophils, PMN from RA patients' synovial fluids had an activated phenotype, characterized by increased expression of CD11b, decreased expression of leukosialin, CD43, and the appearance on the plasma membrane of an azurophil granule protein, CD63. High levels of soluble TNF-R were measured in RA synovial fluids. Nevertheless, membrane TNF-R levels and p55 and p75 proportions were similar to those of PMN from normal blood. These results suggest the existence of regulatory mechanisms which maintain a stable neutrophil expression of TNF-R as well as a balance between both types of receptors in inflammatory situations where neutrophils are strongly activated.

Antigens, CD↗
PubMed1995

Immigrant families coping with schizophrenia. Behavioral family intervention v. case management with a low-income Spanish-speaking population.

BACKGROUND: This investigation compared the effectiveness and cross-cultural applicability of behavioural family management (BFM) and standard case management in preventing exacerbation of symptoms and relapse in schizophrenia. METHOD: Forty low-income Spanish-speaking people with a diagnosis of schizophrenia were randomly assigned to receive standard case management or behavioural family management after stabilisation with neuroleptic medication. RESULTS: Survival analyses indicated that among the less acculturated patients BFM was significantly related to greater risk of exacerbation of symptoms. Among the more acculturated patients, risk of exacerbation could be predicted by medication compliance but not by type of intervention. In analyses of symptom severity and functional status at 1-year follow-up, the level of patient acculturation was found to be significantly related to various measures of treatment outcome. CONCLUSION: Sociocultural factors affect responses to different types of intervention. The results did not support earlier findings of a beneficial effect of BFM when applied to a socioculturally diverse population.

Acculturation↗
PubMed1995

Third place winner of the Conrad Jobst Award in the gold medal paper competition. Prevention of spinal cord dysfunction in a new model of spinal cord ischemia.

Paraplegia or paraparesis caused by temporary cross-clamping of the aorta is a devastating sequela in patients after surgery of the thoracoabdominal aorta. No effective clinical method is available to protect the spinal cord from ischemic reperfusion injury. A small animal (rat) model of spinal cord ischemia is established to better understand the pathophysiological events and to evaluate potential treatments. Eighty-one male Sprague-Dawley rats weighing 300 g to 350 g were used for model development (45) and treatment evaluation (36). The heparinized and anesthetized rat was supported by a respirator following tracheostomy. The thoracic aorta was cannulated via the left carotid artery for post-clamping intra-aortic treatment solution administration. After thoracotomy, the aorta was freed and temporarily clamped just distal to the left subclavian artery and just proximal to the diaphragm for different time intervals: 0, 5, 10, 15, 20, 25, 30, 35, and 40 minutes (five animals per group). The motor function of the lower extremities postoperatively showed consistent impairment after 30 minutes clamping (5/5 rats were paralyzed), and this time interval was used for treatment evaluation. For each treatment, six animals per group were used, and direct local intra-aortic infusion of physiologic solution (2 mL) at different temperatures with or without buffer substances was given immediately after double cross-clamp to protect the ischemic spinal cord. Arterial blood (2 mL) was infused in the control group. The data indicate that the addition of HCO3-(20 mM) to the hypothermic (15 degrees C) solution offered complete protection of the spinal cord from ischemic injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1995

A non-linear compartmental model to describe forage degradation kinetics during incubation in polyester bags in the rumen.

A new model for describing forage degradation kinetics during incubation in the rumen using polyester bags is presented. Attention is given to dealing with the problem of deviations from exponential behaviour in the early stages of degradation by devising a function capable of representing exponential or sigmoidal trends. This is achieved by allowing part of the fractional degradation rate to vary with time of incubation, thus enabling responses other than those expected under simple first-order kinetics to be described. Seven sets of data consisting of 620 curves were analysed to study the performance of the new model compared with a commonly used exponential model. The proportion of significantly better fits varied from set to set. The new model deals successfully with sigmoidal behaviour and, thus, provides a means of analysing the degradation profiles of low-quality forage feeds.

Animal Feed↗
PubMed1994

Expression of the L-type pyruvate kinase gene and the hepatocyte nuclear factor 4 transcription factor in exocrine and endocrine pancreas.

The L-pyruvate kinase (L-PK) gene is slightly active in normal and tumoral endocrine pancreatic tissues while, in vivo, this gene is not transcribed in the exocrine pancreas. Nevertheless, the L-PK gene is re-expressed at a very low level in cultured 266.6 cells derived from an exocrine pancreas carcinoma. The L-PK gene is early activated in endodermal tissues, e.g. yolk sac and primitive intestine; it remains transcribed in fetal pancreas. In adult, L-PK gene expression is restricted to some endocrine cells. Hepatocyte nuclear factor (HNF) 1 and HNF4 are the main tissue-restricted transcription factors involved in tissue-specific expression of the L-PK gene. HNF1 concentration is similar in liver and all pancreatic cells. HNF4 concentration is high in liver, much lower in islets of Langerhans, endocrine pancreatic tumors, and cultured insulinoma cells, and is scarcely detectable in adult exocrine pancreas. This distribution of HNF4 parallels the expression of the L-PK gene. In vivo footprinting experiments show that the HNF1 binding site is similarly occupied in both adult liver and adult pancreas, in which this gene is practically inactive. In this latter tissue, however, the HNF4 binding site is differently occupied with respect to the liver. Since the chromatin structure remains open around the L-PK promoter in pancreas, the L-PK gene can probably be re-expressed under certain circumstances, for instance in cancerous pancreatic cells.

Animals↗
PubMed1994

Aluminium allergy in patients hyposensitized with aluminium-precipitated antigen extracts.

During hyposensitization therapy with aluminium-precipitated antigen solutions, a small % of patients develop persistent subcutaneous nodules at the injection site; the existence of delayed sensitivity to aluminium has been implicated in the pathogenesis of these nodules. We studied the prevalence of aluminium sensitivity (using patch, prick and intradermal tests) and common contact allergens (TRUE Test) in 20 healthy subjects, and in 40 patients treated with aluminium-containing extracts, 20 of whom had persistent subcutaneous nodules that remained for more than 2 months, the other half having no nodular reactions or nodules that remained for less than 2 months. Aluminium sensitivity was found only in those patients of the treated group who had persistent nodular reactions, 4 cases of positivity to an aluminium chloride patch test being found. All 4 cases were women, nodules remained for more than 6 months, and intracutaneous tests were negative. 3 of them also had contact sensitivity to nickel. In 2 cases, nodules were removed for histological and histochemical examination, showing non-specific inflammatory granulomas, and aluminium crystals being found in only 1 case. It is concluded that delayed sensitivity to aluminium appears to be implicated in the pathogenesis of persistent nodular reactions, but sensitivity to aluminium was not found in patients treated with aluminium-precipitated extracts without persistent nodular reactions.

Adolescent↗
PubMed1994

Serotypic differentiation of rotaviruses in field samples from diarrheic pigs by using nucleic acid probes specific for porcine VP4 and human and porcine VP7 genes.

Of 216 fecal and intestinal samples collected from nursing or weaned diarrheic pigs in the United States and Canada, 57 were identified as group A rotavirus positive by RNA electrophoresis and silver staining. Fifty-seven and 52 rotavirus-positive samples were analyzed by hybridization with Gottfried and OSU PCR-derived gene 9 and 4 probes, respectively. Only 17 samples were identified with either homologous VP4 (P)- or VP7 (G)-coding genes or both. One rotavirus identified as G4 and P7 was similar to the previously characterized interserotype rotavirus, SB-1A. Additional hybridization analyses were performed with PCR-derived probes prepared from gene 9 cDNA of the human rotaviruses Wa (G1), DS-1 (G2), and P (G3) and of the porcine rotavirus YM (G11). Eleven of 52 samples collected and analyzed from swine in Ohio, California, and Nebraska were identified as G11. No samples with G1-, G2-, or G3-type specificities were detected among the 25 of 57 rotavirus-positive samples analyzed with human rotavirus-derived probes. Further investigations with a PCR-derived gene 4 probe prepared from porcine rotavirus YM revealed hybridization specificities similar to those of the OSU gene 4 probe.

Animals↗
PubMed1994

Nucleocapsid-glycoprotein interactions required for assembly of alphaviruses.

We have studied interactions between nucleocapsids and glycoproteins required for budding of alphaviruses, using Ross River virus-Sindbis virus chimeras in which the nucleocapsid protein is derived from one virus and the envelope glycoproteins are derived from the second virus. A virus containing the Ross River virus genome in which the capsid protein had been replaced with that from Sindbis virus was almost nonviable. Nucleocapsids formed in normal numbers in the infected cell, but very little virus was released from the cell. There are 11 amino acid differences between Ross River virus and Sindbis virus in their 33-residue E2 cytoplasmic domains. Site-specific mutagenesis was used to change 9 of these 11 amino acids in the chimera from the Ross River virus to the Sindbis virus sequence in an attempt to adapt the E2 of the chimera to the nucleocapsid. The resulting mutant chimera grew 4 orders of magnitude better than the parental chimeric virus. This finding provides direct evidence for a sequence-specific interaction between the nucleocapsid and the E2 cytoplasmic domain during virus budding. The mutated chimeric virus readily gave rise to large-plaque variants that grew almost as well as Ross River virus, suggesting that additional single amino acid substitutions in the structural proteins can further enhance the interactions between the disparate capsid and the glycoproteins. Unexpectedly, change of E2 residue 394 from lysine (Ross River virus) to glutamic acid (Sindbis virus) was deleterious for the chimera, suggesting that in addition to its role in nucleocapsid-E2 interactions, the N-terminal part of the E2 cytoplasmic domain may be involved in glycoprotein-glycoprotein interactions required to assemble the glycoprotein spikes. The reciprocal chimera, Sindbis virus containing the Ross River virus capsid, also grew poorly. Suppressor mutations arose readily in this chimera, producing a virus that grew moderately well and that formed larger plaques.

Alphavirus↗