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Biomedical subjects

M Ramirez

Publications and source records attributed to M Ramirez.

At least 91 records · Page 5Linked to original sources
PubMed1995

Transport and metabolism of adenosine in the perfused human placenta.

Uptake and metabolism of adenosine by human placenta were studied using the single-circulation paired-tracer technique. When isolated cotyledons were perfused through the fetal (basal) circulation at mean pressures of 36 +/- 3.3 mmHg and mean flow rates of 6.6 +/- 0.3 ml/min the maximal [3H]adenosine uptake was 51.3 +/- 3.9 per cent. The uptake was not changed when the vascular resistance was pharmacologically increased. Adenosine uptake was significantly inhibited by adenosine, inosine and nitrobenzylthioinosine (NBMPR), but was unaffected by hypoxanthine. The kinetic analysis of adenosine transport showed it to be a saturable and, Na(+)-independent process, with a Km of 60.8 microM and a Jmax of 0.148 mumol/min. Thin layer chromatographic analysis showed that about 65 per cent of [3H]adenosine was metabolized (10-30 sec) in a single passage through the fetoplacental circulation. [3H]hypoxanthine and [3H]adenine were the major products recovered in the venous perfusate. In the presence of NBMPR the fractional recovery of [3H]adenine and [3H]phosphorylated derivatives was reduced while that of [3H]hypoxanthine was increased. These overall results show that the uptake of adenosine is a Na(+)-independent, NBMPR-sensitive, carrier-mediated process, which appears to be specific for nucleosides, and suggests that metabolization of adenosine proceeds both intra- and extracellularly.

Adenosine↗
PubMed1995

Evidence for the geographic spread of a methicillin-resistant Staphylococcus aureus clone between Portugal and Spain.

Methicillin-resistant Staphylococcus aureus (MRSA) isolates collected during a 7-month period in 1992 and 1993 at Hospital Pulido Valente (340 beds), Lisbon, Portugal, were characterized by a combination of genotypic and phenotypic methods. Clonal identities were determined by probing ClaI digests (i) with a mecA probe and (ii) with a Tn554 probe and (iii) by pulsed-field gel electrophoresis (PFGE) patterns of chromosomal SmaI digests. mecA-ClaI type I was predominant among these isolates (38 of 43). Most of these (37 of 38 [97.4%]) were associated with a single Tn554 pattern, pattern E, and the majority (23 of 38 [61%]) also showed a relatively uniform chromosomal background, as indicated by PFGE (PFGE pattern A). The major clone (mecA-ClaI type I::Tn554 type E and PFGE pattern A) at Hospital Pulido Valente was indistinguishable by these molecular typing criteria from the dominant clone that had been identified in two major current outbreaks of MRSA disease in Spain (Barcelona and Madrid). The Portuguese and Spanish clones also had a common heterogeneous class 3 phenotype and identical multidrug resistance patterns. The data presented in this work support the notion that MRSA clones can spread across considerable geographic distances.

Cross Infection↗
PubMed1994

Tibial hemimelia syndrome: prenatal diagnosis by real-time ultrasound.

The tibial hemimelia syndrome is a rare autosomal dominant condition associated with limb deficiencies. We recently diagnosed this condition in a pregnancy at 16.5 weeks' gestation by ultrasound and a positive family history. To our knowledge, this represents the first case to be detected prenatally.

Adult↗
PubMed1994

Prenatal diagnosis of unilateral megalencephaly by real-time ultrasonography.

Unilateral megalencephaly is a rare anomaly of neuronal cell migration. We recently diagnosed this condition in a fetus at 20 weeks' gestation with ultrasonography and magnetic resonance imaging. The pregnancy was terminated and postmortem magnetic resonance imaging and autopsy confirmed the diagnosis. To our knowledge this represents the first case to be prenatally diagnosed with certainty.

Adult↗
PubMed1994

Systemic and local cytokine profiles in endotoxin-induced preterm parturition in mice.

OBJECTIVE: Our purpose was to determine whether endotoxin-induced preterm parturition is preceded by a change in the maternal serum and amniotic fluid concentrations of tumor necrosis factor-alpha, interleukin-6, and interleukin-1 alpha. STUDY DESIGN: C3H/HeN pregnant mice at 15 days of gestation (70% gestation) were randomized to receive an intraperitoneal injection of phosphate-buffered saline solution or lipopolysaccharide (50 micrograms/mouse). Blood (n = 93) and amniotic fluid (n = 58) were collected at 1, 4, and 10 hours after lipopolysaccharide injection. Tumor necrosis factor-alpha, interleukin-6, and interleukin-1 alpha were determined with sensitive and specific enzyme-linked immunoassays. RESULTS: The injection-to-delivery interval was shorter in mice injected intraperitoneally with 50 micrograms lipopolysaccharide than in phosphate-buffered saline solution-treated mice (median 15.5 hours, range: 10 to 105 hours vs median 88.5 hours, range: 53 to 105 hours; p < 0.001). In comparison with phosphate-buffered saline solution-treated mice, a distinct serum cytokine pattern was observed in lipopolysaccharide-treated mice. Concentrations of tumor necrosis factor-alpha were detectable 1 and 4 hours after lipopolysaccharide injection (median 874 pg/ml, range: < 100 to 8000 pg/ml, p < 0.001; and median 263 pg/ml, range: < 100 to 927 pg/ml, p < 0.001, respectively). Concentrations of interleukin-6 were elevated at 1, 4, and 10 hours (median 11.8 ng/ml, range: 6 to 500 ng/ml, p < 0.001; median 27.1 ng/ml, range: 4.5 to 192 ng/ml, p < 0.001; median 1.95 ng/ml, range: < 0.05 to 35 ng/ml, p < 0.015, respectively). Concentrations of interleukin-1 alpha were significantly increased 4 hours after lipopolysaccharide injection (median 102 pg/ml, range: < 15 to 306 pg/ml, p < 0.001). A cytokine pattern distinct from serum was observed in amniotic fluid of lipopolysaccharide-treated mice. In comparison with controls, concentrations of interleukin-6 were significantly elevated 4 and 10 hours after treatment with lipopolysaccharide (median 0.88 ng/ml, range: 0.40 to 2.7 ng/ml, p < 0.025; and median 4 ng/ml, range: 1.9 to 33.6 ng/ml, p < 0.001, respectively). Interleukin-1 alpha was elevated 10 hours after lipopolysaccharide treatment (median 185.3 pg/ml, range: 38 to 511 pg/ml, p < 0.015). Tumor necrosis factor-alpha was not significantly increased in amniotic fluid. CONCLUSION: Preterm delivery after lipopolysaccharide administration is preceded by the appearance of dramatic increases in maternal serum concentrations of tumor necrosis factor-alpha, interleukin-6, and interleukin-1 alpha and in amniotic fluid concentrations of interleukin-6 and interleukin-1 alpha.

Amniotic Fluid↗
PubMed1994

Interleukin-1 receptor antagonist (IL-1ra) production by human amnion, chorion, and decidua.

PROBLEM: This study was conducted to determine whether (1) conditioned media from unstimulated primary cultures of human amnion, chorion, or decidua contain detectable concentrations of IL-1ra in vitro, and (2) bacterial endotoxin (LPS), tumor necrosis factor-alpha (TNF-alpha), or IL-1-beta (IL-1 beta) stimulate amnion, chorion, or decidua to produce increased amounts of IL-1ra. METHOD: Placentae were obtained from women at term with intact membranes before the onset of labor. Amnion, chorion, and decidual cells were isolated by standard procedures and grown to confluence. Cells were then cultured in quadruplicate for 16 h in tissue culture medium supplemented with 10% fetal calf serum or, additionally, with various concentrations of Escherichia coli LPS, TNF-alpha, or IL-1 beta. Culture supernatants were collected, and concentrations of IL-1ra were quantitated by a sensitive and specific enzyme-linked immunosorbent assay for IL-1ra. RESULTS: Results showed that primary cultures of amnion and chorion from 4 of 9 and decidua from 10 of 12 placentae had detectable rates of production of IL-1ra (ranges: 0.08-6.5, 0.42-12.1, and 1.55-96.5 pg IL-1ra/microgram protein/16 h, respectively). In addition, LPS (10-1,000 ng/ml) and IL-1 beta (0.1-10 ng/ml), but not TNF-alpha (0.01-100 ng/ml), stimulated decidual cells to release/secrete increased amounts of IL-1ra compared with media alone (range: 2.5-400 pg IL-1ra/microgram protein/16 h, P < 0.0001). In contrast, neither LPS, TNF-alpha, or IL-1 beta could stimulate amnion or chorion to release/secrete IL-1ra. CONCLUSIONS: These results indicate (1) that amnion, chorion, and predominantly decidua, can release or secrete IL-1ra in vitro, and (2) that LPS and IL-1 beta can stimulate decidual cells to produce increased amounts of IL-1ra.

Amnion↗
PubMed1994

Immunochemical identification of Brucella abortus lipopolysaccharide epitopes.

Sera from Brucella abortus-infected and -vaccinated bovines recognized four lipopolysaccharide (LPS) determinants: two in the O-polysaccharide (A and C), one in the core oligosaccharide from rough Brucella LPS (R), and one in lipid A (LA). From 46 different hybridomas secreting monoclonal antibodies (MAbs) against various LPS moieties, 9 different specificities were identified. Two epitopes, A and C/Y, were present in the O-polysaccharide. Two epitopes were found in the core oligosaccharide (R1 and R2) of rough Brucella LPS. MAbs against R1 and R2 epitopes reacted against LPS from different rough Brucella species; however, MAbs directed to the R2 epitope also reacted against enterobacterial LPS from deep rough mutants. Three epitopes (LA1, LA2, and LA3) were located in the lipid A backbone. Different sets of MAbs recognized two epitopes in the lipid A-associated outer membrane protein (LAOmp3-1 and LAOmp3-2). LPS preparations from smooth brucellae had small amounts of rough-type LPS. Although LPS from rough brucellae did not show smooth-type LPS in western blots (immunoblots), two hybridomas generated from mice immunized with rough B. abortus produced antibodies against smooth B. abortus LPS. Results are discussed in relation to the structure and function of B. abortus LPS and to previous findings on the epitopic density of the molecule.

Animals↗
PubMed1993

Comparison of the course to end-stage renal disease of type 1 (insulin-dependent) and type 2 (non-insulin-dependent) diabetic nephropathy.

Is the course leading to diabetic end-stage renal disease similar for Type 1 (insulin-dependent) and Type 2 (non-insulin-dependent) diabetes mellitus? We identified all diabetic end-stage renal disease patients starting renal replacement therapy from 1989 to 1991 in two urban counties in Texas. Three ethnic/racial groups were enrolled: Mexican Americans, non-Hispanic Whites, African Americans. Patients were interviewed and their medical records, both inpatient and out-patient, were abstracted for relevant diagnostic and therapeutic information. We attempted to obtain records as far back as the onset of diabetes or hypertension and from all physicians who had cared for the patient. An historical algorithm was used to determine diabetic type. Of the patients enrolled, 91 were Type 1 and 438 were Type 2 diabetic patients. Type 1 diabetic patients had higher mean glucose levels in the first 10 years of diabetes (16.3 vs 11.4 mmol/l) but lower systolic blood pressures (148 vs 157 mmHg). The duration of diabetes prior to end-stage renal disease was longer for Type 1 than Type 2 patients (22 vs 17 years). Type 1 diabetic patients were more likely to have other microvascular complications (retinopathy, neuropathy, gastroparesis), less likely to have coronary disease (myocardial infarction and congestive heart failure), and had similar rates of stroke and vascular surgery procedures (carotid endarterectomy, coronary artery bypass surgery, aortofemoral bypass). Type 1 and Type 2 diabetic patients were just as likely to have a first degree relative with hypertension (60.5 vs 65.5%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

The diagnostic and prognostic value of amniotic fluid white blood cell count, glucose, interleukin-6, and gram stain in patients with preterm labor and intact membranes.

OBJECTIVE: Our goal was to compare the value of amniotic fluid tests in the detection of microbial invasion of the amniotic cavity and in the relationship with the amniocentesis-to-delivery interval and neonatal complications in patients with preterm labor and intact membranes. STUDY DESIGN: Amniotic fluid was retrieved by transabdominal amniocentesis from 120 patients with preterm labor and intact membranes. Fluid was cultured for aerobic and anaerobic bacteria and for mycoplasmas. Amniotic fluid analysis included a Gram stain, white blood cell count, glucose and interleukin-6 determinations. Logistic regression and Cox's proportional hazards model were used for analysis. RESULTS: (1) The prevalence of positive amniotic fluid cultures was 9.2% (11/120); (2) patients with microbial invasion had a shorter amniocentesis-to-delivery interval and a higher neonatal complications rate than patients with a negative culture; (3) the most sensitive test for the detection of microbial invasion of the amniotic cavity was amniotic fluid interleukin-6 determinations (cutoff 11.3 ng/ml) (sensitivity; for interleukin-6 100%, for glucose 81.8%, for white blood cell count 63.6%, and for Gram stain 63.6%; p < 0.05 for all comparisons); (4) the most specific test was the Gram stain of amniotic fluid (specificity: for Gram stain 99.1%, for white blood cell count 94.5%, for interleukin-6 82.6%, and for glucose 81.6%; p < 0.01 for all); (5) of all amniotic fluid tests, interleukin-6 determinations were the only ones that had significant relationship with the amniocentesis-to-delivery interval and neonatal complications. CONCLUSION: Interleukin-6 concentrations in amniotic fluid are better indicators of microbial invasion of the amniotic cavity, amniocentesis-to-delivery interval, and neonatal complications than the amniotic fluid Gram stain, glucose concentration, or white blood cell count.

Adult↗
PubMed1993

Regional distribution of soluble and membrane-bound aminopeptidase activities in rat brain.

Soluble and membrane-bound aminopeptidase activities in 11 regions of the rat brain were assayed using L-Leucine-2-naphthylamide as a substrate. In addition, two metabolic enzymatic activities were compared: lactate dehydrogenase and aspartate aminotransferase. All enzymatic activities showed significant regional differences when the data were analyzed statistically. Soluble aminopeptidase and aspartate aminotransferase activities were significantly lower in cortical than in subcortical areas. Membrane-bound aminopeptidase activity levels were higher in cortical areas. Lactate dehydrogenase activities did not differ between cortical areas and the rest of the zones studied. However, although no wide regional differences were found for the other enzymatic activities, membrane-bound aminopeptidase varied markedly across brain regions: a fivefold difference was observed between zones such as parietotemporal cortex and medulla. The differential distribution of this enzymatic activity is consistent with the hypothesis that it could be responsible for the enzymatic inactivation of some neuroactive peptides.

Aminopeptidases↗
PubMed1993

Children in homeless families: risks to mental health and development.

This study examined the psychological adjustment of 159 homeless children in comparison with a sample of 62 low-income children living at home. In each group, ages ranged from 8 to 17 years. As expected, homeless children were found to have greater recent stress exposure than housed poor children, as well as more disrupted schooling and friendships. Child behavior problems were above normative levels for homeless children, particularly for antisocial behavior. Across the 2 samples, however, behavior problems were more related to parental distress, cumulative risk status, and recent adversity than to housing status or income. Results suggest that homeless children share many of the risks and problems of other American children being reared in poverty.

Adaptation, Psychological↗
PubMed1993

A primary care nursing model in long-term care facilities: evaluation of impact on affect, behavior, and socialization.

A primary care model of delivery of nursing aide care was implemented and evaluated in one small, rural nursing home and one large, urban facility. Experimental unit residents received primary care consisting of permanent assignment of nursing aide, a team approach and enhanced communication. The urban experimental residents improved significantly in behavior and affect as measured across several sources, while the comparison group declined or remained the same. Significant improvements in behavior and social activities were observed among the experimental rural nursing home residents as contrasted with the comparison group after implementation of primary care nursing. It was concluded that primary care nursing as applied to nursing attendants in long-term care is beneficial to residents in terms of decreasing disturbed behavior and improved affect.

Affect↗
PubMed1992

Immunologic and genetic characterization of S180, a cell line of murine origin capable of growing in different inbred strains of mice.

Some of the immunologic and genetic properties of the cell line S180 have been examined. These cells grew without restrictions in the peritoneal cavity of different inbred strains of mice and invariably killed the animals. With Northern blots it was demonstrated that S180 cells contained class I mRNAs but failed to transcribe B2m genes. However, under experimental conditions, a protective humoral immune response mediated by cytotoxic antibodies and complement against S180 cells was obtained through non-H-2 antigens in C57BL/6J mice.

Animals↗
PubMed1992

Infection and labor. VIII. Microbial invasion of the amniotic cavity in patients with suspected cervical incompetence: prevalence and clinical significance.

OBJECTIVE: The purpose of this study was to determine the prevalence and clinical significance of microbial invasion of the amniotic cavity in patients presenting with cervical dilatation in the midtrimester of pregnancy. STUDY DESIGN: Amniocentesis for microbial studies was performed in women admitted with cervical dilatation > or = 2 cm, intact membranes, and without active labor between 14 and 24 weeks of gestation. Amniotic fluid was cultured for aerobic and anaerobic bacteria, as well as for mycoplasmas. Gram stain was performed on all samples. RESULTS: The prevalence of microbial invasion of the amniotic cavity was 51.5% (17/33). The most common microbial isolates were Ureaplasma urealyticum, Gardnerella vaginalis, Candida albicans, and Fusobacterium sp. All patients with microbial invasion of the amniotic cavity had complications. Patients who underwent cervical cerclage in the presence of a positive amniotic fluid culture had rupture of membranes, clinical chorioamnionitis, or pregnancy loss. On the other hand, the prognosis of patients with a negative amniotic fluid culture was better than that of patients with a positive culture. Of 16 patients with a negative amniotic culture, nine were delivered at > 34 weeks. CONCLUSIONS: (1) Microbial invasion of the amniotic cavity occurs frequently in women presenting with cervical dilatation in the midtrimester; (2) the microbiologic state of the amniotic cavity is an important prognostic factor for pregnancy outcome; (3) amniocentesis to determine the microbiologic characteristics of the amniotic cavity should be considered before a cerclage is placed in women presenting with cervical dilatation in the midtrimester.

Abortion, Spontaneous↗
PubMed1992

Preservation of ovarian function by ovarian transposition performed before pelvic irradiation during childhood.

Ovarian transposition in adults has been shown to protect ovarian function in about 60% of cases by reducing ovarian exposure to less than 4 to 7 Gy. We therefore evaluated the effect of ovarian transposition during childhood or adolescence. Eighteen girls had ovarian transposition performed at a mean (+/- SEM) age of 9.4 +/- 1.2 years (range, 1.2 to 16 years). Twelve were prepubertal and six had menstruated at the time of ovarian transposition. The initial abnormalities were Hodgkin disease (5 cases), iliac Ewing sarcoma (3), medulloblastoma (2), ovarian seminoma (1), and vaginal or uterine tumor (7). The irradiation was external in 11 cases and local by vaginal curietherapy in 7 cases. Fifteen girls received chemotherapy. The ovarian transposition was bilateral in 15 patients and unilateral in 3 cases; in the latter the other ovary had been destroyed by the tumor or by abdominal irradiation. Ovaries were placed just below the iliac crest (15 cases) or posterolateral to the uterus (3); thus, the calculated ovarian radiation dose was up to 9.5 Gy. At the time of evaluation (8.6 +/- 0.9 years after ovarian transposition), 16 girls had menstruated and 2 remained amenorrheic because of major lesions of the vagina and uterus caused by the vaginal curietherapy. Basal plasma gonadotropin values were normal. Ovulation was documented in seven cases. Two pregnancies occurred. Complications of ovarian transposition were present in four patients: intestinal occlusion, dyspareunia, functional ovarian cysts, and pelvic adhesions with tubal obstruction. We conclude that ovarian transposition, performed before abdominopelvic irradiation during childhood, can preserve ovarian function. Longer follow-up is required to assess the risk of ovarian dystrophy because of vascular lesions or chemotherapy.

Adolescent↗
PubMed1992

Bilateral distribution of aminopeptidase activities in selected structures of a photoneuroendocrine circuit and other rat brain areas.

Provided that soluble aminopeptidases, the most abundant proteolytic enzymes found in brain, are involved in the metabolism of several neuropeptides, their activity could be a reflect of neuropeptide function. Therefore, in order to analyze their rate of participation, we have measured 4 soluble aminopeptidase activities: leucine aminopeptidase, arginine aminopeptidase, aspartate aminopeptidase, and pyroglutamate aminopeptidase, using arylamide derivatives as substrates, in selected structures integrating the photoneuroendocrine circuit related to the melatonin rhythm generating system and other rat brain areas. The regional distribution of all the activities was heterogenous: a 3-fold (leucine-, arginine- and aspartate-aminopeptidase) and 5-fold (pyroglutamate aminopeptidase) difference was observed between the regions with the highest and lowest activity. Significant differences were displayed between the left and right retina for pyroglutamate aminopeptidase and arginine aminopeptidase activities. High levels of pyroglutamate aminopeptidase were evident in the retina and adenohypophysis, which is consistent with a role for thyrotropin releasing hormone in photoreceptive mechanisms, and support its well established role in controlling thyrotropin releasing hormone in anterior pituitary. The presence of a high activity rate of aspartate aminopeptidase in adenohypophysis implies an active participation of angiotensin peptides at this level.

Aminopeptidases↗
PubMed1992

Black and white dementia caregivers: a comparison of their adaptation, adjustment, and service utilization.

We compared black (n = 33) and white (n = 119) caregivers of dementia patients on indices of adaptation, adjustment, and utilization of supportive services. Black and white caregivers differed most notably on marital and financial/insurance status, but there were few differences between them in their adaptation to dementia responsibilities. Black caregivers, however, evidenced less burden and less desire to institutionalize their relatives and were more likely to report more unmet service needs than were whites.

Adaptation, Psychological↗