Biomedical subjects
A Perez
Publications and source records attributed to A Perez.
Virial expansions for quantum plasmas: Maxwell-Boltzmann statistics.
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In utero ethanol exposure elicits oxidative stress in the rat fetus.
Prior studies in our laboratory have shown that exposure of cultured fetal rat hepatocytes to ethanol (E) blocks epidermal growth factor-dependent replication and that this is paralleled by cell membrane damage, mitochondrial dysfunction, membrane lipid peroxidation (LP), and enhanced generation of reactive oxygen species. These measures of E-mediated oxidative stress (OS) were mitigated by treatment with antioxidants, and cell replication could be normalized by maintaining cell glutathione (GSH) pools. We have now extended these studies to an in vivo model. Rats were administered E (4 g/kg, po) at 12-hr intervals on days 17 and 18 of gestation and killed on day 19, 1 hr following a final dose of E (a total of 5 doses). Fetal and maternal brain and liver were assayed for signs of OS. The 2-day in utero E exposure increased membrane LP in fetal brain as evidenced by increased malondialdehyde (MDA) levels from 1.76 +/- 0.12 SE (nMol/mg protein) to 2.00 +/- 0.08 (p < 0.05) and conjugated dienes from 0.230 +/- 0.006 SE (OD223/mg lipid) to 0.282 +/- 0.006 (p < 0.05). In fetal liver, MDA levels increased from 2.39 +/- 0.08 SE (nMol/mg protein) to 2.87 +/- 0.08 (p < 0.05), whereas dienes differed significantly only between ad libitum controls and the E and pair-fed control groups (p < 0.05). E decreased GSH levels in fetal brain by 19%, from 19.88 +/- 0.72 to 16.13 +/- 1.06 (nMol/mg protein) (p < 0.05). A 10% decrease in GSH was seen in fetal liver (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Sumatriptan (Imitrex) transport by the human placenta.
Sumatriptan (Imitrex), a selective 5-hydroxytryptamine receptor agonist, has been found to be of therapeutic benefit in the acute management of migraine. There is no information on the transfer of this agent across the human placenta. Accordingly, the current study assessed the transport of this drug across the normal term human placenta, using the isolated perfused single cotyledon technique. We found that only about 15% of a single dose of the agent placed in the maternal reservoir crossed into the fetal compartment over 4 hr. Given the average elimination half-life of 2 hr for sumatriptan, it is evident that only very small amounts of the agent will cross from mother to fetus after single doses of Imitrex. Only the parent drug entered the fetal compartment. Metabolites were not detected in the perfusates, but there was evidence of some metabolism of sumatriptan in the placenta. The nature of the metabolites has not been determined. The mechanism of transfer of the drug across the placenta is passive (i.e., the clearance is similar to L-glucose which is passively transported), the rate of transfer is equal in both directions (maternal to fetal and in the reverse), and the drug does not cross into the fetus against a concentration gradient. This passive transport of sumatriptan across the placenta is consistent with its molecular weight, its water solubility, and its slow penetration across the blood-brain barrier in experimental animals.
Determinants of Helicobacter pylori infection and chronic gastritis.
The epidemiology of chronic gastritis was studied before recognition of Helicobacter pylori as its major cause. This case-control study was conducted in an attempt to elucidate causal associations for H. pylori infection and chronic gastritis. A questionnaire emphasizing diet and lifestyle was administered before gastroscopy to patients attending the gastroenterology clinic of Charity Hospital of New Orleans. H. pylori status and histopathology were evaluated independently to classify patients as cases or controls. A positive association was found between H. pylori infection and African American ethnicity as well as smoking. A strong interaction between race and smoking was found. Adequate intake of antioxidant micronutrients, especially vitamin C, was negatively associated with infection prevalence. H. pylori infection was strongly associated with an increased risk of atrophy (odds ratio (O.R.) = 6.4) and intestinal metaplasia of the gastric mucosa (O.R. = 4.7). Both gastric conditions increased in prevalence with age. Intake of antioxidant micronutrients was negatively associated with the risk of atrophy after adjustment for H. pylori infection.
Pilot study of topical calcitriol (1,25-dihydroxyvitamin D3) for treating psoriasis in children.
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Risk of recurrent spontaneous abortion for pregnancies discovered in the fifth week of gestation.
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Ascorbic acid, Helicobacter pylori and Lewis phenotype among blacks and whites in New Orleans.
Gastric juice ascorbic acid concentrations were examined in black and white patients. Significantly lower concentrations were found in blacks, in the absence of a significant difference in the plasma concentration of vitamin C between races. Blacks had higher prevalence of Helicobacter pylori infection, higher gastric pH, more severe acute and chronic inflammation of the gastric mucosa and higher frequency of Lewis (a-b-) phenotype. Although most of these factors have been related to low ascorbic acid levels in gastric juice, none of them could account entirely for the difference between races either individually or after joint consideration. These observations may help to explain the high incidence of gastric carcinoma among the black population in southern Louisiana.
Production of diamondlike carbon films through random compact cluster stacking.
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The Lactational Amenorrhea Method (LAM): a postpartum introductory family planning method with policy and program implications.
It is well accepted that breastfeeding contributes significantly to child survival and child nutrition. Healthful child spacing is associated with improved birth outcomes and maternal recovery. On a population basis, breastfeeding may contribute more to birth spacing than all family planning use combined in many countries. However, while breastfeeding does provide a period of infertility, until recently, there was no reliable way for an individual woman to capitalize on this lactational infertility for her own efficacious child spacing. The Lactational Amenorrhea Method (LAM) is a new introductory family planning method that simultaneously promotes child spacing and breastfeeding, with its optimal nutrition and disease preventive benefits for the infant. LAM, as it is called, is based on the utilization of lactational infertility for protection from pregnancy and indicates the time for the introduction of a complementary family planning method. LAM is recommended for up to six months postpartum for women who are fully or nearly fully breastfeeding and amenorrheic, and relies on the maintenance of appropriate breastfeeding practices to prolong lactational infertility, with the concomitant delay in menses return. A recent clinical trial confirmed the theoretical 98% or higher effectiveness of the method and field trials are demonstrating its acceptability. Nonetheless, some demographers and family planning organizations continue to debate its value. The development, efficacy, and sequelae of the method are presented using data from several studies by the authors.
Virial expansions for quantum plasmas: Diagrammatic resummations.
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Diagnosis of accessory mitral valve tissue by transesophageal echocardiography.
Accessory mitral valve tissue is a rare cause of intracardiac mass and subvalvular left ventricular outflow tract obstruction. The preoperative diagnosis of this congenital anomaly has been facilitated by transthoracic two-dimensional and Doppler echocardiography. However, transthoracic two-dimensional echocardiography cannot identify or correctly diagnose all cases of accessory mitral valve tissue. We report a patient in whom an intracardiac mass detected by transthoracic echocardiography was definitively diagnosed as accessory mitral valve tissue by transesophageal echocardiography.
Swine testis cells contain functional heparan sulfate but are defective in entry of herpes simplex virus.
Herpes simplex virus (HSV) enters and infects most cultured cells. We have found that swine testis cells (ST) produce yields of infectious HSV-1 up to four orders of magnitude lower than those of human embryonic lung (HEL) and HEp-2 cells because of a defect in virus entry. For ST cells, virus binding is reduced, DNA from input virus cannot be detected, and virus proteins are not synthesized. Polyethylene glycol treatment of ST cells after exposure to HSV allows viral entry, protein synthesis, and productive infection. Transfection of viral genomic DNA that bypasses the normal entry process produces similar yields of infectious virus from ST, HEL, and HEp-2 cells. Therefore, all three cell lines can support the HSV replicative cycle. Biochemical analyses and inhibition of sulfation by sodium chlorate treatment show that ST cells contain amounts and types of heparan sulfate (HS) similar to those of highly susceptible cells. HSV infection of sodium chlorate-treated HEL and ST cells indicates the presence of a second, non-HS receptor(s) on susceptible HEp-2 and HEL cells that is missing, or not functional, on poorly susceptible ST cells. We conclude that ST cells are defective in HSV entry, contain functional HS, but lack a functional non-HS receptor(s) required for efficient HSV-1 entry. Further, ST cells provide a novel resource that can be used to identify, isolate, and characterize an HSV non-HS receptor(s) and its role in the entry and tropism of this important human pathogen.
cAMP does not regulate [Ca2+]i in human tracheal epithelial cells in primary culture.
Human tracheal epithelial cells in primary culture respond to different receptor agonists with different peak intracellular calcium concentrations. From resting concentration 138 +/- 13 nM, bradykinin (0.1 microM) produces an increase to a maximum of 835 +/- 195 nM, histamine (10 microM) to 352 +/- 51 nM, and ATP (5-500 microM) to more than 1500 nM. Nine of 14 cultures also responded to isoproterenol (10 microM), though with a smaller increase, to 210 +/- 29 nM. A response was observed with isoproterenol, and epinephrine, but not norepinephrine, phenylephrine or methoxamine, was inhibited by propranolol but not phentolamine, and so this appeared to be a beta-adrenergic response. However, no response could be detected to adenosine, prostaglandin E2 or forskolin, agents that activate adenylate cyclase, or to permeant analogs of cAMP (CPT-cAMP or db-cAMP). The intracellular calcium response to isoproterenol did not follow either the time-course or the desensitization pattern of the cAMP response. Thus, this response to isoproterenol is not mediated by cAMP. No relation was demonstrated between cAMP production by other agonists and the response of intracellular calcium. Pretreatment with agents that increase cAMP did not affect the calcium responses to ATP or bradykinin. Thus, cAMP does not regulate intracellular calcium concentration in human tracheal epithelial cells. The variation in peak intracellular calcium responses to various agonists may be explained by the presence of multiple second messengers (other than cAMP), multiple intracellular pools of calcium, or cell heterogeneity. The agonists tested had the same relative potency in cells from patients with cystic fibrosis as in non-cystic fibrosis cells.
Legionnaires' disease outbreak in a haemodialysis unit.
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Diamondlike carbon films obtained by low energy cluster beam deposition: Evidence of a memory effect of the properties of free carbon clusters.
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