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Biomedical subjects

F Medina

Publications and source records attributed to F Medina.

At least 19 recordsLinked to original sources
PubMed2005

Ozonation of activated carbons: Effect on the adsorption of selected phenolic compounds from aqueous solutions.

The impact of ozonation on textural and chemical surface characteristics of two granular activated carbons (GAC), namely F400 and AQ40, and their ability to adsorb phenol (P), p-nitrophenol (PNP), and p-chlorophenol (PCP) from aqueous solutions have been studied. The porous structure of the ozone-treated carbons remained practically unchanged with regard to the virgin GAC. However, important modifications of the chemical surface and hydrophobicity were observed from FTIR spectroscopy, pH titrations, and determination of pH(PZC). As a rule, the ozone treatment at either room temperature (i.e., about 25 degrees C) or 100 degrees C gave rise to acidic surface oxygen groups (SOG). At 25 degrees C primarily carboxylic acids were formed while a more homogeneous distribution of carboxylic, lactonic, hydroxyl, and carbonyl groups was obtained at 100 degrees C. The experimental isotherms for phenolic compounds on both GAC were analyzed using the Langmuir model. Dispersive interactions between pi electrons of the ring of the aromatics and those of the carbon basal planes were thought to be the primary forces responsible for the physical adsorption whereas oxidative coupling of phenolic compounds catalyzed by basic SOG was a major cause of irreversible adsorption. The exposure of both GAC to ozone at room temperature decreased their ability to adsorb P, PNP, and PCP. However, when ozone was applied at 100 degrees C adsorption was not prevented but in some cases (P and PNP on F400) the adsorption process was even enhanced.

Adsorption↗
PubMed2005

Systemic autoimmune diseases co-existing with chronic hepatitis C virus infection (the HISPAMEC Registry): patterns of clinical and immunological expression in 180 cases.

OBJECTIVES: To describe the clinical and immunologic characteristics of a large series of patients with systemic autoimmune diseases (SAD) associated with chronic hepatitis C virus (HCV) infection. METHODS: We analysed 180 patients diagnosed with SAD and chronic HCV infection seen consecutively at our centres during the last 10 years. The clinical and immunological patterns of disease expression were compared with 180 SAD-matched patients without chronic HCV infection. RESULTS: A total of 180 HCV patients fulfilled the classification criteria for the following SAD: Sjogren's syndrome (n = 77), systemic lupus erythematosus (n = 43), rheumatoid arthritis (n = 14), antiphospholipid syndrome (n = 14), polyarteritis nodosa (n = 8) and other SAD (n = 24). One hundred and thirty (72%) patients were female and 50 (28%) male, with a mean age at SAD diagnosis of 50 years. The main immunologic features were antinuclear antibodies in 69% of patients, cryoglobulinaemia in 62%, hypocomplementaemia in 56% and rheumatoid factor (RF) in 56%. Compared with the SAD-matched HCV-negative group, SAD-HCV patients presented a lower prevalence of females (P = 0.016), an older age at SAD diagnosis (P = 0.039) and a higher prevalence of vasculitis (P < 0.001) and neoplasia (P < 0.001). Immunologically, SAD-HCV patients presented a lower prevalence of antinuclear (P = 0.036), anti-extractable nuclear antigen (P = 0.038) and anti-DNA (P = 0.005) antibodies, and a higher frequency of RF (P = 0.003), hypocomplementaemia (P < 0.001) and cryoglobulins (P < 0.001). CONCLUSIONS: In comparison with an SAD-matched HCV-negative population, SAD-HCV patients were older and more likely to be male, with a higher frequency of vasculitis, cryoglobulinaemia and neoplasia. This complex pattern of disease expression is generated by a chronic viral infection that induces both liver and autoimmune disease.

Antibodies, Antinuclear↗
PubMed2003

Isolation, maturational level, and functional capacity of human colon lamina propria plasma cells.

BACKGROUND AND AIMS: Large numbers of plasma cells (PC) localise in the intestinal lamina propria (LP) where they play a critical role in the defence against pathogens. This study analyses the level of maturation reached by normal human colon LPPC in comparison with that of bone marrow (BM) PC. METHODS: A technique was designed to purify LPPC by combining collagenase digestion of the mucosal layer and immunomagnetic selection of CD54(+) LP cells. It provided highly purified PC, as demonstrated by morphology, CD38(h) phenotype, and cytoplasmic IgA staining criteria. This procedure allowed comparison of in vitro functional capacities and a broad phenotypic analysis of BMPC and LPPC. RESULTS: LPPC and BMPC exhibited identical expression of differentiation markers (CD19(-/+), CD20(-), HLA-DR(low/-), VS38c(high)), survival molecules (CD95 (low/-), Bcl-2(+)), and B cell transcription factor profile, as well as similar in vitro Ig secreting kinetics (14 days) and lack of susceptibility to apoptosis by CD95 ligation. In contrast, they markedly differed in adhesion molecule expression, as LPPC showed higher levels of CD44 and CD21 and were alpha 4 beta 7(+) whereas BMPC lacked this integrin and expressed higher levels of CD49d and CD31. CONCLUSION: These data indicate that PC at effector sites of the humoral response (BM and LP) show similar high differentiation, survival, and functional features but display a distinctive pattern of adhesion molecules, probably related to their respective homing locations.

Bone Marrow Cells↗
PubMed2002

Left-handed-media simulation and transmission of EM waves in subwavelength split-ring-resonator-loaded metallic waveguides.

At microwave frequencies, hollow metallic waveguides behave in certain aspects as a "one-dimensional plasma." This feature will be advantageously used for simulating the propagation of electromagnetic (EM) waves in left-handed metamaterials provided the hollow waveguide is periodically loaded with split ring resonators. It will be shown that EM transmission in this structure is feasible within a certain frequency band even if the transverse dimensions of the waveguide are much smaller than the associated free-space wavelength. This effect can be qualitatively and quantitatively explained by the left-handed metamaterial theory, thus providing a new experimental validation for such a theory.

Journal Article↗
PubMed2001

The antiquity of rheumatoid arthritis: a reappraisal.

OBJECTIVE: To demonstrate the existence of rheumatoid arthritis (RA) before the 19th century. METHODS: Survey of primary and secondary references on the history of rheumatic diseases. RESULTS: Paleopathological evidence suggests the existence of RA in America since 8000 BC and in Europe since the 7th century. Descriptions and representations of a symmetric chronic polyarthritis producing characteristic deformities can be found in Rome since 100 BC and India since 500 BC. The first clinical distinction between RA and gout was published in Mexico in 1578. Different historical conditions contributed to lack of recognition of RA by official medicine before 1800. The recognition of RA as a distinct entity in the 19th century was influenced by socioeconomic circumstances. CONCLUSION: RA is not a recent disease. Historical investigation can provide useful clues on its pathogeny.

Arthritis, Rheumatoid↗
PubMed2000

Chronic lymphocytic leukemia B cells inhibit spontaneous Ig production by autologous bone marrow cells: role of CD95-CD95L interaction.

A variable degree of humoral immunodeficiency is a common feature in patients with B-cell chronic lymphocytic leukemia (B-CLL). The aim of this study was to explore the possibility that B-CLL cells play a direct role in this phenomenon. To this end, patients' bone marrow (BM) immunoglobulin (Ig)-secreting cells were cocultured with autologous purified B-CLL cells. The results show that tumoral cells inhibited the spontaneous IgG secretion by BM plasma cells, and this effect increased after PMA-induction of B-CLL cells. This inhibitory process was proportional to the number of B-CLL cells added and depended on cellular contact. Adhesion molecules did not appear to be involved in the cellular interaction, because the inclusion of blocking antibody to a variety of these proteins did not reverse the inhibitory phenomenon. However, the addition of monoclonal antibody that blocked the function of either CD95 or CD95L clearly reversed B-CLL cell inhibition on autologous BM plasma cells. These latter cells were shown to express CD95, and B-CLL cells contained detectable quantities of CD95L at the level of messenger RNA and protein. Annexin V-binding experiments revealed increased apoptosis of BM Ig-secreting cells when cocultured with autologous B-CLL cells. Finally, this inhibitory phenomenon might be operative in vivo because (a) there was a good correlation between the intensity of the inhibitory effect in vitro and the serum IgG level exhibited by every patient and (b) B-CLL cells also inhibited in vivo antigen-induced IgG-tetanus toxoid-secreting cells obtained from normal immunized subjects. Collectively, these data suggest that B-CLL cells inhibit autologous CD95-bearing Ig-secreting cells by the interaction with CD95L present on B-CLL cells and, hence, contribute to the state of humoral immunodeficiency that occurs in these patients.

Adult↗
PubMed2000

Purification of human tonsil plasma cells: pre-enrichment step by immunomagnetic selection of CD31(+) cells.

BACKGROUND: The advancement of knowledge about the biology of human normal plasma cells (PC) is hampered by their low frequency and difficult isolation. The aim of this study is to design a way of purifying these cells. METHODS: To this end, advantage was taken of the fact that human tonsil PC expressed surface CD31 at higher levels than the rest of tonsil B cells. RESULTS: The immunomagnetic selection of CD31(+) cells from tonsil B cells increased by a factor of 12 the proportion of PC, determined as CD38(high) cells. This method recovered half of the initial number of PC, and did not alter the PC functions, because IgG secretion was similar in control B cell cultures as well as in cultures of B cells obtained at successive steps of the selection procedure. In addition, CD38(high) cells pre-enriched by this technique were readily isolated by FACS sorting and clearly identified as PC. CONCLUSIONS: Therefore, immunomagnetic pre-enrichment of CD31(+) cells is an efficient method that allows the complete purification of human functional PC.

Antigens, CD↗
PubMed2000

Interaction of alpha-melanotropin (alpha-MSH) and noradrenaline in the median eminence in the control of female sexual behavior.

In the present study, we examined the effects of the injection of alpha-melanotropin (alpha-MSH), noradrenaline (NA), and dopamine in the median eminence of ovariectomized-adrenalectomized rats on female sexual behavior. The animals were primed with l0 microg of estradiol benzoate, and 52-54 h later they were injected into the median eminence with either 1 microl of artificial cerebrospinal fluid, 1 microg/rat alpha-MSH, 200 ng/rat NA, 200 ng or 2 microg/rat dopamine, in 1 microl of artificial cerebrospinal fluid. Both alpha-MSH and NA significantly stimulated sexual behavior. This effect was antagonized by two beta-adrenergic antagonists: propranolol (500 ng/rat) and metoprolol (400 ng/rat) applied 15 min before the alpha-MSH or NA. The alpha-adrenergic antagonist prazosine (500 ng/rat) was ineffective in reducing the effect of alpha-MSH. The vehicle and dopamine at both doses had no effect on sexual activity. These results indicate that alpha-MSH and NA in the median eminence stimulate female sexual behavior and that NA mediates the action of alpha-MSH via beta-receptors.

Adrenalectomy↗
PubMed1999

Surface molecule loss and bleb formation by human germinal center B cells undergoing apoptosis: role of apoptotic blebs in monocyte chemotaxis.

Human tonsil germinal center (GC) B cells rapidly undergo apoptosis in culture. Annexin-V binding shows an early event in this process. In the present study, this method has been used to label apoptotic GC B cells and to analyze additional surface molecules. The expression of all of the molecules studied was reduced in apoptotic (annexin-V(+)) GC B cells, and the reduction was more marked for CD11a, CD21, CD22, CD49d, and CD54, molecules that participate in survival interaction for GC B cells. The analysis of CD54, one of the molecules that was more drastically reduced, showed that GC, but not mantle zone, B cells actively secrete CD54 to the culture supernatant (SN). The secreted CD54 was partly released from the GC B cells in a particulate form as demonstrated by centrifugation. Further experiments using filtration, fluorescence microscopy, electron microscopy, and flow cytometry analysis showed that GC B cells released to the culture SN a population of spherical membranous vesicles of about 0.18 micrometers in size, similar to the blebs described in other apoptosis systems. Bleb formation depended on active metabolism, Ca(2+), and, in part, on microfilament integrity. GC B-cell-derived blebs were clearly associated with apoptosis, as antiapoptotic stimuli prevented their formation. In addition, GC B-cell-derived blebs contained the adhesion molecules previously studied. Consequently, bleb formation might contribute to the surface molecule loss occurring in apoptotic GC B cells. Finally, a chemotaxis assay showed that GC B-cell blebs were chemotactic for human monocytes, suggesting that this mechanism might operate in vivo.

Antigens, CD↗
PubMed1998

The inter-relationship between gonadal steroids and POMC peptides, beta-endorphin and alpha-MSH, in the control of sexual behavior in the female rat.

Estradiol benzoate (10 microg EB) given to ovariectomized-adrenalectomized rats induced sexual receptivity in half the animals and increased alpha-MSH in the preoptic area, ventromedial nucleus (VMN) and arcuate nucleus (ARC), in all the animals, although levels were significantly higher in the VMN and ARC of the receptive (R) subgroup. EB also raised levels of beta-endorphin in the VMN and ARC in the R rats only. POMC expression was not altered. EB did not affect alphaMSH in extra-hypothalamic areas, but addition of progesterone, raised levels in the septum, amygdala, hippocampus and caudate putamen. Only in the VMN, ARC and septum were the steroid-induced increases correlated with onset of sexual behavior.

Animals↗
PubMed1998

Anti-neutrophil cytoplasmic autoantibodies in leprosy.

The objective was to evaluate the frequency of cytoplasmic and peripheral antineutrophil cytoplasmic antibodies (ANCA) in patients with leprosy, and to correlate the presence of ANCA with type and disease activity. Consecutive patients with leprosy were assessed clinically, and IgG ANCA were measured by indirect immunofluorescence. The presence of three of the following was used to assess disease activity: reactional state, fever, new cutaneous lesions, erythrocyte sedimentation rate and C-reactive protein. Sixty-four patients were studied and divided according to the Ridley-Jopling classification: of 38 patients with lepromatous leprosy, eight (21%) had perinuclear (p) ANCA and two (6%) had cytoplasmic ANCA. ANCA titres ranged from 1:20 to 1:320. Of six borderline leprosy patients, one (16%) had p-ANCA. All 20 tuberculoid leprosy patients and 65 healthy control subjects had negative ANCA. There was no correlation between ANCA titres and disease activity in positive patients. ANCA, mainly those with a perinuclear pattern, may be present in leprosy, especially in the lepromatous pole. This disease should be added to the spectrum of diseases with ANCA positivity.

Adult↗
PubMed1998

Measurement of damage in 210 Mexican patients with systemic lupus erythematosus: relationship with disease duration.

The Systemic Lupus International Collaborating Clinics/American College of Rheumatology (SLICC/ACR) Damage Index is a validated instrument specifically designed to ascertain damage in SLE; this instrument has been applied mainly to Caucasians and African-American SLE patients. The objective of this study was to assess damage using the SLICC/ACR Damage Index in Mexican SLE patients. The SLICC/ACR Damage Index was applied to 210 consecutive SLE patients with disease of variable duration. The SLICC/ACR Damage Index was assessed by review of hospital clinical records, interview and physical examination. One hundred and seventeen (55.5%) patients had some damage. The proportion of patients with damage increased significantly with disease duration (33% at 1-60 months, 66% at 61-120 months and 70% at > or = 121 months, P < 0.001). The main organ systems involved were musculoskeletal (osteonecrosis), neuropsychiatric (neuropathy, seizures), gonadal (amenorrhea prior to age 40 years), ocular (cataracts), renal (glomerular filtration < 50%) and peripheral vascular (permanent damage by venous thrombosis). Damage was frequent, increased over time, particularly for ocular, renal, musculoskeletal and gonadal. Patients who experienced damage were older, had a longer disease duration, a greater number of ACR criteria at diagnosis, and were more likely to have renal involvement and antibodies to dsDNA. The damage occurred in many different domains and started to develop early after disease onset. Mexican patients had more peripheral vascular and gonadal involvement compared with published data from non-Hispanic SLE populations.

Activities of Daily Living↗
PubMed1998

Insulin stimulates testosterone biosynthesis by human thecal cells from women with polycystic ovary syndrome by activating its own receptor and using inositolglycan mediators as the signal transduction system.

To determine whether insulin stimulates human ovarian testosterone production in the polycystic ovary syndrome by activating its own receptor and using inositolglycan mediators as the signal transduction system, thecal cells from polycystic ovary syndrome women were isolated and cultured. Insulin and insulin-like growth factor I stimulated thecal testosterone biosynthesis. Antibody blockade of the insulin receptor abolished insulin's stimulatory action, whereas effective antibody blockade of the insulin-like growth factor I receptor did not alter insulin's stimulation of thecal testosterone biosynthesis. A chiro-inositol containing glycan (INS-2) increased thecal testosterone biosynthesis. Preincubation of cells with an antiinositolglycan antibody (A23939 or alpha IGP) abolished insulin's stimulatory effect, but not that of hCG. These findings suggest that inositolglycans serve as the signal transduction system for insulin's stimulation of human thecal testosterone biosynthesis.

Adult↗
PubMed1998

Paleopathology in osseous remains from the 16th century. A survey of rheumatic diseases.

OBJECTIVE: To describe the rheumatic conditions found in skeletal remains of Amerindian ancestry disinterred from a 16th century Mexican cemetery. METHODS: A physical anthropologist and 2 rheumatologists surveyed the recovered skeletal remains. RESULTS: We examined the skeletal remains of 443 subjects. We found 19 cases of Pott's disease, 17 of osteoarthrosis in various anatomical locations, 2 spondyloarthropathies, probably ankylosing spondylitis or diffuse idiopathic skeletal hyperostosis, one probable septic arthritis in the stemoclavicular joint, and 2 compression fractures of the spine. We found no cases of gout or rheumatoid arthritis. CONCLUSION: This is the first report on the presence of rheumatic conditions in colonial Mexico. Studying the remains of these populations can provide useful information about the origin and evolution of different rheumatic conditions.

Adult↗
PubMed1997

Differences in the UV-crosslinking patterns of the poliovirus 5'-untranslated region with cell proteins from poliovirus-susceptible and -resistant tissues.

The restricted tissue tropism observed in poliovirus infection is not governed solely by the expression of the poliovirus receptor (PVR) gene, but might be controlled at stages beyond virus entry, such as translation, replication, or assembly. Translation of poliovirus RNA by a cap-independent mechanism requires interactions of the 5'-untranslated region (5'UTR) with cell proteins. To determine whether the patterns of these interacting proteins differ in HeLa cells and permissive and nonpermissive tissues, UV-crosslinking assays using the poliovirus 5'UTR and tissue extracts from PVR transgenic mice were performed. The results indicate a correlation between the presence of a 97-kDa UV-crosslinked protein and permissivity to poliovirus infection. Acquired poliovirus susceptibility in in vitro-cultured kidney cells also correlates with the presence of a 97-kDa crosslinked band. The interaction of the 97-kDa protein from HeLa cells and mouse brain with the poliovirus 5'UTR is stable and specific. Whether the 97-kDa protein plays a role in poliovirus translation and tissue susceptibility remains to be determined.

Animals↗