Search PubMed⌕ Search

Biomedical subjects

R Alvarez

Publications and source records attributed to R Alvarez.

At least 181 records · Page 10Linked to original sources
PubMed1992

[Incidence of Borrelia burgdorferi infection in isolated facial paralysis. A prospective study].

Between the causes of facial paralysis, similar to Bell's palsy, recently are included those due to some families of spirochaeta (Borrelia burgdorferi) transmitted through tick-bite. These bacteria, besides de facial palsy, may produce several degrees of lymphocytic meningitis and subsequently the paralysis of the face, sometimes clumsy or recurrent. The treatment being the antibiotic drugs, never the corticoids. In the paper are explained prospectively the incidence of this disease in the AA's environment.

Adolescent↗
PubMed1991

Standard Reference Materials for dioxins and other environmental pollutants.

The National Institute of Standards and Technology issues approximately 1100 Standard Reference Materials (SRMs) certified for chemical composition or physical properties. A number of these SRMs has been developed to assist chemists in analyzing environmental samples more reliably for chlorinated dioxins and other organic pollutants. Certification of the pollutant concentration in a natural matrix SRM is based on concordant analyses by the NIST Organic Analytical Research Division using at least two independent methods. For a calibration solution, such as SRM 1614, Dioxin (2,3,7,8-TCDD) in Isooctane, certification is based on agreement of the calculated concentration based on the gravimetric preparation and the concentration as determined experimentally. SRM 1614 also includes a 13C-labeled 2,3,7,8-TCDD for use as an internal standard in methods based on gas chromatography/mass spectrometry. The certified concentrations (ng g-1) are 98.3 +/- 3.3 for the unlabeled dioxin and 95.6 +/- 1.5 for the labeled dioxin. The certificates for SRM 1588, Organics in Cod Liver Oil, and SRM 1589, Polychlorinated Biphenyls (as Aroclor 1260) in Human Serum, provide noncertified concentrations of dioxins. Concentrations of chlorinated dioxins in two urban particulate SRMs have been reported in the literature.

Dioxins↗
PubMed1991

[Tropical spastic paraparesis and HTLV-I. The first case in Spain].

The first patient with myelopathy associated with T-cell leukemia/lymphoma virus infection (HTLV-I) in Spain is reported. Although this condition is endemic in several areas from the Caribbean Sea, South America, Africa and Japan, some cases have been reported in European countries, generally in immigrant patients, residents in endemic zones or patients having received transfusions. In the present case the infection was probably acquired in a tropical zone through blood transfusion. The patient was a 60-year-old female who had been living in Peru during the last 25 years. In that country aortocoronary bypass was carried out for ischemic heart disease. During operation she received blood transfusion. One and a half year later she developed progressive spastic parapesia with impaired sphincter control. Other causes were ruled out, and the diagnosis was confirmed by HTLV-I antibody determination with ELISA and Western blot.

Female↗
PubMed1991

Stimulation of prostaglandin D2 receptors on human platelets by analogs of prostacyclin.

RS-93427, a novel analog of prostacyclin, increased adenylate cyclase activity in human platelet membranes (EC50 = 42 nM) to approximately the same maximum level as that produced by prostacyclin (EC50 = 87 nM). The concentration-response curve for RS-93427 appeared to be monophasic. However, a selective prostaglandin D2 antagonist (BW A868C) significantly reduced the stimulation of adenylate cyclase produced by low concentrations of RS-93427 (3.2 to 32 nM). RS-93520, a stereoisomer of RS-93427, also stimulated adenylate cyclase activity but in a biphasic pattern. BW A868C reduced the activation produced by low concentrations of RS-93520 with a 100-fold shift in the response curve. Maximum stimulation by RS-93520 (4.5-fold) was less than that obtained with prostaglandin D2 (7.3-fold). Thus, the stimulation of adenylate cyclase activity by low concentrations of RS-93520 is due to an interaction with prostaglandin D2 receptors while the activation by RS-93427 is mediated by both prostacyclin and prostaglandin D2 receptors. Additional data in support of these conclusions was obtained when these prostaglandins were tested as inhibitors of ADP-induced platelet aggregation in the presence or absence of BW A868C. The potent stimulation of prostaglandin receptors with chimeric molecules provides some insight into the structural features required for receptor activation.

Adenosine Diphosphate↗
PubMed1991

Tegafur-induced acral hyperpigmentation.

Four patients with colorectal cancer treated with tegafur (a fluoropyrimidine structurally similar to 5-fluorouracil) noted a macular, spotted hyperpigmentation limited to the palms, soles, nails, and glans penis. Histopathologic examination disclosed epidermal basal hyperpigmentation with a lentiginous pattern. Mucocutaneous lesions resolved spontaneously two months after treatment was discontinued. This peculiar phenomenon seems to represent a previously unreported side effect of this cytotoxic drug.

Aged↗
PubMed1990

[Postherpetic vasculopathy. A study of 3 cases in immunosuppressed patients].

We report three cases of postherpetic vasculopathy in immunologically compromised patients. Two had ophthalmic herpes zoster, contralateral to the physical signs, and the third case developed after disseminated herpes zoster. The initial CT images consisted of small ischemic infarcts in capsular regions and basal ganglia. The arteriography showed images consistent with vasculitis or thrombosis of great vessels of the Willis' polygon, which were ipsilateral to the herpetic lesion in two cases. In one patient the neurological defect remained stable, while the other two developed new ischemic episodes, all in the same cerebral hemisphere. It can be assumed from the delayed development of neurologic disease after cutaneous lesions that some cases go unnoticed if the zoster infection is not specifically looked for in retrospect.

Adult↗
PubMed1990

Inhibition of in vivo tumor growth by a monoclonal IgM antibody recognizing tumor cell surface carbohydrates.

We have shown previously that IgM from Ehrlich tumor (ET)-immunized mice, recognizing ET cell surface carbohydrates, protects control mice to a subsequent tumor challenge. The factors involved in such IgM-mediated protection were unknown, since it was independent of complement activation. Here, we have extended these in vivo studies by means of monoclonal IgM antibodies. Two of them (A10 and E1), strongly recognizing ET cells and with specificity to ET cell surface carbohydrates, were selected. The results show that A10 (but not E1 or unrelated IgM antibodies) is able to protect nonimmunized mice against ET growth. Protection by A10 was also seen by reducing 800-fold the initial dose; however, E1 was unsuccessful whatever the dose used. A10-mediated protection was observed in C3-defective mice (cobra venom factor treated) or in C5-deficient DBA/2, but not in silica-treated animals. Endotoxin removal did not affect the protection afforded by A10 while specific IgM depletion prevented any protective effect. In addition, the relationship between natural antibodies of IgM isotype recognizing ET cell surface carbohydrates and mouse strain resistance to this tumor is established. Similarly, this natural resistance seems to be complement independent but macrophage mediated. Therefore, these results indicate that some IgM molecules recognizing cell surface carbohydrates may participate in in vivo tumor suppression by a macrophage-dependent mechanism.

Animals↗
PubMed1990

[Encephalic toxoplasmosis in patients with the acquired immunodeficiency syndrome. A clinico-radiological study and the therapeutic results in 78 cases].

During a 40-month period 78 episodes of encephalic toxoplasmosis (ET) were diagnosed in 57 patients among 394 with acquired immunodeficiency syndrome (AIDS) (based on CDC criteria) in the Hospital Clinic from Barcelona. 38 patients were parenteral drug abusers (66.7%), 17 were homosexual males (29.8%) and 2 were heterosexual females (3.5%). ET was the first opportunistic infection in 28 patients (49.1%). The most common symptoms at the time of diagnosis were focal neurological signs (62.8%) and fever (52.6%). Usually, computed tomography showed single or multiple hypodense lesions (70.3%) with ring-like (46.1%) or nodular (28.3%) uptake. Serology (indirect immunofluorescence) was diagnostic in only 24 cases (42.1%). The acute episodes were treated with the combination pyrimethamine/sulfadiazine (P/S) during 3-6 weeks, and folinic acid was associated. If the patient had previous allergy to sulfonamides or allergy developed during the acute phase, clindamycin (C) was given instead of S. The patients surviving the acute episode (49, 86, 0%) underwent, if they consented, maintenance therapy with P/S two days per week (15 patients) or with C if sulfonamide allergy was present (10 patients). No relapse was observed in those receiving P/S, but 40% of those treated with P/C relapsed. It was concluded that ET is a common opportunistic infection in the AIDS patients, that the treatment of the acute phase with P/S or with P/C is satisfactory, and that maintenance therapy with P/S two days per week may be effective to prevent relapses.

Acquired Immunodeficiency Syndrome↗
PubMed1990

A single column method for the assay of adenylate cyclase.

An improved, one-step method for the separation of cyclic AMP from other nucleotides on disposable columns of neutral aluminum oxide is described. The method consists of several modifications of an established assay for adenylate cyclase. These modifications were designed to increase the sensitivity of the method, to decrease the time required for column preparation, and to eliminate the variable elution patterns for cyclic AMP that are obtained when using aluminum oxide from different commercial sources. Uniform elution patterns and high recoveries (approximately 80%) of cyclic AMP were obtained when 0.1 M ammonium acetate was used to elute cyclic AMP instead of Tris-HCl buffer. Prior to column chromatography, the adenylate cyclase reactions were terminated with the addition of hydrochloric acid and the mixtures were heated to degrade acid-labile nucleotides that would otherwise elute with cyclic AMP from aluminum oxide columns. Disposable polypropylene columns, fabricated with a reservoir and fast-flow filters, were used for column chromatography. Low blank values, generally less than 15 dpm/assay tube, were obtained when the acidified reaction mixtures were applied directly to aluminum oxide columns without prior neutralization. The proposed method should be useful for the routine assay of adenylate cyclase activity.

Adenylyl Cyclases↗
PubMed1990

An ultrastructural study of the spleen of the ranid frog Rana perezi.

The spleen of Rana perezi is encapsulated by connective tissue and shows by light microscopy two areas with no obvious border: the white pulp and the red pulp. The white pulp-lymphoid clusters are scattered throughout the organ and contain lymphocytes, reticular cells, and some plasma cells. The red pulp displays two different portions. The predominant region consists of reticular cells, lymphocytes, a variety of other leucocytes, and cells undergoing division. This area possibly performs a haemopoietic function. The smaller portion of the red pulp is characterized by reticular-phagocytic cells and may be haemocaretic in its function. Macrophages and pigmented cells occur in both white and red pulp. The organization of the spleen of R. perezi can be considered as a transitional or intermediate state between the primitive condition seen in certain fishes and amphibians and the more complex organ of ammiotes.

Animals↗
PubMed1990

Thymus of Rana perezi: presence of interdigitating cells.

In the thymus of Rana perezi, as in other anuran amphibians, there exist two different portions, cortex and medulla. In both sections epithelio-reticular cells are observed as are lymphocytes, macrophages, and granulocytes. In addition, the medulla shows cysts and secretory, myoid, and hypertrophied epithelio-reticular cells. In the cortex, plasma cells and interdigitating cells were also observed. Interdigitating cells make contact with lymphocytes. This finding provides morphological support for the hypothesized role of interdigitating cells in antigen presentation.

Animals↗
PubMed1990

Central nervous system toxoplasmosis in AIDS patients: efficacy of an intermittent maintenance therapy.

Fifty-five episodes of central nervous system (CNS) toxoplasmosis developing in 43 of the 329 AIDS cases seen at our institution were diagnosed during a 34-month period and were prospectively studied. Acute episodes were treated with a pyrimethamine/sulfadiazine (P/S) combination for a mean of 21 days. Because of a previously known major allergy to sulfonamides, three episodes were treated with clindamycin instead of sulphadiazine. In those patients who accepted maintenance therapy, a combination of P/S or pyrimethamine and clindamycin (P/C) was administered 2 days per week. Thirty-six patients (83.7%) survived the first episode. Four of these 36 were lost to further study. Six of the 12 (50%) who decided not to undergo maintenance therapy relapsed (mean follow-up: 12 months). Fourteen patients were given P/S and none relapsed while they were on maintenance therapy (mean follow-up: 10.3 months). Six patients received an intermittent maintenance treatment with P/C and one relapsed 2 months after starting the maintenance therapy (mean follow-up: 13.7 months). We conclude that an intermittent (2 days per week) maintenance treatment for CNS toxoplasmosis with P/S was effective in preventing relapses, although prospective randomized studies remain to be done.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Foot growth in children age one to five years.

As part of the protocol on the Development of the Child's Arch, foot growth studies were monitored prospectively in 107 children from 1 year of age till 5 years of age. Under 15 months of age, growth necessitated a 1/2 size footwear change in less than 2 months; from 15 months to 2 years of age, 1/2 size increase occurred every 2 to 3 months; from 2 to 3 years of age, 1/2 size change every 3 to 4 months; and from 3 to 5 years of age, 1/2 size change every 4 months. Although foot growth in boys and girls is parallel, boys' feet tend to average one size longer and one size wider. Width growth remained proportional to length growth throughout the study.

Age Factors↗
PubMed1990

Purchasing principles to reduce acquisition and inventory costs.

Knowing how, what, when, and where to negotiate are all part of the system that finally determines how much you pay for products and services. Knowing the primary and secondary objectives of materiel management is important in establishing purchasing and inventory policies and procedures. Negotiating all of the terms and conditions up front, before you finalize any deal, is important to minimize your acquisition, operating, disposal, and inventory costs and to maximize profit. Most purchasers and negotiators only bargain for part of the costs; then they have to bargain to try to control the rest of the costs or they are at the mercy of others. Prepare to negotiate for all the factors that will influence the final operating cost from the beginning to the end of the negotiation process.

Communication↗