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Biomedical subjects

L Guzman

Publications and source records attributed to L Guzman.

At least 19 recordsLinked to original sources

Historical and current perspectives of neuroactive compounds derived from Latin America.

Plants and invertebrates in Latin America have contributed to a great extent in the use, discovery and development of novel neuroactive tools. Significantly, these neuroactive drugs have proven to be particularly important for our current understanding of the physiology and pharmacology of the nervous system. In addition, these discoveries have helped to build the modern and successful pharmacological business that we know today. For example, curare helped to introduce the use of muscle relaxing agents into modern surgical techniques. The discovery of cocaine from the leaves of Peruvian coca plants was instrumental in the discovery of local anesthetics. The search and discovery for useful neuroactive compounds derived from Latin America has also been ongoing in other areas and new applications for quinine, capsaicin and epibatidine were recently described. Besides these organic compounds, several peptides produced by spiders and other invertebrates to hunt their prey also induce effects in channels and membrane receptors at very low concentrations, indicating their high potency and selectivity. It is likely that new pharmaceutics will be developed from these molecules. The interest to renew the search for new compounds is timely, since largely unexplored lands, such as the Amazon and Patagonia, hold an important number of plants and animals that contain exciting new active compounds. With the introduction of new techniques to isolate, identify and characterize the molecular targets and actions of chemical entities, together with the need for more potent and selective compounds to treat neurological conditions, it is necessary to broaden the current exploratory effort in order to find more beneficial uses.

Animals↗

A comparative analysis of abandoned street children and formerly abandoned street children in La Paz, Bolivia.

AIMS AND METHODS: A comparative study of abandoned street children and formerly abandoned street children was conducted in La Paz, Bolivia, representing the first such comparative assessment. Between August and December 1997, all abandoned street children in La Paz, Bolivia, who were willing to participate (n = 124) were interviewed repeatedly at night using standardised questionnaires to collect information on family history, demographics, socioeconomics, drug use, and physical/sexual abuse. The same questionnaires were administered to all former abandoned street children who chose to enter a local orphanage (n = 35). RESULTS: The persistent street children differed greatly from those who entered the orphanage, most markedly in their higher risk of police abuse (95% versus 38%), absence from school (84% versus 19%), engagement in robbery (26% versus 4%), paint thinner use (88% versus 41%), alcohol use (58% versus 12%), and a serious medical problem (53% versus 20%). The risks for street children increased rapidly with age. CONCLUSIONS: A cascade of adverse outcomes afflicts the vast majority of abandoned street children in La Paz, which cumulate with age and diminish the likelihood of successful rehabilitation through lasting placement in an orphanage or residential home. Informed by these findings, the investigators operate a home for abandoned street children in La Paz.

Absenteeism↗

[Medicine and history. Concerning of the case of a man with a tumour on his forehead].

This case report is about the sickness of a 59 year old priest, politician and war veteran who died in 1844. The case history is based on the detailed report of his doctor, gathered in a diary and later published. The collected clinical data relied exclusively on touch and observation. The patient's illness started with a painful lump on his forehead that was in part excised. Surgical exploration revealed a soft tissue mass that bled easily and involved the frontal bone. In the following months, the lesion, which had been treated with complex topical medications, became ulcerated and extended to the orbit and the chin. The patient died postrated and in severe undernutrition one year after the onset of the symptoms. The case discussion, presented in the format of a clinicopathological conference, concluded that a metastasis of a renal cell carcinoma or an osseous lymphoma were the more likely diagnoses.

Argentina↗

A novel inert collagen matrix for hypospadias repair.

PURPOSE: In select patients with hypospadias in whom genital skin is insufficient alternative tissues are needed for urethral reconstruction. Although skin and mucosal grafts may be used, they may increase hospitalization and morbidity. We explored the feasibility of using a bladder submucosal, collagen based inert matrix as a free graft substitute for urethral repair. MATERIALS AND METHODS: Four patients with a history of hypospadias underwent repeat hypospadias repair using a collagen based inert matrix for urethral reconstruction. The inert collagen matrix was trimmed to size as needed for each patient. The neourethra was created by anastomosing the matrix in an onlay fashion to the urethral plate with continuous 6-zero polyglactin sutures. The created neourethra size ranged from 5 to 15 cm. RESULTS: After a 22-month followup 3 of the 4 patients had a successful outcome in regard to cosmesis and function. One patient in whom a 15 cm. neourethra was created had a subglanular fistula. CONCLUSIONS: The use of a collagen inert matrix appears to be beneficial in patients who have undergone previous hypospadias repair and who may lack sufficient genital skin for reconstruction.

Adolescent↗

Open reduction and internal fixation of acetabular fractures.

Between 1982 and 1995, 84 patients with displaced acetabular fractures underwent open reduction and internal fixation in our institution. The mean follow-up was 5.5 years with a minimum of 2 years. There were 33 simple and 51 complex fractures according to the classification of Judet and Letournels. Reduction after operation was anatomical in 49% of the patients, satisfactory in 24%, and unsatisfactory in 27%. Using Merle d'Aubigné's scale, the clinical results were excellent in 39% of the patients, good in 29%, fair in 8%, and poor in 24%. Factors of statistical significance associated with a poor clinical outcome were T-shaped fractures, unsatisfactory reduction (> 3 mm residual displacement), age > 40 years and development of avascular necrosis. Acetabular surgery is demanding, and a high rate of complications can be expected. Trauma centres should designate a group of surgeons who will consistently treat these fractures in order to obtain more experience and better results.

Acetabulum↗

Blood bank leukocyte infusions as remission induction therapy in a case of acute lymphoblastic leukemia.

A 15-year-old female with pre-pre B ALL in third relapse was treated with administration of eight blood bank leukocyte concentrates per day for 5 days. The total number of mononuclear cells per kilogram of weight was 4.89 x 10(8). On the fifth day of infusions the patient was in complete remission (CR), asymptomatic and with a normal CBC. No secondary effects were found. The patient remained in CR without treatment for 10 weeks before relapsing again. The possibility of reaching a short-lived, clinically relevant response, using blood bank leukocyte infusions, is a promising new approach for the treatment of leukemia.

Adolescent↗

Protective effect of boldine in experimental colitis.

The cytoprotective and anti-inflammatory effects of boldine in an experimental model of acute colitis are reported. The administration of boldine to animals with colitis induced by the intrarectal administration of acetic acid, was found to protect against colonic damage as expressed by major reductions in the extent of cell death, tissue disorganization, and edema. Boldine also reduced the colonic neutrophil infiltration, as measured by the myeloperoxidase activity, but it did not significantly affect tissue lipoperoxides. Boldine was found to preserve the colonic fluid transport, a function otherwise markedly affected in the tissue of acid-treated animals. Results presented here provide experimental evidence supporting new cytoprotective and anti-inflammatory properties of boldine.

Animals↗

Purification and characterization of the high molecule weight microtubule associated proteins from neonatal rat brain.

The changes in the levels of microtubule-associated proteins (MAPs) during advanced embryonic stages, neonatal and adult organisms reflect the importance of these cytoskeletal proteins in relation to the morphogenesis of the central nervous system. MAP-1B is found in prenatal brains and it appears to have the highest levels in neonatal rat brains, being a developmentally-regulated protein. In this research, a fast procedure to isolate MAP-1B, as well as MAP-2 and MAP-3 from neonatal rat brains was designed, based on the differential capacity of poly L-aspartic acid to release MAPs during temperature-dependent cycles of microtubule assembly in the absence of taxol. The high molecular weight MAP-1B was recovered in the warm supernatants after microtubular protein polymerization in the presence of low concentrations of polyaspartic acid. Instead, MAP-2 and a 180 kDa protein with characteristics of MAP-3 remained associated to the polymer after the assembly. Further purification of MAP-1B was attained after phosphocellulose chromatography. Isolation of MAP-2 isoforms together with MAP-3 was achieved on the basis of their selective interactions with calmodulin-agarose affinity columns. In addition, MAP-2 and MAP-3 were also purified on the basis of their capacities to interact with the tubulin peptide beta-II (422-434) derivatized on an Affigel matrix. However, MAP-1B did not interact with the beta-II tubulin fragment, but it showed interaction with the Affigel-conjugated beta-I (431-444) tubulin peptide. The different MAPs components were characterized by western blots using specific monoclonal antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Zn(II) transport and distribution in rat spermatids.

Zn(II) is an essential trace element. In spermatozoa, Zn(II) modulates metabolism and chromatin condensation. The mechanisms of uptake and distribution of this ion in sperm cells have not been explored. In rat spermatids, our results indicate that 1) 65Zn(II) binds with fast kinetics to a labile, presumably extracellular, compartment. This binding is temperature insensitive and not modified by metabolic inhibitors. 2) Entry of 65Zn(II) in the absence of externally added proteins occurs through a mediated transport system that allows exchange to reach steady state in approximately 15 min at 34 degrees C. 3) Upon entering the cells, 65Zn(II) binds tightly to cellular organelles. 4) Exchangeable Zn(II) bound to cytoplasmic proteins plus free intracellular Zn(II) appears to be < 20% of total exchangeable Zn(II). 5) The intracellular exchangeable Zn(II) compartment is decreased by metabolic inhibitors, showing a direct or indirect link between energy metabolism and cellular Zn(II) levels. 6) 65Zn(II) efflux from rat spermatids is a process with a rate constant of 0.16 +/- 0.13 min-1 at 34 degrees C. This exit rate of Zn(II) is likely to be affected by Zn(II) release from cytoplasmic binding sites or organelles.

Animals↗

[Water absorption and resistance to wear of 2 newly invented composite resins].

Two recently built composites, one for posterior teeth, and the other for general employ, were evaluated in relation to their water absorption and resistance to wear by means of the "scratch test". Critical loads and attrition of the two materials were also evaluated, with statistical analysis. The results supported the good qualities of the two composites, which are to be considered very advanced in the field of esthetic reconstruction materials.

Absorption↗

Hemodynamic effects of nitrendipine on systolic ventricular function, diastolic ventricular function, and peripheral circulation in essential hypertension.

Twenty patients (aged 33-60 years) with mild to moderate essential hypertension were studied to assess systolic ventricular function, diastolic ventricular function, and peripheral hemodynamic changes induced by nitrendipine during rest and effort, comparing the acute and chronic treatment phases. We used a randomized, placebo-controlled, double-blind, crossover protocol in the acute phase and a paired, placebo group controlled study, with 20 mg single oral daily dose for a 3-week treatment period (chronic phase). The cardiac and peripheral hemodynamic parameters were quantified by noninvasive radionuclides techniques. During acute treatment, peripheral hemodynamics showed a predominantly arteriolar vasodilatory effect with a significant fall in the previously elevated forearm vascular resistance values (-38%, p less than 0.01) and an important increase in forearm blood flow (+49%, p less than 0.01) without any changes in venous capacity. Simultaneously, nitrendipine produced a significant drop in total peripheral resistance (-36%, p less than 0.01), systolic blood pressure (-13%, p less than 0.01), and diastolic blood pressured (-17%, p less than 0.01). The sudden reduction in left ventricular (LV) afterload caused a reflex increase in heart rate (HR) (+12%, p less than 0.01), cardiac index (+37%, p less than 0.01), LV ejection fraction (+17%, p less than 0.01), and peak ejection rate, with an important decrease in LV end systolic volume (-30%, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Experimental chemotherapy and toxicity in mice of three mebendazole polymorphic forms.

In an attempt to test the biological activity of three polymorphic forms of mebendazole (MBZ), called A, B and C, both the LD50 in mice after oral (p.o.) and intraperitoneal (i.p.) administration and the anthelmintic effect of these forms on the enteral and parenteral phases of the nematode Trichinella spiralis were studied. We observed that the polymorphic form A was the least toxic and effective against T. spiralis. The use of the polymorph C is advisable for oral treatment with MBZ in mice, having in mind its lower toxicity with regard to the polymorphic form B and its similar anthelmintic effects.

Administration, Oral↗

Placental abnormalities in systemic lupus erythematosus: in situ deposition of antinuclear antibodies.

We studied 5 placentae from patients with systemic lupus erythematosus (SLE) for the presence of immunopathologic changes. We found antinuclear antibodies (ANA) deposited along the villi, trophoblast and amnion producing a lupus band-like pattern. The ANA were IgG class and had C3 fixing activity. Of the T cell subsets found in the placenta, OKT8 was the predominant type in patients with SLE and controls. All the patients were ANA positive, and 1 was also positive for anti-Ro(SSA). One newborn, positive for ANA and anti-Ro(SSA), developed neonatal lupus, 1 infant with a cardiac septal defect was ANA negative, and the other infants were normal. Our study demonstrates that in pregnant women with SLE, ANA deposition occurs in the placenta in situ.

Antibodies, Antinuclear↗

Evaluation and management of children with sacral agenesis.

Sacral agenesis is a rare congenital anomaly of the lower vertebral column which usually produces lower urinary tract dysfunction. Sixteen children with varying degrees of sacral agenesis and urinary symptoms were extensively evaluated. The neurologic lesion varied from no denervation to a complete loss of sacral motor and sensory function. The treatment instituted was individualized and based on specific urodynamic and radiologic findings. Overall, 12 of the 16 children (75%) achieved continence. Clues to the diagnosis including symptoms, physical findings, and the relationship to maternal diabetes are discussed.

Abnormalities, Multiple↗