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Biomedical subjects

J L López

Publications and source records attributed to J L López.

At least 19 recordsLinked to original sources
PubMed1999

Maximal and explosive force production capacity and balance performance in men of different ages.

A group of 32 healthy men (M) divided into three different age groups, i.e. M20 years [mean 21 (SD 1); n = 12], M40 [mean 40 (SD 2); n = 10] and M70 [mean 71 (SD 5); n = 10] volunteered as subjects for examination of maximal and explosive force production of leg extensor muscles in both isometric and dynamic actions (squat jump, SJ and counter movement jump, CMJ, and standing long-jump, SLJ). The balance test was performed on a force platform in both isometric and dynamic actions. Maximal bilateral isometric force value in M70 was lower (P < 0.001) than in M40 and as much as 46% lower (P < 0.001) than that recorded in M20 (P < 0.001). The maximal rate of force development (RFD) on the force-time curve was in M70 lower (P < 0.001) than in M40 and as much as 64% lower than in M20. The heights in SJ and CMJ and the distance in SLJ in M70 were lower (P < 0.001) than in M40 and M20 (P < 0.001). In response to modifications of the visual surroundings the older subjects were 24%-47% (P < 0.05 and P < 0.001) slower in their response time in reaching the lit centre (TT) and remained 20%-34% (P < 0.001) less time inside the centre (TC) from the overall time of lighting than M40 and M20, respectively. In both older groups the individual values of isometric RFD correlated significantly (P < 0.05) with the individual balance values of TT and TC. The present results would suggest that the capacity for explosive force production declines drastically with increasing age, even more than maximal muscle strength. Aging may also lead to impaired balance with a decrease in event detection and speed of postural adjustments. The decreased ability to develop force rapidly in older people seems to be associated with a lower capacity for neuromuscular response in controlling postural sway.

Adult↗
PubMed1999

[Adherence to very active antiretroviral treatment: impact of individualized assessment].

BACKGROUND: To determine if the intervention of individual advice improves adherence and effectiveness to highly active antiretroviral therapy. METHODS: Randomized open trial. Patients treated with zidovudine + lamivudine + indinavir were assigned (2/1) to conventional care or individual advise. Individual advise consists in adaptation to treatment to patient style of live and detailed information of therapy. Adherence were estimated with structured interview and pillo counts and were considered correct when more than 90% of prescribed drugs were taken. RESULTS: Patients 170, conventional care: 110 and IA: 60. FOLLOW-UP: 24 weeks. Baseline characteristics were similar in both groups. Correct adherence were estimated in 52.7% of conventional care and in 76.7% of individual advise (p = 0.002, relative risk: 1.45; CI 95%: 1.16-1.82). Undetectable viral load (NASBA < 50 copies/ml) in 54.5% of conventional care and in 65% of individual advise (p = 0.18, relative risk: 1.19; CI 95%: 0.93-1.53). Reduction of viral load in the conventional care group 1.02 +/- 0.5 log10/ml, and in the individual advise group 1.98 +/- 0.7 log10/ml. CONCLUSION: The individual advice improve adherence with a tendency to improve effectiveness of highly active antiretroviral therapy.

Adult↗
PubMed1998

Distribution of hepatitis B virus genotypes in two different pediatric populations from Argentina.

Differences in pathogenesis and the probability of becoming a chronic carrier depend on the age at which hepatitis B virus (HBV) infection is acquired, ranging from 82% in infants less than 6 months of age to 15 to 30% in older children. HBV genotypes from 22 pediatric patients from two areas that differ in prevalence have been determined. Phylogenetic analysis shows a clear difference between the genotype distribution in Buenos Aires, a low-prevalence area, and that found in Gualeguay, Entre Ríos, a high-prevalence area. While the analysis allocated the sequences in the Buenos Aires group to genotypes A (36%), D (9%), and F (55%), the Gualeguay group presented exclusively genotype A isolates with very low nucleotide divergence, which suggests a strong founder viral population. The high prevalence of genotype F in the Buenos Aires group and its high intragroup heterogeneity agree with the American origin of this genotype.

Argentina↗
PubMed1997

Increased prevalence of genotype F hepatitis B virus isolates in Buenos Aires, Argentina.

The genomic coding region of the hepatitis B surface antigen (HBsAg) was partially sequenced from 12 HBsAg-positive sera of carriers residing in Buenos Aires, Argentina. A phylogenetic analysis groups the 12 isolates into genotypes A (n = 4), B (n = 1), D (n = 2), and F (n = 5). The occurrence of genotypes A and D is not unexpected, considering the mainly European origin of the studied population. The high prevalence of genotype F and its genetic composition support the suggestion that F strains originated in native populations of the New World.

Amino Acid Sequence↗
PubMed1996

Rearrangement of one RAR-alpha gene in an acute promyelocytic leukemia case with t(15;17) and t(6;17) involving chromosomes 17 band q21.

Acute promyelocytic leukemia (APL) is a specific type of acute myelogenous leukemia characterized by a typical morphology and by a translocation between chromosomes 15 and 17, t(15;17)(q22;q21). Because this translocation is not found in other subtypes of acute myelogenous leukemias, it has become an important marker in the diagnosis and treatment of APL. Here we report a case with apparent absence of t(15;17) cells by cytogenetic techniques at diagnosis. At relapse, a metaphase FISH analysis (not dependent on chromosomal quality), followed by G-banding, was performed. t(15;17) was detected in 60% of the metaphases. In 30% of metaphases, an additional t(6;17) was detected involving the other chromosome 17 at band q21. In parallel, a molecular study (using the Southern blotting technique) was carried out and a single molecular rearrangement of the RAR-alpha gene was detected implying that RAR-alpha was not rearranged in the t(6;17) translocation.

Adult↗
PubMed1995

Heterolignanolides: antitumor activity of furyl-, thienyl-, and pyridyl analogs of lignanolides.

A new class of heteroaromatic analogs of lignans, called heterolignanolides, have been tested against several tumor cell lines. These compounds carry diverse heterocyclic rings, instead of the trimethoxyphenyl ring found in the natural lignans yatein and podorhizol. They have moderate antineoplastic activity (P-388, A-549, HT-29) compared with that of yatein. None of the tested compounds has discernible antiviral (HSV-1, VSV) or enzyme inhibitor (ADA, DHFR, GST) activity.

Animals↗
PubMed1995

Synthesis, antitumoral and antiviral evaluation of halo- and demethyl-yatein derivatives.

Several chloro- and iodo-lignanolides have been obtained by direct halogenation of aromatic rings from yatein and 4'-O-demethylyatein. They were assayed as antineoplastics, in order to check the influence in the activity of substitution in both aromatic rings. Although these compounds show a modest antineoplastic activity, it is far from that displayed by yatein and podophyllotoxin. These results confirm that demethylation and the introduction of halo substituents diminish the activity of lignans of the dibenzylbutyrolactone type.

Animals↗
PubMed1995

[Detection and characterization of pre-core mutants of hepatitis B virus (HBV) in chronically infected patients].

Hepatitis B virus infection is responsible of an important number of world morbimortality. This is associated to severe liver outcome such as cirrhosis and hepatocellular carcinoma. Diverse factors influence the severity of liver injury produced by Hepatitis B Virus (HBV): the emergence of HBV mutants unable to secrete "e" antigen (pre-core mutants), the virus and host genetic heterogenicity and immune system competence. Particularly, the presence of pre-core mutants in chronic carriers is associated a low response to interferon therapy. We present paper is to present evidence as to the presence of these mutants in chronically infected, HBeAg negative patients (HBsAg positive) in Argentina. Viral DNAs were extracted from sera of nine patients, amplified by PCR and characterized by restriction enzyme assay. All of them appear to be pre-core mutants according with serological markers and a very low level of viral DNA detected in serum. Further genetic characterization of one of them by nucleotide sequence analysis of the pre-core region let allowed us to show modifications at codon 15 and 28 both of them previously described for pre-core mutants.

Base Sequence↗
PubMed1994

[An evaluation of the SMAST questionnaire for the diagnosis of alcoholism in primary care. The Self-Administered Short Michigan Alcoholism Screening Test].

OBJECTIVE: To validate a self-administrable version of the SMAST questionnaire for diagnosing alcoholism at the primary care level. DESIGN: A descriptive study of a crossover type. SETTING: An urban health centre. PATIENTS AND OTHER PARTICIPANTS: 497 patients over 15, selected at random from the log-book of daily demand, answered the questionnaire. 46 patients with 2 or more positive replies concerning alcoholism (SMAST positive) were invited to a subsequent appointment, as were 40 with a lower score (SMAST negative). 30 from each group attended. MEASUREMENTS AND MAIN RESULTS: The presence of alcoholism was examined by looking at the compliance with the diagnostic criteria of the DSM-III-R and/or the existence of alcohol consumption equal to or above 30 grams a day in women and 60 in men, in those patients who attended the subsequent appointment. 20 SMAST++ positives and two negatives were diagnosed as alcoholics. There was good correlation between daily alcohol consumption in grams and SMAST scoring (r = 0.60; CI's 95%: 0.41-0.74). SMAST showed 50.48% sensitivity, 96.48% specificity and positive and negative predictive values of 66.67% and 93.33%, respectively. By means of a logistical regression analysis, it was clearly shown that the SMAST questions which best forecast the existence of alcoholism were the first two. CONCLUSIONS: The SMAST questionnaire is a very specific test for diagnosing alcoholism within primary care, although its only moderate sensitivity does not recommend it for screening purposes.

Adult↗
PubMed1994

A versatile approach to the synthesis of combretastatins.

A new and versatile synthesis of combretastatins has been developed. Starting from commercially available materials, 2-phenyl-2-benzyl-1,3-dithianes were easily prepared and used as intermediates in the synthesis of several families of combretastatins. This approach facilitates the preparation of representative intermediates in a few steps, with or without an oxygenated function in the ethylenic residue. Many different analogues suitable for pharmacological evaluation can also be obtained from some of these intermediates.

Antineoplastic Agents, Phytogenic↗
PubMed1994

[Laparoscopy assisted vaginal hysterectomy at the Dr. Sótero del Río Hospital].

Twenty three cases of vaginal hysterectomy performed between june 1993 and june 1994 with the aid of laparoscopy were analyzed in Dr. Sótero del Río Hospital. Average ages, parity, date of previous surgeries and associated pathology do not differ from the general population of the patients of the hospital. The results obtained in our series show that the procedure presents comparative advantages if compared with the classical abdominal hysterectomy by shortening the intrahospitalary stay, improving the postsurgical pain and the ventilating mechanic and by contributing to a faster return to work. The complication observed are normal for this type of surgery, however, a proper previous training in laparoscopic surgery and vaginal surgery is essential to limit these complications to a minimum.

Adult↗
PubMed1994

[Early bacterial infections in 103 patients treated with bone marrow transplantation].

PURPOSE: To analyse bacterial infections in the period immediately following bone-marrow transplantation. PATIENTS AND METHODS: A retrospective study of 174 febrile episodes appearing on 103 patients treated with bone-marrow transplantation in 1990 and 1991 was carried out, special attention being paid to the bacterial infections. RESULTS: Virtually all patients (100/103) had at least one febrile episode, and its infectious character was documented in 54% of the instances. Gram-positive germs were most commonly present, 85% of the bacteria isolated, and coagulase-negative staphylococci, especially St epidermidis, predominated (60%). Different species of streptococci, mostly of the viridans group, were isolated in 22% of the blood cultures attained in the first febrile episodes. The mortality due to infection in the series as a whole was 4.8%. CONCLUSIONS: Infections by gram-positive germs, especially coagulase-negative staphylococci, are commonly found among the patients subjected to bone-marrow transplantation. Increased streptococci infections, mostly of the viridans group, are also appreciated. These facts, along with decreased number of gram-negative infections, must be born in mind when designing initial antimicrobial coverage for these patients.

Adolescent↗
PubMed1993

Synthesis and biological activity of bromolignans and cyclolignans.

Nine lignan derivatives (4-12) have been obtained from (-)-yatein by treatment with DDQ and NBS. They showed moderate antineoplastic activity (P-388, A-549, HT-29) compared with podophyllotoxin, but some of them have a better therapeutic index. None of the tested compounds shows anti-viral (HSV-1, VSV) or enzyme inhibitor (ADA, DHFR, GST) activities.

Adenosine Deaminase Inhibitors↗
PubMed1993

[3 families with a congenital factor X deficiency, one of them with an associated factor XII deficiency].

Factor X deficiency constitutes one of the most uncommon congenital bleeding disorders. Here we report three families with Factor X deficiency, one of them with an associated deficit of Factor XII. Family I presented Red variant deficiency (low functional and antigenic activity, the latter in higher levels than the former). In Family II functional activity was low but antigenic one was normal (Prower defect). Besides, an heterozygous deficiency of factor XII was diagnosed. Although genetic analysis supports the hypothesis of combined deficiency, the study was possible in only two generations of the propositus, so a multiple familial deficiency could not be discarded. Finally, Family III suffered from a "classic" or Mr. Stuart deficiency (low levels in functional and immunological assays). Besides, crossed immunoelectrophoresis showed a grossly pathological pattern.

Adult↗
PubMed1992

Cholesterol embolism to the skin.

The clinical features of a patient with cholesterol embolism are presented. Histopathological examination showed the typical clefts of cholesterol in the skin and renal vessels. We believe this entity is under-reported in the dermatological literature.

Cholesterol↗