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Biomedical subjects

G Rojas

Publications and source records attributed to G Rojas.

At least 19 recordsLinked to original sources
PubMed2005

Pan-African polyspecific antivenom produced by caprylic acid purification of horse IgG: an alternative to the antivenom crisis in Africa.

A polyspecific Pan-African antivenom has been produced from the plasma of horses immunized with a mixture of the venoms of Echis ocellatus, Bitis arietans and Naja nigricollis, the three most medically important snakes in sub-Saharan Africa. The antivenom is a whole IgG preparation, obtained by caprylic acid precipitation of non-IgG plasma proteins. The antivenom effectively neutralizes the most important toxic activities of the three venoms used in the immunization in standard assays involving preincubation of venom and antivenom before testing. This antivenom compares favourably with other antivenoms designed for use in Africa with respect to neutralization of the toxins present in the venom of E. ocellatus. Caprylic acid fractionation of horse hyperimmune plasma is a simple, convenient and cheap protocol for the manufacture of high quality whole IgG antivenoms. It constitutes a potentially valuable technology for the alleviation of the critical shortage of antivenom in Africa.

Animals↗
PubMed2004

Hypovolaemic shock by rat bites. A paradigmatic case of social deprivation.

This report describes an unusual complication of a comparatively common problem of rat bites, causing a near fatal case of hypovolaemic shock. An 8 month old girl was bitten on her head and hands by Norway rats (Rattus norvegicus) while sleeping after falling from her parent's bed. She could not be attended to because of her parents' alcoholic condition. She was found in hypovolaemic shock. She required ventilatory and haemodynamic support for five days. At late follow up, the child had no medical problem. In this case, evident social risk factors include extreme poverty, poor hygiene, and rat infested environment, which are frequently associated in potential rat bite victims.

Animals↗
PubMed2003

[Social status and health of young people in the German Federal State of Brandenburg].

UNLABELLED: In the German Federal State of Brandenburg, reporting on health and social issues is closely linked. This also applies to the present article, which attempts to describe the social and health situation of young people in Brandenburg. The aim is to define future priorities in health prevention. METHODS: In addition to data from official statistics (on demographic trends, employment and social security) and from surveys conducted among young adults, the results from serial medical and dental examinations of 10th-grade pupils are presented. RESULTS: The number of young citizens in Brandenburg aged 16-25 will rise until the middle of the decade but then fall sharply. This will apply in particular to the rural areas far from Berlin. Sociological studies show that "work and family" enjoy the highest priority among people. However, less educated young people are increasingly doubtful about their ability to live their lives according to these priorities. According to medical statistics, every tenth young person suffers from allergies (especially allergic rhinitis). The same applies with regard to orthopaedic data. Approx. 5% of young people are obese, pupils of special schools more frequently than grammar school pupils. DISCUSSION: Healthy schooling, healthy professional training and good opportunities on the labour market are the key pillars of health policy in Brandenburg. The social and health situation of young people in Brandenburg is a complex issue and can only be improved by networking and cooperation among of all parties concerned.

Adolescent↗
PubMed2003

Education and income: which is more important for mental health?

STUDY OBJECTIVE: To assess which indicators of socioeconomic status are associated with an increased prevalence of common mental disorders. DESIGN: Cross sectional household survey. SETTING: Santiago, Chile. PARTICIPANTS: Random sample of adults aged 16-65 residing in private households. MAIN RESULTS: Less education (odds ratio 2.44, 95% confidence intervals 1.50 to 3.97), a recent income decrease (odds ratio 2.14, 1.70 to 2.70), and poor housing (odds ratio 1.53, 1.05 to 2.23), were the only socioeconomic status variables that remained significantly associated with an increased prevalence of common mental disorders after adjustments. The prevalence of common mental disorders was also higher among people with manual unskilled occupations, overcrowded housing, and lower per capita income but these associations disappeared after adjustment for other explanatory and confounding variables. CONCLUSIONS: There is a strong, inverse, and independent association between education and common mental disorders. However, income was not associated with the prevalence of common mental disorders, after adjusting for other socioeconomic variables. Similar results have been found in other Latin American studies but British studies tend to find the opposite, that income but not education is associated with common mental disorders. Understanding the impact of socioeconomic factors on mental health requires research in poor as well as rich countries.

Adolescent↗
PubMed2002

Sympathetic blockade significantly improves cardiovascular alterations immediately after spinal cord injury in rats.

Immediately after an experimental spinal cord injury (SCI) in rats, there is a large fall in mean arterial pressure (MAP) and heart rate (HR), followed by an abrupt increase in MAP. To better understand the mechanism involved in these early cardiovascular alterations, we tested the effect of treatment with ganglionic and sympathetic blockers in anesthetized rats subjected to T-5 SCI. Fall in MAP was partially diminished by propranolol and pentolinium, while increase in MAP was abolished by propranolol and pentolinium. Adrenalectomy did not diminish the fall in MAP and HR, however, the increase in MAP was significantly reduced. Likewise, propranolol and pentolinium completely abolished the effects in HR. These data suggest that the early cardiovascular alterations secondary to SCI results from an increased parasympathetic activity and a sympathetic withdrawal.

Adrenergic beta-Antagonists↗
PubMed2002

First account on the larval biology of a Litomosoides filaria, from a bat.

Litomosoides filariae are parasites of unrelated groups of hosts, including bats, marsupials, ancient and modern rodents. The four life cycles to-date elucidated, develop in terrestrial mammals and, at least experimentally, in the mite Ornithonyssus bacoti. A batch of mites was fed on an infected bat, Artibeus jamaicensis captured in Costa Rica, and 18 days later one infective larva was recovered. Its morphology was similar to that of other Litomosoides species, with the characteristic long buccal capsule. These first accounts on the larval biology of Litomosoides from Microchiroptera confirm the unity of the genus which supports the view that it has passed from one group of hosts to another by means of captures.

Acaridae↗
PubMed2001

The rfaH gene, which affects lipopolysaccharide synthesis in Salmonella enterica serovar Typhi, is differentially expressed during the bacterial growth phase.

We have cloned and sequenced the rfaH gene from Salmonella enterica serovar Typhi strain Ty2. The gene showed a high degree of similarity to the rfaH genes from Escherichia coli K-12 and S. enterica serovar Typhimurium. A rfaH mutant was constructed by site-directed mutagenesis. This mutant produced a rough lipopolysaccharide (LPS), with an incomplete core region. The defect in LPS expression that results from the rfaH mutation was corrected by a plasmid carrying the intact gene. The plasmid-borne rfaH gene also restored normal LPS synthesis in a rfaH mutant of E. coli. Reverse transcription-polymerase chain reaction analyses were performed to determine the effects of various environmental conditions on the expression of rfaH. The transcription of rfaH showed a growth-phase-dependent regulation, with maximal expression at the late exponential phase. Other environmental conditions, such as temperature or medium osmolarity, did not affect transcription of rfaH.

Cloning, Molecular↗
PubMed2001

Kringles of the plasminogen--prothrombin gene family share conformational epitopes with recombinant apolipoprotein (a): specificity of the fibrin-binding site.

Monoclonal antibodies directed against recombinant apolipoprotein (a) (r-apo(a)) lacking plasminogen-like KIV-2 repeats were used to identify structurally related conformational epitopes in various members of the plasminogen-prothrombin gene family. A number of procedures including a fibrin-binding inhibition immunoassay and surface plasmon resonance studies were used. Two antibodies (A10.1 and A10.4) recognised common conformational structures in r-apo(a), prothrombin, factor XII, plasminogen and its tissue-type and urokinase-type activators. In contrast, two other antibodies recognised specifically an epitope comprising residues of the lysine-binding site (A10.2) or close to it (A10.5) and inhibited the fibrin-binding function of r-apo(a) (IC(50)=36 pmol/l and 9.76 nmol/l, respectively). Interestingly, these antibodies distinctly recognised the elastase-derived fragments of plasminogen K4 (A10.2) and K1+2+3 (A10.5) without affecting plasminogen binding to fibrin. These results suggest that highly conserved conformational regions are common to various proteins of the plasminogen-prothrombin gene family and are in agreement with the concept that these proteins constitute a monophyletic group derived from an ancestral gene.

Antibodies, Monoclonal↗
PubMed2001

Mechanisms involved in the cardiovascular alterations immediately after spinal cord injury.

The early cardiovascular effects resulting from an acute spinal cord injury (SCI) produced by a contusion procedure at T5-T6 were evaluated in anaesthetized rats. The mean arterial pressure (MAP) and heart rate (HR) were measured during one hour after the injury. A marked decrease in MAP and HR was observed immediately after injury, followed by an abrupt increase in MAP. These changes were observed between 3 and 9 min and the basal values were recovered after 20 min. Fall in the MAP and HR and increase in MAP induced by SCI were abolished by atropine. The interruption of the parasympathetic outflow by vagotomy also significantly diminished the fall and increase in MAP and the fall in HR. Likewise, pre-treatment with nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) completely abolished the effects produced by SCI. These data suggest that after SCI the decrement in MAP and HR was probably due to acetylcholine release from parasympathetic fibers and NO from endothelial source probably by a cholinergic stimulation. Additionally, the MAP increase observed was probably due to a reflex compensatory vasoconstriction.

Acetylcholine↗
PubMed2001

Choledocholithiasis: new approach to an old problem.

The old problem of diagnosis and treatment of choledocholithiasis is analyzed in light of recent developments in the field of radiology and surgery. The traditional indications for common bile duct (CBD) exploration resulted in a large number of unnecessary manipulations of the bile ducts. The same is now true of the widespread use of endoscopic retrograde cholangiopancreatography. With the advent of magnetic resonance imaging cholangiography, which can clearly demonstrate CBD calculi by means of a noninvasive, complication-free technology, we should abandon the old indications for CBD exploration and be more conservative regarding the diagnosis and management of this condition. In an era of minimally invasive surgery we are seeing a significant reduction in the number of patients with choledocholithiasis.

Cholangiography↗
PubMed2001

Antimicrobial evaluation of certain plants used in Mexican traditional medicine for the treatment of respiratory diseases.

Eighteen crude extracts, including six hexanic, six chloroformic and six methanolic from six different plant species used in Mexican traditional medicine for the treatment of respiratory infections, were evaluated for potential antimicrobial activity against Staphylococcus aureus, Enterococcus faecalis, Streptococcus pneumoniae, Streptococcus pyogenes, Escherichia coli, and Candida albicans. The minimal inhibitory concentration was determined for each extract using a two-fold dilution assay. The results showed that 16 crude extracts (89%) exhibited antimicrobial activity against at least one of the microorganisms tested at concentrations of 5 mg/ml or below. The extracts from Gnaphalium oxyphyllum, Gnaphalium americanum, and Crescentia alata possessed strong antimicrobial activity against the pathogens tested.

Anti-Bacterial Agents↗
PubMed2001

Common mental disorders in Santiago, Chile: prevalence and socio-demographic correlates.

BACKGROUND: There have been relatively few surveys in Latin America that have attempted to estimate the prevalence of psychiatric morbidity in private households. AIMS: To determine the prevalence of common mental disorders and socio-demographic correlates among adults from Santiago, Chile. METHOD: Cross-sectional survey of private households with a probabilistic sampling design was used. Common mental disorders were measured using the Clinical Interview Schedule-Revised (CIS-R). RESULTS: Three thousand eight hundred and seventy adults were interviewed. Twenty-five per cent were CIS-R cases and 13% met criteria for an ICD-10 diagnosis. Low education, female gender, unemployment, separation, low social status and lone parenthood were associated with a higher prevalence. CONCLUSIONS: Prevalence rates were higher than those found in urban areas of Great Britain, both for ICD-10 diagnoses and 'non-specific neurotic disorders'. Similar socio-demographic factors were associated with an increased prevalence of common mental disorders in Chile as in the UK. There is a need to unify methodologies to be able to compare results internationally.

Adolescent↗
PubMed2001

Microbiological condition of ground meat retailed in Monterrey, Mexico.

Eighty-eight samples of ground meat were randomly collected from retail stores in the metropolitan area of Monterrey, Mexico, and were analyzed for microbial contamination. Methods were those recommended by the Mexican regulation and/or the U.S. Food and Drug Administration. Over 75% of the samples contained > 10(5) total mesophilic microorganisms per g, and over 40% had >10(6) total coliforms per g. Fecal coliforms were present in most samples. Staphylococcus aureus was detected in 2.3% of the samples, Salmonella spp. in 11.4%, Listeria spp. in 62%, and L. monocytogenes in 16%. Escherichia coli was detected in 76% of samples, but none was serotype O157:H7. Shigella spp. was not found in any sample. Fusarium spp. and Mucor spp. were detected in 3.4% of the samples, and low levels of yeast in 93%. The microbiological quality of the ground meat analyzed was unsatisfactory, and the product could be an important cause of food poisoning.

Animals↗
PubMed2000

Comparative study on the ability of IgG and Fab sheep antivenoms to neutralize local hemorrhage, edema and myonecrosis induced by Bothrops asper (terciopelo) snake venom.

The ability of sheep antivenoms, consisting of whole IgG molecules or Fab fragments, to neutralize local hemorrhage, edema and myonecrosis induced by Bothrops asper venom was comparatively studied in mice. The two antivenoms were produced from the same batch of hyperimmune plasma and were adjusted to the same neutralizing potency against these effects in assays where venom and antivenoms were incubated prior to injection. Thus, if differences are observed in experiments involving independent injection of venom and antivenoms, they would depend on the pharmacokinetic profiles of the products. Despite the observation that both antivenoms neutralized the three effects if preincubated with venom, neutralization was only partial when antivenoms were administered i.v. at various time intervals after envenomation. No significant differences were observed between IgG and Fab antivenoms concerning neutralization of hemorrhagic and edema-forming activities, whereas IgG antivenom was slightly more effective in neutralizing myotoxic activity in experiments involving independent injection of venom and antivenom. These results do not support the hypothesis that Fab fragments are more effective than whole IgG molecules in the neutralization of locally-acting toxins from B. asper venom.

Animals↗
PubMed2000

Neutralization of crotaline snake venoms from Central and South America by antivenoms produced in Brazil and Costa Rica.

A study was performed on the ability of antivenoms, produced in Brazil and Costa Rica, to neutralize lethal, hemorrhagic and coagulant activities of the venoms of 16 species of Central and South American snakes of the subfamily Crotalinae. Neutralization of lethality was studied by two different methods routinely used in the quality control of antivenoms at Instituto Butantan (IB) and Instituto Clodomiro Picado (ICP). Both antivenoms neutralized the majority of the venoms studied, but the values of effective doses 50% (ED(50)) differed markedly depending on the method used. In general, higher potencies were obtained with the method of ICP, where a challenge dose corresponding to 4 LD(50)s is used, than with the method of IB, where a challenge dose of 5 LD(50)s is employed. All venoms induced hemorrhagic activity in the mouse skin test, which was effectively neutralized by the two antivenoms. All venoms, except those of Porthidium nasutum and Bothriechis lateralis, induced coagulation of human plasma in vitro and both antivenoms were effective in the neutralization of this activity. In conclusion, our results provide evidence of an extensive cross reactivity between these antivenoms and Central and South American crotaline snake venoms.

Animals↗
PubMed1999

A simple visual immunoassay (VIA) for the semiquantitative determination of plasma elastase levels.

Elastase levels are an important marker of the extent and severity of inflammatory processes. We describe a visual immunoassay based on two monoclonal antibodies for the semi-quantitative determination of plasma elastase levels. The method is rapid, reliable, easy to perform, and does not require special laboratory equipment. There is coincidence of our results with those obtained by quantitative methods. The assay is suitable to obtain information for the management of patients in most intensive care units.

Animals↗
PubMed1999

Recent progress in biotechnology of Mexican medicinal plants.

Based on traditional medicinal knowledge, it was possible to identify the plant species Solanum chrysotrichum as the source of a new antimycotic agent designated SC-1. Cell suspension batch cultures from this plant were established in shake flasks, in which the production of SC-1 was optimized, reaching values fifty times higher than those registered in field grown plants. Large-scale cultivation of the active biomass from S. chrysotrichum was established in 10 l airlift bioreactors, and productivity levels of SC-1 were increased by 60% when using a draw-fill mode in the bioreactors.

Biotechnology↗