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P Carrasco

Publications and source records attributed to P Carrasco.

30 records · Page 2Linked to original sources
PubMed1994

The desired field-performance characteristics of new improved vaccines for the developing world.

Although the vaccination initiatives undertaken during the past decade are the cornerstones for protecting the world's children and helping to ensure their survival and development, the vaccines currently being employed may become obstacles for further disease reduction or eradication. Their characteristics complicate or increase the burden on health care infrastructures to maintain or expand vaccine delivery systems. This paper examines an experience with the vaccine technologies that currently are being used by immunization programs in developing countries, illustrating the field problems and obstacles associated with their use. It discusses the advantages and benefits that would accrue if new or improved, heat-stable, multi-antigen vaccines that require only one or two, preferably oral, doses were to become available.

Child Health Services↗
PubMed1993

Developmental and organ-specific changes in DNA-protein interactions in the tomato rbcS3B and rbcS3C promoter regions.

Sites of DNA-protein interaction were mapped in the promoter regions of two of the five genes encoding the small subunit of ribulose-1,5-bisphosphate carboxylase (rbcS) in tomato. The two genes, designated rbcS3B and -3C, are actively transcribed in cotyledons of light-grown seedlings and in leaves, but are transcriptionally inactive cotyledons of dark-grown seedlings, in young and mature tomato fruit, and in roots. The combination and order of conserved DNA sequence elements in the promoter regions of the two genes are essentially identical, but differ considerably from that found in the promoters of the other three tomato rbcS genes, which show different transcription patterns. Nuclear extracts from cotyledons of 7-day-old tomato seedlings, and from leaves and young tomato fruit of mature plants defined multiple DNase I-protected sites in the promoter regions of both genes. The protection patterns were organ-specific, and encompassed previously identified conserved DNA sequence motifs as well as uncharacterized sequences. In contrast, nuclear extracts from mature tomato fruit and roots of 7-day-old seedlings failed to protect any of the promoter sequences, implying that DNA-binding proteins required for transcription of rbcS3B and -3C are inactive in these organs. These results are somewhat surprising since DNA-binding proteins from cotyledons of dark-grown seedlings and young fruit interact with the two promoters, although rbcS3B and -3C are not transcribed in these organs. The basis for transcriptional regulation of these two genes is discussed and the detailed pattern of DNase I protection in the promoter regions of the two genes is presented.

Base Sequence↗
PubMed1993

Developmental and organ-specific changes in DNA-protein interactions in the tomato rbcS1, rbcS2 and rbcS3A promoter regions.

DNase I footprinting assays were used to map sites of DNA-protein interaction in the promoter regions of three of the five genes encoding the small subunit of ribulose-1,5-bisphosphate carboxylase (rbcS) in tomato. Organ-specific differences in DNase I protection patterns were observed using nuclear extracts derived from cotyledons, leaves, young fruit, mature fruit, and roots of tomato, implying that organ-specific transcription of these genes is controlled at the level of DNA-protein interaction. The three genes, designated rbcS1, -2 and -3A are similarly expressed in cotyledons of dark-grown seedlings, in immature tomato fruit, and in leaves under conditions of water stress. These three genes share at least three DNA sequence motifs, including the G-box sequence, which are apparently not present in the other two tomato rbcS genes. We find protection of one or more of these sequences in the aforementioned organs, indicating that the corresponding DNA-binding proteins could function in directing differential expression of the genes, although functional studies would be required to establish this point. While most of the DNase I protections encompass previously identified conserved sequence motifs and their flanking sequence, we also observe protection of additional sequences, many of which occur in the region of the transcription start site.

Base Sequence↗
PubMed1993

Characterization of Chilean hazel nut sweet cookies.

A series of studies were carried out to test the effect of the incorporation of Chilean hazel nut flour in sweet cookies at the levels of 0%, 5%, 10%, 15% and 20%. The proximate chemical analysis of the different flour mixtures showed a regular increase from 7.2 to 12.2%, 14.5% to 18.8% and 1% to 2.2%, respectively, decreasing at the same time with the percentages of water and carbohydrates. Chemical amino acid scores of leucine and threonine in wheat flour improved with the incorporation of Chilean hazel nut flour. The farinographic evaluation made to the different blends showed several changes occurred with the incorporation of Chilean hazel nut flour to wheat flour. These included increase in water absorption, decrease in dough developing time and weakening of the dough. Sensory characteristics such as appearance, texture, flavor and also acceptability improved with the incorporation of Chilean hazel nut flour into the cookie formulas.

Amino Acids↗
PubMed1991

Eradication of poliomyelitis: progress in the Americas.

In the span of 5 years since the eradication initiative was launched and only 3 years since external funds were made available, PAHO has been able to develop and implement a comprehensive program strategy for polio eradication that includes the following components: achievement and maintenance of high immunization levels (which include the supplemental strategies of national immunization days and mop-up operations); effective surveillance to detect all new cases; and a rapid response to the occurrence of new cases. Despite yearly increases in the number of cases of acute flaccid paralysis reported to the surveillance system, a decline in reported confirmed cases of polio has occurred since 1986 to record low levels in 1989. Cases in 1989 were reported from only 0.7% of the counties in the Americas. The occurrence of 24 wild-type virus isolates in 1989 were limited to only three geographic areas: northwestern Mexico; the northern Andean Region; and northeastern Brazil. At this writing the clock is ticking with only 3 months left to achieve the goal of interrupting transmission by the end of 1990. If the current level of effort is sustained and special efforts are directed at the remaining foci of infection, the eradication of the transmission of wild-type poliovirus from the Americas can be achieved. Continued external financial support will be critical if the effort is to succeed. The prospect of poliomyelitis eradication in the Americas led the 41st World Health Assembly of WHO to adopt a resolution in May, 1988, to eradicate the indigenous transmission of wild-type poliovirus from the world by the year 2000.(ABSTRACT TRUNCATED AT 250 WORDS)

Central America↗
PubMed1991

Developmental and organ-specific changes in promoter DNA-protein interactions in the tomato rbcS gene family.

The five genes encoding ribulose-1,5-bisphosphate carboxylase (rbcS) from tomato are differentially expressed. Transcription of the genes is organ specific and developmentally regulated in fruit and light regulated in cotyledons and leaves. DNase I footprinting assays were used to map multiple sites of DNA-protein interaction in the promoter regions of all five genes and to determine whether the differential transcriptional activity of each gene correlated with developmental or organ-specific changes in DNA-protein interactions. We show organ-specific differences in DNase I protection patterns, suggesting that differential transcription of rbcS genes is controlled at least in part at the level of DNA-protein interactions. In contrast, no changes were detected in the DNase I footprint pattern generated with nuclear extracts from dark-grown cotyledons versus cotyledons exposed to light, implying that light-dependent regulation of rbcS transcription is controlled by protein-protein interactions or modification of DNA binding proteins. During development of tomato fruit, most DNA-protein interactions in the rbcS promoter regions disappear, coincident with the transcriptional inactivation of the rbcS genes. In nuclear extracts from nonphotosynthetic roots and red fruit, the only detectable DNase I protection corresponds to a G-box binding activity. Detection of other DNA binding proteins in extracts from these organs and expression of nonphotosynthetic genes exclude the possibility that roots and red fruit are transcriptionally inactive. The absence of complex promoter protection patterns in these organs suggests either that cooperative interactions between different DNA binding proteins are necessary to form functional transcription complexes or that there is developmental and organ-specific regulation of several rbcS-specific transcription factors in these organs. The DNase I-protected DNA sequences defined in this study are discussed in the context of conserved DNA sequence motifs and previously characterized binding sites.

Base Sequence↗
PubMed1990

Changes in the Level of Peptidase Activities in Pea Ovaries during Senescence and Fruit Set Induced by Gibberellic Acid.

The activities and changes in the levels of exopeptidase and endopeptidase activities were characterized in unpollinated ovaries of Pisum sativum L. cv Alaska during senescence and early fruit development induced by gibberellic acid (GA(3)). Two aminopeptidases and one iminopeptidase were electrophoretically separated. These peptidases were sensitive to inhibitors of sulfhydryl proteases. Carboxypeptidase activity was inhibited by phenylmethyl sulfonyl fluoride. An azocasein-degrading endopeptidase, sensitive to thiol protease inhibitors, was also found. An increase in the specific activity of aminopeptidase during both fruit development and ovary senescence was observed. In contrast, the specific activity of carboxypeptidase and endopeptidase increased only during senescence of the ovary. Changes in exopeptidase activity in senescing ovaries could be mainly the consequence of a greater stability to proteolysis while the rise in endopeptidase activity appeared to be due to new or increased synthesis of the enzyme. These results suggest that endopeptidase, and not amino or carboxypeptidase, plays a key role in the senescence of pea ovaries and that the changes in unpollinated ovaries leading to ovary senescence or fruit development can be controlled by gibberellins.

Journal Article↗
PubMed1980

The world's last endemic case of smallpox: surveillance and containment measures.

On 31 October 1977, the world's last known case of endemic smallpox was discovered in Merca, Somalia. The source of infection was quickly identified; 19 days previously, the male patient had been in contact with two other cases for not more than 15 minutes, but the surveillance activities surrounding these cases did not identify him as a contact. The patient was isolated and containment and surveillance activities and a vaccination campaign were rapidly instituted; 161 contacts were identified, 41 of whom had not been vaccinated within the last three years. The patient recovered and fortunately no other cases occurred.

Adult↗
PubMedDate not supplied

Field evaluation of a simplified unit-dose syringe for administration of measles vaccine.

Ezeject is a plungerless syringe prefilled with lyophilized measles vaccine. Ezeject syringes were compared with standard 3-cc syringes and 10-dose measles vaccine vials in the vaccination of 884 Guatemalan infants 8-23 months of age. Vaccination was performed by experienced vaccinators and by individuals without prior vaccination experience who received 2.5-3 hours of training. The overall seroconversion rate following administration was 96%, regardless of the type of syringe used or of the experience of the vaccinator. No significant adverse events were observed in children vaccinated with the new syringes. Although incomplete emptying was noted in 87% of the Ezeject syringes used, this had no effect on the serologic response to measles vaccine. Aspiration for detection of blood before injection of the vaccine was performed significantly (P less than .001) less frequently with Ezeject than with 3-cc syringes by both experienced and inexperienced personnel. Inexperienced vaccinators administered measles vaccine significantly faster (P less than .001) with Ezeject than with 3-cc syringes, but the times were similar for experienced vaccinators. Ezeject is an acceptable alternative to standard syringes for the administration of measles vaccine. Several design modifications that would improve the handling of the device and eliminate the possibility of its reuse have been suggested.

Antibodies, Viral↗
PubMedDate not supplied

Strategies for poliomyelitis eradication in developing countries.

Oral polio vaccine (OPV) delivered only through routine services does not appear to interrupt wild virus transmission in the developing countries. The experience in the Americas, which despite intensive surveillance has not confirmed any cases of paralytic poliomyelitis due to wild poliovirus since 23 August 1991, has shown the necessity of delivery of additional doses of OPV through mass campaigns targeted at all children under five years of age regardless of their previous immunization status and in special mop-up operations targeted at this same age group in areas categorized as at high risk of virus transmission, such as those that harbored the virus in the recent past. High-risk areas were determined by empirical observations, which were subsequently confirmed by molecular epidemiology which indicated the presence of several "reservoirs" that helped maintain transmission over several years. During mop-ups, OPV is delivered house by house. This paper discusses the rationale for the utilization of these strategies and outlines the phases for their preparation and evaluation, with illustrations from recent experiences with the last cases of paralytic poliomyelitis in the Americas.

Adolescent↗