Biomedical subjects

H Krieger

Publications and source records attributed to H Krieger.

At least 19 recordsLinked to original sources

PubMed2003

The association of genetic markers and malaria infection in the Brazilian Western Amazonian region.

Almost all individuals (182) belonging to an Amazonian riverine population (Portuchuelo, RO, Brazil) were investigated for ascertaining data on epidemiological aspects of malaria. Thirteen genetic blood polymorphisms were investigated (ABO, MNSs, Rh, Kell, and Duffy systems, haptoglobins, hemoglobins, and the enzymes glucose-6-phosphate dehydrogenase, glyoxalase, phosphoglucomutase, carbonic anhydrase, red cell acid phosphatase, and esterase D). The results indicated that the Duffy system is associated with susceptibility to malaria, as observed in other endemic areas. Moreover, suggestions also arose indicating that the EsD and Rh loci may be significantly associated with resistance to malaria. If statistical type II errors and sample stratification could be ruled out, hypotheses on the existence of a causal mechanism or an unknown closely linked locus involved in susceptibility to malaria infection may explain the present findings.

Adolescent↗

PubMed2002

Ethnic admixture composition of two western Amazonian populations.

A small riverine community, Portuchuelo (8 degrees 37'S, 63 degrees 49'W), and a rural county, Monte Negro (10 degrees 15'S, 63 degrees 18'W), both in the state of Rondĵnia, Brazil, were studied for the purposes of ascertaining health conditions and the causes of the variability of some infectious diseases. The sample included 181 inhabitants of Portuchuelo and 924 of Monte Negro. Data on 11 blood polymorphisms (ABO, Rh, MNSs, Kell, Fy, haptoglobin, hemoglobin, ACP1, PGM1, GLO1, and CA2) were used to determine the ethnic composition of the inhabitants of Portuchuelo and Monte Negro. The contributions of Africans, Amerindians, and Europeans to the ethnic composition of the studied populations were, respectively, 0.21 +/- 0.046, 0.44 +/- 0.064, and 0.35 +/- 0.069 in Portuchuelo; and 0.25 +/- 0.032,0.12 +/- 0.046, and 0.63 +/- 0.054 in Monte Negro.

Blood Group Antigens↗

PubMed2002

A rural community in a Brazilian Western Amazonian Region: some demographic and epidemiological patterns.

Some demographic and epidemiological patterns of the rural population of Monte Negro, locality situated in the State of Rondônia (Brazil), Western Amazonia, are described based on a sample of 924 randomly selected individuals, approximately 10% of the whole population. The main features of this sample are (1) the illiteracy rates in the parental generation were 23% for fathers and 20% for mothers. Among children, this figure dropped to 6%; (2) housing in Monte Negro is characterized by being constructed with wood (92%), and also a floor (75%). Nevertheless, only 32% of these houses had electric energy; (3) the mean ages for the parental generation were 41.9 for males and 36.3 for females. These values for the offspring generation were 12.2 and 10.5, respectively; (4) the sex-ratio of the offspring generation was 1.32;(5) the bioassay of kinship was estimated as.033 for this long range migrant population; (6) the prevalence of some macrophage dependent infectious disease was conspicuously high; (7) the reported number of malarial episodes among males and females was statistically different, suggesting that malaria may be, in part, a "professional" disease; (8) the prevalence of serum-positive reactions against B-hepatitis is distressing. It has a strong age dependence and reaches 74% among adult males. Conversely, signs of active infection (AgHbs) rises to 16% among children.

Adult↗

PubMed2001

Mannan-binding lectin enhances susceptibility to visceral leishmaniasis.

Levels of the serum opsonin mannan-binding lectin (MBL) were directly correlated with the probability of developing visceral leishmaniasis. Monocytes infected with MBL-opsonized Leishmania chagasi promastigotes secreted higher levels of tumor necrosis factor alpha and interleukin-6 than cells infected with nonopsonized parasites. Our findings indicate that MBL can modulate the clinical outcome of infection with L. chagasi and the function of infected macrophages.

Adolescent↗

PubMed2001

No evidence of linkage between Mitsuda reaction and the NRAMP1 locus.

Thirty sib-pairs were ascertained through unrelated lepromatous probands. They consisted of 22 healthy individuals and 8 leprosy patients. The Mitsuda reactions of all sibs were evaluated both macroscopically and histologically, and high molecular weight genomic DNA was extracted from the white blood cells of all sib-pairs. Three DNA polymorphisms identified by polymerase chain reaction (274C/T, D543N, 1729 + 55del4) were used as chromosome markers at the NRAMP1 locus. Sib-pair comparisons did not disclose any sign of close linkage between the Mitsuda reaction and the genetic markers.

Adult↗

PubMed1999

The epidemiology of malaria in Rondonia (Western Amazon region, Brazil): study of a riverine population.

We report on a longitudinal study concerning the incidence of malaria in a riverine population (Portuchuelo) settled on the riverbanks of Rio Madeira, in the State of Rondonia, Brazil. We found the incidence of malaria to be seasonal, prevailing in the dry months of June and July. The Annual Parasite Index (API) was 292/1000 inhabitants, almost three times that of the state of Rondonia for the same period. In contrast with other studied Rondonian populations, malaria in Portuchuelo was more prevalent in youngsters < 16 years old, particularly in the 0-1 year age group. Adults were relatively spared, particularly those over 50 years. Besides being indicative of indoor transmission, these facts may suggest the existence of a certain degree of acquired resistance to infection and/or of lessened symptoms in older people. Riverine populations are spread over the entire Amazon region where most of its members were born. Due to the permanent presence of malaria among riverine populations, we are proposing that they may act as perennial reserves of malaria and, therefore, as sources of infection for migrants or eventual settlers at their vicinity. To date, the opposite view has been generally held. Anopheles darlingi, the main vector species in the area, is essentially sylvatic, which contributes to make the control of malaria highly problematic. The only hopes for control rest on permanent surveillance and the prompt treatment of patients, which are also problematic considering the vastness of the Amazon region and the remoteness of some of its riverine settlements.

Adolescent↗

PubMed1999

[Determination of monitor radiation scattering contribution in photon radiation of clinical electron linear accelerators].

BACKGROUND: Modern linear accelerators permit the use of irregular fields due to their flexible collimator systems with separately movable jaws or multileaf collimators. When using such irregular fields in the clinical practice output factors have to be corrected for enhanced backscatter to the dose monitor as compared with the conventional block shieldings. METHODS: A method is presented to detect the monitor backscatter contributions to the output factor for irregular field settings. RESULTS: The monitor backscatter factors have been measured using a telescopic device for 2 different treatment head geometries (Varian Clinac 2100C/D, General Electric Saturne 15) and for 3 photon radiation qualities (nominal energies X6, X18, X12). A method is introduced to calculate the monitor backscatter for arbitrary irregular treatment fields from the experimental data for square or rectangular fields. CONCLUSIONS: Besides the corrections for changes in phantom scatter and changes in the aperture, corrections for monitor backscatter have to be taken into account in many clinical cases. They can contribute up to more than 10% compared with the monitor values for free regular fields.

Humans↗

PubMed1999

Causal analysis of the variability of IgA, IgG, and IgM immunoglobulin levels.

The interindividual variability of IgA, IgG, and IgM immunoglobulin levels was studied using path analysis in a northeastern Brazilian sample (nuclear families) to determine the genetic and/or environmental causes of their variation. The path analysis model decomposes the phenotype into genetic causes (autosomal and X-chromosome-linked genes) and environmental causes. A significant familial aggregation, mainly resulting from autosomal components, was detected for the 3 immunoglobulin levels. The values of genetic heritability were h2 = 0.410 +/- 0.030 for IgA, h2 = 0.617 +/- 0.020 for IgG, and h2 = 0.540 +/- 0.023 for IgM, and the values for environmental-cultural heritability were c2 = 0.085 +/- 0.034 for IgA, c2 = 0.084 +/- 0.027 for IgG, and c2 = 0.023 + 0.023 for IgM. Our results did not show a heritable component resulting from X-chromosome-linked genes on IgM levels, as suggested by some studies (Wood et al. 1969; Grundbacher 1972; Purtilo and Sullivan 1979). Some additional results were that (1) age and IgA concentration were positively correlated, with IgA level increasing gradually from childhood to adulthood (p < 0.001); (2) sex and the age X sex interaction act on IgG concentration (p < 0.01); (3) age and IgM concentration are correlated (with children presenting lower levels than adults, especially in males, p < 0.01); and (4) a significant association exists between sex and IgM level (with females presenting higher levels than males, p < 0.001).

Adult↗

PubMed1998

Lack of evidence of a major gene acting on postaxial polydactyly in South America.

Data on polydactyly were obtained from two large samples: the Latin American Collaborative Study of Congenital Malformations (ECLAMC), and from a migrant Northeastern Brazilian population of rural origin (Hospedaria). ECLAMC is a case-control clinical epidemiological program comprising 10,035 individuals distributed among 2,030 segregating nuclear families. Hospedaria data consisted of 6,586 examined individuals belonging to 1,040 nuclear families. Using complex segregation analysis methodology we found no evidence of two loci (a major gene and a modifier locus) acting on postaxial polydactyly in the present study. Very high heritability values (in a classical multifactorial model) of postaxial polydactyly were detected, for several sets of analyses in ECLAMC and in Hospedaria. For the whole ECLAMC sample there is a peculiar suggestion of a major recessive gene effect responsible for the trait; however, no comparison with a model involving transmission probabilities (tau) was possible in this highly heterogeneous sample. If the whole ECLAMC sample is divided in subsamples, according to Black admixture proportions, the same multifactorial picture emerges. Two different inheritance patterns were verified for hand (HP) and foot (FP) postaxial polydactyly: For HP there is evidence of a non-Mendelian transmission mechanism, while for FP the parental/sib transmission appears to be due only to multifactorial causes.

Brazil↗

PubMed1997

Hormonal and experiential correlates of maternal responsiveness during pregnancy and the puerperium in human mothers.

Two studies were undertaken (1) to determine whether human mothers undergo a change in maternal responsiveness during pregnancy before the birth of the baby, as shown for other mammalian species, and (2) to establish whether a relation exists between changes in maternal feelings and attitudes and changes in hormones. In both studies prospective first-time mothers completed an extensive set of questionnaires, covering a broad range of issues, including a set of 76- to 100-item likert scales concerning attitudes toward infants, childbirth, pregnancy, caretaking, and other interpersonal relationships. In the first cross-sectional study, mothers completed the questionnaires at one of seven time points, ranging from prior to pregnancy to 3 months postpartum. In the longitudinal study, questionnaires were completed repeatedly throughout this same time period. In addition, blood was taken at these same time points and assayed by RIA for plasma concentrations of the steroids, estradiol, progesterone, testosterone, and cortisol. The primary findings are (1) feelings of nurturance grow during pregnancy and from pregnancy to postpartum; in the cross-sectional study, for most of the factors relating to infants or mothering, pregnancy and postpartum responses were more positive than prepregnancy responses; in the longitudinal study, many of these factors also showed elevations across pregnancy itself, as well as further elevations with the birth of the infant. (2) Pregnancy hormones were not related to the growth of attachment to the infant across pregnancy. (3) However, the pattern of change in the ratio of estradiol to progesterone from early to late pregnancy was related to postpartum attachment feelings. (4) Finally, hormonal correlates of attachment feelings may reflect effects both on feelings of nurturance directly and, indirectly, on mothers' feelings of well-being.

Adolescent↗

PubMed1996

The inheritance of factors associated with joint mobility.

From a sample of 1,500 individuals belonging to 442 migrant nuclear families from northeastern Brazil, information on the interphalangial mobility was obtained: (a) the grades of extension of both the right and left thumbs and (b) the angle (in degrees) formed by the distant and proximal phalanx of the thumb. The first principal component of these variables was estimated and called "extensibility." A negative association of extensibility and age, as well as with inbreeding, was detected. Complex segregation analysis was applied to extensibility and both a multigenic mechanism and an extra transmissible component were detected. Mendelian inheritance was rejected, while a model with multifactorial inheritance, together with a factor that is inherited with a transmission probability different from 1/2 (tau = 0.63), was not rejected. These findings were supported by path analysis, which showed an important biologic inheritance (h2 = 0.675) and the existence of a small but significant cultural component (c2 = 0.003). The observed "inbreeding" effect, therefore, could not be attributed to a genetic mechanism and probably is the effect of concomitant environmental variability.

Brazil↗

PubMed1996

Investigation on seasonality of twin births in Brazil.

The hypothesis of seasonality of twin births was investigated in two important maternity hospitals in the State of São Paulo, Brazil. The study included 1,386 twin births that occurred among 154,699 deliveries from 1984 to 1993. No evidence of seasonality has been detected either for the twin birth rate considered as a whole or for dizygotic twinning rate. The distributions of these rates fitted well sinusoidal regression curves but the cyclic trend did not correspond to any specific season.

Analysis of Variance↗

PubMed1996

Twinning rate in a southeastern Brazilian population.

The twinning incidence from 1984 to 1993 was investigated in Campinas, State of São Paulo, Brazil and the analyzed data were combined with previous series from the same population. This study has shown that the mean annual incidences and the standard deviations for DZ, MZ and DZ plus MZ twins for the period of 1984 to 1993 are estimated respectively as 4.7 +/- 0.92, 4.1 +/- 1.11, and 8.8 +/- 0.87 per 1,000. In the same period the mean annual incidence of triplets was 0.15 +/- 0.16. It was also shown that the incidence of DZ twins is steadily decreasing since 1925, while the incidence of MZ pairs, after a period of decline is increasing since the sixties, due perhaps to the widespread use of oral contraceptives. Concerning the twinning rate as a whole, it has been shown that its declining trend has disappeared over the last few years.

Brazil↗

PubMed1996

Hypoendemic malaria in Rondonia (Brazil, western Amazon region): seasonal variation and risk groups in an urban locality.

A longitudinal epidemiologic survey (1989-1991) plus a cross-sectional parasitologic, clinical, and sociodemographic survey (July-October 1990) were conducted in Candeias do Jamary, a village with approximately 7,000 inhabitants in Rondonia, Brazil. Analysis of the results revealed hypoendemic malaria with a complex epidemiology. Plasmodium vivax predominated over P. falciparum infections while infections with P. malariae were absent. Malaria is present throughout the year but was clearly seasonal with epidemic outbreaks in the dry season from June to August. Malaria prevalence was lower in children less than 10 years of age and significantly higher in young adult males, which represent the high-risk group. The incidence of locally acquired infections (autochthonous cases) was significantly lower in the rainy season as compared with the dry season. This is not true with respect to heterotochthonous (imported) malaria cases, that is, malaria acquired elsewhere by Candeias residents, most of whom are male adults working outside the town. In both cases, however, the age and sex distribution of prevalence and its relationship with occupational activities indicate a predominance of outdoor transmission. The results of the cross-sectional survey are in agreement with those of the longitudinal passive survey and, in addition, disclose the absence of asymptomatic infection.

Adolescent↗

PubMed1996

[A proposal for dosage and volume specification and documentation in HDR brachytherapy].

BACKGROUND: Modern computer-aided brachytherapy techniques and the various clinical and radiobiological methods require a review and standardization of dose specification and documentation in brachytherapy. METHOD: The methods and the extent of the dose specification and documentation have been analysed on the base of known international and national procedure. A new modified report has been prepared for the standardized dose specification for HDR-brachytherapy techniques. RESULT: Brachytherapy treatments are supposed to be documented in 3 different levels (I to III), the extent of which depending on the treated volume, the therapeutic aim and the equipment available. CONCLUSION: The extent of documentation and dose specification proposed in this paper requires the close cooperation of radio-oncologists and medical physicists. It seems to be advantageous to use prepared sheets or computer prints in order to minimize the time and efforts for a sufficient documentation.

Brachytherapy↗

PubMed1995

Annual variation of sex ratio in twin births and in singletons in Brazil.

The annual variation of the sex ratio (SR) of 1385 twin births was analyzed and compared to that of 85909 singletons. These births referred not only to live births but also to stillbirths in two southeastern Brazilian maternity hospitals from 1984 to 1993. While the annual variation of the SR of singletons was very small, that of twin births was extremely high, due to the significant heterogeneity of the annual data. It is suggested that the large SR annual variation of the twin birth might be a consequence of the variation of male or female monozygotic twins. The hypothesis that twin births show a lower sex ratio than singletons could be supported by the present data.

Adult↗

PubMed1995

Thermal coronary angiography for intraoperative patency control of arterial and saphenous vein coronary artery bypass grafts: results in 370 patients.

BACKGROUND AND AIM OF THE STUDY: Early graft failure is often associated with technical failures and is therefore potentially avoidable. We used thermal coronary angiography (TCA) for intraoperative graft patency control in 370 patients undergoing routine coronary artery bypass graft surgery to determine whether consequent intraoperative bypass graft control may result in improved patency rates. METHODS: The temperature differences generated in between the myocardium and the grafts by injecting cold cardioplegic solution into the proximal end of a vein graft or by warmer blood running through an internal thoracic artery (ITA) graft were detected using three different infrared camera systems. The resulting "heat pictures" were evaluated for anastomotic patency and to outline graft anatomy. RESULTS: A total of 693 vein grafts were visualized. In 9.4% TCA failed to produce usable images. In the remaining 628 grafts, TCA revealed intraoperative patency in 98.8%. Out of 370 ITA grafts, only 14 could not be sufficiently visualized by TCA. Nineteen ITA occlusions (5.3%) were found: 5 intimal flaps; 11 suture imposed strictures; and 3 proximal ITA occlusions. All occluded grafts were subsequently revised or replaced. All sequential ITA as well as 15 right ITA grafts proved to have patent anastomoses. CONCLUSION: Using TCA an early graft dysfunction rate of 1% for vein grafts and 5.3% for ITA grafts could be demonstrated. Most occlusions were due to technical mistakes at the distal anastomosis. TCA outlines grafts and the attached coronaries by temperature differences without the need for a contrast agent. There is no interference with the surgical procedure. It is an ideal, noninvasive method to immediately document the success or failure of myocardial revascularization.

Adult↗

PubMed1995

Familial aggregation of Leishmania chagasi infection in northeastern Brazil.

A sample of 1,604 individuals belonging to 243 nuclear families from an endemic area of visceral leishmaniasis (Jacobina, Bahia State, Brazil) was studied to disclose the intrafamilial pattern of infection. Significant father to offspring, mother to offspring, and sibling to sibling associations, in contrast a with nonsignificant father to mother association, clearly indicate a familial aggregation of the infection, with a strong suggestion of at least partial genetic involvement.

Adult↗