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H R de Vries

Publications and source records attributed to H R de Vries.

At least 19 recordsLinked to original sources
PubMed2006

Colour oscillations in arterioarterial anastomoses reflect natural differences in donor and recipient oxygenation and hematocrit.

Our aim was to show that the colour difference between brighter and darker red, occasionally observed as an oscillating boundary in the recipient and donor parts of an arterioarterial anastomosis in severe twin-twin transfusion syndrome (TTTS), is a consequence of natural differences in blood oxygenation and hematocrit developing between donor and recipient twins. As method we defined a theoretical model of the placenta with dimensions from pathology examination. From literature we determined the optical absorption and scattering properties of all tissue components, and hematocrit and oxygen saturation values for donor and recipient twins. From our placental model we simulated the spectrum of back-scattered light by standard Monte Carlo photon propagation computations and calculated the colour of chorionic arterial and venous blood vessels by applying the physics theory of colour perception. Our computations demonstrate that recipient arterial blood is somewhat brighter red than donor arterial blood. The strong colour differences seen after laser coagulation of all anastomoses but the arterioarterial were explained from an angiotensin II cut-off in the recipient due to obliteration of arteriovenous anastomoses, causing a temporary increase in recipient placental perfusion and hence in blood oxygenation. In conclusion, natural differences in recipient versus donor blood oxygen saturation and hematocrit in severe TTTS explain the observed colour differences between brighter and darker red observed in the recipient and donor parts of arterioarterial anastomoses.

Arterio-Arterial Fistula↗
PubMed1990

Aflatoxin excretion in children with kwashiorkor or marasmic kwashiorkor--a clinical investigation.

A group of five children with kwashiorkor, seven with marasmic kwashiorkor and one underweight child were given an aflatoxin-free diet consisting of maize meal and milk powder. Blood specimens were collected on admission; on day 4 and 10, 24 hour urine and stool samples were collected for the first ten days. Serum, urine and stool samples were analysed for aflatoxins using high performance liquid chromatography with fluorescent detection, after various extraction and clean-up procedures. The children with kwashiorkor and marasmic kwashiorkor excreted aflatoxins in stools for up to 9 and 6 days after admission respectively. No aflatoxins were detected in the stools or urine of the underweight child. In kwashiorkor, urinary excretion ceased after 2 days, while in marasmic kwashiorkor urinary excretion persisted for 4 days. In stools, B1 was the type of aflatoxin detected most frequently in kwashiorkor and least frequently in marasmic kwashiorkor. Aflatoxin M2 was frequently detected in the stools of both groups of children. Estimates of the total amount of aflatoxin excreted by kwashiorkor and marasmic kwashiorkor indicate that these children were harbouring up to 4 micrograms/kg body weight at the time of admission. These findings establish that aflatoxins accumulate in body fluids and tissues in kwashiorkor and marasmic kwashiorkor which is only slowly eliminated.

Aflatoxin B1↗
PubMed1989

[The humane killing of fishes, amphibia, reptiles and birds].

Methods, whether or not acceptable in the correct killing of fish, amphibians, reptiles or birds, are reviewed. The acceptable or unacceptable character of each of these techniques is commented upon. The techniques are differentiated into mechanical, chemical and physical methods. Of all mechanical techniques, rendering an animal unconscious by a sharp blow on the head, followed by rapid decapitation is an acceptable method. Of the chemical techniques, inhalation of Halothane, CO2 + O2, or ether, are usually acceptable. Cutaneous absorption by bathing in a solution of the anaesthetic tricaine sulphonate (MS 222) is the method of choice in fish and amphibians. The injectable anaesthetics T61 and pentobarbital-Na are acceptable in all groups of animals. Physical techniques such as supercooling, heating or electrocution are either unacceptable or impracticable in veterinary practice. Attention is paid to the effects of each of these techniques on the animal, the executing individual and the owner. Technical details of the methods most preferable in the humane killing of animals are discussed.

Amphibians↗
PubMed1988

Climatic conditions and kwashiorkor in Mumias: a retrospective analysis over a 5-year period.

Hospital records from a rural hospital in Kenya were retrospectively analysed for the total monthly admissions for kwashiorkor and all other forms of malnutrition over a 5-year period. These figures were related to the climatic conditions that prevailed during the year as derived from the records of a meteorological station in the area. The peak prevalence for kwashiorkor coincided each year with the season during which relative humidity was highest. The prevalence of kwashiorkor is discussed in relation to variable aflatoxin formation, which is influenced by seasonal changes in weather conditions.

Child↗
PubMed1987

Aflatoxins and kwashiorkor in Kenya: a hospital based study in a rural area of Kenya.

Aflatoxin analyses were undertaken on sera and urines of 41 children admitted to a rural hospital in Kenya with kwashiorkor, marasmus, marasmic kwashiorkor or normal nutrition (Wellcome Classification). Aflatoxins were detected most frequently and at highest concentrations in the sera of kwashiorkors who, conversely, showed aflatoxins least frequently in their urine and in concentrations that were disproportionately low compared with serum/urine aflatoxin levels in other groups. These findings indicate altered aflatoxin metabolism in kwashiorkor and support the hypothesis that there are special relationships between aflatoxins and kwashiorkor.

Aflatoxins↗
PubMed1987

Congenital dislocation of the knee: a description of four cases in rural Kenya.

Four infants with congenital dislocation of the knee seen in rural Kenya are described. All presented in the first 5 days after birth. Three were treated with a posterior plaster slab, renewed at 2 weekly intervals for 6 weeks. One infant was treated by passive exercises, taught to the mother. At the last follow-up at 6 weeks, all the infants had almost normal knee flexion and hyperextension of the joint was no longer possible. The need for early treatment, which can be quite simple and is highly effective, is emphasized.

Casts, Surgical↗
PubMed1973

[Paget's disease].

Explore the source record for details and available documents.

Osteitis Deformans↗