Ensuring safe blood in the Americas

This issue will deal not only with blood banks as the places where blood is collected and processed, but also with the whole spectrum of transfusion medicine. Blood has a special place in the culture of our civilizations as symbolizing strength and the vital force of life. Its use in forms that may seem macabre to us now found its way into many ancient rituals. All physicians regard blood with some awe since so far there is no substitute for it, and its transfusion may be regarded as the first organ transplant ... Most of the blood collected in Latin America and the Caribbean is still through replacemrnt donation. Although this practice is being strongly discouraged, it is easy to see its genesis. There must be few more gratifying feelings than that of giving one's own blood not to go into some great amorphous pool but to help someone who is known and loved. We have seen increased promotion of standards and norms for blood banks in the countries and sustained efforts to rationalize the large number of blood banks that are currently operating under a large number of different schemes in the countries. Because there is increased screening of blood, the number of transfusional infections has ben reduced, and this has been documented very clearly in the case of Chagas' disease. I have been pleased to see the emphasis placed on education, even by distance, and the dissemination of both technical and popular information (AU)

Promoting quality blood services in the Region of the Americas

Over the past several years, great progress has been made in the safety of blood transfusion available in the Region of the Americas. The screening of blood units for infectious markers has increased. Of the 5.9 million units of blood collected in Latin America and the Caribbean in 1997, 68 1666 (1.1 percent) were not screened for human immunodeficiency virus (HIV); 77 095 (1.3 percent) for hepatitis B, and 343 858 (5.8 percent) for hepatitis C. The corresponding figures for 2001 are 6338 (0.09 percent) for HIV, 8797 (0.13 percent) for hepatitis B, and 60 112 (0.88 percent) for hepatitis C, despite the fact that the number of units collected that year had increased to 6.8 million. The units not screened for HIV came from five countries, two of which test over 99 percent of the blood collected and another two at least 85 percent. Sixteen countries do not have universal screening for hepatitis C. Of these, five do not test for hepatitis C at all. The quality of screening also appears to have improved in the Region. Training activities, development of standard operating procedures, implementation of quality standards, and the use of appropriate testing kits contribute to better laboratory performance. Nevertheless, there are still many challenges ahead in terms of achieving desired levels of safety and availability of blood (AU)

Effect of Aqueous neem (azadirachta indica) extract on testosterone and other blood constituents in male rats: a pilot study

Effect of oral administration of crude aqueous neem extract on serum testosterone and other blood constituents was studied in the male Wistar rats for 10 weeks. The neem treatment resulted in significant decreases (p,0.01) in total testosterone, total bilirubin and K+ in serum. There were also increases (p<0.05) in packed cell volume, mean corpuscular haemoglobin concentration, red blood cell, white blood cell and lymphocyte counts without showing any cytotoxic effects in the body (AU)

Nosocomial Klebsiella pneumoniae colonization in a neonatal special care unit

During the 1950s Staphylococcus aureus was the most frequently reported cause of nosocomial infection in hospitals. This paper describes an outbreak of colonization and infection due to Klebsiella pneumoniae in 14 infants in a neonatal special care unit

Evaluation of a membrane (Nuclepore) filtration method using capillary blood for the detection of microfilariae

The efficacy of a membrane (Nuclepore) filtration technique using capillary blood (100 mm 3) for the detection of blood-circulating microfilariae was investigated during a prevalence survey for Wuchereria bancrofti and Mansonella ozzardi in north Trinidad by comparing results thus obtained with results from conventional thick smear preparations (25mm3) and from membrane (Nuclepore) filtration of venous blood (1 ml). Prevalence rates of W. bancrofti were 14 percent by thick smear, 17 percent by filtration of capillary blood and 6 percent by filtratioon of venous blood. For M. ozzardi the corresponding rates were 27 percent, 29 percent and 31 percent. A total of 389 persons was examined by all three methods. Microfilaria detection rates for both of the filtration techniques were significantly higher than by thick smear preparation, with the exception of results for M. ozzardi obtained by filtration of capillary blood. There was no significant difference between the number of positive persons detected by filtration of capillary blood and filtration of venous blood. Significantly higher microfilaria densities per unit volume of blood were recorded by thick smear preparation and filtration of capillary blood than by filtration of venous blood. Whereas results for the two capillary blood techniques were similar. In the detection of low density microfilaraemias, membrane filtration of capillary blood provides a practical and sensitive alternative to venous blood filtration and has the additional advantage of capilary blood collection rather than venepuncture.(AU)

ELISA for Schistosoma mansoni infection: durability of blood spots on filter paper

We investigated the persistence of seropositivity for Schistosoma mansoni infection by ELISA in blood spots on filter paper strips stored for up to 16 weeks under conditions ranging from "tropical" temperatures and humidity to storage at -20 degrees Centigrade. High humidity (60 to 85 percent RH) appeared to cause greater deterioration of samples than high temperatures. Storage in a dessicator at 30 degrees Centigrade was as effective as storage in a freezer at -20 degrees Centigrade (Summary)

Haematological indices in normal negro children: a Jamaican cohort from birth to five years

Haematological indices, including total haemoglobin, mean cell haemoglobin concentration, red cell count, mean cell volume, mean cell haemoglobin, reticulocytes, and serum iron values, in a cohort of 243 randomly selected Negro children with normal haemoglobin genotype, followed from birth to 5 years, are reported. Total haemoglobin fell rapidly from high levels at birth to a plateau at 2-6 months, a secondary fall occurred after 6 months and a gradual increase after 18 months. The red cell count also fell rapidly, but increased after 2 months to a plateau and then slowly declined from age 1-5. Mean cell volume and mean cell haemoglobin fell continously from birth to the lowest values at 15 months and then progressively increased to the age of 5 years. Serum iron levels were low at one year of age (mean 9.7 mumol/1) increasing slowly by age 4 and sharply by age 5. Mean cell haemoglobin concentration fell gradually to 1-1 1/2 years and then increased progressively to age 5. Values for Hb, MCHC, MCV, and MCH were consistently and often significantly lower in males before the age of 2 years, compatible with greater depletion of iron stores. Serum iron values were generally lower in males but there was no sex difference at one year when highly significant differences in Hb, MCHC, MCV, and MCH occurred. The cause of sex differences in early haematological development is currently unclear (AU)

Blood parasites of some Jamaican birds

The prevalence of avian hematozoa in 1791 birds of 80 species and 22 families from Jamaica was determined. Species of Haemoproteus were the most common hematozoan encountered. Species of Leucocytozoon were diagnosed only in three over-wintering North American migrants and the genus was absent in native Jamaican birds. The low prevalence of infection (7.4 percent) of blood parasites in Jamaican birds was closely similar to that seen in Neotropical birds and far below that noted for the Nearctic avifauna of the same families. Prevalence in adult and young birds was virtually identical; transmission occurred primarily during the period February to April (AU)

The prevalence and distribution of Mansonella ozzardi in coastal north Trinidad, W. I

A day blood smear survey for Mansonella ozzardi in the north coast communities of Trinidad recorded a prevalence of 4.8 percent in 4,488 persons examined. Prevalence rates were highest in the four western-most communities, where the vector, Culicoides phlebotomus, is a severe nuisance problem. Prevalence rates increased with age and were higher in males than in females. Mean microfilaria densities were low in both sexes up to 50 years of age but in older males the density increased with age. Wuchereria bancrofti infections were detected in five of the ten communities surveyed. (AU)

Dengue in the Caribbean: virus isolation in a mosquito (Aedes pseudoscutellaris) cell line

During outbreaks of dengue fever in the Caribbean in 1977 and 1978 a continuous cell line derived from Aedes pseudoscutellaris was successfully used for the isolation of dengue virus strains from acute human sera, 238 strains were isolated and culture fluid was successfully used as antigen for the identification of several strains. The isolates all produced a marked syncytial cytopathic effect often visible as early as four days after inoculation. The method was successfully employed in the field where, because of their low optimal incubation temperature, the cells suffered no ill effects under ambient conditions. The isolation method was found to be much more sensitive than conventional mouse inoculation (AU)

Immune responses during human schistosomiasis mansoni. III. Regulatory effect of patient sera on human lymphocyte blastogenic responses to schistosome antigen preparations

The in vitro lymphocyte blastogenesis capabilities of patients with schistosomiasis mansoni were tested against phytohemagglutinin (PHA), Candida albicans extract,and soluble preparations of schistosome eggs (SEA), adult worms (SWAP), or cercariae (CAP). When patients lymphocytes were cultured un medium which contained 5 percent human (homologous) normal (uninfected) serum, they responded well to PHA and Candida extract. The responses induced by SEA were maximal in patients with early Schistosma mansoni infections, while reactivity against SWAP and CAP increased during chronic infection. These responses, induced by the Schistosome-derived antigenic preparations,were suppressed if the homologous normal serum supplement of the culture medium was replaced with either the patient's own (autologous) serum, or that of another S. mansoni patient. All sera were heat-inactivated (56 degree C/ 30 min) prior to use. In contrast, responses against the non-specific mitogen (PHA) and the unrelated antigen (Candida extract), were not altered by these changes of the serum supplementation of the media. The degree of suppression by patient serum was not changedby increasing the serum percentage in the medium from 5 percent to 25 percent. The suppressive effects of patient sera on responses induced by SEA and SWAP were increased in relationship to the duration of the serum donor's S. mansoni infection. Preincubation of lymphocytes in suppressive patient sera for 30 min at 37 degree C did not reduce the expected level of responsiveness if the cells were subsequently cultured in homologous-normal serum supplemented medium. The data indicate that during S. mansoni infection patients develop serum component(s) which specifically interfere with the responsiveness of their lymphocytes in regard to certain schistosome-derived antigenic preparations. The immunoregulatory events described could participate in the modulation of immunopathology, the maintenance of chronic worm survival and the prevention of full expression of protective immune responses. (AU)

Effect of starvation on renal metabolism in the rat

The effects of starvation an the acid base status of the rat and on the gluconeogenic and ammoniagenic capacity of rat renal-cortical slices were examined. Starvation for 48 or 72 hrs did not affect acid-base status, and urinary ammonia production did not change. Kidney cortical slices from starved as compared to fed rats showed increased gluconeogenic capicity when incubated with the substrated pyruvate, succinate, fumarate, malate, 2-oxoglutarate, glutamine and glutamate. Renal cortical tissues from starved rats also had increased activity of the gluconeogenic enzyme phosphoenolpyruvate carboxykinase. Renal cortical slices from starved rats did not differ from those of fed rats in the ability to produce ammonia from glutamine or glutamate, nor was there any difference in the activity of glutaminase between these groups. These results show that renal gluconeogenic capacity is increased in starved rats in the absence of systemic acidosis, and starvation does not lead to an increase in urinary ammonia excretion or renal ammoniagenic capacity. (AU)

Hemoglobin F Port Royal (alpha2G gamma2 125 GLU leads to Ala)

A Gy-chain variant, Hb F Port Royal, with an electrophoretic mobility intermediate between Hb S and Hb C was found in a Jamaican-Negro infant, and made up to 14-15 percent of the total Hb F. A glycinamidation procedure was employed to aid in the determining the amino-acid residu substitution of gamma 123 Glu leads to Ala, and the presence of glycine in position 136. (AU)

Regulation of renal cortex ammoniagenesis. I. Stimulation of renal cortex ammoniagenesis in vitro by plasma isolated from acutely acidotic rats

We studied the acute renal metabolic response in rats made acidotic by a single oral dose of ammonium chloride. Cortical slices from acutely (2-h) acidotic rats utilized more glutamine and produced more ammonia and glucose from glutamine than slices from normal animals. When cortical slices from normal rats were pretreated in vitro with plasma isolated from acutely acidotic rats, they achieved similar increases in glutamine utilization, ammonia formation, and gluconeogensis from glutamine. We did not observe such stimulation in normal cortical slices pretreated in a low pH-low bicarbonate medium. Our data show that a non-dialysable factor is present plasma from acutely acidotic rats that may be responsible for the early increase in the urinary ammonia observed in such animals (AU)

Screening cord bloods for detection of sickle cell disease in Jamaica

A cord-blood screening program, designed primarily for detecting sickle cell disease, has been in operation for seven months (8 000 samples) at a large maternity unit in Kingston, Jamaica. We describe techniques of cord-blood collection and electrophoretic investigation on both cellulose acetate and agar gel. These methods appear to give rapid, valid results at minimal expense and are well adapted to screening large populations (AU)