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Biomedical subjects

A Barnes

Publications and source records attributed to A Barnes.

At least 145 records · Page 8Linked to original sources
PubMedDate not supplied

Effects of untreated bed nets on the transmission of Plasmodium falciparum, P. vivax and Wuchereria bancrofti in Papua New Guinea.

The impact of untreated bed nets on the transmission of human malaria and filariasis in a village in a hyperendemic area of Papua New Guinea was studied. In anopheline mosquitoes, the Plasmodium falciparum sporozoite antigen positivity rate, filarial infection rates and human blood indices dropped significantly after bed nets were introduced. This reduction in human-vector contact did not affect mosquito density as no significant difference in either landing rates or indoor resting catches was found. The number of bed nets in a house and ownership of dogs were factors significantly associated with a reduction in the number of indoor resting mosquitoes. However, the reduction in the P. falciparum sporozoite antigen rate in mosquitoes was not accompanied by a reduction in either malaria parasite or antibody prevalences or titres against the P. falciparum circumsporozoite protein.

Adolescent↗
PubMedDate not supplied

Factors affecting transmission of Wuchereria bancrofti by anopheline mosquitoes. 3. Uptake and damage to ingested microfilariae by Anopheles gambiae, An. arabiensis, An. merus and An. funestus in east Africa.

Laboratory observations were made on the uptake of microfilariae (mf) of Wuchereria bancrofti by Anopheles gambiae, An. arabiensis, An. merus and An. funestus. Over host mf densities ranging from 450/ml to 1735 mf/ml neither the percentage of mosquitoes ingesting mf nor the mean number of mf per mosquito was correlated to host mf density. All mosquito species damaged mf during ingestion but the proportion harmed was independent of host mf density. The mean proportion damaged was 0.67 in An. gambiae, 0.51 in An. merus, 0.47 in An. Arabiensis and 0.26 in An. funestus. A comparison of the mean number of undamaged mf ingested and the number of larvae in the thoracic muscles revealed that not all undamaged mf were able to reach the thoracic muscles.

Africa, Eastern↗
PubMedDate not supplied

An evaluation of the hydrogen sulphide water screening test and coliform counts for water quality assessment in rural Malaysia.

The H2S water screening test and the membrane filtration faecal coliform count were compared with Escherichia coli counts for water samples collected from household water sources and domestic drinking water in rural Malaysia. Water samples were taken from 151 wells, 44 taps supplying water from the treated municipal supply and 192 domestic stored water supplies. E. coli were detected in 20% of the samples (42% of wells, 7% of tap water and 6% of drinking water). Excellent correlation (Spearman's rank correlation rs = 0.93) was found between the faecal coliform and E. coli counts for all sample types. The H2S method was poorly correlated whether read at 18 or 30 h. False positive rates were highest for well water, and false negative rates were highest for both well and drinking water samples, with low E. coli counts. The faecal coliform test was an excellent predictor of the presence of E. coli in these water samples, while the H2S test was very inadequate.

Enterobacteriaceae↗
PubMedDate not supplied

Does transfusion using a syringe infusion pump and small-gauge needle cause hemolysis?

Hemolysis of two- and nine-day-stored sedimented red blood cells (hematocrit 65%), infused by a constant-rate syringe delivery pump through a 25-gauge needle was investigated. Fifteen-ml aliquots of blood were pumped through the system at flow rates of 10.6, 20.5, and 70 ml/hour. Plasma-free hemoglobin and potassium were measured and compared to controls. Significant red blood cell hemolysis occurred during passage through this infusion system, and the amount of hemolysis was greater with nine-day-stored cells. These cells showed more hemolysis with slower flow rates, but the two-day-stored cells were not affected by rate of flow.

Blood Preservation↗
PubMedDate not supplied

Intravenous Imferon masquerading as an acute hemolytic transfusion reaction.

The case of a 74-year-old woman with a history of chronic iron deficiency anemia requiring transfusion is reported. Shortly after receiving intravenous iron-dextran, the patient was transfused with two units of crossmatch compatible packed red blood cells and subsequently experienced severe racking chills associated with mild elevation of temperature. In the evaluation of this febrile reaction, her serum exhibited a distinct red-brown discoloration which was interpreted as free hemoglobin. Laboratory studies performed to evaluate the possibility of acute intravascular hemolysis were all within normal limits. Subsequent investigation revealed that the color of the recipients serum was due to iron-dextran. Caution is urged in the evaluation of patients for hemolytic transfusion reactions who have been administered intravenous iron-dextran, since the drug imparts a red-brown tinge to the plasma which may be misinterpreted as free hemoglobin.

Acute Disease↗
PubMedDate not supplied

Blood component therapy during the neonatal period: a national survey of red cell transfusion practice, 1985.

A questionnaire to determine patterns of neonatal red cell transfusion practice during 1985 was mailed to 2200 blood banks of American Association of Blood Banks (AABB) institutional members and children's hospitals. There were 915 responses (41.6%); 785 responses (86%) contained sufficient data for analysis. The majority (70.6%) of 785 responding hospitals were community/urban institutions. However, more highly specialized, pediatric hospitals were also represented by 92 university/tertiary-care hospitals (11.7% of respondents) and 29 children's hospitals (3.7% of respondents). Two-thirds of hospitals performed a major antiglobulin crossmatch (rather than an abbreviated one) before all neonatal red cell transfusions. The red cell preparation most frequently selected for small-volume transfusions was ABO and Rh group-specific red cell concentrates. When performing only large-volume exchange transfusions, 19.2 percent of hospitals used whole blood; all others prepared reconstituted units of red cells plus fresh-frozen plasma, a practice that frequently causes exposure to two donors per unit. Another practice likely leading to multiple donor exposure is the use of fresh-frozen plasma to adjust the hematocrit of red cell preparations to a predetermined value prior to a small-volume transfusion. Over one-half of hospitals adjusting hematocrits used plasma, presumably from one donor, to dilute packed red cells from another donor, a practice that has no apparent medical benefit. Most hospitals (63.4%) provided red cells with a reduced risk of transmitting cytomegalovirus; blood from seronegative donors was selected by 65 percent of hospitals. The majority of hospitals, including most of the community/urban hospitals, did not irradiate blood products before transfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Transfusion↗
PubMedDate not supplied

A calibration service for biomedical instrumentation maintenance laboratories.

An in-house calibration laboratory for the Biomedical Instrumentation Maintenance Services of the hospitals in the West of Scotland was established in 1993. This paper describes the development of this calibration service in the context of an overall quality system and also estimates its costs. Not only does the in-house service have many advantages but it is shown to be cost effective for workloads exceeding 260 items per annum.

Biomedical Engineering↗
PubMedDate not supplied

Effects of level of retrieval success on recall-related frontal and medial temporal lobe activations.

Brain dedicated single photon emission computed tomography (SPECT) was used to compare the neuroactivation produced by the cued recall of response words in a set of studied word pairs with that produced by the cued retrieval of words semantically related to unstudied stimulus words. Six of the 12 subjects scanned were extensively trained so as to have good memory of the studied pairs and the remaining six were minimally trained so as to have poor memory. When comparing episodic with semantic retrieval, the well-trained subjects showed significant left medial temporal lobe activation, which was also significantly greater than that shown by the poorly trained subjects, who failed to show significant medial temporal lobe activation. In contrast, the poorly trained subjects showed significant bilateral frontal lobe activation, which was significantly greater than that shown by the well-trained subjects who failed to show significant frontal lobe activation. The frontal activations occurred mainly in the dorsolateral region, but extended into the ventrolateral and, to a lesser extent, the frontal polar regions. It is argued that whereas the medial temporal lobe activation increased as the proportion of response words successfully recalled increased, the bilateral frontal lobe activation increased in proportion to retrieval effort, which was greater when learning had been less good.

Adult↗
PubMedDate not supplied

Delayed vascular reactivity to ischemia in diabetic microangiopathy.

To investigate vascular responses in insulin-dependent diabetic patients both with and without retinopathy, we have assessed vasodilation by forearm transcutaneous pO2 measurement after 10 min of ischemia produced by a sphygmomanometer cuff. Diabetic patients with proliferative retinopathy had a delayed vasodilatory response at 60 s (mean +/- SD pO2 = 9 +/- 3 mm Hg) compared with those having diabetes without retinopathy (15 +/- 4 mm Hg, P less than 0.01) and matched normal subjects (14 +/- 4 mm Hg, P less than 0.01). Recently diagnosed insulin-dependent diabetic patients had a very similar response (15 +/- 5 mm Hg) to matched normal subjects (15 +/- 3 mm Hg). The diminished vascular reactivity may be a consequence of microangiopathy and neuropathy, although patients with an impaired vascular response might be particularly at risk from the development of capillary closure.

Adult↗
PubMedDate not supplied

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Community Health Nursing↗