PubMed Health⌕ Search

Biomedical subjects

R J Lambert

Publications and source records attributed to R J Lambert.

36 records · Page 2Linked to original sources
PubMed1994

Monitoring local food security and coping strategies: lessons from information collection and analysis in Mopti, Mali.

Save the Children Fund (UK) established a local food security monitoring project in the Mopti region of Mali, which was operational between 1987 and 1993. This article describes some of the lessons learnt from this experience of monitoring food security and coping strategies. It illustrates how coping strategies can be an important element in tracking vulnerability in the Sahel, but that interpretation is complex and there are limitations to their use. Secondly, consideration must be given to the institutional context in which information systems are set up. Information providers must be linked institutionally to response mechanisms, to ensure that data are fed systematically into the design, implementation and monitoring of appropriate response.

Agriculture↗
PubMed1989

Evaluation of a superactivated charcoal paste and detergent and water in prevention of T-2 toxin-induced local cutaneous effects in topically exposed swine.

T-2 toxin (6 mg) dissolved in 90% DMSO was topically applied to nine 9-cm2 sites on the dorsum of each of nine young, crossbred, specific pathogen-free, female pigs, 20.6 +/- 1.9 kg in weight. A superactive charcoal paste (SAC) and/or a soap-and-water wash (SOAP) was applied to eight of the T-2-exposed sites on each animal. These treatments were applied at various times postexposure ranging from 5 to 65 min. The site that received T-2 alone served as a positive control. DMSO was applied to a tenth site on each pig as a negative control. Animals were killed 1, 3, or 6 days after treatment. Skin lesions were examined and graded grossly and histologically. No adverse systemic clinical signs were observed in any of the animals. Marked reddening and slight swelling of the T-2 toxin-treated positive control sites were present throughout the study. Ulceration of this site was first noted on Day 3. All therapeutic regimens effectively reduced lesion severity resulting from T-2 toxin application. Significant differences in relative effectiveness were also seen between treatments. In each significant pair, the ordering of mean lesion severity was SAC/SOAP less than SAC or SOAP and SOAP less than SAC. As a single treatment, SOAP appears to be more effective than SAC in reducing lesion severity. These results failed to provide unequivocal evidence of an additive therapeutic effect when SAC and SOAP were used sequentially on the same site.

Administration, Topical↗
PubMed1988

Experimental T-2 toxicosis in swine following inhalation exposure: clinical signs and effects on hematology, serum biochemistry, and immune response.

Nine- to ten-week-old, male castrated, specific pathogen-free derived pigs, weighing 34 to 42 kg, were exposed to a T-2 toxin aerosol (390 micrograms/liter, 1.5 microM mass median aerodynamic diameter) for a time period which allowed an amount equivalent to 8 mg/kg to be nebulized (six pigs). Control animals (five pigs) were exposed to an equivalent amount of the nebulized vehicle. Pigs were immunized subcutaneously with sheep red blood cells on Days 0 and 21. Whole blood and serum samples were taken periodically for clinical pathologic and immunologic studies. Pigs were closely observed, and daily rectal temperatures and weekly weights were measured. The T-2-treated pigs vomited and exhibited cyanosis, anorexia, lethargy, lateral recumbency, slightly elevated rectal temperature, and depressed body weight gain. The lymphocyte count decreased while the neutrophil count increased. The concentrations of total serum protein and hemoglobin declined. There was a marked increase in serum alkaline phosphatase activity on Day 1, followed by a marked and persistent decrease. Mitogen-induced (Con A, PHA, and PWM) blastogenic responses of peripheral blood mononuclear cells and hemagglutination titers to SRBC were also transiently decreased. Thus, inhalation exposure of pigs to a sublethal dose of T-2 toxin caused clinical signs of toxicity and adverse effects on clinical pathologic parameters and immune responses; however, most of these effects were short-lived. The changes described in our study resemble those reported in pigs given T-2 toxin by intravascular injection.

Administration, Inhalation↗
PubMed1988

The efficacy of superactivated charcoal in treating rats exposed to a lethal oral dose of potassium cyanide.

Due to the apparent low binding capacity of activated charcoal for potassium cyanide (KCN) in vitro, the use of oral activated charcoal therapy for oral exposure to cyanide compounds is controversial. In our study, rats were given a lethal oral dose of ground granular KCN (35 or 40 mg/kg) in a gelatin capsule followed immediately by either 4 g/kg of superactivated charcoal in a 20% suspension or a similar volume of deionized water. Signs of cyanide toxicosis occurred rapidly, with a mean time to signs of 3.3 and 2.7 minutes in control animals receiving 35 or 40 mg/kg KCN, respectively. All 26 of the control rats showed signs, and all but one in the 35 mg/kg group died within 19 minutes. Only 12 of 26 rats treated with superactivated charcoal showed signs of KCN toxicosis and eight of those animals died. Oral exposure of rats to lethal doses of KCN can be treated effectively by immediate administration of superactivated charcoal.

Administration, Oral↗
PubMed1987

Therapeutic efficacy of superactive charcoal in rats exposed to oral lethal doses of T-2 toxin.

Superactive charcoal, a compound known to complex with many toxins, was evaluated in this study for its effectiveness in preventing death in rats given an oral lethal dose of 8 mg/kg body weight of T-2 toxin. The median effective dose of oral superactive charcoal in preventing deaths in rats was 0.175 g/kg body weight. Concurrent use of cathartics, such as sorbitol, magnesium sulfate and sodium sulfate, to facilitate removal of the superactive charcoal:T-2 toxin complex formed in vivo did not enhance the survival rates of rats. One gram per kilogram body weight oral superactive charcoal enhanced survival times and survival rates in rats given 8 mg/kg of T-2 toxin as late as 3 hr after the T-2 toxin was administered. Some benefit in survival rate may be derived from giving the superactive charcoal as late as 5 hr after the T-2 toxin.

Administration, Oral↗
PubMed1987

Plant factors controlling seed set in maize : the influence of silk, pollen, and ear-leaf water status and tassel heat treatment at pollination.

In maize (Zea mays L.) large decreases in kernel number result when low water potentials (Psi(w)) and high temperatures occur during pollination. To gain insight into the basis for the decreased seed set, silk, pollen, and ear-leaf Psi(w), the capability for silk osmotic adjustment, and pollen appearance were measured to determine their relationship to seed set. A multiple-eared or prolific (high carbohydrate availability to the pistillate inflorescence) hybrid (B73 x FR25), a heat sensitive hybrid (WF9 x A632), and a commercial hybrid (B73 x Mo17) were studied. A cross-pollination experiment, with pollination limited by pollen amount, was conducted to determine the impact on seed set of water and heat stressing the tassel and water stressing the ear. At low Psi(w), silk Psi(w) and seed set were decreased whereas pollen Psi(w), appearance, and viability were unaffected. High temperature resulted in a 2 megapascal decrease in pollen Psi(w), visually damaged pollen being shed, decreased pollen viability, and, in two of the hybrids, substantially decreased pollen shed. Prolificacy did not result in increased silk solute accumulation but did result in superior seed production by the pistillate inflorescence at low Psi(w). The magnitude of the decrease in silk solute potential was small (0.2 megapascal) and similar for all genotypes. One hybrid maintained a relatively high silk turgor but this hybrid also decreased the most in seed production when the pistillate inflorescence was water deficient. These results indicated an adverse effect of high temperature on pollen development, a positive relationship between seed production and silk water status, and no advantage to high silk turgor after silk emergence in maintaining seed production. Additionally, there was no evidence of variation in silk solute regulation capability among hybrids which varied in prolificacy, a trait important in drought tolerance, but the seed production of the pistillate inflorescence of the prolific hybrid was least affected by water deficit.

Journal Article↗
PubMed1987

Experimental T-2 toxicosis in swine following inhalation exposure: effects on pulmonary and systemic immunity, and morphologic changes.

Thirty-four, 9- to 11-week-old, male castrated, crossbred, specific pathogen-free derived pigs were exposed to a T-2 toxin aerosol at a nebulized dose of 0 or 9 mg/kg in pairs, each pair consisting of 1 control and 1 T-2 treated pig which were exposed on the same day. Twenty to 30% of the toxin (1.8 to 2.7 mg/kg) was retained by the pigs. Five pairs were killed on each of 1, 3 and 7 days after dosing. Two pairs of pigs were designated as a 0.33-day group when one T-2 treated pig died and the other was killed in a moribund state at 8 to 10 hours after dosing. The pulmonary and systemic immunity and morphologic changes of the lungs and other organs were examined. Bronchoalveolar lavage was performed to obtain alveolar macrophages (AM) and pulmonary lymphocytes (PL). The phagocytic ability of AM and mitogen-induced blastogenic responses of enriched PL and peripheral blood lymphocytes were evaluated. Clinically, all of the T-2 treated pigs vomited and were cyanotic, anorexic, lethargic and laterally recumbent. In the 0.33-, 1-, and 3-day T-2 treated pigs, there was a marked reduction in AM phagocytosis and mitogen-induced blastogenic responses of PL but not of peripheral blood lymphocytes. Mild to moderate, multifocal interstitial pneumonia was seen in the majority of the T-2 treated pigs. In pigs dying following inhalation of T-2 toxin, there was a more severe pneumonia, as well as marked necrosis of lymphoid tissues, severe necrohemorrhagic gastroenteritis and edema of the gall bladder wall, and multifocal necrosis of the heart and pancreas. Thus, inhalation exposure to T-2 toxin can result in clinical signs and morphologic changes resembling those reported previously in pigs given T-2 toxin intravascularly (iv) at a dose of 1.2 mg/kg (approximate LD50) or greater, as well as death. Mild pulmonary injury as well as transient impairment of pulmonary immunity was present in pigs surviving inhalation exposure.

Administration, Inhalation↗
PubMed1986

Systemic distribution of blood flow during T-2 toxin induced shock in swine.

Three groups of swine (6 per group) were used to determine hemodynamic and blood flow alterations induced by T-2 toxin. Two groups were dosed at 0.6 or 2.4 mg/kg T-2 toxin, and one group served as a vehicle control (70% ethanol). Organ blood flow was determined at 0 hr (predosing) and at 90-min intervals for 6 hr postdosing using 15-micron diameter radionuclide labeled microspheres injected into the left atrium. Hemodynamic parameters were obtained at the same time points. The infusion of T-2 toxin resulted in reductions in cardiac output. This trend appeared to reverse itself in the low dose animals after 3 hr, whereas in the high dose group, cardiac output continued to decline. Mean aortic pressure (MAP) declined in a dose dependent fashion which tended to parallel the reduction observed in cardiac output. Heart rate was increased in both groups treated with T-2 toxin. Blood flow, to the brain, heart, and kidneys decreased following exposure to the toxin. The relative percentage of cardiac output received by these organs, however, was maintained despite the drop in blood flow. Pancreatic and splenic blood flows were the most severely compromised as a result of T-2 toxicosis. Consequently, the percentage of cardiac output going to the pancreas and spleen was dramatically reduced. Adrenal, hepatic, and total gastrointestinal blood flows increased or did not change from control values. As a result, the percentage of cardiac output supplying these organs increased.

Animals↗
PubMed1982

Interaction of carbon and nitrogen metabolism in the productivity of maize.

Five maize (Zea mays L.) hybrids, FS854, B73 x Mo17, B84 x Mo17, B73 x B77, and P3382, grown under field conditions, were sampled at intervals during the grain-filling period. Plants were subdivided into stalks (including sheaths), leaves, and kernels. These parts were assayed for dry weight, reduced nitrogen, and extractable nonstructural carbohydrates. The duration and rates of net nitrate reduction and photosynthesis were approximated by the changes over time in the accumulation of reduced nitrogen and dry weight by the plant (total, above ground), respectively.Data on the accumulation of reduced nitrogen and dry weight by the plant show that decreases in nitrate reduction preceded (in time and extent for four of the hybrids and in extent for FS854) decreases or cessation of photosynthesis. FS854 continued to accumulate reduced nitrogen and dry matter throughout the grain-filling period.The patterns of change in stalk carbohydrate and reduced nitrogen during the early stages of ear development show the stalk serves as a storage reservoir and that these reserves were remobilized during the final stages of grain development. The marked increase and maintenance of dry weight and carbohydrate content of stalks until 34 days after anthesis, shows the capacity of the leaves to produce photosynthate through the first half of the grain-filling period exceeds the needs of the ear and/or the transport system. In contrast, stalk nitrogen content shows a slight increase up to 12 days after anthesis and decreases continually thereafter. Leaf nitrogen was lost continuously throughout grain development. The potential capacity of the plant to supply newly reduced nitrogen was inadequate to support initiation and early development of the kernels without remobilization of vegetative nitrogen. Of the two hybrids having delayed leaf senescence, FS854 with its initially higher concentration and content of reduced nitrogen in the stalk, initiated and developed a bigger ear than P3382, which had lower levels of stalk nitrogen.Three of the five hybrids had ;near linear' rates of accumulation of kernel dry weight, whereas none of the hybrids had linear rates of gain in kernel nitrogen. All hybrids had maximum or near maximum rates of gain of kernel nitrogen between 26 and 34 days after anthesis and a marked reduction (41-52%) of rates in the following sampling interval. These decreases are concurrent with decreases in rates of nitrate reduction (nitrogen accumulation) by the whole plant for four of the hybrids and with decreases in remobilization of nitrogen from the vegetation of FS854. Data for the ratio of rates of accumulation of dry weight/reduced nitrogen by the kernels versus time after anthesis, show that the accumulation of dry weight and reduced nitrogen are independent of each other. The variations in the ratio values appear best related to variations in the availability of nitrogen from the vegetation.

Journal Article↗
PubMed1970

Chromosome pairing within genomes in maize-Tripsacum hybrids.

When the ten chromosomes of maize were inserted inlto a polyploid (2n = 72) Tripsacum dactyloides background they formed up to five pairs at meiosis. Two plants that each contained 36 Tripsacum and 14 maize chromosomes were deprived from the F(1) of maize x Tripsacum. Chromo. somes of these plants frequently formed 25 bivalents, 18 between Tripsacum chromosomes and seven between maize chromosomes. Maize chromosomes could be distinguished from Tripsacum chromosomes on the basis of size. The withint-genome pairing is probably induced by the genetic background.

Chromosomes↗
PubMed1969

Inheritance of nitrate reductase activity in Zea mays L.

Since the F(1) hybrid (B14 x Oh43) had been shown to have a higher (heterotic) level of nitrate reductase activity than either inbred parent (B14 or Oh43), studies were undertaken to determine the mode of inheritance. Standard methods for determining Mendelian inheritance were used to study segregation for level of nitrate reductase activity of individual plants. The genetic material used was the inbreds B14 and Oh43, F(1), F(1) backcrossed to both parents, F(2), F(3), and F(4) generations of the cross B14 x Oh43. The plant material was grown in the field and in growth chambers. It was shown that the maize inbreds B14 and Oh43 differ at two loci that control the level of nitrate reductase activity. Each inbred is homozygous for a dominant or partially dominant allele at one locus and homozygous recessive at a second locus. The locus at which B14 carries a dominant allele carries the recessive allele in Oh43. Oh43 has both a higher in vivo rate of synthesis of nitrate reductase and higher in vivo and in vitro loss of enzyme activity (decay) than B14. Thus, the rates of both enzyme synthesis and decay are factors governing the level of nitrate reductase activity in corn. The data suggest that the heterotic level of nitrate reductase activity in the F(1) hybrid is the result of inheritance of qualities that gives it "intermediate" rates of enzyme synthesis and decay.

Crosses, Genetic↗