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Biomedical subjects

M A Pass

Publications and source records attributed to M A Pass.

At least 37 records · Page 2Linked to original sources
PubMed1988

Vaccination as a possible means of preventing lantana poisoning.

The toxic triterpene acids lantadene A and lantadene B were isolated from Lantana camara and conjugated to bovine serum albumen or haemocyanin. The conjugates were emulsified with complete Freund's adjuvant and injected into sheep and cattle. Vaccinated animals produced antibodies against the toxic compounds. Cholestasis was less severe in vaccinated than in non-vaccinated sheep challenged with a toxic dose of lantana. The results indicated a mild protective effect of vaccination against the hepatotoxic effects of lantana toxins.

Animals↗
PubMed1986

Current ideas on the pathophysiology and treatment of lantana poisoning of ruminants.

Lantana poisoning in ruminants results from the ingestion of toxic varieties of the plant Lantana camara, which contain the triterpene acids lantadene A and lantadene B. Poisoning results in intrahepatic cholestasis and the consequences of the liver injury include jaundice, photosensitisation and ruminal stasis. The decreased ruminal motility causes toxic material to be retained in the rumen and continuous absorption of toxins from the rumen maintains the disease. Lantana poisoning can best be treated by preventing further absorption of toxins. This can be achieved by giving a large quantity of activated charcoal into the rumen together with a large volume of a multiple electrolyte solution to stimulate ruminal motility and rehydrate the animal. Treatment for photosensitive dermatitis should also be given.

Animals↗
PubMed1985

Effect of alcohol and aldehyde dehydrogenase inhibitors on the toxicity of 3-nitropropanol in rats.

The nitrocompounds 3-nitropropanol (NPOH) and 3-nitropropionic acid (NPA) were shown to be equally toxic when injected intraperitoneally into male Wistar rats. The LD50 for NPOH was 0.58 mmol/kg and for NPA it was 0.56 mmol/kg. NPOH was rapidly metabolized to NPA but this conversion was suppressed by prior administration of ethanol or 4-methylpyrazole to inhibit alcohol dehydrogenase. Administration of ethanol or 4-methylpyrazole before NPOH protected rats from intoxication. However, if the alcohol dehydrogenase inhibitors were given after the nitroalcohol, toxicity still occurred. Administration of the aldehyde dehydrogenase inhibitor diethyldithiocarbamic acid had little effect on the conversion of NPOH to NPA and did not alter the toxicity of NPOH. It was concluded that NPOH and NPA are equally toxic to rats but that NPOH is toxic due to its being rapidly converted to NPA.

1-Propanol↗
PubMed1985

A relationship between hepatic metabolism of reduced lantadene A and its toxicity in rats and sheep.

The metabolism of the cholestatic triterpene acid reduced lantadene A has been studied in susceptible and resistant rats and in sheep which are susceptible to intoxication. Sheep and susceptible female rats produced a similar major metabolite and rats produced a second metabolite which was a glucuronide. These metabolites were also observed in extracts of bile canalicular membranes prepared from intoxicated rats. Resistant male and female rats produced a similar major metabolite which was different to those synthesized by susceptible animals. It is concluded that in rats and sheep there is a correlation between the type of metabolites produced in the liver and the susceptibility to intoxication by reduced lantadene A.

Animals↗
PubMed1984

Administration of activated charcoal for the treatment of lantana poisoning of sheep and cattle.

The use of activated charcoal for treating lantana poisoning was investigated. When 500 g of activated charcoal was given orally with toxic Lantana camara, it protected sheep against intoxication. Administration to sheep of 500 g of activated charcoal in 4 1 of electrolyte solution orally 6 days after the onset of lantana poisoning and then 4 1 of electrolyte solution the next day, was followed by recovery from the intoxication. Mortality was significantly higher in intoxicated sheep given only the electrolyte solution and in untreated sheep. Six cows with naturally occurring lantana poisoning were treated with 2-2.5 kg of charcoal in 20-30 1 of electrolyte solution given by stomach tube and all the animals recovered. It is recommended that sheep with lantana poisoning be treated orally with 500 g of activated charcoal in 4 1 of electrolyte solution, and that cattle be given 2 kg of charcoal in 20 1 of electrolyte solution. Supportive treatment for photosensitization and dehydration may also be required.

Animals↗
PubMed1984

Use of 13C nuclear magnetic resonance spectroscopy for the evaluation of hepatic drug-metabolizing enzyme activity in perfused mouse livers.

Experiments were performed to determine whether the activity of hepatic drug-metabolizing enzymes could be estimated in intact livers by 13C NMR spectroscopy. 13C-labelled aminopyrine was administered to isolated perfused mouse livers and the rate of decline in the NMR signal arising from the drug was used to estimate the half-life of aminopyrine. The technique was sufficiently sensitive to discriminate between the enzyme activities in normal livers and in livers whose enzyme activity was enhanced by treatment with sodium phenobarbitone. It was also demonstrated that demethylation of aminopyrine was not impaired in perfused livers from mice infected with Plasmodium berghei.

Aminopyrine↗
PubMed1984

Absorption of 3-nitropropanol and 3-nitropropionic acid from the digestive system of sheep.

When 3-nitropropanol (NPOH) was injected into the rumen (30 mg/kg), abomasum (10 mg/kg) or small intestine (10 mg/kg) of sheep, it was rapidly absorbed and converted to 3-nitropropionic acid (NPA). The reticulo-rumen was the major site of absorption for the miserotoxin aglycone but the abomasum and the small intestine also had the capacity to absorb NPOH. When NPA was injected into different regions of the alimentary tract, the reticulo-rumen was also the major site of absorption. Absorption of NPA or NPOH from the small intestine was much more rapid than from the abomasum. Plasma levels of NPA and inorganic nitrite were higher after dosing with NPOH than with NPA indicating a more rapid rate of uptake of the aglycone.

1-Propanol↗
PubMed1984

Absorption of 3-nitropropanol (miserotoxin aglycone) from the compound stomach of cattle.

Miserotoxin, the toxic component of certain Astragalus spp. (Leguminosae), was rapidly hydrolyzed to 3-nitropropanol (NPOH) in the rumen of cattle dosed with timber milkvetch (A. miser var. serotinus). The aglycone showed a rapid rate of disappearance from the rumen with an average half-life of 1.24 h. In contrast to the passage of Co-EDTA, which showed an exponential rate of increase in the abomasum, NPOH was not detected in abomasal fluid collected from dosed cattle. Rapid absorption of NPOH from the rumen was shown by plasma levels of 3-nitropropionic acid (NPA) and inorganic nitrite, but conversion of NPOH to NPA was not observed to any significant extent in the rumen.

1-Propanol↗
PubMed1984

Conversion of 3-nitropropanol (miserotoxin aglycone) to 3-nitropropionic acid in cattle and sheep.

The metabolism of intravenously administered 3-nitropropanol (miserotoxin aglycone) was examined in cattle and sheep using high-pressure liquid chromatography (HPLC) to determine nitrocompounds in plasma. 3-Nitropropanol (NPOH) showed a rapid rate of decay and simultaneously, 3-nitropropionic acid (NPA) was detected at comparable levels in plasma. In animals dosed with NPOH, the observed NPA decayed at a slower rate than NPOH. Nitrite levels in plasma were more closely related to NPA than to NPOH. Therefore, metabolism of NPOH is linked to NPA and this could provide a common basis for the toxicity of these compounds in cattle and sheep.

1-Propanol↗
PubMed1983

Changes in rumen contents associated with lantana poisoning of sheep.

The effects of lantana poisoning on the microbial populations of the rumen and on fermentation within the rumen were compared to the effects of starvation in sheep. The protozoal and bacterial populations of the rumen were decreased to the same extent by lantana poisoning and starvation. Fermentation appeared to continue for several days in the rumen of lantana-poisoned animals, as shown by the concentrations of volatile fatty acids and ammonia, and the pH and rH of rumen fluid. It is suggested that this was due to retention of plant material in the static rumen of lantana-poisoned animals. It is concluded that lantana toxins do not affect rumen microorganisms directly and that the changes observed in lantana-poisoned animals are probably due to anorexia and rumen stasis.

Ammonia↗
PubMed1983

The mechanism of ruminal stasis in lantana-poisoned sheep.

The effect of poisoning by the plant Lantana camara L. on reticulo-ruminal motility was investigated in sheep. There was a marked decrease in forestomach motility 4-6 h after dosing with the plant and motility continued to be depressed throughout the course of the disease. The effect of lantana on motility was characterized by a decrease in the number and median amplitude of forestomach movements. This was in contrast to the effect of starvation which caused a decrease in only the number of forestomach movements and even this effect was less severe than in lantana-poisoned animals. The effects of lantana on the components of the reflex which controls rumen motility were examined. No evidence was found for a direct effect of lantana toxins on the stretch and tactile receptors in the reticulum; on the vagus nerves; on the gastric centre or on the muscle of the forestomach. However, evidence was found to support an hypothesis that stasis of the rumen in lantana poisoning is due to inhibitory influences arising from the damaged liver. The evidence included a correlation between the onset of ruminal stasis and liver injury; a relationship between the severity of liver injury and ruminal stasis and the finding that denervation of the liver converted the pattern of forestomach movements in intoxicated animals to that seen in starved animals. It is concluded that stasis of the rumen in lantana-poisoned animals is due at least initially, to inhibitory neural impulses arising from the damaged liver and to the effects of anorexia.

Animals↗
PubMed1983

Effect of lantana on the composition of the extracellular fluid of sheep.

Experiments were done to examine the effects of lantana poisoning on the composition of the extracellular fluid of sheep. Packed cell volume and total plasma protein increased after dosing with lantana and plasma osmolality increased markedly in the days prior to death. During the early stages of the disease plasma electrolytes were unchanged except for a decrease in potassium, but electrolyte levels varied late in the disease. A metabolic acidosis gradually developed as the disease progressed. It is concluded that fluid, electrolyte and acid-base imbalances are minor in the early stages of intoxication, but in the terminal stages of the disease, some major changes occur.

Ammonia↗
PubMed1982

Puerperal and perinatal infections with group B streptococci.

Twenty-one patients were seen with puerperal sepsis owing to group B streptococci (GBS), resulting in an attack rate of 2/1,000 deliveries. Most were young primiparous black women from a population with a known high incidence of GBS carriage. The association among abdominal delivery, endometritis, and puerperal sepsis was striking. Cultures of the birth canal or lochia were commonly positive for the same serotype recovered from the blood. Forty-seven patients with nonbacteremic GBS infections were seen; 27 had endometritis or amnionitis. Twenty patients had GBS urinary tract infection: Eight infections occurred prenatally, seven at delivery, and five post partum. Seven neonates developed serious GBS infections; intrauterine exposure occurred in at least four cases. Fetal exposure to GBS also occurred in three of four cases in which parturients with GBS bacteremia were delivered of their infants by cesarean section. Because of the high incidence of puerperal and perinatal GBS infections in this population, antibiotic prophylaxis regimens may be beneficial.

Adolescent↗
PubMed1982

Effect of amitraz on contractions of the guinea-pig ileum in vitro.

1. The effect of the formamidine pesticide amitraz on the motility of isolated pieces of guinea-pig ileum was studied. 2. Contractions of the ileum stimulated by histamine and the histamine H1 agonists 2-methylhistamine and 2-pyridylethylamine were inhibited by amitraz at a concentration of 1 microgram/ml. 3. Amitraz did not inhibit contractions stimulated by acetylcholine, methacholine or dimethylphenylpiperazinium. 4. When pieces of intestine were left exposed to amitraz for several minutes they began to contract. These contractions appeared as rhythmic contractions and their strength did not appear to be increased by increasing the concentration of amitraz. 5. It is concluded that amitraz inhibits the action of histamine H1 agonists on the guinea-pig ileum and itself has a weak agonist effect.

Animals↗
PubMed1982

Anorectal and vaginal carriage of group B streptococci during pregnancy.

A longitudinal prospective study of carriage of group B streptococci during pregnancy was conducted in 2,540 women over a three-year period. Carriage was documented in 18% of the women by anorectal culture, in 4% by vaginal culture, and in 13% by simultaneously obtained anorectal and vaginal cultures (overall carriage rate, 35%). The rate and pattern of carriage were nearly identical from year to year. In sequential cultures in the second and third trimesters of 754 women, carriage rates were 31% and 28%, respectively; only 17% of the women were carriers in both trimesters. (1) Persistence of carriage was most common when the initial anorectal swabs were positive, (2) spread from the intestinal tract to the vagina occurred, and (3) the intestinal tract was commonly the primary site of acquisition in patients with previously negative cultures. The intestinal tract appears to be a primary reservoir for group B streptococci and the likely source of vaginal or urogenital colonization in pregnant women.

Adolescent↗
PubMed1981

Absorption of the toxins of Lantana camara L. from the digestive system of sheep.

When lantana was given into different regions of the alimentary tract, absorption sufficient to cause intoxication occurred from the stomachs, small intestine and large intestine, but absorption from the small intestine was quantitatively the most important. However, it was shown that the passage of ingesta into the small intestine decreased markedly a few hours after the toxin was given and it is suggested that absorption from all areas of the gastrointestinal tract is important for the progression of the disease. When bile was diverted away from the small intestine, animals were still intoxicated by lantana. This indicates that bile is not important for absorption of lantana toxins. Other experiments indicated that the lantana toxins are transported to the liver mainly in the portal blood.

Animals↗