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Biomedical subjects

T Mackenzie

Publications and source records attributed to T Mackenzie.

28 records · Page 2Linked to original sources
PubMed1984

Effect of clonidine therapy on renal hemodynamics in renal transplant hypertension.

Antihypertensive medications have a variable effect on renal hemodynamics and may contribute to renal insufficiency in some patients. Since clonidine has actually been found to improve renal hemodynamics in patients with essential hypertension, we studied the effects of clonidine therapy in patients with renal transplant hypertension. Baseline measurements of BP and renal hemodynamics were made in six patients after two weeks of therapy with furosemide. Clonidine was then added and titrated until BP was controlled. Repeated measurements of renal hemodynamics were made four and 16 weeks after clonidine therapy was begun. Glomerular filtration and effective renal plasma flow as assessed by inulin and aminohippurate sodium clearances were preserved during prolonged clonidine therapy.

Adult↗
PubMed1979

Duration of anti-adhesive and bactericidal activities of milk from vaccinated sows on Escherichia coli O149 in the digestive tract of piglets during the nursing period.

Piglets were exposed orogastrically to Escherichia coli to enable study of the duration of anti-adhesive and bactericidal activities of milk of sows vaccinated with a K88 enriched E coli vaccine. There was a marked increase in the number of the challenge strain in the digestive tract of weaned piglets of all ages (between 888 and 2144 per cent). In contrast, there was a decrease in their number (75 per cent) in the day-old colostrum-fed piglets. When the piglets were two weeks old milk was still capable of reducing the rate of proliferation of the pathogen but at five weeks it proliferated at equal rates in the digestive tract of both suckling and weaned litter-mates. The rate of adhesion of the K88 positive E coli to the small intestine of colostrum deprived piglets was high (5 x 108/g). Rate of adhesion fell gradually in weaned piglets from 5.4 x 107/g at two weeks to 2.0 x 106/g at four to five weeks of age. In contrast, resistance of the small intestine of suckling pigs to adhesion by K88-positive E coli remained relatively stable through the five week period of nursing bacterial counts ranging from 5 x 104/g to 3 x 104/g of tissue.

Adhesiveness↗
PubMed1978

Criteria for choosing amino acid therapy in acute renal failure.

Metabolic studies were performed on 19 patients with acute renal failure. Therapy included intravenous hyperalimentation using 15 to 20 g of essential amino acids or 20 to 40 g of essential plus nonessential amino acids and hypertonic glucose (37 to 50%). The effect of this parenteral feeding appears to be primarily pharmacological. Hypertonic glucose promotes the hyperinsulinemia important to be membrane function, the operation of the sodium pump, and cell metabolism. Administration of high biological value crystalline amino acdis potentiates the effect of insulin by inhibiting protein breakdown and promoting protein synthesis, particularly in muscle. This reduces tissue catabolism and urea formation, and promotes potassium, magnesium, and phosphate homeostasis. The branched-chain ketogenic amino acids valine, leucine, and isoleucine may be of particular importance. When indicated, administration of renal failure hyperalimentation and peritoneal or hemodialysis can be expected to complement each other and accelerate recovery. This intravenous fluid therapy, in turn, must be coordinated with proper hemodynamics, usually requiring a colloidal solution to maintain intravascular volume, and cardiotrophic agents such as digitalis and dopamine. Early use of renal failure can be expected to demonstrate the most striking response in terms of survival, early recovery from acute renal failure, and the preservation of physiological homeostasis.

Acute Kidney Injury↗
PubMed1976

The effect of colostrum or past colibacillosis on the adhesion of Escherichia coli to the small intestine of the pig.

Nursing litters of vaccinated (K88 antigen) and non-vaccinated gilts as well as weaned piglets, which had recovered from natural colibacillosis, were exposed to Escherichia coli O149: K91(B), K88ac(L) orogastrically and 3-4 h after exposure a proportion of each group was killed for adhesion studies; others were kept for clinical observations. From killed piglets duodenal contents were collected and after washing of the duodenum by standardised techniques it was homogenised. Viable counts of E coli O149 in these specimens were carried out and compared. Colicounts in the duodenal contents and in the homogenate of washed duodenum of naturally infected piglets were also compared. There was less than tenfold difference in counts of K88-positive E coli between duodenal contents and washed duodenum of piglets which were (A) naturally infected, (B) colostrum deprived and experimentally infected, or (C) were from colostrum fed groups where those litter mates which were kept for clinical observation died of colibacillosis. There was 10(3)-10(5)-fold difference in E coli O149 counts between comparable specimens from piglets which (a) recently recovered from K88-positive E coli infection at the time of oral challenge or (b) were from colostrum fed groups where those litter mates which were kept for clinical observation survived oral challenge. It is concluded that adhesion of K88-positive E coli to the epithelium of the anterior small intestine of the pig is a feature of natural as well as experimental colibacillosis. Such adhesion may be prevented by (i) earlier natural infection of K88-positive E coli or (ii) by the ingestion of colostrum of K88 antigen vaccinated dams.

Animals↗
PubMed1976

In vitro studies on the antimicrobial effects of colostrum and milk from vaccinated and unvaccinated pigs on Escherichia coli.

Unsupplemented porcine colostrum and milk exhibited a powerful bactericidal effect for porcine strains of E coli incubated in vitro at 37 degrees C. This activity was independent of complement but was susceptible to acid pH, to the presence of soluble iron and to the selective immunoprecipitation of IgG, IgA and IgM. Manifestation of bactericidal activity required bacteria in an active state of metabolism and the length of incubation was an important factor in demonstrating the quality of the anticoli activity, ie, proliferation-inhibitory, bacteriostatic or bactericidal. Whey obtained by acid precipitation or by the application of rennin was devoid of bactericidal activity but was capable of slowing down proliferation of E coli. There was no correlation between lysozyme and anticoli activity although the complete removal of lysozyme by adsorption on to bentonite reduced bactericidal titres. With very few exceptions the highest bactericidal titres were recorded for colostrum, but even 28 days post partum about one half of 22 undiluted milk samples exhibired bactericidal activity.

Animals↗
PubMedDate not supplied

Alcohol effects on the facial expressions of anxiety patients undergoing a panic provocation.

Using subjects with panic disorder, we investigated the effect of alcohol on expressive-emotional facial reactions to a well-known laboratory panic provocation procedure (inhalation of 35% carbon dioxide). Subjects consuming alcohol (vs. a placebo) displayed lower levels of emotional masking and fear/distress facial responses; however, differences were significant only for emotional masking. A composite variable combining the masking and fear/distress scores was also significantly lower in the group consuming alcohol. To the extent that masking behavior is a valid proxy for fear/distress responding, then the latter finding supports the conclusion that alcohol reduced negative affectivity associated with the inhalation. However, we also note the possibility that alcohol reduced masking directly without affecting fear/distress. We make parallel recommendations for future research that treats masking behavior as a nuisance variable on the one hand, or a dependent variable of potential importance on the other. We conclude that expressive-behavioral measures appear to be both feasible and potentially informative in alcohol research.

Administration, Inhalation↗
PubMedDate not supplied

Expectancies for alcohol to affect tension and anxiety as a function of time.

Alcohol outcome expectancies have been linked to drinking behavior on both empirical and theoretical grounds. Although typically measured as a static construct, we hypothesized that expectancies may be time-specific. Subjects rated their expectancies for a moderate amount of alcohol to increase, decrease, or not change their level of tension and anxiety. Ratings were repeated for when the intoxicating effects of the drinking would be: (1) "at their peak;" (2) "nearly worn off;" and (3) "completely worn off" (Time Epochs 1-3, respectively). As predicted, most subjects (72%) expected alcohol to reduce tension and anxiety at Time Epoch 1; however, significantly fewer subjects expected this effect at Time Epochs 2 and 3 (25% and 2%, respectively). Conversely, few subjects expected alcohol to worsen tension and anxiety at Time Epoch 1 (3.5%); however, significantly more subjects expected this effect at Time Epochs 2 and 3 (31% and 34%, respectively). Expectancies for Time Epoch 1 related most strongly to several measures of alcohol use, including drinking for the purpose of reducing tension (whole sample) and drinking frequency (men but not women). These findings show that tension-reduction expectancies are not stable over the course of a drinking episode and suggest the possibility of a treatment approach aimed at amplifying attention to expectancies for alcohol's more negative longer-term effects.

Adult↗
PubMedDate not supplied

Randomized trial of a portable, self-administered decision aid for postmenopausal women considering long-term preventive hormone therapy.

Although practice guidelines suggest that postmenopausal women learn about the benefits and risks and consider their values when deciding about hormone therapy, the optimal decision-support method has not been established. In a randomized controlled trial, the authors compared the efficacy of a general educational pamphlet with that of a tailored decision aid. The pamphlet briefly summarized benefits, risks, and likely beneficiaries in general terms. The decision aid, delivered via booklet and audiotape, provided: detailed benefits and risks using functional terms and probabilities tailored to clinical risk; and steps for considering the issue in a woman's own situation, including a value-clarification exercise. Compared with the pamphlet group, the decision-aid group had statistically significant (p < 0.05) improvements in terms of realistic personal expectations of the benefits and risks, decisional conflict, and perceived acceptability of the intervention. Levels of general knowledge about the main benefits and risks were comparable for the two interventions. It is concluded that tailored decision aids prepare women for decision making better than do general pamphlets.

Aged↗