Search PubMed⌕ Search

Biomedical subjects

J Nolan

Publications and source records attributed to J Nolan.

At least 163 records · Page 9Linked to original sources
PubMed1981

A survey for resistance in cattle ticks to acaricides.

A survey was made from late 1976 to late 1977 to determine the extent of resistance to acaricides in the cattle tick Boophilus microplus in Queensland. Questionnaires and requests for samples of ticks were forwarded to more than 900 randomly selected stock owners in the tick infested area which had been divided into 4 regions. Far North, Coastal North, Coastal Cental and South East. The response measured by the number of tick samples tested was 43%. The prevalence of resistance to organophosphorus (OP) compounds was highest in South East where 96% of the farms had OP-resistant ticks and 95% had the Biarra strain and lowest in Far North where 12% of the farms had OP-resistant ticks and 10% had the Biarra strain which was the predominant one in all regions. The highest percentages of the Ridgelands strain (35%) and the Tully strain (30%) occurred in Coastal North. The South East had the highest percentage of Mt Alford (30%). Although chlorinated hydrocarbons were banned for use in control of ticks in 1962, 49% of the farms in South East had some ticks resistant to dieldrin but in Far North it was only 2%. DDT-resistant ticks, which because of cross resistance to synthetic pyrethroids will affect the future use of this group, were present on 8% of the farms in both Coastal North and Coastal Central and 3% in South East and Far North. No resistance to the amidines, chlordimeform, chloromethiuron or amitraz was found.

Animals↗
PubMed1981

Evaluation of the potential of systemic slow release chemical treatments for control of the cattle tick (Boophilus microplus) using ivermectin.

Stall and field trials with cattle infested with various acaricide-resistant strains of cattle tick, have demonstrated the potential of ivermectin as a systemic tickicide. A dosage of 200 micrograms/kg, administered subcutaneously to animals naturally infested in the field, gave satisfactory tick control for 21 days, after an initial lag period of 2 days immediately following treatment, during which significant numbers of ticks survived. Daily subcutaneous treatments, administered so as to simulate slow release, indicated that a dosage of 15 micrograms/kg/day should give complete tick control if the chemical could be released continuously from a subcutaneous implant. The potency of ivermectin assessed by in vitro tests against engorged adults, suggests that the tickicidal activity could be associated with the parent compound per se rather than a metabolite.

Animals↗
PubMed1979

Analysis of costs and outcomes of renal transplantation at one center. Its implications.

A cost increase of more than 900% for medical services to dialysis patients and transplant recipients has been projected during the decade 1974 to 1984. To evaluate the role of renal transplantation in the End-Stage Renal Disease Program, we analyzed direct costs and patient outcomes in 466 consecutive transplants at our center. A successful transplant from either a living related or cadaver donor cost less than +7,000 per year for two years of graft function. The cost of transplants rejected during the second year also proved cost-effective when compared with the yearly costs of maintenance-facility hemodialysis. Patient survival was 100% at two years for recipients of a transplant from a living related donor and 84% at two years for recipients of a transplant from a cadaver. Renal transplantation can reduce the rising costs for end-stage renal disease patient care, without reducing life expectancy.

Adolescent↗
PubMed1979

The potential of some synthetic pyrethroids for control of the cattle tick (Boophilus microplus).

As part of a continuing programme to aid in the development of new acaricides, the potentials of three synthetic pyrethroids, permethrin, cypermethrin and decamethrin, were assessed against a range of resistant strains of the cattle tick (Boophilus microplus). The compounds were shown to be acaricidal, with decamethrin the most effective, giving efficient control of susceptible and organo-phosphorus resistant strains of the cattle tick at concentrations as low as one fifth of those previously used for any commercial acaricide. However higher concentrations were required for satisfactory control of the DDT-resistant strain. Permethrin-selection of a field strain containing a low percentage of DDT-resistant ticks led to rapid development of resistance to a level equivalent to that of the DDT-resistant strain. Further selection increased resistance to permethrin to a higher level than that shown in the DDT-resistant strain. This increased resistance to permethrin appears to be restricted mainly to this compound and is not associated with a marked increase in resistance to cypermethrin, decamethrin or DDT. The potential of organo-phosphorus compounds to potentiate the pyrethroids when the two classes of compounds are used as mixtures against the pyrethroid-resistant and susceptible strains was confirmed.

Animals↗
PubMed1978

Cardiac risk factors and complications in non-cardiac surgery.

In an attempt to assess cardiac risk in non-cardiac surgery, 1001 patients over 40 years of age who underwent major operative procedures were examined preoperatively, observed through surgery, studied with at least one postoperative electrocardiogram, and followed until hospital discharge or death. Documented postoperative myocardial infarction occurred in only 18 patients; though most of these patients had some pre-existing heart disease, there were few preoperative factors which were statistically correlated with postoperative infarction. Postoperative pulmonary edema was strongly correlated with preoperative heart failure, but 21 of the 36 patients who developed pulmonary edema did not have any prior history of heart failure. Nearly all of these 21 patients were elderly, had abnormal preoperative electrocardiograms, and had intraabdominal or intrathoracic surgery. In the absence of an acute infarction, bifascicular conduction defects, with or without PR interval prolongation, never progressed to complete heart block. Spinal anesthesia protected against postoperative heart failure but not against other cardiac complication. By multivariate regression analysis, postoperative cardiac death was significantly correlated with (a) myocardial infarction in the previous 6 months; (b) third heart sound or jugular venous distention immediately preoperatively; (c) more than five premature ventricular contractions per minute documented at any time preoperatively; (d) rhythm other than sinus, or premature atrial contractions on preoperative electrocardiogram; (e) age over 70 years; (f) significant valvular aortic stenosis; (g) emergency operation; (h) a 33% or greater fall in systolic blood pressure for more than 10 minutes intraoperatively. Notably unimportant factors included smoking, glucose intolerance, hyperlipidemia, hypertension, peripheral atherosclerotic vascular disease, angina, and distant myocardial infarction.

Adult↗
PubMed1977

Multifactorial index of cardiac risk in noncardiac surgical procedures.

To determine which preoperative factors might affect the development of cardiac complications after major noncardiac operations, we prospectively studied 1001 patients over 40 years of age. By multivariate discriminant analysis, we identified nine independent significant correlates of life-threatening and fatal cardiac complications: preoperative third heart sound or jugular venous distention; myocardial infarction in the preceding six months; more than five premature ventricular contractions per minute documented at any time before operation; rhythm other than sinus or presence of premature atrial contractions on preoperative electrocardiogram; age over 70 years; intraperitoneal, intrathoracic or aortic operation; emergency operation; important valvular aortic stenosis; and poor general medical condition. Patients could be separated into four classes of significantly different risk. Ten of the 19 postoperative cardiac fatalities occurred in the 18 patients at highest risk. If validated by prospective application, the multifactorial index may allow preoperative estimation of cardiac risk independent of direct surgical risk.

Age Factors↗
PubMed1976

Biochemical genetics of resistance to organophosphorus acaricides in three strains of the cattle tick, Boophilus microplus.

Three aspects of the biochemical genetics of resistance to organophosphorus compounds in the Biarra (B), Mackay (M) and Ridgelands (R) strains of the cattle tick B. microplus were studied. These were: decreased acetylcholinesterase (AChE) activity in adult brains of strains B and M; decreased AChE sensitivity to inhibitors in adult brains and in larvae of strains B, M and R; and increased detoxication in larvae and adult females of strain M. Comparisons were made with a susceptible reference strain (S). Microspectrophotometric estimations of AChE activity in histochemical preparations of whole brains showed that hybrids had levels of activity approximately intermediate between those of the parental strains. Homogenates of brains from hybrids assayed biochemically gave similar but more precise results which indicated that decreased brain AChE activity was neither recessive nor dominant (degree of dominance, D = +0-02) in strain B and incompletely recessive (D = -0-26) in strain M. The proportions of brains showing decreased AChE activity in testcross and F2 progenies indicated that decreased AChE activity in strains B and M is controlled by single autosomal genes. Inhibition of AChE at diagnostic concentrations of coroxon in brains of B, B x S hybrid and S types suggested that decreased sensitivity of AChE in strain B is incompletely dominant (D = +0-10). Kinetic studies on coroxon inhibition of AChE in brain homogenates of B, B x S hybrid and S types revealed the presence of each parental AChE component in hybrids in equal amounts and the absence of a hybrid enzyme. Dimethoxon inhibition of AChE in brains, their homogenates and larval homogenates of B, M and R types showed that decreased AChE sensitivity was a major mechanism of resistance to dimethoate strongly expressed in B x S and M x S hybrids. The proportion of brains showing decreased AChE sensitivity to coroxon in testocross and F2 progenies indicated that decreased AChE sensitivity in strain B is controlled by a single autosomal gene. The degree of dominance of increased degradative metabolism of coumaphos in strain M was variable; the hydrolytic rate in all M x S hybrids was similar to that of M but the overall detoxication rate in hybrids was lower. Genetic control of detoxication is discussed.

Acetylcholinesterase↗
PubMed1976

Post-traumatic hepatic dysfunction as a major etiology in post-traumatic jaundice.

Thirty-eight patients who had sustained acute trauma, profound hemorrhagic shock, and massive transfusion were studied prospectively to determine the predominant etiologic factors in the development of post-traumatic jaundice. An analysis of clinical and biochemical factors occurring in association with each bilirubin peak in the postoperative course found the jaundice related to transfusion and surgery in 11 instances, to sepsis and septicemia in 15 instances, and to hepatic dysfunction in 23 instances. Results indicated that admission estimates of SGOT and LDH levels, the height of the bilirubin peak and the postoperative day on which it occurs, and the white cell count and GGT at the time of the peak may be of use in the differential diagnosis. Four case reports were used to emphasize the fluctuating pattern of jaundice and the different etiologic factors that may predominate. Light and electron microscopy from three patients illustrated the structural alterations that accompany the biochemical impairment of liver function and enable a more precise appreciation of this syndrome. Hepatic dysfunction appears to be implicated in a high proportion of patients who develop post-traumatic jaundice, which frequently occurs as part of a spectrum of multiple organ failure.

Adolescent↗