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Biomedical subjects

K A McLean

Publications and source records attributed to K A McLean.

At least 19 recordsLinked to original sources
PubMed2006

In vivo prediction of internal fat weight in Scottish Blackface lambs, using computer tomography.

From a calibration trial involving computer tomography (CT) scanning and dissection of 45 lambs, a prediction equation was derived to estimate total internal fat weight in Scottish Blackface lambs from measurements taken on cross-sectional CT images. Using data from two cross-sectional images (at the hip and loin) internal fat can be predicted with relatively high accuracy (adjusted R(2) = 62.2%, r = 0.79). The derived equation was then used to predict internal fat weights in a further 427 Scottish Blackface lambs from a separate trial. Phenotypic correlations were calculated between predicted internal fat weight and weights of total carcass fat, muscle and bone, predicted using previously derived equations. When considering absolute tissue weights, adjusted for fixed effects, internal fat showed the strongest positive correlation with carcass fat (0.58), followed by muscle (0.36), and then by bone (0.32). When tissue weights were adjusted for fixed effects and total carcass weight (so considering tissue weights relative to size), internal fat showed a lower correlation with carcass fat weight (0.36) and negative correlations with muscle (-0.35) and bone (-0.19). These results provide the basis for more complex studies of relationships (phenotypic and genetic) between internal fat in hill lambs and economically important traits, such as carcass composition and survival of lambs, and tissue levels in different depots in hill ewes.

Adipose Tissue↗
PubMed2006

Microscopy and culture for Trichomonas vaginalis: are both required?

Many genitourinary medicine clinics have stopped routinely performing both wet preparation microscopy and cultures to diagnose Trichomonas vaginalis (TV). Our directorate stopped microscopy when screening asymptomatic women. This audit considers whether both tests continue to be warranted for symptomatic female patients. The discrepancy between microscopy and culture results leads us to recommend that both remain necessary. Sampling standardization and improved documentation are discussed.

Adult↗
PubMed2000

Effect of human immunodeficiency virus-1 protease inhibitors on the clearance of human herpesvirus 8 from blood of human immunodeficiency virus-1-infected patients.

The effect of human immunodeficiency virus-1 protease inhibitors on the frequency of human herpesvirus 8 DNA detection from peripheral blood of human immunodeficiency virus-positive persons was evaluated. Thirty-three human immunodeficiency virus-seropositive male patients were studied longitudinally. DNA from open reading frame 26 of the human herpesvirus 8 genome was amplified by the polymerase chain reaction from the CD45+ fraction of peripheral blood before and after the introduction of protease inhibitor therapy. Human herpesvirus 8 IgG status, CD4+ cell counts, and human immunodeficiency virus-1 plasma viral load were also assessed before and after therapy. When both reverse transcriptase inhibitor and protease inhibitor treatment were introduced at the same time, there was an increase in CD4+ T cell counts (P=0.0041), a decrease in human immunodeficiency virus plasma load (P=0.0584), and a decrease in the detection rate of human herpesvirus 8 DNA (P=0.0077). Introducing protease inhibitor to patients already receiving reverse transcriptase inhibitor treatment was associated with an increase in CD4+ T cell counts (P=0.0003), a decrease in human immunodeficiency virus plasma viral load (P=0.0911), and a decrease in the human herpesvirus 8 detection rate (P=0.0412). No significant changes in the titters of anti-human herpesvirus 8 IgG were observed. Treatment with human immunodeficiency virus-1 protease inhibitors is therefore associated with the clearance of human herpesvirus 8 DNA from peripheral blood of human immunodeficiency virus-infected patients. The concomitant decrease in the human immunodeficiency virus plasma load and increase in the peripheral CD4+ cell count suggest that an amelioration in the immune defect following reduction in the burden of human immunodeficiency virus-1 infection is responsible for the clearance of human herpesvirus 8 by protease inhibitors.

Adult↗
PubMed2000

The effect of opioid antagonism and environmental restriction on plasma oxytocin and vasopressin concentrations in parturient gilts.

Oxytocin plays an important role at parturition due to its involvement in uterine contractions, foetal expulsion and the onset of maternal behaviour. The role of the related neurohypophysial hormone, vasopressin, is less clear; however, there is some evidence that it is also involved in maternal behaviour and its role in osmotic regulation is well established. The aim of this study was to investigate the inhibitory effects of endogenous opioids on these hormones during the expulsive phase of parturition in the pig, and to examine how opioid restraint interacts with environmental restriction. The subjects of this study were 31 Large Whitex Landrace primiparous sows (gilts). An indwelling jugular catheter was implanted under general anaesthesia at 12 days before the expected parturition day (EPD). From 5 days before the EPD 15 of the gilts were individually housed in a restrictive parturition crate without straw and 16 were individually housed in a straw-bedded pen. Blood samples were taken with increasing frequency towards and during parturition through a catheter extension to reduce disturbance. At 7.5 min after the birth of the first piglet half of the gilts in each environment received a dose of the opioid receptor antagonist naloxone (1 mg/kg, i.v.) with the remaining gilts receiving saline as a control. Overall, there was no effect of environment on either circulating oxytocin or vasopressin. However, both oxytocin and vasopressin were inhibited by endogenous opioids during the expulsive phase. The inhibitory effects of opioids on these hormones did not appear to have any adverse effects on the progress of parturition as judged by cumulative piglet birth intervals. The regulation of the opioid inhibition of oxytocin and vasopressin during parturition is discussed in relation to other neurotransmitters and whether opioid inhibition of these neurohypophysial hormones is part of the 'normal' physiological response to parturition or whether it is stress-induced.

Analysis of Variance↗
PubMed2000

Lesbians and cervical screening.

Confusion exists in clinical practice about whether lesbians should be offered routine cervical smears. We found cervical smear abnormalities in a sample of 624 lesbians, including those who had never been sexually active with men. These findings suggest that lesbians should be routinely offered cervical cytology as part of the national screening programme. Evidence of human papilloma virus (HPV) infection in the 'exclusively lesbian' group indicates that sexual transmission of HPV may occur between women. The belief by some lesbians that they have less need for cervical smears, coupled with poor uptake of cervical screening by a significant proportion, demonstrates a need for education of lesbians and health service providers.

Adult↗
PubMed1998

The effect of environment on plasma cortisol and beta-endorphin in the parturient pig and the involvement of endogenous opioids.

Previous work has indicated that plasma cortisol increases during farrowing in the pig suggesting increasing physiological stress. The aim of this study was to determine changes in plasma cortisol and beta-endorphin over farrowing in the pig to obtain a more detailed profile of pituitary and adrenal release at this time and also to investigate the involvement of endogenous opioids in the mediation of the HPA axis. Indwelling jugular catheters were implanted, under general anaesthesia, in 31 Large White x Landrace gilts approximately 15 days before the expected parturition day (EPD). Gilts were moved into either a farrowing crate, without straw (n = 15), or a straw-bedded pen (n = 16) 5 days before the EPD. Samples were taken during the pre-farrowing period and then during farrowing itself. At 7.5 min after the birth of the first piglet (BFP), gilts either received naloxone, an opioid antagonist, (1 mg kg(-1) body weight, i.v.) or a control dose of saline. Plasma beta-endorphin increased following the BFP but remained fairly constant over the third and fourth hour of farrowing. Plasma cortisol continued to increase over the 4 h following the BFP. Changes seen in these hormones were generally insensitive to the environment and there was little evidence of opioid mediation of the HPA axis at parturition. From these results it is suggested that certain aspect(s) of parturition itself stimulate the HPA axis. However it is unknown if the rise in plasma cortisol is a result of some stress-inducing factor of the parturition process or whether it reflects a metabolic function. The study also demonstrates the lack of any inhibitory mediation of the HPA axis by endogenous opioids at parturition.

Animals↗
PubMed1998

Investigation of the relationship between farrowing environment, sex steroid concentrations and maternal aggression in gilts.

Maternal oestrogen and progesterone have been shown to be important in the initiation of maternal behaviour. Thirty-three Large White x Landrace gilts, housed in groups during pregnancy, were observed and aggressive interactions recorded. Individuals had jugular catheters implanted 14.5 (s.e. 0.34) days before their expected parturition date (EPD). Five days before EPD gilts were randomly allocated and moved to either a conventional farrowing crate (C; without straw, 16 gilts) or a pen (P; 2.1 x 3.1 m2; with straw bedding, 17 gilts). Blood samples were taken at frequencies determined by the proximity to farrowing onset. Piglets were removed at birth and returned 2 h after placental expulsion. The reaction of each gilt to her piglets was monitored. Gilts savaging piglets were sedated with azaperone (n = 8). There was no overall effect of farrowing environment on oestradiol and progesterone concentrations. The pre-farrowing ratio of progesterone to oestradiol was higher for (P) gilts (0.45 vs. 0.25, (P) vs. (C); S.E.D. 0.085, P < 0.05) as was their overall maximum oestradiol level (3.39 vs. 2.29 ng/ml, (P) vs. (C); S.E.D. 0.39, P < 0.01). In contrast to progesterone, oestradiol patterns varied considerably between individuals. Dominance rank value during pregnancy, but not levels of aggression, correlated positively to pre-farrowing oestradiol concentrations. Treatment with azaperone was not related to farrowing environment, piglet weight or litter size. Azaperone treated gilts showed a higher pre-farrowing oestradiol to progesterone ratio (0.55 vs. 0.29, +/- azaperone; S.E.D. 0.10, P < 0.05), significantly higher levels of oestradiol post-partum (0.7 vs. 0.19 ng/ml, +/- azaperone; S.E.D. 0.20, P < 0.001) and significantly lower levels of aggression during pregnancy (1.68 vs. 2.23 aggressive interactions/h, +/- azaperone; S.E.D. 0.15, P < 0.001). The results indicate that there are no major effects of farrowing environment on sex steroid concentrations. Maternal aggression under these conditions appears to be negatively related to aggression during pregnancy, but this is not reflected in plasma concentrations of sex steroids around parturition.

Aggression↗
PubMed1998

Disorders of fat distribution in HIV infection.

Alterations in body shape due to fat loss and/or redistribution have been described in HIV-infected individuals and associated with the use of antiretroviral (ARV) combination therapy. Certain of these changes have been referred to as peripheral lipodystrophy (LD) and we describe 12 patients who were recognized with this condition between September 1997 and February 1998. It occurred in 12.5% of patients on ARV combination therapy that included a protease inhibitor (PI). In early descriptions the emphasis was on the abdomen, which may be grossly enlarged. In our patients this feature was much less marked. Patients with LD were significantly older than those on PI therapy who did not develop this condition (P=0.016). Although all had raised triglyceride (TG) levels, the elevations were not severe (maximum=6.3 mmol/l). CD4 lymphocyte and viral load levels suggested an optimal response to ARV therapy at the time LD developed. Appearances may be disfiguring but no serious systemic consequences of LD have been observed. Most individuals have chosen to remain on their present ARV combinations. When LD occurs, it appears to be a marker of effective response to anti-HIV therapy.

Adult↗
PubMed1998

Co-trimoxazole desensitization in HIV-seropositive patients.

Co-trimoxazole (trimethoprim-sulphamethoxazole) is an effective prophylactic agent against Pneumocystis carinii pneumonia (PCP). However, it is associated with a high frequency of adverse reactions in immunocompromised patients which may preclude its use. Fourteen patients with a definite history of adverse reactions to co-trimoxazole on standard PCP prophylactic dosage were selected for desensitization using a regimen of gradual incremental exposure over an 11-day period. Eight (57.1%) were successfully desensitized and have continued on oral co-trimoxazole at maximum 21 months' follow-up. This report demonstrates that oral desensitization as an outpatient procedure is an effective and safe option for both primary and secondary PCP prophylaxis in HIV-seropositive patients with previous adverse drug reactions.

Adult↗
PubMed1997

Opioid-mediated changes in nociceptive threshold during pregnancy and parturition in the sow.

This study aimed to investigate if pregnancy-induced hypoalgesia occurs in the sow, and to examine the role of endogenous opioids which are known to be released in response to nociception. Sixteen Large White x Landrace multiparous sows were tested in straw bedded pens (2.5 x 2.5 m) during weeks 4, 8 and 12 of pregnancy and over the farrowing period. Testing involved thermal stimulation of eight areas on the rear-quarters of the sows with a CO2 infra-red laser until a physical response was seen (tail flick, leg move or muscle twitch) or for a maximum of 16 s. Over the farrowing period testing was more frequent, and at 3.75 h after the birth of the first piglet, half the sows received an injection (i.m.) of an opioid antagonist naloxone (N) (1 mg kg(-1) body weight) with the remainder receiving a control dose of saline (S). Responses were recorded 15 and 30 min post-injection. There was no significant difference between response times over weeks 4, 8 and 12 of pregnancy (P = 0.152), however a significant rise was seen from week 12 to 5 days before parturition (P = 0.002). Response times continued to rise until the birth of the first piglet by which time the majority of sows had stopped responding within 16 s (P < 0.001). Response times fell over days 1, 2 and 7 post-partum. After administration of naloxone response times fell compared to control animals at 15 min (P < 0.001) and 30 min (P < 0.01) post-injection. These results suggest that nociceptive threshold increases during late pregnancy in the sow, perhaps as an endogenous defence against labour pain, and that during parturition this change in nociceptive threshold is, at least in part, opioid-mediated. Oxytocin is known to be inhibited by endogenous opioids at parturition, thus future research should consider the potential role of increased nociception at birth as a negative feedback to oxytocin release.

Animals↗
PubMed1995

Age-associated alterations in thirst and arginine vasopressin in response to a water or sodium load.

We have examined simultaneous changes in thirst, plasma osmolality and arginine vasopressin, after oral water loading or hypertonic saline infusion. The studies were carried out in the same subjects, comprising young controls aged 26.8 years (SD 4.8, n = 10) and health status-defined elderly people aged 72.1 years (SD 3.1, n = 10). Water loading caused significant falls in plasma osmolality (p < 0.001) and thirst (p < 0.001), but there was no variation with age. Infusion with 462 mmol/l of sodium chloride increased plasma osmolality significantly (p < 0.001), but there was no variation with age (p = 0.12). The perception of thirst during the osmotic loading experiment was recorded differently by the two age groups (p < 0.0001). However, linear regression analysis showed no age difference in the relationship between thirst and plasma osmolality during osmotic loading. During osmotic loading the relationship between the plasma concentration of arginine vasopressin in response to increasing plasma osmolality varied significantly (slope: p = 0.02; intercept: p = 0.02). Plasma arginine vasopressin rose more rapidly with increasing plasma osmolality in old subjects.

Adult↗
PubMed1995

Xamoterol improves the control of chronic atrial fibrillation in elderly patients.

Twenty digitalized elderly patients with chronic atrial fibrillation were randomized into a double-blind cross-over study. None was in overt heart failure and all were taking < 80 mg frusemide daily. They received xamoterol 200 mg b.d. for 2 months with their usual dose of digoxin for 1 month and placebo digoxin for the other month. Twenty-four-hour heart rate analysis was done at baseline and at the end of each treatment period. Compared with baseline digoxin, xamoterol alone significantly increased nocturnal minimum heart rate [85 +/- 17 vs. 62 +/- 9 (mean +/- SD), p < 0.0001] without affecting daytime maximum heart rate (132 +/- 18 vs. 122 +/- 20, p = NS). Compared with baseline digoxin, xamoterol plus digoxin significantly increased nocturnal minimum heart rate (68 +/- 8, p < 0.05) and reduced daytime heart rate (114 +/- 17, p < 0.05). The mean number of pauses > 1.5 s was significantly reduced by xamoterol alone. Walking distance in 6 minutes was 406.1 +/- 27.1 m (mean +/- SE) at baseline and improved significantly on both treatments (450.3 +/- 19.8 on xamoterol; p < 0.02 and 453.7 +/- 19.2 on xamoterol plus digoxin; p < 0.01). No significant change was found in subjective measurements of palpitations, breathlessness and well-being using visual analogue scales. Xamoterol combined with digoxin improves effort tolerance and heart-rate control by reducing diurnal tachycardia and nocturnal bradycardia and pauses.

Adrenergic beta-Agonists↗
PubMed1994

Combination diuretic treatment in severe heart failure: a randomised controlled trial.

OBJECTIVES: (a) To test the hypothesis that a fixed 3 day course of the combination of a thiazide and loop diuretic is as effective as more prolonged treatment in the management of severe resistant cardiac failure. (b) To compare two thiazide diuretics (bendrofluazide and metolazone) in combination with loop diuretics in the treatment of severe resistant cardiac failure. DESIGN: Randomised study with a 2 x 2 factorial design. SETTING: Provincial teaching hospital. PATIENTS: 33 consecutive patients (40 episodes) admitted with severe congestive cardiac failure (New York Heart Association class III or IV) unresponsive to intravenous loop diuretics for 48 hours. MAIN OUTCOME MEASURES: Change in daily weight and serum electrolytes and clinical improvement in heart failure. RESULTS: Diuresis was established during 37 of 40 episodes; of the rest two patients died in hospital. On 36 occasions improvement was sufficient to allow discharge from hospital. Median (range) maximal weight loss was -5.05 (-11.3 to 1.6) kg after the addition of bendrofluazide and -5.6 (-12.2 to 4.8) kg after the addition of metolazone (NS). Area under the body weight loss against time curves showed no significant difference between the two thiazide diuretics. Median (range) maximal weight loss after three days of treatment was -5.4 (-12.2 to 4.8) kg and -5.5 (-10.3 to 1) kg after a more prolonged course of median (range) 5.6 (1 to 13) days (NS). Area under the body weight loss time curves showed no significant difference between the two durations of treatment. Bendrofluazide was associated with fewer electrolyte disturbances. CONCLUSIONS: Bendrofluazide and metolazone were equally effective in establishing a diuresis in patients with severe congestive cardiac failure resistant to loop diuretics. A fixed three day course of the combination was as effective as a longer course.

Adolescent↗