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Biomedical subjects

T J Maling

Publications and source records attributed to T J Maling.

At least 37 records · Page 2Linked to original sources
PubMed1990

Kinetics of sodium-lithium countertransport in normotensive and hypertensive subjects.

The kinetic parameters Vmax and Km of erythrocyte sodium-lithium countertransport (Na-Li CT), and the lithium cell to plasma ratio (Li C:P) measured 24 h after a 1-g oral dose of Li2CO3, were determined in 14 normotensive (NT) and 14 untreated mild hypertensive (HT) males matched for age and weight. Li C:P and Na-Li CT were strongly correlated (r = -0.73), p less than 0.001), confirming the validity of Li C:P as an in vivo index of Na-Li CT. No differences in Li C:P (NT: 0.27 +/- 0.07; HT: 0.23 +/- 0.06), Na-Li CT (NT: 0.39 +/- 0.10 mmol/L/h; HT: 0.43 +/- 0.10 mmol/L/h), Vmax (NT: 0.58 +/- 0.16 mmol/L/h; HT: 0.68 +/- 0.20 mmol/L/h), or Km (NT: 1.5 +/- 0.4 mmol/L; HT: 1.6 +/- 0.9 mmol/L) were found between NT and HT. Our data do not support the marker concept of erythrocyte Na-Li CT in human hypertension.

Adult↗
PubMed1989

Racial differences in platelet counts in New Zealand men.

Healthy Maori males were found to have higher platelet counts (mean 295 x 10(9)/L: SD 46) compared to healthy nonMaori males (mean 253 x 10(9)/L; SD 50). Maori males had higher weights (mean 88.4 kg; SD 12.5) than nonMaori males (mean 81.0 kg; SD 9.0); and the platelet count was significantly correlated with weight (r = 0.30; p = 0.003). After weight adjustment significant differences between Maori and nonMaori males for platelet counts remained. These findings have implications for laboratory reference ranges, and may be of epidemiological significance in cardiovascular disease.

Adult↗
PubMed1989

Saliva lithium: a poor predictor of plasma and erythrocyte levels.

Lithium levels were measured in plasma, erythrocytes and saliva in 28 patients to determine the accuracy of saliva lithium as a predictor of plasma and erythrocyte levels. The range and mean lithium levels (mmol/L) found in the three compartments were as follows: plasma, mean = 0.72, range 0.17-1.33; erythrocyte, mean = 0.33, range 0.03-0.7; saliva, mean = 1.21, range 0.36-3.9. High levels of inter-individual and intra-individual variation were found in plasma/saliva and erythrocyte/saliva lithium level ratios. We recommended that saliva lithium measurements should not be used to monitor lithium therapy.

Adult↗
PubMed1989

The k-complex vasoconstrictor response: evidence for central vasomotor downregulation in borderline hypertension.

Central sympathetic outflow and the baroreflex were measured as an integrated cardiopressor response to a noise stimulus during normal sleep, in 13 normotensives and 14 borderline hypertensives. The pressor response latency was prolonged in the borderline hypertensives, and the stimulus-induced increase in systolic and diastolic intra-arterial pressure was greater in the borderline hypertensives (23.0 +/- 7.3-16.2 +/- 5.6 mmHg) compared with the normotensives (16.7 +/- 5.9-13.6 +/- 4.6 mmHg; P less than 0.001), but the heart rate was not increased. Despite the increased pressor response, the baroreflex-mediated fall in the heart rate following the pressor response was reduced in the borderline hypertensives, indicating secondary adaptation to hypertension and a resetting, or downregulation, of central vasomotor control mechanisms in the borderline hypertensives relative to normotensives.

Acoustic Stimulation↗
PubMed1989

Individual variability of amiodarone distribution in plasma and erythrocytes: implications for therapeutic monitoring.

The complexity of amiodarone disposition in blood and tissues gives rise to difficulty in determination of optimal therapeutic monitoring strategies. We have defined the within-patient variability of plasma and erythrocyte amiodarone and desethylamiodarone concentrations and electrocardiogram intervals [PR and corrected QT (QTc)] in 27 patients each sampled on three to four occasions during long-term stable amiodarone therapy. All individual repeated measurements were included in the concentration-effect analysis. The mean within-patient coefficients of variation for amiodarone and desethylamiodarone were significantly greater in erythrocytes, 46.0 and 24.5%, respectively, compared with plasma, 12.7 and 12.3%. Amiodarone and desethylamiodarone were significantly greater in erythrocytes, 46.0 and 24.5%, respectively, compared with plasma, 12.7 and 12.3%. Amiodarone and desethylamiodarone were strongly correlated (r = 0.29 p less than 0.004). There was a 10-fold variability in erythrocyte amiodarone for a given plasma level. These data emphasize the highly variable cellular distribution of amiodarone and desethylamiodarone in the same patient on stable dosage over time. Plasma amiodarone was significantly correlated with dosage (r = 0.98), and percent change in QTc, (r = 0.56, p less than 0.0001), but there was a fourfold variation in plasma amiodarone for a given QTc. Side-effect frequency was not related to plasma or erythrocyte amiodarone or desethylamiodarone concentrations. A clinically useful relationship between plasma concentration and effect could not be consistently demonstrated for amiodarone in the same individual during stable dosage.

Adult↗
PubMed1989

Heart rate variability during hypoglycaemia.

A diabetic patient with parasympathetic neuropathy underwent 24-h ECG monitoring. During the 24 hours the patient had a hypoglycaemic event. Heart rate variability was greatly increased during this time, though heart rate was unaltered. The reasons for the sudden increase are unknown but may indicate a fruitful line for further research.

Arrhythmias, Cardiac↗
PubMed1989

Is clonidine useful in the treatment of alcohol withdrawal?

The comparative efficacy of clonidine and chlormethiazole has been examined in the management of acute alcohol withdrawal. A double blind randomized study was conducted in consecutive patients admitted to a hospital detoxification unit. Patients were assessed regularly by a standard alcohol withdrawal rating-scale. Thirty-two patients received either clonidine or chlormethiazole in reducing dosages over 96 hr. All the patients receiving chlormethiazole had uneventful withdrawals. However, eight patients treated with clonidine were withdrawn from the trial due to hallucinations (two), seizures (two), symptomatic orthostatic hypotension (three) or drowsiness (one), indicating that clonidine is less effective than chlormethiazole in the prevention of the major manifestations of alcohol withdrawal.

Adult↗
PubMed1988

Neuroleptic malignant syndrome: a review of the Wellington experience.

The neuroleptic malignant syndrome is a potentially lethal complication of central dopamine antagonism. We report five cases, occurring in the Wellington region in the last 4 years. Three of the cases are reported in detail and the diagnostic difficulties and therapeutic strategies are reviewed. Particular attention is drawn to the use of the depot intramuscular phenothiazine formulations which were clearly implicated in our experience.

Adult↗
PubMed1988

Whole blood storage solution for erythrocyte sodium and sodium-lithium countertransport rate determination.

A solution consisting of heparinized and buffered isosmolar magnesium chloride is described in which whole blood may be stored for preservation of erythrocyte sodium (Na) and membrane sodium-lithium countertransport (Na-Li CT). Correlation (r) of fresh versus 24-h stored erythrocytes for Na was 0.990 (y = 0.30 + 0.956x) and for Na-Li CT was 0.995 (y = -0.014 + 1.022x). Na-Li CT rate was preserved in the storage solution for up to five days and erythrocyte Na concentration for at least 24 h. The solution should find application in epidemiological studies of erythrocyte Na and Na-Li CT rate in human essential hypertension as the blood specimens require no centrifugation or erythrocyte washing procedures prior to laboratory analysis.

Biological Transport↗
PubMed1988

Effect of blood sample tubes on amiodarone and desethylamiodarone concentrations.

We have investigated the change in amiodarone and desethylamiodarone concentrations in blood sampled from three different Vacutainer tubes: (a) sodium heparin, (b) gel separator (SST), and (c) no additive (plain tube). Amiodarone and desethylamiodarone concentrations were determined by a reverse-phase high pressure liquid chromatography technique in samples from 12 subjects on chronic amiodarone therapy. Amiodarone concentrations were significantly lower in plasma compared with serum from either gel separator (11.5%, p = 0.05) or no additive (13.5%, p = 0.01) tubes. Desethylamiodarone concentrations were significantly lower in plasma compared with serum from gel separator tubes (8.5%, p = 0.04) and were slightly lower compared with no additive tubes (4.4%, p = 0.41). Serum amiodarone and desethylamiodarone concentrations from either no additive or gel separator tubes yielded similar results. We conclude that significant amiodarone and desethylamiodarone concentration differences occur between serum and plasma, and that no binding of amiodarone and desethylamiodarone to the separator gel occurs.

Amiodarone↗
PubMed1987

Assay of sodium-lithium countertransport rate by direct measurement of erythrocyte lithium concentrations.

A method is described for the in-vitro measurement of erythrocytic sodium-lithium countertransport rate (SLC) by direct assay of intra-erythrocytic lithium (Li) concentrations in Li loaded cells during controlled Li efflux. Bicarbonate stimulated erythrocytic Li loading to an approximate intracellular concentration of 3 mmol/l can be achieved within 4 min. Maximum SLC rates are achieved at intra-erythrocytic concentrations greater than 2.5 mmol/l. Lithium efflux is linear over 0-60 min, and independent of pH change. The within-batch coefficient of variation for positive displacement pipetting of Li loaded erythrocytes is 2.8%. Storage of erythrocytes in isosmotic MgCl2 for 24 h had no effect on the SLC. Intra-individual coefficient of variation for SLC was less than 6%. The reference range for Caucasian subjects (n = 43) was 0.14-0.49 mmol Li +/l erythrocytes/h.

Antiporters↗
PubMed1987

Hypokalaemic and electrocardiographic effects of aminophylline and salbutamol in obstructive airways disease.

The hypokalaemic and electrocardiographic effects of nebulised salbutamol (2.35 mg x 2, 120 min apart) and intravenous aminophylline (6 mg/kg followed by 0.5 mg/kg/hr infusion) alone and in combination, were investigated in eight patients with stable asthma. Both agents produced significant hypokalaemia, mean maximum for salbutamol 0.55 mmol/l, mean maximum for aminophylline 0.29 mmol/l. Salbutamol increased the QTc interval and depressed T-wave amplitude whilst aminophylline decreased PR interval. These effects were increased when they were given in combination but were highly variable between individuals. It is likely that arrhythmias may be precipitated in patients with hypoxaemia, acidosis or those with preexisting cardiovascular disease.

Administration, Inhalation↗