Lithium and hematopoiesis.

Some of lithium''s effects on blood cell formation suggest that the element may be of value in treating hematologic disorders. Lithium enhances granulopoiesis and thereby induces neutrophilia. Two possible mechanisms of action are suggested: a direct action on the pluripotent stem cells, or an inhibition of the suppressor cells (thymus-dependent lymphocytes) that limit hematopoiesis. Lithium also inhibits erythropoiesis. Although most studies use concentrations at or above pharmacologic levels there is evidence that lithium plays a role in normal cell metabolism.     

Lithium treatment: prescribing and monitoring habits in hospital and general practice.

OBJECTIVES--To define current clinical practice of lithium prescribing and monitoring and to compare hospital based practice with general practice. DESIGN--Prospective study of doctors'' practice. SETTING--Psychiatric hospital day and outpatient facilities and general practices in Edinburgh and Midlothian district (population 600,000). SUBJECTS--458 patients taking lithium who had been stabilised and who remained as outpatients during the year of study. 219 were treated by their general practitioner and 190 by the hospital; 49 had shared care or care transferred during the study. MAIN OUTCOME MEASURES--Daily dose, duration of treatment, psychiatric diagnosis, mean annual serum lithium concentration, frequency of occurrence of and response to raised serum concentrations. RESULTS--Compared with hospital doctors general practitioners were more likely to prescribe lithium three or more times daily (43/219 (general practice) v 10/190 (hospital); chi 2 = 18.6, p = 0.001) and to estimate serum concentrations less frequently (4.5 v 5.3 measurements/year; t = 3.04, p = 0.003), and their patients were more likely to experience raised lithium concentrations (39/219 v 17/190; chi 2 = 6.8, p = 0.01). One third of doctors made no response to raised lithium concentrations in the next six weeks. CONCLUSIONS--General practitioners and hospital doctors care for similar types of patients and the stringency of lithium surveillance varies greatly among doctors. Certain aspects of practice give cause for concern and could be improved by following more uniform guidelines.     

Mice deficient in oxytocin manifest increased saline consumption following overnight fluid deprivation

Male mice (9-13 mo of age) in which the gene for oxytocin (OT) had been deleted (OT -/-) were administered 0.5 M sodium chloride (NaCl) solution or tap water as a two-bottle choice test following overnight fluid deprivation (1600 to 1000 the following day). Compared with wild-type cohorts (OT +/+), OT-deficient mice ingested sevenfold greater amounts of saline in the first hour following reintroduction of fluids, P < 0.001, and fourfold greater amounts at the end of 6 h, P < 0.02. No significant difference in total water ingested was noted between the two genotypes at the end of either 1 or 6 h. If food deprivation accompanied the overnight fluid deprivation and food was reintroduced 1 h after the reintroduction of both water and saline, OT -/- mice still ingested greater amounts of saline, but not water, than OT +/+ mice at both 1 h, P < 0.001, and 6 h, P < 0.02. No differences were noted between genotypes in the daily intake of 0.5 M NaCl solution or water during a 3-day observation period before the overnight fluid deprivation. The volume of saline consumed in each 24-h observation period represented about one-tenth of the total fluids ingested in each genotype. We conclude that OT -/- mice display an enhanced salt appetite compared with OT +/+ mice when fluid deprived overnight. The salt appetite was only apparent in the presence of a perturbation such as fluid deprivation, which predisposes the animal to moderate hypovolemia. The observations support an inhibitory role for OT in the control of sodium appetite in mice.     

Lithium treatment induces a hypersensitive-like response in tobacco

Treatment of tobacco ( Nicotiana tabacum L.) plants with lithium induces the formation of necrotic lesions and leaf curling as in the case of incompatible pathogen interactions. Further similarities at the molecular level include accumulation of ethylene and of salicylic and gentisic acids, and induced expression of pathogenesis-related PR-P, PR5 and PR1 genes. With the exception of PR1 induction, lithium produced the same effects in transgenic tobacco plants that do not accumulate salicylate because of overexpression of the bacterial hydroxylase gene nahG. On the other hand, inhibition of ethylene biosynthesis with aminoethoxyvinylglycine prevented lithium-induced cell death and PR5 expression. These results suggest that lithium triggers a hypersensitive-like response where ethylene signalling is essential.