Extensive Mitochondrial Heteroplasmy in Natural Populations of a Resurging Human Pest, the Bed Bug (Hemiptera: Cimicidae).

Homoplasmy, the occurrence of a single mitochondrial DNA haplotype within an individual, has been the accepted condition across most organisms in the animal kingdom. In recent years, a number of exceptions to this rule have been reported, largely due to the ease with which single nucleotide polymorphisms can be detected. Evidence of heteroplasmy-two or more mitochondrial variants within a single individual-has now been documented in a number of invertebrates; however, when present, heteroplasmy usually occurs at low frequencies both within individuals and within populations. The implications of heteroplasmy may be far reaching, both to the individual in relation to its health and fitness, and when considering the evolutionary dynamics of populations. We present novel evidence for frequent mtDNA heteroplasmy in the bed bug, Cimex lectularius L. (Hemiptera: Cimicidae). Our findings show that heteroplasmy is common, with 5 of 29 (17%) populations screened exhibiting two mitochondrial variants in a ∼1:2 ratio within each individual. We hypothesize that the mechanism underlying heteroplasmy in bed bugs is paternal leakage because some haplotypes were shared among unrelated populations and no evidence for nuclear mitochondrial DNA sequences was detected.

Cyclic adenosine monophosphate in brain areas: microwave irradiation as a means of tissue fixation.

Amounts of cyclic adenosine monophosphate in discrete regions of the brain were estimated after exposure of rats to microwave irradiation. Amounts were highest in the cerebellum and brainstem, intermediate in the hypothalamus and midbrain, and lowest in the hippocampus and cortex. Decapitation increased the concentration of cyclic adenosine monophosphate in all brain areas, although the increase in the cerebellum was three to four times greater than that in other areas. Microwave irradiation may provide a means of rapidly fixing brain tissue in situ while permitting easy dissection of the brain. In this way artifacts produced by decapitation can be eliminated, and concentrations of heat-stable compounds in the brain can be estimated under conditions which more closely approximate those in vivo.

Insulin inhibition of lipolysis of human adipocytes: the role of cyclic adenosine monophosphate.

To gain information on the manner in which insulin suppresses lipolysis in man, isolated adipocytes, prepared from subcutaneous adipose tissue, were incubated with insulin (100 microunits/ml) alone and in combination with isoproterenol (10(-7) M or 10(-8) M). Cyclic AMP concentration was measured at 60 min; glycerol release, used as an index of lipolysis, was determined at 45 and 75 min. Insulin consistently reduced both basal and stimulated cyclic AMP and glycerol release: the degree of suppression of each was comparable. In subsequent experiments, the ability of insulin to suppress glycerol release stimulated by isoproterenol, theophylline, and dibutyryl cyclic AMP (dbcAMP), respectively, was compared. Insulin substantially reduced the raised levels of cyclic AMP and glycerol release prompted by isoproterenol and theophylline, but it had little effect on increases caused by dbcAMP. These findings support the view that reduction in cyclic AMP is an important component in the regulation of fat mobilization by insulin.

In-vitro observations on isolated adipose tissue cells from hyperobese subjects.

Isolated adipose tissue cells were prepared from subcutaneous samples obtained from nine morbidly obese subjects weighing from 187 to 306% of ideal body weight. The responsiveness of these adipocytes to a number of test substances was determined by measuring cellular cyclic AMP concentration at one-half hour and glycerol release at four hours. Theophylline (10(-3) M) and epinephrine (10(-5) M) stimulated lipolysis; theophylline stimulated an increase in cyclic AMP, while epinephrine failed to prompt a significant change in the nucleotide. Neither the alpha blocker, phentolamine (10(-5) M), nor the beta blocker, propranolol (3 X 10(-5) M), affected lipolysis or cyclic AMP; when these agents were incubated in combination with epinephrine, changes occurred indicative of the presence of both alpha and beta adrenergic receptor sites. Insulin significantly reduced both basal and stimulated lipolysis but failed to affect cyclic AMP. With minor exceptions, adipocytes from hyperobese subjects behaved similarly to cells from unselected donors; at the concentration used, there was no evidence of resistance to insulin.

Site of free-fatty-acid inhibition of lipolysis by human adipocytes.

When human adipocytes were incubated in albumin-free buffer, isoproterenol failed to stimulate an increase in either cyclic AMP or glycerol release. Cells incubated for 1/2 hr with 4% albumin and isoproterenol had a striking increase in cyclic AMP; this effect was markedly reduced when FFA concentration was increased by the addition of sodium oleate. When incubation was prolonged to 4 hr, the cyclic AMP concentration of stimulated cells fell towards the basal level. This decline in the level of cyclic AMP was prevented by frequent change in buffer. The ability of epinephrine and sodium fluoride to stimulate the adenylyl cyclase of human adipocyte membranes was not affected by the addition of sodium oleate. However, when intact cells were preincubated for 1 hr with added sodium oleate, the responsiveness to epinephrine of membranes derived from the cells was reduced. No such alternation in responsiveness to sodium fluoride occurred. These results indicate that the inhibitory effect of FFA on lipolysis is associated with a reduced production of cyclic AMP; the latter effect may be the consequence of FFA inhibition of adenylyl cyclase.

Addiction treatment for the nurse.

Health care workers, including nurses, have a higher risk of addiction than other professionals. The addicted nurse is often difficult to identify and has special needs in treatment and recovery. The goal of the treatment provider is to help the nurse return to productivity in the nursing profession, and at the same time, help the nurse preserve dignity. The nurse's right, recovery and return-to-work process, and legal considerations are all important aspects of addiction treatment.

Hospital pricing policies: the simple economics.

Changes in hospital reimbursement structures and the shrinking inpatient service market are forcing hospitals to reexamine their pricing strategies. This article examines historical hospital pricing, the effect of pricing in a competitive market and considerations for hospitals moving toward competitive pricing for services.