[Effect of cigarette smoking on skin perfusion of the hand]. / Einfluss des Zigarettenrauchens auf die Hautdurchblutung der Hand.

BACKGROUND: Cigarette consumption leads to postoperative wound healing disturbances by impairing skin circulation. MATERIALS AND METHODS: Fourteen nonsmokers and 44 smokers were investigated and classified according to age (<40 and >40 years) and duration of cigarette consumption. Circulation at the tip of the middle finger was measured in both groups under standard conditions with laser Doppler imaging. RESULTS: There was a reduction in skin blood circulation of 24% in smokers (young 39%, older 11%, P=0.001) and 30% in nonsmokers (young 35%, older 18%, P=0.019). With longer duration of cigarette consumption, the effect grew weaker (<10 years 25%, 11-30 years 18%, >30 years 15%). There was no correlation between the number of cigarettes consumed per day and impaired circulation. CONCLUSION: Younger subjects react to cigarette consumption with a stronger reduction in circulation. In elective surgery, especially in young smokers we recommend a 6- to 8-week nicotine abstinence prior to surgical intervention.

Low-power laser light in the healing of burns: a comparison between two different wavelengths (635 nm and 690 nm) and a placebo group.

BACKGROUND AND OBJECTIVE: Studies on the influence of low-power laser light on wound healing have shown inconsistent results, or, as in the case of burns, are very scarce. We have studied the effects of two different low-power diode laser lights on the healing of burns in rats. STUDY DESIGN/MATERIALS AND METHODS: Thirty rats were burned on both flanks and randomly allocated to one of three study groups. In group A, both wounds remained untreated; in groups B and C, one wound each was irradiated with 635 nm or 690 nm laser light (1.5 J/cm(2)), whereas the other wound remained untreated. Diameter, redness, and edema of the wounds were examined daily. RESULTS: Between and within groups, diameter, redness, and edema of the wounds were similar throughout the entire observation period. Irradiation of the burns did not accelerate wound healing when compared with control wounds. CONCLUSION: We conclude that neither 690 nm nor 635 nm low-power laser light produced any beneficial effects on the healing processes of burns in rats.

The effects of nootropics on memory: new aspects for basic research.

The mechanism through which nootropics of the piracetam type (i.e., piracetam itself and its analogues oxiracetam, pramiracetam, and aniracetam) improve memory is still uncertain. Its elucidation will, however, not only mark an advance in the treatment of cognitive disorders, but also shed light on the basic processes of memory storage. Although the great majority of the findings available so far seem to suggest cholinergic mechanisms, divergent results are obtained whenever parallel experiments are performed with two or more of these compounds. More recent observations indicate that interactions with steroids take place. All four compounds are inactive in adrenalectomized laboratory animals; chemical blockade of the adrenal cortex with aminoglutethimide and pretreatment which epoxymexrenon, a potent mineralocorticoid antagonist, eradicated the memory-enhancing effect of all four substances.

Blockade of the nootropic action of piracetam-like nootropics by adrenalectomy: an effect of dosage?

The present experiments demonstrate that the absence of any memory-improving action of nootropics in adrenalectomized animals cannot be ascribed to an effect of dosage. Doses of 1, 10, 100, 1000 and 3000 mg/kg p.o. of piracetam, oxiracetam, aniracetam or pramiracetam are ineffective in adrenalectomized mice.

NMDA receptor antagonists can enhance or impair learning performance in animals.

The effects of NMDA receptor antagonism on learning and memory were investigated using competitive (DL-2-amino-7-phosphonoheptanoate, AP7) and non-competitive (MK 801) blockers in three different learning tasks. Administration (i.p.) of drugs prior to training resulted in impaired learning performance in the place-navigation and dark-avoidance paradigms, and improved performance in the step-down passive avoidance task; however, using this treatment protocol, the possibility of drug-induced non-mnemonic effects modifying learning performance could not be excluded. Drug administration immediately post-trial had no effect in the place-navigation paradigm, and improved retention performance in the dark-avoidance and step-down avoidance tasks. The similar results obtained with both types of antagonist indicate that the observed effects are indeed due to NMDA receptor blockade, and hence that such blockade modifies learning in a task-dependent manner. Exclusion of non-mnemonic effects by using the post-trial treatment regime demonstrates that NMDA antagonists facilitate learning of passive avoidance tasks.

Do piracetam-like compounds act centrally via peripheral mechanisms?

The pharmacological mechanism of action of the piracetam-like nootropics is still obscure. Their unique feature is that they exert distinct effects on memory, but show hardly any biochemical activity and are practically devoid of toxic effects. Our results indicate that the memory-enhancing action of these substances is dependent on the presence of the adrenals, suggesting that their central effects might be mediated by peripheral mechanisms.