Crescimento e índices de troca gasosa em plantas de pepino irrigadas com água enriquecida com CO2

Avaliou-se o efeito do enriquecimento da água de irrigação com CO2 sobre índices fisiológicos de desenvolvimento e troca gasosa de folhas de plantas de pepino do tipo japonês, cultivados em ambiente protegido. Os experimentos realizados em duas épocas do ano foram instalados em delineamento experimental de blocos ao acaso com 4 tratamentos e 5 repetições. Os tratamentos foram constituídos pelos híbridos Hokuho e Tsuyataro, irrigados com água comum ou enriquecida com CO2, em uma concentração de 1 no primeiro e 0,25 no segundo experimento. A produção de massa de material seco e área foliar adotaram tendência exponencial, não sendo possível observar o início da diminuição da taxa de produção de massa do material seco aos 63 dias após transplante (DAT). A taxa de crescimento da comunidade e taxa de crescimento relativa do híbrido Hokuho irrigado com água comum foi diferente do irrigado com água enriquecida com CO2, no entanto, no híbrido Tsuyataro foram semelhantes. A taxa de assimilação líquida atingiu a máxima pendente na fase de crescimento vegetativo e floração, e foi reduzida drasticamente após os 20 DAT no híbrido Hokuho, e após os 35 DAT no híbrido Tsuyataro. A razão de área foliar diminuiu ligeiramente nos dois híbridos com o desenvolvimento do cultivo. No início observaram-se diferenças entre irrigação com água comum e enriquecida com CO2, porém após 20 DAT não se apreciaram mais diferenças. Quanto a troca gasosa, a taxa assimilatória líquida de CO2 e de transpiração, conductância estomática e eficiência no uso da água foram semelhantes entre plantas irrigadas com água comum e enriquecida com CO2 durante o primeiro semestre. Já no segundo semestre, maiores valores foram registrados pelas plantas irrigadas com água enriquecida.

Effect of narcosis with CO2 on the ovarian development in queens of Apis mellifera (Hymenoptera, Apini)

Exposure of 1, 4, 7 & 10 day-old virgin queens of Apis mellifera Linne 1758 for 1 min to CO2 accelerated their ovarian development, having a similar effect as mating on the initial formation of the ovarian follicles. In 3 day-old queens the exposure to CO2 enhanced the initial stage of germ cell differentiation into oocytes and nurse cells in the ovarioles, a developmental stage only seen in 5 day-old untreated virgin queens, the age at which they are ready to mate. In 10 day-old untreated virgin queens, some regions of the ovarioles presented tissue disorganization and many cells with pycnotic nuclei. However, narcotized virgin queens of the same age did not present such ovary degeneration. Conversely, they showed nitid follicle formation, arising in the ovarioles' initial differentiation between nurse and oocytic chambers, although still without vitellogenesis. The accelerative effect of CO2 is limited to the ages near to those proper for mating, since 15 and 18 day-old treated virgin queens presented ovaries with extensive regions of high tissue disorganization and a great number of cells with pycnotic nuclei. According to the results, the narcosis presented three levels of effect on the ovary of honeybee virgin queens: 1) accelerated the germ cell differentiation, 2) preserved the tissue integrity even after the queen mating period and 3) stimulated the initial differentiation of a vitellarium. This later condition was only seen in untreated queens after mating. All these effects are not maintained if the queen is kept virgin beyond 15 days old.

Ovarian ultrastructure in virgin queens of Apis mellifera L. narcotized by CO2

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Regulation of ventilation in the caiman (Caiman latirostris): effects of inspired CO2 on pulmonary and upper airway chemoreceptors

In order to study the relative roles of receptors in the upper airways, lungs and systemic circulation in modulating the ventilatory response of caiman (Caiman latirostris) to inhaled CO2, gas mixtures of varying concentrations of CO2 Were administered to animals breathing through an intact respiratory system, via a tracheal cannula by-passing the upper airways (before and after vagotomy), or via a cannula delivering gas to the upper airways alone. While increasing levels of hypercarbia led to a progressive increase in tidal volume in animals with intact respiratory systems (Series 1), breathing frequency did not change until the CO2 level reached 7%, at which time it decreased. Despite this, at the higher levels of hypercarbia, the net effect was a large and progressive increase in total ventilation. There were no associated changes in heart rate or arterial blood pressure. on return to air, there was an immediate change in breathing pattern; breathing frequency increased above air-breathing values, roughly to the same maximum level regardless of the level of CO2 the animal had been previously breathing, and tidal volume returned rapidly toward resting (baseline) values. Total ventilation slowly returned to air breathing values. Administration of CO2 via different routes indicated that inhaled CO2 acted at both upper airway and pulmonary CO2-sensitive receptors to modify breathing pattern without inhibiting breathing overall. Our data suggest that in caiman, high levels of inspired CO2 promote slow, deep breathing. This will decrease deadspace ventilation and may reduce stratification in the saccular portions of the lung.

Locus coeruleus noradrenergic neurons and CO2 drive to breathing

The Locus coeruleus (LC) has been suggested as a CO2 chemoreceptor site in mammals. In the present study, we assessed the role of LC noradrenergic neurons in the cardiorespiratory and thermal responses to hypercapnia. To selectively destroy LC noradrenergic neurons, we administered 6-hydroxydopamine (6-OHDA) bilaterally into the LC of male Wistar rats. Control animals had vehicle (ascorbic acid) injected (sham group) into the LC. Pulmonary ventilation (plethysmograph), mean arterial pressure (MAP), heart rate (HR), and body core temperature (T-c, data loggers) were measured followed by 60 min of hypercapnic exposure (7% CO2 in air). To verify the correct placement and effectiveness of the chemical lesions, tyrosine hydroxylase immunoreactivity was performed. Hypercapnia caused an increase in pulmonary ventilation in all groups, which resulted from increases in respiratory frequency and tidal volume (V-T) in sham-operated and 6-OHDA-lesioned groups. The hypercapnic ventilatory response was significantly decreased in 6-OHDA-lesioned rats compared with sham group. This difference was due to a decreased V-T in 6-OHDA rats. LC chemical lesion or hypercapnia did not affect MAP, HR, and T-c. Thus, we conclude that LC noradrenergic neurons modulate hypercapnic ventilatory response but play no role in cardiovascular and thermal regulation under resting conditions.

Hypercarbic cardiorespiratory reflexes in the facultative air-breathing fish jeju (Hoplerythrinus unitaeniatus): the role of branchial CO2 chemoreceptors

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Surgical treatment of earlobe keloid with CO2 laser radiation: Case report and clinical standpoints

Keloids are considered to be benign hyperproliferative growths of dense fibrous tissue and overabundant deposition of disorganized, thick, hyalinized collagen that result from an abnormal tissue response to cutaneous injury. Keloids do not have a specific cause, although genetic predisposition is heavily implicated. We present a case report of a patient with an earlobe keloid that was treated with carbon dioxide laser radiation (CO2) with an 0.8-mm focus, 7 W, a power density of 2.5 W/cm(2), in a continuous mode. The patient was seen for follow-up 6 months later. An intact hole for placement of an earring was observed with a very good esthetic and functional result.

Surgical treatment of squamous cell carcinoma of tongue with carbon dioxide laser radiation (CO2)

In this clinical study, we proposed to observe the efficacy of the treatment of squamous cell carcinoma of the tongue (SCCT) by carbon dioxide (CO2) laser surgery. Twelve patients with SCCT were treated with excisional surgery using the CO2 laser with a spot size of 0.8 mm, 10 W, power density of 2.5 W/cm(2) in continuous mode, and under constant vacuum removal of the plume. The post surgical clinical evaluations were done every day until the sutures were removed and then every 7 days up to 1 month postoperatively. Subjects were re-examined quarterly until the fifth year post surgery. After 5 yr of follow-up for all subjects, there was no recurrence of the SCCT at the involved sites. The functional and aesthetic results observed were excellent. It is concluded that CO2 laser ablation of SCCT is an extremely useful surgical technique that can provide a clean field and is capable of providing surgical results consistent with accepted principles of oncological surgery. (C) 2012 Laser Institute of America.