Oral Biofilm Cryotherapy as a Novel Ecological Modulation Approach.

Oral cryotherapy is used in dentistry as a safe, simple, and low-cost treatment for a variety of oral lesions. It is well known for its ability to aid in the healing process. However, its effect on oral biofilms is unknown. As a result, the purpose of this study was to assess the effects of cryotherapy on in vitro oral biofilms. In vitro multispecies oral biofilms were grown on the surface of hydroxyapatite discs in symbiotic or dysbiotic states. CryoPen X+ was used to treat the biofilms, whereas untreated biofilms served as control. One set of biofilms was collected for study immediately after cryotherapy, whereas another group was reincubated for 24 h to permit biofilm recovery. Changes in biofilm structure were analyzed with a confocal laser scanning microscope (CLSM) and a scanning electron microscope (SEM), while biofilm ecology and community compositional changes were analyzed with viability DNA extraction and quantitative polymerase chain reaction (v-qPCR) analysis. One cryo-cycle immediately reduced biofilm load by 0.2 to 0.4 log10 Geq/mL, which increased with additional treatment cycles. Although the bacterial load of the treated biofilms recovered to the same level as the control biofilms within 24 h, the CLSM detected structural alterations. Compositional alterations were also detected by SEM, corroborating the v-qPCR findings that showed ≈≤10% incidence of pathogenic species compared to nontreated biofilms that encompassed ≈45% and 13% pathogenic species in dysbiotic and symbiotic biofilms, respectively. Spray cryotherapy showed promising results in a novel conceptual approach to the control of oral biofilms. Acting selectively by targeting oral pathobionts and retaining commensals, spray cryotherapy could modify the ecology of in vitro oral biofilms to become more symbiotic and prevent the evolution of dysbiosis without the use of antiseptics/antimicrobials.

[Increased success rate in umbilical venous catheter positioning by posterior liver mobilization]. / Intérêt du refoulement hépatique pour repositionner un cathéter veineux ombilical « sous-hépatique ¼ dans la veine cave inférieure.

OBJECTIVE: To evaluate prospectively the benefit of posterior liver mobilization during umbilical venous catheterization to place the umbilical venous catheter (UVC) in the central position (inferior vena cava). PATIENTS AND METHODS: Sixty-five successive newborn infants admitted in 3 neonatal intensive care units who required a UVC were enrolled over a 4-month period. UVC positions were assessed by X-ray. UVCs were placed either in an adequate position (at the right atrial-inferior vena cava junction, indicating success) or inserted within the portal system (failure). In this case, the UVC was drawn back to the 3cm mark and then, an additional attempt to insert the UVC was made during lateroposterior liver mobilization by the operator's hand. The success and failure rates at 1st and 2nd attempts were evaluated and compared. Characteristics of the population and possible catheter-related complications were recorded. RESULTS: A total of 31 of 65 (55%) UVC insertions failed at the 1st attempt. Among these UVCs, 16 (52%) were correctly repositioned in the central position by hepatic mobilization. The success rate increased by 50% (p<0.05). No life-threatening complications were observed during the procedure. CONCLUSION: Hand liver mobilization during umbilical venous catheterization improves the rate of adequate insertion of the UVC into the inferior vena cava. It is a simple, quick, and safe procedure.

Ventilatory threshold measurement to evaluate maximal endurance performance.

The ventilatory (anaerobic) threshold during short-term exercise has been defined as the O2 uptake (VO2) immediately below the VO2 at which pulmonary ventilation (VE) increases disproportionally relative to VO2 and the ventilatory threshold for long-term exercise as the VO2 immediately below the VO2 at which the VE continues to increase with time rather than attain a steady state. Maximal endurance performance was determined by measurement of the maximal endurance time during treadmill runs at 90%, and 70% of the previously determined VO2 max. The purpose of the present study was to investigate how maximal endurance performance was related to both ventilatory thresholds and to VO2max, and to select which variable best explained maximal endurance performance. The subjects were 11 healthy males. Maximal endurance performance was significantly correlated with the ventilatory threshold for long-term exercise and VO2max. A stepwise multiple regression analysis indicated that maximal endurance performance was best predicted by the ventilatory threshold for long-term exercise. Combination of variables could not improve the prediction. It is concluded that the ventilatory threshold for long-term exercise better explains maximal endurance performance than VO2max or the ventilatory threshold during short-term exercise.

Transdiaphragmatic, esophageal and gastric pressures during maximal static inspiratory and expiratory efforts in young subjects: effects of maneuver and sex.

Esophageal (Pes), gastric (Pga) and transdiaphragmatic (Pdi) pressures were measured in 6 young healthy men and 6 women during maximal static inspiratory and expiratory efforts. Interindividual variations were large for all pressures, but the measurements were highly reproducible within each subject. During maximal inspiratory efforts without instruction as to the type of breathing, Pga was often around zero whereas during standardized maximal inspiratory efforts (i.e. with protruded abdomen), Pdi and Pga increased significantly and Pes tended to be less negative. Thus, maximal strength of the diaphragm is only measured during standardized efforts. During maximal expiratory efforts Pes and Pga tended to be larger during spontaneous than during standardized maneuvers (i.e. with retracted abdomen), and to increase with lung volume. The clinical information obtained from Pdi, Pes and Pga during maximal inspiratory and expiratory efforts is probably not more specific than that from transrespiratory pressures (i.e. measurements at the mouth), except for standardized inspiratory efforts which may allow differentiation of intercostal-accessory and diaphragm-abdominal dysfunction.

Effects of thoracic or abdominal strapping on exercise performance.

In eleven young healthy subjects, vital capacity was reduced by 30% by thoracic or abdominal strapping and the effects of this on maximal work capacity, ventilation and circulation were examined. During exercise as well as at rest, tidal volume and stroke volume were reduced and respiratory frequency and heart rate were increased with both types of strapping. Cardiac output appeared to be decreased. Thoracic strapping was slightly but significantly more impeding than abdominal strapping: residual volume, tidal volume and maximal work capacity were smaller. In both instances, the decrease in maximal performance was apparently due to ventilatory as well as circulatory limitation.

Ventilatory thresholds during short- and long-term exercise.

The ventilatory (anaerobic) threshold for short-term exercise was defined as the work rate or O2 uptake (VO2) immediately below the work rate at which ventilation increased disproportionately relative to work rate or VO2, and the ventilatory threshold for long-term exercise as the work rate or VO2 immediately below the work rate at which ventilation continued to increase with time rather than attain a steady state. The purpose of the present study was to investigate how both thresholds relate to each other and how they relate to other measures of physical performance capacity. The subjects were eight healthy males, 20-53 yr of age. Maximal performance capacity was estimated by measurements of maximal O2 uptake (VO2 max) and by endurance performance during a 12-min distance run. A high interrelationship was found between the two thresholds (r = 0.84), and each threshold expressed in VO2 (ml X min-1 X kg-1) correlated highly with VO2 max (r = 0.87 and r = 0.75, for short-term and long-term exercise, respectively). When the two thresholds were expressed as a percentage of VO2 max, neither threshold showed a significant relationship with VO2 max. Endurance performance was significantly correlated with both the ventilatory threshold for short-term and long-term exercise (r = 0.73 and 0.82, respectively). A stepwise multiple regression analysis indicated that the distance run in 12 min was best predicted by VO2 max (R2 = 0.66) or the ventilatory threshold for long-term exercise (R2 = 0.63). It is concluded that the ventilatory threshold for long-term exercise is a more specific measure to explain running performance than is the threshold during graded exercise.

Anaerobic threshold for long-term exercise and maximal exercise performance.

The anaerobic threshold during graded exercise (GXT, AT1) was determined as the exercise level initiating a curvilinear increase in ventilation (VE), and during prolonged exercise (PXT, 40 min, AT2) as the maximal exercise level where still a steady state for VE can be reached. Subjects were 8 healthy males, 20 to 53 years of age. Maximal exercise capacity was estimated by means of 1) VO2 max 2) max time on bicycle ergometer at 200 Watts and 3) maximal distance run within 12 min (Cooper test). VO2 max was significantly related to AT1, GXT (r = 0.85, 0.01 less than p less than 0.001) and to AT2, PXT (r = 0.75, 0.05 less than p less than 0.01). Also a significant correlation was found between the endurance exercise capacity (= 200 Watts) and both AT1 (r = 0.80; 0.05 less than p less than 0.01) and AT2 (r = 0.84; 0.01 less than p less than 0.001). Finally only AT2 was significantly correlated with the Cooper test (r = 0.81; 0.01 less than p less than 0.001), no significant relationship was found for AT1 (r = 0.68; p less than 0.05). In conclusion AT1 reached the highest correlation with a short maximal exercise test such as VO2 max, in contrast to AT2, which showed the highest correlation with endurance exercise such as Cooper test or maximal exercise time at 200 Watts.

Some anthropometric and functional dimensions of the pygmy (Kivu Twa).

At the Institut pour la Recherche Scientifique en Afrique Centrale (I.R.S.A.C.), Station of Lwiro on Lake Kivu, Republic of Zaire, anthropometric and spirometric measurements were made on 25 male members of a pygmy clan, living the traditional hunter-gatherer's life on the slopes of the Mitumba mountain range. The response of 15 men to graded exercise was tested on a bicycle ergometer. The morphology of the Kivu Twa was in agreement with that described for pygmies in the same general area. Blood pressure was extremely low, 99/64 (SD +/- 12/11) mm Hg, and was not affected by age. Lung volumes were small compared to those of Europeans, and fitted well the standards for the 'Bantu' in South Africa. The vital capacity of adult men was 3.183 (SD +/- 0.151)l and the one-second forced expiratory volume 2.558 (SD +/- 0.11)l. Their cardiovascular response to increasing physical work-loads was similar to that of other population samples in Central Africa and quite close to those of the Equator Twa. The maximum aerobic power, calculated indirectly, was small, 1.957 (SD +/- 0.158)l/min, but when expressed per kg body weight was 42.5 (SD +/- 5.2) ml min-1 kg-1, comparable to that of many other populations.