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N Banchero

Publications and source records attributed to N Banchero.

At least 37 records · Page 2Linked to original sources
PubMed1982

On comparing regression lines with unequal slopes.

For the situation in which the slopes of two regression lines may differ, procedures are discussed for the comparison of the lines at a single X, simultaneous comparison at several values of X, and determination of the range of X for which the difference between the lines is large enough to be statistically significant. These useful procedures have previously been discussed but do not seem to be well known. Their usefulness in the analysis of physiological data is demonstrated with data arising from a study of pulmonary response to hypoxia.

Adaptation, Physiological↗
PubMed1980

Chronic hypoxia does not affect guinea pig skeletal muscle capillarity.

The soleus and gastrocnemius muscles of chronically hypoxic guinea pigs were analyzed for capillary supply and myoglobin concentration. Weanling male guinea pigs were exposed to a simulated altitude of 5,100 m and an average ambient temperature of 22% C for 2, 4, 6, 10 and 14 weeks (range of BW 244--965 g). The soleus and gastrocnemius-plantaris muscles of one leg were analyzed for myoglobin concentration while the soleus and medial head of the gastrocnemius of the contralateral leg were cut at the midpoint, frozen and sectioned in a cryostat. The myosin ATPase method was used to visualize fibers and capillaries. Values of muscle weight, fiber cross sectional area, capillary density, capillary to fiber ratio and the number of capillaries around the fiber were compared to the values of the same parameters from normoxic guinea pigs selected to match the average body weights of the hypoxic animals. The growth rates of the two groups were not different. No significant differences in the regression lines for the normoxic and hypoxic animals were found so that when the data were combined no significant differences in the normoxic lines were introduced by adding the values of the hypoxic animals. The myoglobin values were significantly higher only in the hypoxic soleus after 14 weeks of exposure.

Aging↗
PubMed1980

Lung morphometry in guinea pigs acclimated to hypoxia during growth.

The effect of chronic hypoxic exposure on lung development has been assessed in growing guinea pigs (Cavia porcellus). Weanling males of initial W = 229 g were acclimated to a PO2 of 80 Torr for 2-14 weeks before sacrifice (range of W = 244-965 g). Growth was the same in hypoxic animals as in controls maintained at a PO2 of 133 Torr (range of W in controls = 89-1274 g). Lungs were fixed by tracheal instillation of glutaraldehyde and examined morphometrically with the electron microscope. Within 3 weeks of exposure, lung volume (VL) and alveolar surface area (Sa) were significantly increased by 32% and 27% respectively in the hypoxia acclimated animals compared to controls of similar W. However, these differences were progressively reduced with increasing time of exposure, and mean values of VL and Sa were not different between groups when W greater than 900 g. Chronic hypoxia accelerated lung development towards normal adult dimensions to a degree remarkably similar to that reported in cold acclimated guinea pigs. These findings are compatable with the theory of adaptive lung growth mediated by increased pulmonary blood flow, and suggest anatomical limitations to such growth related to an animal's age.

Adaptation, Physiological↗
PubMed1980

Increased capillary supply in skeletal muscle of guinea pigs acclimated to cold.

The ATPase technique was used to visualize blood capillaries and to study fiber composition in 10-micrometer transverse sections of guinea pig gastrocnemius and soleus muscles. A control group of newborn, weanling, juvenile and adult male guinea pigs (GP) (BW = 89-1274 g) was studied in a 20-24 degrees C environment (22 degrees C GP) while 2-3 week old animals were exposed continuously to 5 degrees C for 2-18 weeks before sacrifice (5 degrees C GP) (BW = 239-1074 g). Body weight gain was not affected by cold exposure; however, the gastrocnemius and soleus muscles of the 5 degrees C GP grew at a slower rate than did the muscles of the 22 degrees C GP. The equations relating fiber cross sectional area (FCSA) and muscle weight (MW) were not different between the 22 degrees C GP and 5 degrees C GP for the soleus and gastrocnemius. Therefore, in both muscles at the same BW, FCSA was smaller in the 5 degrees C GP than in the 22 degrees C GP. In both of the two muscles of each group, capillary density (CD) decreased hyperbolically with increasing FCSA, while the capillary to fiber ratio (C/F) and the average number of capillaries around each fiber (CAF) increased linearly with increasing FCSA. The regression lines for CD, C/F and CAF versus FCSA for both muscles were parallel between groups, but at any FDSA, the CD, C/F and CAF were greater in the 5 degrees C GP than in the 22 degrees C GP. Percent fiber composition of the gastrocnemii of the 22 degrees C GP and 5 degrees C GP were not different; however, at the same FCSA each fiber type had a greater capillary supply in the 5 degrees C GP. The increased capillarity in the gastrocnemius and soleus muscles of the 5 degrees C GP suggests an improved capacity for oxygenation, a response which would correlate well with the increased oxygen utilization during prolonged cold exposure.

Adaptation, Physiological↗
PubMed1980

Lung morphometry in guinea pigs acclimated to cold during growth.

Weanling male guinea pigs, Cavia porcellus [initial weight (W) = 200-250 g], were chronically acclimated to 5 degrees C for 2-18 wk before they were killed. Controls were raised at 22 degrees C. Food and water were given ad lib., and growth was the same in both groups. Under pentobarbital anesthesia (30 mg/kg), lungs were fixed by tracheal instillation of glutaraldehyde and processed for electron microscopy. Lung volume (VL, ml) was measured by displacement; alveolar and capillary surface areas (SA and Sc, m2) were determined morphometrically. Regressions of lung variables vs. W at 22 degrees C (range of W = 89-1,274 g) were as follows: VL = 0.175 W0.676, SA = 0.0097 W0.759, and Sc = 0.0055 W0.825; for 5 degrees C animals (range of W = 239-1,074 g): VL = 0.384 W0.584, SA = 0.0334 W0.594, and Sc = 0.032 W0.562. The total arithmetic mean thickness of lung tissue did not vary with W, and averaged 1.39 microns at 22 degrees C and 1.41 microns at 5 degrees C. VL, SA, and Sc are significantly greater in 5 degrees C guinea pigs than in 22 degrees C animals when W = 300-600 g, but are indistinguishable between groups when W > 700 g. Chronic increases in oxygen consumption, which occur with prolonged exposure to cold, result in accelerated lung development in immature guinea pigs toward normal adult dimensions.

Acclimatization↗
PubMed1979

Changes in the capillarity of skeletal muscle in the growing rat.

Capillary density (CD), capillary to fiber ratio (C/F), fiber cross sectional area (FCSA) and fiber composition were measured in the soleus and the gastrocnemius (medial head) muscles of rats weighing between 99 and 666 g. Muscle samples obtained from the anesthetized animal were rapidly frozen (-130 degrees C) sliced transversely at 16--18 micrometers, and treated histochemically by the ATPase method after preincubation at pH's of 4.0 and 4.4 to visualize capillaries and typify fibers. In both muscles the FCSA was positively related to body weight (BW) and muscle weight. At a given BW, the FCSA of the soleus was greater than that of the gastrocnemius. In both muscles CD decreased hyperbolically with FCSA (soleus: CD = 1.0613 X 10(6)/FCSA + 298.71; gastrocnemium: CD = 1.0349 X 10(6)/FCSA + 240.74). At the same time a positive linear correlation between C/F and FCSA was found (soleus: C/F = 3.92 X 10(-4) FCSA + 0.82; gastrocnemius: C/F = 2.90 X 10(-4) FCSA + 0.93). At a given FCSA, CD and C/F were greater in the soleus than in the gastrocnemius because of differences in fiber composition between the two muscles. The soleus had only oxidative fibers (STO and FTOG) whereas the gastrocnemius had 54% glycolytic fibers (FTG). The very large variability in CD and C/F values reported in the literature could, in part, be due to the differences in capillarity observed with maturation. A change in fiber composition with BW was observed in the soleus, but no systematic change occurred in the gastrocnemius.

Adenosine Triphosphatases↗
PubMed1979

Respiration in conscious dogs at rest and during exercise.

25 mongrel dogs (average b.w. 24.6 kg) were studied on several occasions at rest and during treadmill exercise of up to 10 mph (15% incline). Minute ventilation (VE), oxygen consumption (VO2), carbon dioxide production (VCO2), tidal volume (VT) and respiratory frequency (f) were determined at rest and at each level of exercise. Individual variability in resting VO2 was considerable (71--695 ml/min). Most often the dogs panted, with VE's above 25 liters/min and f's above 100 min-1. The averate VE/VO2 was 109 at rest. VO2 was linearly related to VE (VO2 = 9.17 VE + 66.9; r = 0.80). Differences in resting VE were largely due to differences in f (f = 3.57 VE + 21.2; r = 0.82). Considerable individual variability in VO2 for a given work load was also observed during exercise. Some dogs showed significant differences in VO2 from experiment to experiment while running at a given treadmill speed. These differences were largely related to the levels of VE. VE/VO2 decreased to 50. We found a leveling off of VO2 (at about 60 ml/min/kg) at treadmill speeds of 5 mph, suggesting that the maximal VO2 in dogs is less than previously reported.

Animals↗
PubMed1978

Oxygen cost of breathing in dogs.

The O2 cost of breathing has been calculated in awake and anesthetized dogs breathing spontaneously. Respiratory variables were measured in tracheostomized dogs in the standing position, while supported in a canvas sling, at room temperatures between 20 and 23 degrees C. Minute ventilation ranged between 3 and 53 liters/min while VO2 ranged from 61 to 686 ml/min. VE, VO2 and f varied considerably from measurement to measurement even though body temperatures and experimental conditions changed very little. VO2 increased with VE: VO2 = 10.2 VE + 58.4 r = 0.94. A cubic polynomial equation was also calculated for these data: VO2 = 11.6 + 19.0 VE-0.42 (VE)2 + 0.0057 (VE)3. Awake dogs showed panting and considerable hyperventilation (PACO2 = 22.5 +/- SD of 4.5 mm Hg). Anesthetized dogs had lower average values of f, VE and VO2; while average PACO2 was 29.1 +/- 4.5 mm Hg. VO2 and VE measured when the dogs were anesthetized, paralyzed and artifically ventilated were related by this equation: VO2 = 5.9 VE + 87.5, r = 0.88. The O2 cost of breathing, calculated by subtracting the regression equation obtained while the dogs were under artificial respiration, from the cubic polynomial equation, increased with increasing VE in a curvilinear fashion. The values for O2 cost of breathing at high levels of ventilation were high because dogs' lungs are small. After correcting for lung size, values for O2 cost of breathing were similar to those in humans.

Anesthesia↗
PubMed1978

Effects of added airway dead space on VO2 in dogs.

In dogs breathing spontaneously with added dead space, 198, 298 and 548 ml, the O2 consumption is a function of minute ventilation. This relationship (VO2 = 9.3 VE + 81.6; r = 0.95) was the same as that found in dogs breathing spontaneously with normal dead space. With added dead space, average tidal volumes increased but not enough to compensate for the added volume and, thus, dogs achieved alveolar ventilation mainly by using the fatest molecules of gas in the airway, because of the conical shape of the velocity profile of gas molecules. When the values for VO2 and f were grouped according to different VTS, VO2 was found to be a linear function of f. Also, for a given f, VO2 increased progressively with VT; however, the higher the f, the more taxing a given increase in VT was. Over a certain range of respiratory frequencies, dogs could reduce f and increase VT without significantly affecting VO2.

Animals↗