A Comparison of the Photophysical, Electrochemical and Cytotoxic Properties of meso-(2-, 3- and 4-Pyridyl)-BODIPYs and Their Derivatives

Boron dipyrromethene (BODIPY) dyes bearing a pyridyl moiety have been used as metal ion sensors, pH sensors, fluorescence probes, and as sensitizers for phototherapy. A comparative study of the properties of the three structural isomers of meso-pyridyl-BODIPYs, their 2,6-dichloro derivatives, and their corresponding methylated cationic pyridinium-BODIPYs was conducted using spectroscopic and electrochemical methods, X-ray analyses, and TD-DFT calculations. Among the neutral derivatives, the 3Py and 4Py isomers showed the highest relative fluorescence quantum yields in organic solvents, which were further enhanced 2-4-fold via the introduction of two chlorines at the 2,6-positions. Among the cationic derivatives, the 2catPy showed the highest relative fluorescence quantum yield in organic solvents, which was further enhanced by the use of a bulky counter anion (PF₆^-). In water, the quantum yields were greatly reduced for all three isomers but were shown to be enhanced upon introduction of 2,6-dichloro groups. Our results indicate that 2,6-dichloro-meso-(2- and 3-pyridinium)-BODIPYs are the most promising for sensing applications. Furthermore, all pyridinium BODIPYs are highly water-soluble and display low cytotoxicity towards human HEp2 cells.

BBIQ, a pure TLR7 agonist, is an effective influenza vaccine adjuvant

Better adjuvants are needed for vaccines against seasonal influenza. TLR7 agonists are potent activators of innate immune responses and thereby may be promising adjuvants. Among the imidazoquinoline compounds, 1-benzyl-2-butyl-1H-imidazo[4,5-c]quinolin-4-amine (BBIQ) was reported to be a highly active TLR7 agonist but has remained relatively unexplored because of its commercial unavailability. Indeed, in silico molecular modeling studies predicted that BBIQ had a higher TLR7 docking score and binding free energy than imiquimod, the gold standard TLR7 agonist. To circumvent the availability issue, we developed an improved and higher yield method to synthesize BBIQ. Testing BBIQ on human and mouse TLR7 reporter cell lines confirmed it to be TLR7 specific with significantly higher potency than imiquimod. To test its adjuvant potential, BBIQ or imiquimod were admixed with recombinant influenza hemagglutinin protein and administered to mice as two intramuscular immunizations 2 weeks apart. Serum anti-influenza IgG responses assessed by ELISA 2 weeks after the second immunization confirmed that the mice that received vaccine admixed with BBIQ had significantly higher anti-influenza IgG1 and IgG2c responses than mice immunized with antigen alone or admixed with imiquimod. This confirmed BBIQ to be a TLR7-specific adjuvant able to enhance humoral immune responses.

Erratum to: Antimicrobials: a global alliance for optimizing their rational use in intra-abdominal infections (AGORA)

[This corrects the article DOI: 10.1186/s13017-016-0089-y.].

Study on relationship between the nutritional status and dental caries in 8-12 year old children of Udaipur City, India

BACKGROUND

The future health of individuals depends on the well being of the children of today. Proper nutrition for children is very important. The most commonly used index of obesity and over weight is Body Mass Index. The growth of children should be monitored using the Body Mass Index (BMI) and risk factors assessed through a dietary and physical activity history. The increase in obesity is attributed to increased carbohydrate consumption among children. Obesity and caries are both diet-based conditions that share a cause that is, excessive ingestion of fermentable carbohydrates.

OBJECTIVE

This study was undertaken to determine the association of nutritional status with dental caries in 8 to 12 year old children of Udaipur city.

METHOD

The present study was conducted on a random sample of 1000 boys and girls, aged 8-12 years. The children were selected from schools located in the Udaipur City, Rajasthan. The schools examined were of government and private sector schools in Udaipur city. The children from schools of Udaipur city was taken in the study with male, female and age group ratio as per distribution in population. A proforma was used to record children's age, gender, school, year, height, weight, parental income and dental caries status. Statistical analysis was done using Statistical Package of Social Science (SPSS Version 15; Chicago Inc., USA).

RESULT

It was found that caries free individuals were more from normal nutritional status group with 134 (13.4 %) subjects where as only 11 (1.1 %) of subjects obese children were found caries free.

CONCLUSION

Study shows that the children with normal BMI for age had more caries in their primary teeth, as well as in their permanent teeth, than the overweight children.

Fluoride concentration in community water and bottled drinking water: a dilemma today

BACKGROUND

Because of the potential for contamination of municipal water supplies, people appear to be turning to alternative sources for their pure drinking water.

OBJECTIVES

The present study analyzed the fluoride concentration in community water and bottled drinking water sold in Faridabad city.

METHODS

A comparative evaluation of fluoride content in community water supply and bottled drinking water was done using ion-selective electrode method. The community water samples were collected from six different areas (i.e. north zone, south zone, east zone, west zone and central zone) in the city from public health water supply taps while bottled drinking water samples were randomly picked from grocery shops or supermarkets.

RESULTS

The fluoride concentration in the community water supply in this study ranges from 0.11 to 0.26 mg/L with mean fluoride concentration of 0.17 mg/L. The mean concentration of fluoride in bottled drinking water was 0.06 mg/L. The differences observed between mean of two water samples was statistically significant.

CONCLUSION

The results obtained from the present study clearly state that the fluoride concentration was insufficient in community water supply from all the areas and also was deficient in bottled drinking water sold in Faridabad city. So, Alternative sources of fluorides should be supplemented for optimal dental benefits from the use of fluoride.

Preventing dental caries in children: Indian scenario

The prevalence of dental caries in developing countries like India is increasing to an alarming level in contrast to developed countries where it has decreased because of variety of preventive measures at the community and individual level. There is no State or Centre funded programs for prevention of dental diseases in India. The present review enlists the targeted prevention of dental caries in permanent teeth of 6 to 16 years old children presenting for dental care.

The use of Soluble Metal-Polyselenide Complexes as Precursors to Binary and Ternary Solid Metal Selenides

The use of several soluble metal polychalcogenides to prepare solid state materials is presented. Thermal gravimetric analysis (TGA) data, under inert atmosphere, of the molecular compounds (Ph4P)2[Cd(Se4)2], (Ph4P)4[Cu2Se14], (Ph4P)2[Cu4Se12], (Ph4P)4[In2Se21] and (Et4N)3[M3Se15], (M=In, TI), show that the corresponding binary solid state compounds are formed as single phases at temperatures as low as 530°C. We have grown films of CdSe, Cu2-xSe, β-In2Se3, TISe and CuInSe2 using these complexes as precursors. The films were prepared by pyrolysis of green precursor films, cast from DMF solutions. CuInSe2 was prepared by co-thermolysis of Cu/Sex and In/Sex complexes. The chemical, X-ray, spectroscopic and electron microscopic characterization of these molecular precursor-derived films as well as their charge transport characterization is reported.

Depression and anxiety among US adults: associations with body mass index

BACKGROUND

Obesity is associated with an increased risk of developing a variety of chronic diseases, most of which are associated with psychiatric disorders. We examined the associations of depression and anxiety with body mass index (BMI) after taking into consideration the obesity-related comorbidities (ORCs) and other psychosocial or lifestyle factors.

METHODS

We analyzed the data collected from 177,047 participants (aged>or=18 years) in the 2006 Behavioral Risk Factor Surveillance System. Current depression was assessed by the Patient Health Questionnaire-8 diagnostic algorithm. Lifetime diagnoses of depression, anxiety and ORCs were self-reported. The prevalence of the three psychiatric disorders was age standardized to the 2000 US population. Multivariate-adjusted prevalence ratios were computed to test associations of depression and anxiety with BMI using SUDAAN software.

RESULTS

The age-adjusted prevalence of current depression, lifetime diagnosed depression and anxiety varied significantly by gender. Within each gender, the prevalence of the three psychiatric disorders was significantly higher in both men and women who were underweight (BMI<18.5 kg/m(2)), in women who were overweight (BMI: 25-<30 kg/m(2)) or obese (BMI>or=30 kg/m(2)), and in men who had class III obesity (BMI>or=40 kg/m(2)) than in those with a normal BMI (18.5-<25 kg/m(2)). After adjusting for demographics, ORCs, lifestyle or psychosocial factors, compared with men with a normal BMI, men with a BMI>or=40 kg/m(2) were significantly more likely to have current depression or lifetime diagnosed depression and anxiety; men with a BMI<18.5 kg/m(2) were also significantly more likely to have lifetime diagnosed depression. Women who were either overweight or obese were significantly more likely than women with a normal BMI to have all the three psychiatric disorders.

CONCLUSIONS

Our results demonstrate that disparities in the prevalence of depression and anxiety exist among people with different BMI levels independent of their disease status or other psychosocial or lifestyle factors.

Activation of apoptotic processes during transition from hypertrophy to heart failure in guinea pigs

Changes in oxidative stress and apoptotic process were studied during the progression of a compensated hypertrophy to a decompensated heart failure in guinea pigs. Banding of the ascending aorta resulted in heart hypertrophy. At 10 wk, ventricle-to-body weight ratio and thickness of the interventricular septum as well as the left ventricular wall were increased significantly. Although fractional shortening and ejection fraction were decreased, there were no signs of heart failure. Furthermore, there was no increase in wet-to-dry weight ratios for the lungs and liver at this stage. However, at 20 wk, heart failure was characterized by a significant depression in heart function as indicated by a decrease in fractional shortening, and ejection fraction and a lesser increase in wall thickness from diastole to systole. Animals also showed clinical signs of heart failure, and the wet-to-dry weight ratios of the lungs and liver were significantly higher. Cardiomyocyte oxidative stress was significantly higher in the 20-wk aortic-banded group. The ratio of Bax to Bcl-xl showed an increase at 10 wk, and there was a further increase at 20 wk. Mitochondrial membrane potential in the aortic-banded animals was significantly decreased at 10 and 20 wk. Cytochrome c levels were higher in the cytosol compared with the mitochondria, leading to a considerable increase in the expression of p17 subunit of caspase-3. At 20 wk, both early and late stages of apoptosis were observed in isolated cardiomyocytes. It is suggested that an increase in oxidative stress initiates mitochondrial death pathway during the hypertrophic stage, leading to apoptosis and heart failure at a later stage.

Oral fluorescein angiography with the scanning laser ophthalmoscope in diabetic retinopathy: a case controlled comparison with intravenous fluorescein angiography

AIM

To compare the performance of oral fundus fluorescein angiography with a confocal scanning laser ophthalmoscope (SLO) with intravenous fundus fluorescein angiography (IVFFA) with a fundus camera in the assessment of sight-threatening diabetic retinopathy.

PATIENTS AND METHODS

A total of 25 patients undergoing IVFFA to investigate their diabetic retinopathy were recruited. Participants returned 1 week later and an oral angiogram with the SLO was performed. Six facets of the oral and intravenous angiograms were scored and compared: visualization of the foveal avascular zone (FAZ); branch retinal identification; macular leakage; identification of microaneurysms in areas of macular leakage; peripheral nonperfusion, and leakage from neovascular complexes.

RESULTS

Compared to IVFFA, the FAZ was unreliably visualized with oral angiography (Kappa 0.1, 95% CI 0-0.3). In contrast, macular leakage (Kappa 0.78, 95%, CI 0.72-0.83), identification of microaneurysms in areas of macular leakage (Kappa 0.78, 95%, CI 0.72-0.83), and neovascular complexes (Kappa 1.0) were reliably seen. Analysis of the visualization of peripheral nonperfusion was complicated by the finding that profuse dye leakage from neovascular complexes obscured the view of the peripheral retina. If the five angiograms in which this occurred were excluded, oral angiography identified 23 of the 24 eyes in which significant nonperfusion was found on IVFFA.

CONCLUSION

Oral angiography with the SLO can provide high-quality angiograms that allow judgments to be made about the presence of treatable diabetic maculopathy, proliferative diabetic retinopathy, and peripheral nonperfusion. In the presence of coexisting macular oedema, it proved to be an unreliable technique with which to investigate foveal ischaemia.

Photostabilizers for azadirachtin-A (a neem-based pesticide)

Photostability of azadirachtin-A (a neem based pesticide) has been studied without and with adding stabilizers such as ter. butyl-p-cresol, 8-hydroxy quinoline and ter. butyl hydroquinone as thin film on glass surface and on leaf surface under sunlight and UV light. Half-life of azadirachtin has been found to be 48 min and 3.98 days as thin film under UV light and sunlight and 2.47 days on leaf surface, respectively. 8-Hydroxy quinoline and ter. butyl hydroquinone have been found effective in controlling degradation of azadirachtin under both sunlight and UV light with half-life of 44.42 and 35.90 days under sunlight, and 55.80 and 48.50 h under UV light, respectively. Whereas ter. butyl-p-cresol has been found effective A only under sunlight. Significant decreases in antifeedant and insect growth regulatory activity against third instar larvae of Spodopterra litura has been observed with azadirachtin when exposed to sunlight and UV light. However, by the addition of above stabilizers, the biological activity of azadirachtin-A has been retained even after 24 h of irradiation under UV light and up to 30 days of exposure to sunlight.

Insect growth inhibition, antifeedant and antifungal activity of compounds isolated/derived from Zingiber officinale Roscoe (ginger) rhizomes

Fresh rhizomes of Zingiber officinale (ginger), when subjected to steam distillation, yielded ginger oil in which curcumene was found to be the major constituent. The thermally labile zingiberene-rich fraction was obtained from its diethyl ether extract. Column chromatography of ginger oleoresin furnished a fraction from which [6]-gingerol was obtained by preparative TLC. Naturally occurring [6]-dehydroshogaol was synthesised following condensation of dehydrozingerone with hexanal, whereas zingerone and 3-hydroxy-1-(4-hydroxy-3-methoxyphenyl)butane were obtained by hydrogenation of dehydrozingerone with 10% Pd/C. The structures of the compounds were established by 1H NMR, 13C NMR and mass (EI-MS and ES-MS) spectral analysis. The test compounds exhibited moderate insect growth regulatory (IGR) and antifeedant activity against Spilosoma obliqua, and significant antifungal activity against Rhizoctonia solani. Among the various compounds, [6]-dehydroshogaol exhibited maximum IGR activity (EC50 3.55 mg ml-1), while dehydrozingerone imparted maximum antifungal activity (EC50 86.49 mg litre-1).

Open Framework Structures Based on Sex2- Fragments: Synthesis of (Ph4P)[M(Se6)2] (M = Ga, In, TI) in Molten (Ph4P)2Sex

Polychalcogenide compounds with open polymeric frameworks are rare, and they represent a class of compounds in which microporosity might be achieved. Microporous frameworks that are not oxide-based are now attracting interest because of the combination of catalytic and electronic properties they may simultaneously possess. Three new compounds that may be forerunners to such materials have been discovered and are reported here. The reaction of gallium (Ga), indium (In), and thallium (TI) metal with (Ph(4)P)(2)Se(5) (Ph, phenyl) and an excess of elemental selenium (Se) in a sealed, evacuated Pyrex tube at 200 degrees C yielded small red crystals of (Ph(4)P)[Ga(Se(6))(2)] (I), (Ph(4)P)[In(Se(6))(2)] (II), and (Ph(4)P)[TI(Se(6))(2)] (III), respectively. The [M(Se(6))(2)](-) (M = Ga, In, TI) ions form a two-dimensional, open framework filled with Ph(4)P(+) ions. The [M(Se(6))(2)](n)(n-) structure consists of tetrahedral M(3+) centers and bridging Se(6)(2-) ligands, leading to an extended structure in two dimensions. These layers stack perfectly one on top of the other giving rise to one-dimensional channels running down the c axis that are filled with Ph(4)P(+) cations. These cations are situated in the layers, as opposed to between the layers, and the whole structure can be viewed as a template. Compound II shows remarkable thermal stability and melts congruently at 242 degrees C. Upon cooling to room temperature it gives a glassy phase that recrystallizes upon subsequent heating to 160 degrees C.

A comparison of the bronchodilating effects of a beta-2 adrenergic agent (albuterol) and an anticholinergic agent (ipratropium bromide), given by aerosol alone or in sequence

We evaluated the effect of anticholinergic and beta-adrenergic inhaled bronchodilators, alone or in sequence, in 11 patients with chronic obstructive pulmonary disease. We compared the agents albuterol and ipratropium bromide when each was used as a single aerosol in the maximal dose. After giving a maximal dose of one agent, we compared the effect of adding the other with that of adding a placebo. When used alone, both bronchodilators significantly increased airflow and relieved hyperinflation, and there was no significant difference between the two. After the improvement with the initial bronchodilator, the subsequent effect of a second inhaled bronchodilator was not greater than that of placebo. These results suggest that in the treatment of chronic obstructive pulmonary disease, these two aerosols are usually equipotent in maximal doses and the addition of a second agent is of no practical value. The data support the prescription of a single inhaled agent in most cases but do not rule out the value of combinations of agents under special circumstances.

Measurements of maximum respiratory pressures in polymyositis and dermatomyositis

Measurements of maximum respiratory pressures and routine pulmonary function tests were performed in 8 patients with polymyositis (PM) and 2 patients with dermatomyositis (DM). Serial measurements of routine pulmonary function tests in 8 patients remained unchanged. Maximum respiratory pressures were decreased initially in 7 patients with proximal muscle weakness and clinically active muscle disease and improved with corticosteroid therapy in the 5 patients who were followed serially. In 3 patients with clinically stable disease the maximum respiratory muscle power was normal. Serial measurements of maximum respiratory pressures have been of value in monitoring patients with PM and DM.

Hypomagnesemia and respiratory muscle power

Although hypomagnesemia is common and causes weakness in humans, it is not known what effect its correction has on respiratory muscle power. We designed an experiment to test the hypothesis that correction of hypomagnesemia will improve respiratory muscle power. We measured muscle power and lung volumes in 16 control subjects and 17 patients (11 alcoholics, 6 nonalcoholics) on 3 consecutive days. After baseline measurements on Day 1, patients were randomized and the study was double blinded. Patients were given magnesium intravenously or dextrose as placebo. Measurements were repeated on Day 2, and the patients were then given magnesium if they had previously been given placebo, and vice versa. Measurements were done again on Day 3. There was no significant difference in lung volumes in patients or control subjects over the 3 days. There were no changes in respiratory muscle power in control subjects, but there was an improvement in all parameters of muscle power measured after magnesium therapy in patients. Hypomagnesemia should be excluded as a cause of muscle weakness because its replacement may improve muscle power.

Inhaled lidocaine aerosol changes resting human breathing pattern

We compared resting breathing patterns in twelve normal humans before and after administration of aerosols of normal saline and 4% lidocaine. Experiments were performed in random order on two consecutive days in single blind fashion. At the time of the experiments, neither the subjects nor the people who analyzed the results knew the purpose of the study. Neither saline nor lidocaine aerosols produced changes in FEV1.0 or end-tidal PCO2, or, in the six subjects in whom measurements were made, changes in functional residual capacity or airway resistance. Aerosols of normal saline produced no change of ventilation (VI), breathing frequency (f), tidal volume (VT), duration of inspiration (Ti), mean inspiratory flow (VT/Ti) or the fraction of the breathing cycle devoted to inspiration (Ti/Tt). Lidocaine aerosols, on the other hand, were associated with a decrease in f (P less than 0.01), an increase in Ti (P less than 0.01), an increase in VT (P less than 0.02) and a decrease in VI (P less than 0.05), while VT/Ti and Ti/Tt were unchanged. We conclude that lidocaine aerosols, by compromising the function of vagal airway receptors, altered breathing pattern in normal resting humans, indicating that these receptors play a role in regulating breathing pattern under these circumstances. Though the changes we observed are most simply explained as being due to decreased stretch receptor activity, we cannot be certain that such was the case.

Role of vagal airway reflexes in control of ventilation in pulmonary fibrosis

1. In 10 patients with pulmonary fibrosis and in seven control subjects, we measured the pressure at the mouth 0 . 1 s after onset of an inspiration against occluded airway (P 0 . 1), minute ventilation (VI), breathing frequency (fr), tidal volume (VT), inspiratory duration (Ti) and calculated the mean inspiratory flow (VT/Ti) and the fraction of the breath cycle devoted to inspiration (Ti/T tot.). In the patients measurements were made at normal arterial oxygen saturations (SaO2), before and after lignocaine airway anaesthesia. 2. Efficacy of airway anaesthesia was tested by the cough response to citric acid inhalation. 3. In pulmonary fibrosis P 0 . 1, f1 and VT/Ti were greater than in the control subjects, VT and Ti were smaller and Ti/T tot. and VI were not different. 4. Effective airway anaesthesia did not modify P 0 . 1 and breathing pattern parameters observed in pulmonary fibrosis. 5. These results suggest that airway receptors do not contribute to a major extent to the control of breathing in pulmonary fibrosis.

Ventilatory pattern and drive after acute myocardial infarction

1. In 18 patients with acute myocardial infarction, we measured ventilation, frequency, inspiratory duration and the pressure at the mouth 0.1 s after the onset of inspiration against an occluded airway; mean inspiratory flow and the fraction of the breathing cycle devoted to inspiration were calculated. Measurements were made on 2–3 consecutive days soon after admission and repeated 4–10 days after admission.

2. Eight patients showed no clinical evidence of left heart failure at any time; in these patients no changes in breathing pattern, ventilation or occlusion pressure were observed.

3. Ten patients were in heart failure, as judged by the presence of râles and/or hypoxaemia on day 1 of the study, and all had recovered on the last day. When in failure these patients demonstrated increased minute ventilation, occlusion pressure was increased more than was mean inspiratory flow and their breathing pattern was altered. Tidal volume was similar to that in patients without failure and did not change with time, but frequency was initially high and fell as recovery from failure occurred. The duration of inspiration was decreased during failure, so mean inspiratory flow was increased. The fraction of the breathing cycle devoted to inspiration was constant and similar to that in patients without failure.

4. While in failure no patients were acidotic and not all patients were hypoxaemic; administration of oxygen did not influence results in two patients during failure.

5. These results indicate that clinically detectable pulmonary oedema is associated with increased ventilatory drive, which cannot be explained on the basis of hypoxaemia or hypercapnia. The observed changes in breathing pattern were probably due at least in part to vagal reflexes, and these may have contributed to the increase in drive.

Endogenous opiates and chemical control of breathing in humans

Endogenous opiates are found in large concentrations in the brainstem of vertebrate animals, suggesting that they play a possible role in the central control of breathing. To examine this possible role in human ventilatory control we evaluated the effect of nalozone, a specific opiate antagonist, on the ventilatory and mouth occlusion pressure (P0.1) responses to hypercapnia and hypoxia in 6 normal men 22 to 48 yr of age. In a random double-blind crossover study, each subject received both an intravenous infusion of 50 mg of naloxone and a placebo infusion of normal saline. Ventilatory responses were measured before and 5 min after each infusion. Ventilatory responses to hypercapnia and hypoxia were more marked after both the saline and naloxone infusions, but there was no significant difference in the responses between the 2 infusions. Similarly there was no significant difference in respiratory timing or mean inspiratory flow between the 2 infusions at an arterial oxygen saturation (SaO2) > 95%. We concluded that endogenous opiates have no major influence on the chemical control of breathing in normal humans.

Airway closure and closing volume

Using boluses of radioactive Xe we compared regional N2O uptake with regional perfusion distribution during open glottis breath hold in five seated men. Measurements were made near residual volume, at closing volume (CV), above CV and when possible, between CV and residual volume (RV). At low lung volumes basal N2O uptake was small whereas basal blood flow was not. This discrepancy was interpreted as evidence of airway closure and was quantitated. All subjects showed extensive basal closure near RV. At closing volume four of five subjects demonstrated closure and some closure was evident in these subjects at volumes in excess of CV. The increase in airway closure with decreasing lung volume was much greater below CV than above it. Conventional CV tracings were obtained using helium boluses; the height of phase IV was positively correlated with the change in airway closure between CV and RV as assessed by the N2O technique. The slope of phase III did not correlate with the amount of airway closure measured at CV. We concluded that the conventionally measured CV is not the volume at which airway closure begins but that the onset of phase IV reflects an increase in basal airway closure and the height of phase IV reflects the amount of basal closure between CV and RV.

Alkaline phosphatase activity in normal and denervated skeletal muscle

Changes in the specific activity of alkaline phosphatase in the normal and denervated skeltal muscle have been studied both histochemically as well as biochemically for a maximum period of 8 weeks of its postnatal development. In the normal muscle, a heterogenous population of fibres with respect to the enzyme distribution is observed. Relatively higher levels of enzyme in the denervated muscle and also the proliferation of extrafibillar connective tissue in the diseased muscle show its specific association with the lytic processes.

Ventilatory response to low levels of CO2

Ventilation and Pa(CO2), were measured in six subjects after 10-12 min of breathing 1-2% CO2 during hyperoxia and hypoxia. These inspired CO2 concentrations were achieved in two ways: by enriching the inspirate with CO2 and by having the subjects breathe through dead spaces of 100-400 cm3. Breathing through dead space gave the same results as CO2 enrichment of the inspirate when the effect of the dead spaces on mean inspired CO2 was allowed for. During hyperoxia all subjects demonstrated isocapni hyperpnea in response to mean inspired CO2 concentrations of 1%; ventilation increased without change in PA(CO2). When mean inspired CO2 concentration approximated 1.5% two subjects showed isocapnic hyperpnea, and one subject demonstrated isocapnic hyperpnea in response to mean inspired CO2 concentrations of 2%. The increase in PA(CO2) observed in each subject in response to 2% CO2 in O2 correlated negatively with the slope of that subject's rebreathing CO2 response curve. Hypoxia (PA(O2Y = 45-50 mm Hg) depressed the response to 1% CO2 in that, while hypoxic, no subject showed isocapnic hyperpnea in response to 1% CO2. The isocapnic hyperpnea we observed was chiefly due to increased tidal volume, and was therefore not analogous to the isocapnic hyperpnea observed by others in dogs in response to increases of CO2 in lung gas. When low levels of CO2 produced an increase in PA(CO2) the associated change in ventilation (delta Ve/delta PA(CO2)was much less than that observed while rebreathing 7% CO2. Isocapnic hyperpnea in response to low levels of CO2 is common among normal individuals, and is depressed by hypoxia; the stimulus responsible for this response is unknown.

Differential response to chick skeletal muscle to denervation. A histopathological study with reference to lipid and lipase distribution

The effects of denervation on the three gastrocnemii muscle of chick have been studied with regard to the lipid and lipase distribution on the different fibre types, for a maximum period of 8 weeks after unilateral sciatectomy. The observations exhibit a loss of intrafibrillar lipids which is not on account of enhanced lipolytic activity within the muscle fibres. The lipases also exhibit lowered intrafibrillar activity during the corresponding period and may be one of the several lytic enzymes responsible for the degenerative changes in the muscle cells. The differential response of the three muscles, the muscle bundles in each of them and the different fibre types, to denervation, has been explained on the basis of the balance maintained between the trophic and the intrinsic regulatory mechanisms.

Acid phosphatase activity in normal and denervated chick skeletal muscle

Histochemical and biochemical changes in acid phosphatase activity were studied in the normal and denervated gastrocnemii of chick for a maximum period of 8 weeks. In the normal muscle, fibre heterogeneity with respect muscles exhibit greater susceptibility to degenerative changes on account of denervation. Quantitatively higher enzyme levels in the denervated muscles confirm the lytic role of acid phosphatase.