Esterase activity in the guinea pig thyroid under normal and pathological conditions (vitamin A deficiency) with special regard to cyst-like structures.

By use of different activators and inhibitors, TOCP(tri-o-cresyl phosphate), PCMB (parachloromercury benzoate), NiCl2, Pb(NO3)2, HgCl2, Hg(NO3)2, eserine and sodium taurocholate, it is shown that the esterase in the cyst cells and in group I cells of the guinea pig thyroid probably are A-esterase isoenzymes. The activity in the majority of cyst cells is considerably stronger than in the other thyroid epithelial cells, and it is resistant to Hg inactivation. Neither esterase type nor intensity of the reaction product is altered in group I-II or cyst cells during vitamin A-deficiency. When a normal diet is given, the esterase in all thyroid epithelial cells is very sensitive to sodium taurocholate, while in cyst cells it is rather resistant to this inhibitor at vitamin-A-deficiency.     

Reduced survival of neonates due to vitamin A deficiency during pregnancy in the guinea pig

Neonatal vitamin A stores are limited even in well-nourished full-term infants and are yet smaller in the premature infant. The object of this experiment was to determine whether vitamin A deficiency could be induced in pregnant guinea pigs and, if so, whether it would affect vitamin A status of the neonate. Adult (600 g) guinea pigs were fed a casein-agar diet that was vitamin A deficient (AD). Controls (vitamin A adequate) were orally dosed weekly with 2 mg of retinyl palmitate. Weight gains of dams and birth weights of neonates did not differ. No external signs of deficiency were observed. Six of eight AD and seven of eight vitamin A-adequate dams carried pregnancy to term (greater than or equal to Day 64). One AD dam died during delivery. Liver retinol concentrations were below the detection limit (less than 3 micrograms/g) for all AD neonates and dams and in postpartum serum of AD dams. Of neonates born greater than or equal to Day 64, 15 of 18 AD were dead or moribund compared with 4 of 22 vitamin A adequate. The unexpectedly severe effect on the neonate indicates that the guinea pig will be a sensitive model for investigating the affect of poor maternal vitamin A status on neonatal vitamin A-dependent functions. However, a less severe maternal deprivation should be used for such studies.     

Serum content of vitamin A binding proteins (prealbumin and retinol binding proteins) in normal and pathological conditions

Blood PA and RBP content were estimated in 100 normal subjects (50 men and 50 women). Mean values of 28.2 and 3.75 mg/dl were ascertained for PA and RBP, respectively. The molar ratio RBP/PA was calculated as 0.31 +/- 0.05. Serum concentrations of PA and RBP are seen to be sex-dependent (20% higher in males). Hyperthyroid subjects exhibit a decrease in the two vitamin A-binding proteins whereas no modification could be revealed for hypothyroid states. In patients on maintenance hemodialysis mean serum PA and RBP concentrations were remarkably higher than normal, whereas liver cirrhotic subjects showed a highly significant depression of mean serum RBP and PA values.     

Effect of vitamin C deficiency on hydroxylation of trimethylaminobutyrate to carnitine in the guinea pig

The effect of ascorbate deficiency on carnitine biosynthesis was investigated in young male guinea pigs. Liver and skeletal muscle carnitine levels were reduced in scorbutic animals. Heart and kidney concentrations remained unchanged. ¹⁴C-labeled 4-N-trimethylaminobutyrate was administered to control, pair-fed and scorbutic animals and distribution of isotope in compound present in the liver after 30 min was determined. Control and pair-fed animals converted trimethylaminobutyrate to carnitine faster than scorbutic animals. Injection of ascorbate with the [¹⁴C]trimethylaminobutyrate reversed the decline in trimethylaminobutyrate hydroxylase (EC 1.14.11.1) activity in scorbutic animals.     

Cold acclimation of Ilex aquifolium under natural conditions with special regard to the photosynthetic apparatus

Frost resistance of leaves of holly ( Ilex aquifolium L.) increased from about −9°C in late summer to −24°C in mid-winter. The gradual rise in cold hardiness occurred when the minimum air temperature dropped to 0°C or below and was closely related to increase in the cellular sap concentration. Predominantly, the decrease in the osmotic potential of the cellular sap was caused by sugar accumulation, mainly of sucrose. The capacity of net photosynthesis of the leaves, as well as the total lipid and protein content and the proportion of individual lipids of the thylakoid membranes, did not significantly change during cold acclimation. The gradual shift towards desaturation in the fatty acids of the thylakoid lipids during the hardening period was neither correlated with alterations in the frost resistance nor did it affect the potential efficiency for various light-induced chloroplast membrane reactions such as linear photosynthetic electron transport, photophosphorylation and the proton gradient (ΔpH). It is suggested that in holly leaves reduction in cell volume changes during freeze-thawing and cryoprotection by sugars could play a dominant role for the increase in frost resistance. Seasonal changes in the degree of unsaturation of polar lipids of the thylakoids could contribute to maintain optimal functional efficiency of the membranes at low temperatures rather than to avoid freezing damage.     

Effect of propionate pathway metabolites on the oxidative activity of liver mitochondria under normal conditions and in vitamin B12 deficiency]

We performed a comparative investigation in vivo and in vitro of the propionate and methylmalonate effect on oxidative activity of liver mitochondria in control and vitamin B12-deficient rats and found that efficiency of the effects were less pronounced in vitamin B12-deficient rats. It is also shown that the rates of respiration and phosphorylation decreased in liver mitochondria of vitamin B12-deficient rats.     

Hemodynamics (general and cerebral) and mental activity under normal conditions

Interrelations between the mental work efficiency and changes in total and cerebral hemodynamics during mental activity are considered. Five subgroups of the efficiency are distinguished. Changes in the vegetative reactions considerably differ in the type as well. Basic four types of such reactions are distinguished with allowance for changes in the character of minute blood circulation volume and cerebral blood flow. Comparison of changes in the efficiency of the activity with vegetative changes shows that in the process of the mental activity the vegetative changes are determined by interrelation between the intensity of the mental activity and its efficiency. It was concluded that the higher the activity efficiency, the lower the mental intensity and changes in the total and cerebral hemodynamics and, vice versa.     

Expression of parathyroid hormone-related protein (PTHrP) in parathyroid tissue under normal and pathological conditions

Parathyroid hormone-related protein (PTHrP), a factor responsible for malignancy associated hypercalcemia, plays a physiological roles such as bone development and placental calcium transport. The expression of PTHrP in adult human parathyroid tissues under normal and pathological conditions was analyzed. By immunohistochemistry, PTHrP expression was detected in 86% of normal parathyroid (12/14 cases), 74% of adenomas (14/19) and 89% of hyperplasia secondary to chronic renal failure (16/18). PTHrP protein was observed mainly in the cytoplasm of oxyphil cells, consistent with the localization of its mRNA demonstrated by in situ hybridization. The rate of PTHrP-positive cells was higher in areas consisting of oxyphil cells than in those of non-oxyphil cells, regardless of whether the parathyroid was normal or pathological. In the normal parathyroid, an age-related increase in PTHrP expression was observed with a relative increase in oxyphil cells, reflecting aging and deterioration of parathyroid tissue. In adenoma, cases with a predominance of oxyphil cells expressed PTHrP, whereas clear cell adenoma did not. In secondary hyperplasia, the rate of PTHrP-expressing cells was higher than in normal parathyroid or adenoma, with varying levels of expression among nodules. We speculate that PTHrP could act through the paracrine/autocrine mechanism to regulate proliferation and differentiation of normal and neoplastic parathyroid cells.     

Papain-induced changes in the guinea pig knee joint with special reference to cartilage healing

The repair of articular cartilage following papain injection into the knee joint of the guinea pig was studied by light and electron microscopy, as well as by autoradiography using tritiated thymidine. Papain injection rapidly produced complete degradation of cartilage proteoglycan. Although a number of chondrocytes were also destroyed, the remaining chondrocytes showed mitotic cell division with resultant formation of cell clusters. Such chondrocytic regeneration, however, did not contribute significantly to the repair of cartilage tissue. On the other hand, mesenchymal cells proliferated from the transition zone and extended over the surface of the damaged cartilage. At the peripheral portion of the articular surface, they migrated and differentiated into chondrocytes with the formation of abundant intercellular matrix to produce hyaline cartilage. From these findings, it was apparent that mesenchymal cells in the transition zone were actively engaged in the repair of articular cartilage.     

A mouse model for monitoring calpain activity under physiological and pathological conditions

Calpains are Ca(2+)-dependent cysteine proteases known to be important for the regulation of cell functions and which aberrant activation causes cell death in a number of degenerative disorders. To provide a tool for monitoring the status of calpain activity in vivo under physiological and pathological conditions, we created a mouse model that expresses ubiquitously a fluorescent reporter consisting of eCFP and eYFP separated by a linker cleavable by the ubiquitous calpains. We named this mouse CAFI for calpain activity monitored by FRET imaging. Our validation studies demonstrated that the level of calpain activity correlates with a decrease in FRET (fluorescence resonance energy transfer) between the two fluorescent proteins. Using this model, we observed a small level of activity after denervation and fasting, a high level of activity during muscle regeneration and ischemia, and local activity in damaged myofibers after exercise. Finally, we crossed the CAFI mouse with the alpha-sarcoglycan-deficient model, demonstrating an increase of calpain activity at the steady state. Altogether, our results present evidence that CAFI mice could be a valuable tool in which to follow calpain activity at physiological levels and in disease states.     

A deep-etching study of the guinea pig tracheal cilium with special reference to the ciliary transitional region

The fine structure of the cilium was examined by freeze-fracture-etch studies. In the interior of the transitional region, three types of plate structures were clearly observed. While the terminal plate contained fine fibrillar linkers suspending the central core plates from its peripheral doublet microtubules, two other types of plates had no suspending linkers. At the upper level of transitional region, one of the central microtubules elongated deeper than the other in the space surrounded by ring structure. Axosome-like structure was not observed in our replicas. Central vesicle of the basal body was also suspended by fine fibrillar linkers from peripheral triplets. Though membrane particles of ciliary necklace were recognized on protoplasmic and external fracture faces, and the external surface, particle arrays were not observed on protoplasmic surface. Instead, Y-shaped, cross bridges, one end of which attached to the doublet microtubules, merged in the circular ridge structure at opposite ends. This circular ridge structure at the necklace region may play a role as an anchoring site of both membrane particles of the necklace and cross bridges from peripheral doublet microtubules.