Training-induced bradycardia and intrinsic heart rate in rats

After 10 weeks of treadmill training, female Sprague-Dawley rats had developed a bradycardia at exercise on submaximal work loads. This bradycardia was also present after autonomic denervation and in isolated perfused heart preparations. The heart weight/body weight ratio was increased in these trained animals compared to untrained littermates. Sympathectomized, trained rats developed the same degree of cardiac hypertrophy, but their heart rate after denervation and in the isolated heart was the same as in sympathectomized, untrained rats. It is concluded that the bradycardia of trained and thereafter denervated animals seen in this and a previous investigation represents an adaptation within the heart itself, since it was present in the isolated heart. These results thus provide further evidence for a non-neural component in training-induced bradycardia. Since the trained sympathectomized rats had a cardiac hypertrophy but no reduction of intrinsic heart rate, it seems likely that the myocardial mass is of minor importance for the level of intrinsic heart rate.     

Comparative study of the effect of L-lysine-L-oxidase from Trichoderma harzianum Rifai and Trichoderma viride on nucleic acid synthesis in human tumor cells in vitro

L-lysine-alpha-oxidase, a new fungal enzyme catalyzing oxidative deamination of L-lysine, exerts an inhibitory effect on DNA, RNA and protein synthesis in human cells of carcinoma ovarius (CaOv) in vitro.     

Modification of testicular and thyroid function by chronic exposure to short photoperiod: a comparison in four rodent species

Exposure of male Syrian hamsters (Mesocricetus auratus) for 10 weeks to short photoperiod (SP) providing 10 hr light: 14 hr darkness (10:14 LD) produced a significant reduction in the weights of the reproductive organs, plasma thyroxine (T4) levels and free T4 index (FT4I) compared to the values of animals exposed to long photoperiod (LP, 14:10 LD). C57bl male house mice (Mus musculus) kept in SP (10:14 LD) had reproductive organ weights equivalent to those of mice kept in long days (14:10 LD) and lower T3 uptake (T3U) values. Male gerbils (Meriones unguiculatus) exposed to 13 weeks of SP (10:14 LD) had lower body weights, testes and seminal vesicle weights and higher T3U values compared to LP (14:10 LD) controls. However, no effect was seen on plasma T4 and triiodothyronine (T3) values nor the FT4I and free T3 index (FT3I). White-footed male mice (Peromyscus leucopus) exposed to SP (8:16 LD) had significantly lower testes and seminal vesicle weights while plasma T4 and T3 levels were unaffected. Snell strain house mice (Mus musculus) exposed to SP (8:16 LD) had normal reproductive organ weights compared to the values of LP-exposed (16:8 LD) control animals. However, there was a significant depression in T3 and in the FT3I in the SP animals.     

Localization of cathepsin D in rat liver. Immunocytochemical study using post-embedding immunoenzyme and protein A-gold techniques

Light and electron microscopic localization of cathepsin D in rat liver was investigated by post-embedding immunoenzyme and protein A-gold techniques. By light microscopy, cytoplasmic granules of parenchymal cells and Kupffer cells were stained for cathepsin D. Weak staining was also noted in sinusoidal endothelial cells. In the parenchymal cells many of positive granules located around bile canaliculi. In the Kupffer cells and the endothelial cells, diffuse staining was noted in the cytoplasm in addition to granular staining. By electron microscopy, gold particles representing the antigenic sites for cathepsin D were seen in typical secondary lysosomes and some multivesicular bodies of the parenchymal cells and Kupffer cells. The lysosomes of the endothelial cells and fat-storing cells were weakly labeled. Quantitative analysis of the labeling density in the lysosomes of these three types of cells demonstrated that the lysosomes of parenchymal cells and Kupffer cells are main containers of cathepsin D in rat liver. The results suggest that cathepsin D functions in the intracellular digestive system of parenchymal cells and Kupffer cells but not so much in that of the endothelial cells.     

Alterations in cerebrospinal fluid uridine,hypoxanthine, and xanthine in head-injured patients

1. Examination of the cerebrospinal fluid (CSF) of head-injured patients reveals that the concentration of intraventricular xanthine is elevated and that of uridine is decreased relative to those of adult lumbar CSF. 2. No correlations were observed between CSF lactate and CSF hypoxanthine, xanthine, or uridine, suggesting that changes in purine metabolites and the pyrimidine nucleoside do not index similar cellular events as does lactic acid production. 3. Ventricular CSF from hydrocephalic infants had uridine and hypoxanthine concentrations not significantly different from those of normal adult lumbar CSF, but xanthine was significantly elevated. 4. Since uridine has anticonvulsant properties and is a crucial substrate for cerebral metabolism, it may be useful to evaluate this pyrimidine for use in the management of patients with head injury.     

Microflora of the upper respiratory tract in young children under normal conditions and in respiratory tract diseases. Microbial count of the upper respiratory tract in healthy children and in children with pneumonia

The results of the inoculation of material taken from the anterior section of the nasal cavity and from the pharyngeal mucosa of 50 healthy young children and 298 acute pneumonia patients were analyzed. 23 microbial species were isolated. In the samples taken from the anterior section of the nasal cavity, monocultures were detected in 86 samples and 54 variants of associations including 2-4 species, in 139 samples. In the samples taken from the pharynx, monocultures were detected in 59 samples and 180 variants of associations including 2-6 species, in 282 samples. Differences in the contamination of the nasal cavity and the pharynx in healthy children and in pneumonia patients were revealed. These differences were manifested in the structure of the microflora (monocultures, associations, their composition), the assortment of microbial species and their concentration. In young children with pneumonia the microflora of the upper respiratory tract was found to reflect the severity of acute pneumonia and the intensity of the pathological process in the lungs (uncomplicated, pyodestructive pneumonia, pyodestructive pneumonia with fatal termination, acute purulent pleurisy).     

Purification of smooth-muscle myosin free of calmodulin and myosin light-chain kinase. Susceptibility to oxidation.

Smooth-muscle myosin purified as described by Persechini & Hartshorne [(1983) Biochemistry 22, 470-476] contains trace amounts of calmodulin and myosin light-chain kinase, which can be removed by Ca2+-dependent hydrophobic-interaction chromatography followed by calmodulin-Sepharose affinity chromatography. The resultant column-purified myosin exhibits properties similar to those of the non-purified myosin, e.g. actin activation of the Mg2+-ATPase requires Ca2+/calmodulin-dependent phosphorylation of the two 20 kDa light chains. However, unlike the non-purified myosin, the column-purified myosin undergoes a time-dependent transition to a form which no longer requires phosphorylation for actin activation of the myosin Mg2+-ATPase. This transition is identified as a time-dependent change in conformation of the column-purified myosin from a 10 S to 6 S form and is caused by slow oxidation of the column-purified myosin, since it could be prevented by storage under N2 and reversed by 5 mM-dithiothreitol.     

Capillary growth and diffusion distances in muscle

1. Tissue capillarity in muscle was modelled as square-ordered arrays with capillary-to-fiber ratios (C/F) from 0.5 to 'infinity'. 2. C/F up to two had marked effects on diffusion distances, but C/F above had only slight effects on average distances and almost no effect on maximal distances. 3. Capillary growth during normal maturation results in C/F around two. Thus, capillary growth in adult muscle may not be an adaptive mechanism for reducing diffusion distances.