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Biomedical subjects

J Kucera

Publications and source records attributed to J Kucera.

At least 109 records · Page 6Linked to original sources
PubMed1991

Differentiation of species of Eimeria from the fowl using a computerized image-analysis system.

Oocysts of Eimeria species from the fowl have been identified using a computerized image-analysis system (Leitz T.A.S. Plus Image-Analyser). The system enabled semiautomatic measurement of oocyst dimensions with subsequent species of diagnosis based on graphic statistical evaluation of size and shape of measured parasites. E. mitis, E. acervulina, E. brunetti, E. maxima, E. tenella and complex of E. necatrix and E. praecox were distinguishable both in pure cultures and in mixtures. It was not possible to distinguish E. praecox from E. necatrix using this system.

Animals↗
PubMed1990

Muscle spindles form in paralyzed but not in aneural hindlimbs of fetal rats.

The necessity of innervation and/or neural activity for the formation of muscle spindles was investigated by treating fetal rats with neurotoxins on embryonic day 16 or 17 (E16-17), one or two days prior to the onset of spindle assembly. The neurotoxin-treated soleus muscles were examined on E21 for the presence of spindles and immunocytochemical expression of the slow-tonic myosin heavy-chain (MHC) isoform, which is characteristic of intrafusal fibers. Irreversible destruction of sensory and motor nerves by beta-bungarotoxin prevented the formation of spindles and expression of the slow-tonic MHC. Abolishment of nerve and muscle activity by tetrodotoxin did not block the spindle assembly or expression of the slow-tonic MHC. Thus, the formation and differentiation of spindles is dependent on innervation, but is independent of activity in nerve fibers or muscle cells.

Animals↗
PubMed1990

Myosin heavy chain expression in developing rat intrafusal muscle fibers.

The immunocytochemical expression of several isoforms of myosin heavy chains (MHC) was determined in developing intrafusal and extrafusal fibers of the soleus muscle of prenatal and postnatal rats. At the onset of spindle assembly, both bag2 intrafusal myotubes and primary extrafusal myotubes bound a slow-twitch MHC antibody, whereas the bag1 and chain myotubes expressed a fast-twitch MHC isoform identical to that expressed by secondary extrafusal myotubes. Subsequently, developing intrafusal fibers began to express unique myosin isoforms, and ceased to express some of the myosin isoforms present initially. The initial similarity in MHC composition of intrafusal and extrafusal fibers suggests that these two kinds of mammalian muscle cell originate from a common pool of bipotential myotubes. Differences in MHC expression by intrafusal and extrafusal fibers in adult muscles might result from the effect of sensory neurons on the developing intrafusal myotubes.

Aging↗
PubMed1990

Relation of distribution of conduction velocities to nerve biopsy findings in n-hexane poisoning.

Distribution of conduction velocities (DCV) of sensory fibers in sural nerve was investigated in three patients with n-hexane poisoning. Measurements were made at 1-2 months, 4-9 months, and at 11, 23, and 36 months after ending exposure. A sural nerve biopsy was obtained from one of the patients. The results indicated the characteristic changes of n-hexane toxicity: myelinated nerve fiber degeneration and paranodal swelling, resulting in changes in the fiber diameter distribution. The DCV documented these changes. After removal from toxic exposure, varying degrees of recovery were studied clinically and evaluated with nerve conduction parameters. The DCV reflects the pathological changes in nerve in toxic neuropathy due to n-hexane.

Adult↗
PubMed1990

Origin of intrafusal muscle fibers in the rat.

The expression of several isoforms of myosin heavy chain (MHC) by intrafusal and extrafusal fibers of the rat soleus muscle at different stages of development was compared by immunocytochemistry. The first intrafusal myotube to form, the bag2 fiber, expressed a slow-twitch MHC isoform identical to that expressed by the primary extrafusal myotubes. The second intrafusal myotube to form, the bag1 fiber, expressed a fast-twitch MHC similar to that initially expressed by the secondary extrafusal myotubes. At subsequent stages of development, the equatorial and juxtaequatorial regions of bag2 and bag1 intrafusal myofibers began to express a slow-tonic myosin isoform not expressed by extrafusal fibers, and ceased to express some of the MHC isoforms present initially. Myotubes which eventually matured into chain fibers expressed initially both the slow-twitch and fast-twitch MHC isoforms similar to some secondary extrafusal myotubes. In contrast, adult chain fibers expressed the fast-twitch MHC isoform only. Hence intrafusal myotubes initially expressed no unique MHCs, but rather expressed MHCs similar to those expressed by extrafusal myotubes at the same chronological stage of muscle development. These observations suggest that both intrafusal and extrafusal fibers develop from common pools of bipotential myotubes. Differences in MHC expression observed between intrafusal and extrafusal fibers of rat muscle might then result from a morphogenetic effect of afferent innervation on intrafusal myotubes.

Animals↗
PubMed1990

Treatment with beta bungarotoxin blocks muscle spindle formation in fetal rats.

Sensory and motor fibers of peripheral nerves were irreversibly destroyed in fetal rats by administering beta bungarotoxin (BTX) on embryonic day 16 or 17, after assembly of primary myotubes, but before the formation of muscle spindles. Soleus muscles of toxin-treated fetuses and their untreated littermates were removed just prior to birth and were examined by light microscopy of serial transverse sections for the presence of spindles and immunocytochemical expression of several isoforms of myosin heavy chains (MHC). Untreated muscles exhibited numerous spindles that were innervated by branches of intramuscular nerves and contained muscle fibers expressing a slow-tonic MHC isoform characteristic of the intrafusal but not extrafusal fibers. Toxin-treated muscles were devoid of intramuscular nerve bundles and perineurial structures. Encapsulations of muscle fibers resembling spindles were absent and no myotubes expressed the slow-tonic MHC isoform associated with intrafusal fibers in beta BTX-treated muscles. Thus, the assembly of muscle spindles, formation of the spindle capsule, and transformation of undifferentiated myotubes into the intrafusal fibers that contain spindle-specific myosin isoforms all depend on the presence of innervation in prenatal rat muscles.

Animals↗
PubMed1990

[A new topical preparation for the treatment of burns. I. Technical aspects of preparation].

In the present paper some problems connected with the formulation of a topical preparation of the hydro-ointment type intended for the treatment of deep dermal burns were examined. Sixteen ointment bases containing hydroxypropyl-methylcellulose, hydroxyethylcellulose, Carbopol 934 and Pluronic F-127 as gel-forming substances were evaluated. The local anaesthetic agents carbizocaine and lidocaine served as active ingredients. Suitability of ointment bases was evaluated on the basis of their liberating capability for drugs, rheological properties and washability. The results show that an increase in the concentration of the gel-forming substance in the ointment resulted in a decrease in carbizocaine liberation. A decrease in the released amount of drugs occurred also after an addition of a humectant additive to the ointment base. The local anaesthetic agents under study decreased the viscosity of ointment bases. The highest coefficient of washability was found in the Carbopol ointment base. From the viewpoint of administration, the base with 1% Carbopol, or a combined base with 2% Methocel and 0.5% Carbopol proved to be most suitable.

Anesthetics, Local↗
PubMed1990

[Evaluation of the effect of cadmium exposure in a worker in Ni-Cd storage battery production by biological tests in vivo and the cadmium content of tissues postmortem].

The paper deals with the case of a 49 years old man having been exposed to cadmium in the production of alkaline Ni-Cd accumulators for a long period. It presents and compares the results of some years lasting biological monitoring of the exposition in vivo (beta 2 microglobulin in urine and serum, Cd in urine, blood, serum and hair, Zn in urine, serum and hair, Ni in urine and hair, alpha 1 antitrypsin in serum, dehydratase activity of delta-aminolevulinic acid in blood, cholinesterase activity in blood, etc., with the Cd concentrations found out in the tissues post mortem (nail 12 micrograms/g, cerebrum 0.4 microgram/g, lungs 19 micrograms/g, liver 165 micrograms/g, kidneys 245 micrograms/g). The Cd contents in the tissue were significantly increased compared with the non-exposed population and in fact, they confirmed the data and conclusions from the biological monitoring in vivo signalling the light tubular renal impairment as the most significant symptom of the exposition.

Cadmium↗
PubMed1989

Alteration of intrafusal bundle composition by nerve crush in neonatal rats.

We examined the expression of myosin heavy-chain isoforms in intrafusal muscle fibers of spindles formed in gastrocnemius muscles reinnervated in the presence of exogenous nerve growth factor after nerve crush in neonatal rats. Only 50% of the experimental spindles contained intrafusal fibers that expressed a slow-tonic myosin normally expressed by at least one fiber in every rat spindle. In addition, spindles containing only bag1 and/or chain fibers, but no bag2 fibers, were observed in reinnervated muscles whereas all normal spindles contain a bag2 fiber. These data suggest that afferents retain the capacity to induce the expression of a spindle-specific myosin in a period other than during normal development of intrafusal fibers. However, a scarcity of precursor cells available to become intrafusal fibers when contacted by afferents might have resulted in the alteration of intrafusal bundle composition in some spindles of reinnervated muscles.

Adenosine Triphosphatases↗
PubMed1989

Role of nerve and muscle factors in the development of rat muscle spindles.

The soleus muscles of fetal rats were examined by electron microscopy to determine whether the early differentiation of muscle spindles is dependent upon sensory innervation, motor innervation, or both. Simple unencapsulated afferent-muscle contacts were observed on the primary myotubes at 17 and 18 days of gestation. Spindles, encapsulations of muscle fibers innervated by afferents, could be recognized early on day 18 of gestation. The full complement of spindles in the soleus muscle was present at day 19, in the region of the neuromuscular hilum. More afferents innervated spindles at days 18 and 19 of gestation than at subsequent developmental stages, or in adult rats; hence, competition for available myotubes may exist among afferents early in development. Some of the myotubes that gave rise to the first intrafusal (bag2) fiber had been innervated by skeletomotor (alpha) axons prior to their incorporation into spindles. However, encapsulated intrafusal fibers received no motor innervation until fusimotor (gamma) axons innervated spindles 3 days after the arrival of afferents and formation of spindles, at day 20. The second (bag1) intrafusal fiber was already formed when gamma axons arrived. Thus, the assembly of bag1 and bag2 intrafusal fibers occurs in the presence of sensory but not gamma motor innervation. However, transient innervation of future bag2 fibers by alpha axons suggests that both sensory and alpha motor neurons may influence the initial stages of bag2 fiber assembly. The confinement of nascent spindles to a localized region of the developing muscle and the limited number of spindles in developing muscles in spite of an abundance of afferents raise the possibility that afferents interact with a special population of undifferentiated myotubes to form intrafusal fibers.

Animals↗