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Biomedical subjects

J Dvorák

Publications and source records attributed to J Dvorák.

At least 19 recordsLinked to original sources
PubMed2000

Recombination of chromosomes 3A(m) and 5A(m) of Triticum monococcum with homeologous chromosomes 3A and 5A of wheat: the distribution of recombination across chromosomes.

Recombination of chromosomes 3A(m) and 5A(m) of Triticum monococcum with closely homeologous chromosomes 3A and 5A of T. aestivum was compared with recombination across corresponding homologous chromosome pairs. Differentiation between the homeologues impacted recombination in the proximal regions of the long arms the most and in the distal regions of the long arms the least. It is concluded that this variation principally reflects allocation of multiple crossovers across an arm and positive crossover interference across chromosome arms. Recombination rates between homeologous chromosomes 5A(m) and 5A differed in the opposite sexes.

Recombination, Genetic↗
PubMed1999

Trichobilharzia regenti, a pathogen of the avian and mammalian central nervous systems.

The development of nasal avian schistosomes of the genus Trichobilharzia in their final host is poorly known. Therefore, an experimental infection of ducklings (Anas platyrhynchos f. dom.) by T. regenti was performed. The infection resulted in leg paralysis and orientation/balance disorders of birds. The examination of the duck's spinal cord and brain confirmed the presence of developing parasites in pre-patent as well as patent periods. The absence of the worms in other tissues strongly supports our hypothesis that the parasite migrates through the central nervous system (CNS) to its final location in bird nasal mucosa. The injury level is probably dependent on number of parasites as well as yet unknown host factors. The affinity to the CNS seems to be high; also by exposure of experimental animals to low cercarial doses the growing worms in the CNS were found. In addition to the generally accepted view that bird schistosomes may cause cercarial dermatitis of mammals (including man), there is evidence of a partial development of T. regenti in mouse CNS; in certain cases leg paralysis was also recorded. Therefore, the pathogenesis spectrum caused by bird schistosomes in birds/mammals needs to be reconsidered.

Animals↗
PubMed1999

[Surgical treatment of benign tumors of the thyroid gland].

Based on 22-year experience with surgery of 2107 benign thyroid tumours and data in the literature the authors evaluate some controversial problems from this sphere of thyrology pertaining to the definition and classification of benign tumours, their diagnosis, treatment and subsequent follow-up. Modern diagnostic procedures indicate that the actual number of true benign tumours is smaller than reported in some statistics and the assumption of monoclonal development of tumours is one of the most fundamental characteristics. The authors consider total lobectomy as minimal surgery, in case of uncertainty as regards possible malignancy further procedures depend on final histological examination. If the final finding alters the diagnosis from an originally benign tumour to a malignant one, the authors recommend a two-stage procedure to implement total thyroidectomy. In the authors' opinion total lobectomy is sufficient also in some variants of follicular adenoma--Hürtle's adenoma or atypical adenoma. Then however subsequent dispensarization is essential. After a partial operation (lobectomy) it is important to ensure substitution with thyroid hormones to suppress the function of TSH.

Humans↗
PubMed1999

[Malignant lymphomas of the thyroid gland].

The authors evaluate their experience with malignant lymphomas of the thyroid gland, recorded in 22 patients from a total of 4501 operated on account of thyroid diseases in the course of 22 years. Although thyroid lymphomas are rare, their number is increasing. In localized findings curative procedures can be used, possibly supplemented by operations of the lymph nodes. The method of choice is still radiotherapy and surgery, in particular in lesions restricted to the thyroid gland. The role of chemotherapy is still controversial.

Adult↗
PubMed1998

Epidemiology, physical examination, and neurodiagnostics.

The overall frequency of troublesome neck pain is estimated to be approximately 34%, and it was observed that the frequency of complaints lasting 1 month or longer was higher in women than in men. The prevalence increased with age with regard to both pain duration and chronic pain. A total of approximately 14% of a randomly selected population meets the criteria for chronic neck pain, with complaints lasting for more than 6 months. It could be that the structural transformation of the intervertebral disc, the uncovertebral processes, and the zygapophyseal joints is a process accompanied by disturbed function, ultimately inducing pain. For diagnosis of radicular and myelopathic syndromes, the physical and neurologic examination is enhanced by neurophysiologic assessment. Electromyography, performed with needle electrodes, is the oldest method to diagnose nerve root compression syndromes and is claimed to have no false positive results. Electromyography for radiculopathy is justified if clinical symptoms, such as muscular weakness, don't correlate with clinical findings (diminished or absent reflex), or for documentation of muscle activity if difficult decompressive surgery is expected. For diagnosis of cervical myelopathy by routine examination, the sensory evoked potentials by stimulation of tibial nerve as well as motor evoked potentials from upper and lower extremities are recommended because clinically "silent" myelopathy can be verified by abnormalities in evoked potentials. During history taking, the symptoms possibly attributed to radiculopathy or myelopathy should be differentiated from primary systemic neurologic disorders such as shoulder angiotrophy ("plexus neuritis"), multiple sclerosis, amyotrophic laterals sclerosis, and peripheral neuropathy. The assessment of range of motion, the functional status of shoulder and neck muscles, and palpatory examination of soft tissue is widely used to determine non-operative therapeutic procedures. However, scientifically, the validity of the different testing procedures has not been evaluated satisfactorily.

Cervical Vertebrae↗
PubMed1998

[Bleeding gastroduodenal ulcers from the viewpoint of the surgeon].

The article has discoursed of a diagnosis and a therapy of bleeding peptic ulcer. There has been used the group of the patients admitted at The Surgical Unit of The Faculty Hospital Motol in Prague during two and half years. Urgent endoscopy and endoscopic treatment of indicated findings have been performed as a common procedures. The surgical therapy has been necessary for the part of this patients. Operation's indications, types of the operations and their timing have been discussed.

Humans↗
PubMed1998

Trichobilharzia regenti n. sp. (Schistosomatidae, Bilharziellinae), a new nasal schistosome from Europe.

Members of the genus Trichobilharzia are parasitic in visceral or nasal body parts of their avian hosts. The examination of water snails in South Bohemia revealed a schistosome infection in Radix peregra snails. The experimental infection of ducklings (Anas platyrhynchos, Cairina moschata) confirmed that a new Trichobilharzia species--T. regenti n. sp.--was found. The adults, eggs and larvae (miracidia and cercariae) of the species were morphologically characterized. The adult occupy the nasal blood vessels where they lay the eggs; the miracidia hatch from the eggs directly in the tissue and leave the host during drinking/feeding of the infected birds.

Animals↗
PubMed1998

Restriction fragment length polymorphism and divergence in the genomic regions of high and low recombination in self-fertilizing and cross-fertilizing aegilops species.

RFLP was investigated at 52 single-copy gene loci among six species of Aegilops, including both cross-fertilizing and self-fertilizing species. Average gene diversity (H) was found to correlate with the level of outcrossing. No relationship was found between H and the phylogenetic status of a species. In all six species, the level of RFLP at a locus was a function of the position of the locus on the chromosome and the recombination rate in the neighborhood of the locus. Loci in the proximal chromosome regions, which show greatly reduced recombination rates relative to the distal regions, were significantly less variable than loci in the distal chromosome regions in all six species. Variation in recombination rates was also reflected in the haplotype divergence between closely related species; loci in the chromosome regions with low recombination rates were found to be diverged less than those in the chromosome regions with high recombination rates. This relationship was not found among the more distantly related species.

DNA, Plant↗
PubMed1998

Position effects of ribosomal RNA multigene loci on meiotic recombination in wheat.

Homeologous wheat chromosome arms that differ by the presence or absence of a Nor locus or greatly differ in the numbers of copies of rRNA genes per Nor locus show conspicuous differences in the distribution of recombination. To assess directly the position effects of Nor loci on recombination across chromosome arms, a Triticum monococcum Nor9 haplotype was substituted for Triticum aestivum Nor9 haplotypes on two T. aestivum 1A chromosomes in the isogenic background of cv Chinese Spring. The numbers of rRNA genes in the 1A Nor9 haplotypes are greatly reduced relative to the T. monococcum haplotype. The substitution resulted in reduced recombination rate in the vicinity of the Nor9 locus. An intra-arm compensatory increase was observed in the proximal region of the arm so that the genetic length of the chromosome arm was unchanged. These findings suggest that Nor loci suppress recombination in their vicinity and change recombination patterns in Nor-bearing chromosome arms.

Chromosomes↗
PubMed1998

[The effect of the primary operation on reoperations on the thyroid gland].

The authors analyze the possibility to reduce the number of reoperations of the thyroid gland, based on a group of thyroid operations performed at the Surgical Clinic of the Second Medical Faculty Charles University and Faculty Hospital Motol during the 22-year period from 1975-1997. 507 reoperations from a total number of 4501 thyroid operations amount to 11.3%. In the authors opinion correct indication of the operation is most important as well as the correct extent and technique of the primary operation. The achieved results are except for unilateral temporary lesions of the NLR comparable with primary operations.

Adolescent↗
PubMed1998

[Pancreatic tumors--pessimism, optimism or realism?].

Among 35 patients with the preoperative diagnosis of a tumour of the head of the pancreas who had a radical operation at the Surgical Clinic of the Second Medical Faculty Charles University in Prague-Motol between January 1995 and March 1998 a malignant tumour was confirmed in 24 instances. Another nine patients had a histological finding of chronic pancreatitis and the remaining two patients a benign cystadenoma of the pancreas. The 30-day mortality in the whole group is 5.7% (2/35). Both deaths within 30 days after surgery were due to massive haemorrhage into the upper GIT in patients with pancreatic cancer. The haemorrhage developed within 21 and 30 days after surgery. The source of haemorrhage was not proved unequivocally, neither clinically nor post mortem. Obviously late haemorrhage from some gastrointestinal anastomosis was involved. From a total of 24 patients after Whipple's operation on account of a malignant tumour of the head of the pancreas nine died. The mean survival period was seven months after surgery. Fifteen patients survive and after a mean follow-up period of 14 months the median of survival calculated to the date of March 31 1998 is 17 months for stage UICC I and five months for stage UICC III. Because of the short follow-up period the results cannot be compared properly with data in the contemporary literature but they are promising for further work in this sphere of surgery and evidence that it is correct to refute the nihilist view held in the past. Hitherto achieved therapeutic results in this country and abroad certainly do not justify yet an optimistic view as regards the perspective of patients with carcinoma of the pancreas.

Female↗
PubMed1997

Posterior surgical approach to the lumbar spine and its effect on the multifidus muscle.

STUDY DESIGN: This study investigated the changes in the lumbar muscles after posterior fusion of the lumbar spine and the potential correlation between muscular changes and the persistence of low back pain. OBJECTIVES: To evaluate prospectively the effect of the posterior approach to the spine on the lumbar erector spinae. SUMMARY OF BACKGROUND DATA: The posterior approach to the spine leads to considerable alteration of the erector spinae muscles. An eventual correlation between these changes and persisting pain or other clinical symptoms has not been investigated previously. METHODS: Seventy-five patients undergoing spondylosyndesis for different indications (43 patients) or a second operation for the removal of internal fixation (32 patients) were allotted to the study. In each patient, four biopsy specimens from the lumbar multifidus muscle were harvested; in 14 patients, biopsies were taken at both operations. Size and distribution of the fiber types (I, IIA, IIB, IIC) were determined, and pain scoring (visual analogue scale) and the presence of neurologic deficits were recorded. RESULTS: At the time of the first operation, 88% of the patients showed pathologic changes (altered internal structure, atrophy, type grouping) in one or more biopsies. Statistical analysis showed a correlation between both age and pain and type II (A + B) atrophy. After surgery, the patients showed significantly more biopsies with denervation signs than before surgery. No correlation could be made, however, between the intensity of pain before or after surgery and the relative number of biopsies with signs of denervation. CONCLUSIONS: Posterior surgery causes muscular alterations; however, no correlation with pain or other clinical symptoms could be established. Therefore, in the case of unsatisfactory results after surgery of the lumbar spine, reasons other than muscle damage caused by use of the posterior approach must be considered.

Adolescent↗
PubMed1997

[Contemporary views on thyroid gland surgery].

The authors reflect on changes in the approach of surgeons to patients and operations of the thyroid gland in recent years and emphasize those elements which they had favourable experience in recent years.

Humans↗