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Biomedical subjects

J Valenta

Publications and source records attributed to J Valenta.

At least 19 recordsLinked to original sources
PubMed2006

Identification of Photosystem I and Photosystem II enriched regions of thylakoid membrane by optical microimaging of cryo-fluorescence emission spectra and of variable fluorescence.

Oxygenic photosynthesis of higher plants requires linear electron transport that is driven by serially operating Photosystem II and Photosystem I reaction centers. It is widely accepted that distribution of these two types of reaction centers in the thylakoid membrane is heterogeneous. Here, we describe two optical microscopic techniques that can be combined to reveal the heterogeneity. By imaging micro-spectroscopy at liquid nitrogen temperature, we resolved the heterogeneity of the chloroplast thylakoid membrane by distinct spectral signatures of fluorescence emitted by the two photosystems. With another microscope, we measured changes in the fluorescence emission yield that are induced by actinic light at room temperature. Fluorescence yield of Photosystem II reaction centers varies strongly with light-induced changes of its photochemical yield. Consequently, application of moderate background irradiance induces changes in the Photosystem II fluorescence yield whereas no such modulation occurs in Photosystem I. This contrasting feature was used to identify regions in thylakoid membranes that are enriched in active Photosystem II.

Image Processing, Computer-Assisted↗
PubMed2003

[Role of morphology in medical education, clinical practice and research].

Rapid development of molecular biology, biochemistry, physiology and other sciences has diminished the previously dominant role of morphology in the theoretical part of medical studies. Morphology, closely related to various disciplines, should, however, be included in clinical lectures. Changes in the curricula would require concise and well-structured textbooks, based on recent clinico-morphological studies, for the theoretical parts of both medical and allied health care study programmes. Comprehensive textbooks are still necessary for the specific needs of clinicians and researches.

Anatomy↗
PubMed2002

[Present possibilities in vascular surgery].

Contemporary vascular surgery relies on the progress in imaging techniques and on modern materials for vascular substitutes. The collaboration with radiodiagnosticians enabled the treatment of arterial thromboses by means of fibrinolysis. Radiodiagnostics plays an important role also in the field of endovascular operations, namely percutanous transluminal angioplasty, insertion of stents, and recently in the abdominal aorta aneurysms treatment by means of stents. Long-lasting effects of such operations, namely those in the aorta, have not been fully established and the classical reconstructive surgery has not lost its importance.

Angioplasty, Balloon↗
PubMed2001

Aleukemic granulocytic sarcoma with AML1/ETO fusion gene expression and clonal T cell populations.

We report a unique case of aleukemic granulocytic sarcoma of the neck, originally misdiagnosed as non-Hodgkin's lymphoma (NHL), though chloroma was also suspected due to a greenish macroscopic appearance and the presence of myeloid chloroacetate esterase (CAE)+ cells. The proof of clonal T cell receptor gamma chain (TcRgamma) gene rearrangements in the recurring tumor was deemed to confirm the initial diagnosis of T cell NHL. Altogether five distinct types of clonal TcRgamma gene rearrangements were found in the tumor, bone marrow and peripheral blood. Only retrospectively, using RT-PCR, did we detect the acute myeloid leukemia subset-specific fusion gene AML1/ETO in the frozen samples of the relapsed tumor, as well as in the otherwise unaffected bone marrow and peripheral blood (representing 'minimal initial disease' in the latter two samples). Simultaneous staining verified that the neoplastic CAE+ cells and CD45RO+ T cells were different populations.

Adult↗
PubMed2001

[Surgical treatment of thyroid diseases at the Surgical Clinic of the University Hospital of Plzen 1994-2000].

The authors operated in 1994-2000 at the Surgical Clinic, Faculty Hospital Plzen a total of 793 patients on account of thyroid disease. This group comprised 57 patients with malignant thyroid disease. The mean age of the operated patients was 48.8 years (range 12-89 years). Three patients (0.38%) died within 30 days after operation. The postoperative morbidity was 6.1%. A lesion of the recurrent nerve was recorded during the postoperative period in 24 patients (3.03%) and had a declining trend. Postoperative hypoparathyroidism was recorded in 5.8% (n = 46) injuries of the neighbouring organs in 1.02% (n = 8), oedema of the larynx in 18 patients, i.e. 2.3%. On the whole the authors observed a decline of postoperative complications during the investigation period, the number being lowest in 2000 associated with the number of performed thyroid operations and a change of the surgical strategy.

Adolescent↗
PubMed2000

[Viper (Vipera berus) snake bites].

Cases of snake bites (Vipera berus) have as compared with past years a rising trend in the Czech Republic. This ensues among other factors from a higher prevalence of snakes due to the improving ecological situation. The morbidity of snake bites is of no epidemiological importance, the frequency of snake bites amounts to several tens per year and in some clinically manifest intoxication does not develop. Nevertheless in individual cases, in children weakened subjects, a viper bite may be manifested by a serious and in exceptional instances fatal affection. Within the framework of first aid the authors do not recommend application of a tourniquet or dissecting of the wound because of undesirable potentiation of tissue traumatization. Non-specific treatment involves the administration of corticoids and antihistaminics. Specific immunotherapy, administration of horse antiserum (Ipser Europe, Pasteur Mérieux, France) is indicated only in case of systemic or very severe local symptoms and is associated with the risk of a severe allergic reaction. In case of severe systemic symptoms, symptomatic treatment in a health institution of the appropriate type is of fundamental importance. In all cases observation of the affected subject is recommended to rule out intoxication or the development of possible complications.

Adult↗
PubMed2000

Endogenous fibrinolysis in patients with lower extremity ischemia.

To explore the relationship between disorders of endogenous fibrinolysis and thrombosis in patients with lower extremity ischemia, we measured the activity of tissue plasminogen activator (tPAac) and plasminogen activator inhibitor (PAlac) and the antigens of tissue plasminogen activator (tPAa) and inhibitor (PAla) in plasma from 420 patients treated for lower extremity ischemia. Values and ratios observed were compared with those in healthy volunteers. Additionally, values and ratios in the patients were examined with respect to the severity of ischemia and site of atherosclerotic occlusion or stenosis (pelvic compared with femoropopliteal or crural). Patients with lower extremity ischemia had higher plasma concentrations of PAla (p<0.01) and PAlac (p<0.0001) than healthy volunteers. In patients with rest pain or gangrene, the ratio of tPAac to PAlac was higher than in patients with claudication (p<0.05). The elevation of tPAac in patients with the more severe form of lower extremity ischemia is probably the feedback protective reaction on prothrombotic mechanisms of the organism suffered from severe atherosclerosis. Results did not vary according to the site of occlusion or stenosis. Our study found defects in endogenous fibrinolysis in patients with lower extremity ischemia. A defect in fibrinolysis may contribute to the development of thrombosis in native arteries and bypasses.

Adult↗
PubMed2000

[Prevention of venous thromboembolism].

Deep venous thrombosis and pulmonary embolism, the epidemiologically most important forms of thromboembolic disease still remain one of the most serious problems in medicine. The authors summarize some epidemiological data, the incidence and risk of the disease with regard to the patients condition and the type of insult. The authors mention possible methods of non-specific prevention, types and effectiveness of specific primary and secondary pharmacoprophylaxis and describe physical prophylactic methods. The review offers recommendations for prevention with regard to the assessed risk of the patient and type of insult with special attention to the use of nadroparine.

Anticoagulants↗
PubMed1999

Plasma endothelin levels in patients with abdominal aortic aneurysms.

OBJECTIVES: endothelin 1,2 plays a significant role in the process of atherogenesis and vascular wall injury. The aim of this study was to assess whether plasma endothelin 1,2 levels were elevated in patients with large or symptomatic abdominal aortic aneurysms (AAAs). DESIGN: a prospective open study. MATERIALS AND METHODS: plasma endothelin 1,2 levels were measured in 65 consecutive patients with infrarenal aortic aneurysms and compared with the levels in 44 healthy volunteer controls. The data for abdominal aneurysm patients was analysed in four subgroups: (i) small aneurysms (<5 cm), (ii) large aneurysms (>/=5 cm), (iii) asymptomatic aneurysms and (iv) symptomatic aneurysms. Comparisons were made between endothelin 1,2 levels in aneurysm patients and controls and between the different aneurysm subgroups. RESULTS: a highly significant difference (p<0.0001) was found between aneurysm patients and controls. Patients with large aneurysms had significantly higher levels than patients with small aneurysms (p<0.01). There was no statistical difference in endothelin 1,2 levels between symptomatic and asymptomatic patients; however, the highest levels were found in large, symptomatic aneurysms and the lowest in small, asymptomatic aneurysms. CONCLUSIONS: plasma endothelin 1,2 is an endogenous marker of aneurysm diameter. Further studies are required to determine whether it relates to the rate of growth of aneurysms.

Aged↗
PubMed1999

[Ethical problems in organ transplantation].

Organ transplantation is an accepted therapeutic method with good results, but it is connected with many not only medical but also ethical problems. One of the most important problems is the donor programme. In cadaverous donors the main ethical and legal question is the decision who can issue the consent with organ retrieval; in living donors it is the problem of motivation and financial compensation. Allocation of organs with low compatibility or from non-ideal donors, and the recipient's consent in these cases may involve difficult decisions.

Ethics, Medical↗
PubMed1999

Residual strain in human atherosclerotic coronary arteries and age related geometrical changes.

The opening angles of 16 rings excised from human coronary arteries with different degrees of atherosclerosis were determined 10 hours after death. Atherosclerosis, as a chronic inflammatory response of arterial endothelium and intima, is defined by three degrees of its development. The opening angle decreases more or less linearly with the distance from the right coronary artery orifice. This is in accordance with the functional requirements posed on blood transport into the coronary arteries. A decrease of the opening angle with age is affected by hardening of the arterial wall, among other factors. This is in accordance with a stochastic model of age related changes in the initial modulus of elasticity of the coronary artery. A part of the free energy of smooth muscle cells, fibroblasts, collagen and elastic fibres is used not for creating residual strain but for remodeling the arterial wall structure. The opening angle is also considerably affected by the degree of atheroclerosis. The dependence on age of the external diameter and the thickness of the intact left and right coronary arteries in the vicinity of the aortic sinus was also analyzed in two female and two male subjects. To ensure the objectivity of the results it is necessary to carry out additional experiments and studies in vivo.

Adolescent↗
PubMed1998

Role of crossover bypasses in the treatment of ischemia of the lower extremity.

AIM: To evaluate the role of crossover bypasses in the treatment of the lower extremity ischemia. METHODS: A retrospective study (1978-1997) included 51 patients with 52 femoro- or iliofemoral crossover bypasses. The most frequent indication for crossover bypass was unilateral thrombotic occlusion of the bifurcated graft or unilateral pelvic occlusion (49.0%) and the rest pain (40.4%). The main type of crossover reconstruction was "U" shaped, subcutaneous femorofemoral bypass. The first, third, and fifth year primary patency rates were evaluated using the life table analysis method. RESULTS: The cumulative patency rates were 91.3%, 73.9%, and 54.5% at 1, 3, and 5 years, respectively. Limb amputation had to be performed in five (9.6%) failed reconstructions. In four (7.7%) cases, thrombosis of reconstruction, and in one (1.9%) case, graft infection, caused the bypass occlusion. One patient (1.9%) died within 30 days after surgery from an acute myocardial attack. CONCLUSION: Crossover bypass is an attractive method because of its technical simplicity, low morbidity, and good long-term results.

Aged↗
PubMed1997

[Clinical spectrum of the antiphospholipid syndrome].

Antiphospholipid syndrome (APS) is characterized by multiple arterial and venous thromboses, repeated spontaneous abortions and thrombocytopenia, together with the presence of antiphospholipid antibodies in serum. We present three patients, two men and a woman, at the age of 43, 24 and 23 years respectively. The younger man and the woman had secondary APS and systemic lupus erythematosus, the older man had primary APS. The symptoms and course of the disease were different. The older man lives 17 years after the onset of first symptoms with multiple neurologic disorders, the younger man is symptomless. The woman died several months after the acute onset of the disease.

Adult↗
PubMed1997

[Intubation of afferent lacrimal ducts--a review of techniques].

The authors present a review of various techniques of long-term intubation of efferent lacrimal pathways by a silicone fibre. They use an original way of intubation and intubate the insertion probes of the intubation set from the lower nasal outlet by means of a titanium loop under direct optic control by means of an endoscope. The use of the endoscope makes it possible to reduce the number of complications and iatrogenic damage of the mucosa and it enhances the effectiveness of the procedure. The authors prefer the use of special intubations sets; for young children intubation sets made from soft metal are preferable. At present all their demands are met by the intubation set they developed in collaboration with the Technical University, Prague. During the period between April 1994 and August 1996 the authors used the described technique for bicanalicular intubation of the efferent lacrimal pathways in 127 children and in adult patients 6x. In 86 instances they used an intubation set of Geuder Co., 44 times their own intubation set.

Adult↗
PubMed1997

[Extensive metastases in the thoracic wall as an unusual manifestation of malignant hepatoma].

In a 53-year-old man an extensive tumour of the thoracic wall was extirpated. It was examined histologically and identified as a secondary of a malignant hepatoma. In the second stage a primary hepatic tumour was removed by extended right-sided lobectomy. The case-history provides evidence of a remote secondary of a malignant hepatoma and a successful palliative approach.

Carcinoma, Hepatocellular↗
PubMed1997

Residual stresses in the human aorta and their influences by growth and remodelling.

The aim of the present work is to demonstrate of the influence of the adventitia on distribution of residual stresses in the human aorta. The biomaterial increase in media as well as in adventitia in the course of the aorta's growth is formed by an intussusceptive mechanism of growth. In children's aortas, formative elastin lamellae are wavy with high amplitude perpendicular to the aortic surface. In adults' aortas the waves become smoother (stepwise) towards the adventitia. Also introduced is the growth function, which characterizes the biomaterial growth and the interference between the media and adventitial layers. It is possible to expect an extraordinary variability in the formation of the aortic wall tissue in the course of its growth as a result of metabolic and humoral influences and magnitude of the residual stresses in the course of growth.

Adult↗
PubMed1997

[Aneurysms of the abdominal aorta].

The authors present the experience of the Plzen department with treatment of aneurysms of the abdominal aorta (AAA) during the last five-year period (1992-1996) when they operated a total of 111 AAA in patients with an average age of 67.9 years (44-91 years). The number of symptomatic AAA was 15 (13.5%), 36 ruptures (32.4%). The most frequent risk factor was ischemic heart disease (IHD) in 74 (66.7%) and hypertension in 47 (42.3%) of the patients. Within 30 days after surgery two asymptomatic patients died (3.9%) and three (20%) with symptomatic AAA. The most frequent cause of death was acute myocardial infarction (AIM) in four (80%). Of 36 patients with rupture of AAA 17 (47.2%) died. A statistically significant factor for death of patients with rupture of the AAA was sever shock (blood pressure < 40 mm Hg) before surgery (p < 0.01), blood in the abdominal cavity (p < 0.01) and hypertension in the patient's case history (p < 0.05). Aimed screening of AAA in patients of risk groups and early elective surgery are important for reducing the incidence of ruptures of AAA. A patient with rupture of the AAA needs surgery urgently and unnecessary examination (CT, USG) frequently causes delay and reduces the patient's chance of survival.

Adult↗