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Biomedical subjects

Z Mariak

Publications and source records attributed to Z Mariak.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Optic nerve regeneration: contemporary views and perspectives of clinical use].

Recent extensive advances in neuroscience not only proved that optic nerve has a capacity for functional repair, but made its regeneration a reality in laboratory mammals. Today it is evident that optic nerve after axonotmesis displays signs of very active regeneration. Nevertheless, the regeneration is inhibited by a number of factors acting in the environment of normal CNS. Inhibitors secreted by oligodendrocytes and deposited in the layer of myelin attenuate migration of macrophages and process of phagocytosis, which is indispensable for axon regeneration. Astrocytes, which secrete substances supporting nerve regeneration, can not migrate to the injured axons. Glial scar formation prevent axon regrowth and revascularisation. Moreover, immediate expression of certain genes causes axotomised retinal ganglion cells to undergo process of programmed cell death--apoptosis. At present, regeneration of the optic nerve may be successfully promoted in laboratory set-up with substances which can slow down ganglion cells apoptosis and promote axon regrowth. Peripheral nerve bridges and embryonic transplants offer the regenerating axons more friendly environment than that of the normal, matured CNS. One problem, which can not yet be successfully addressed, is how to lead regrowing axons back appropriately to their original targets to reform patterned connections.

Humans↗
PubMed1999

Direct cooling of the human brain by heat loss from the upper respiratory tract.

This study is the first report on human intracranial temperature in conscious patients during and after an upper respiratory bypass. Temperatures were measured in four subjects subdurally between the frontal lobes and cribriform plate (T(cr)) and on the vault of the skull (T(sd)). Further measurements were taken in the esophagus (T(es)) and on the tympanic membrane. Reinstitution of airflow in the upper respiratory tract under conditions of mild hyperthermia gave a rapid drop in T(cr) of 0.4-0.8 degrees C. In three patients the intracranial temperature at the basal aspect of the frontal lobes fell below T(es). Thus local selective cooling of the brain surface below that of the trunk temperature was shown to occur. Intensive breathing by the patients after extubation for a 3-min period produced a cooling at the site of T(cr) measurement at a rate of up to 0.1 degrees C/min, and this response could be evoked on demand. The results support the view that cooling of the upper airway can directly influence human brain temperature.

Adult↗
PubMed1999

Transcranial color Doppler sonography of basal cerebral arteries in 182 healthy subjects: age and sex variability and normal reference values for blood flow parameters.

OBJECTIVE: Only a limited number of transcranial color-coded Doppler studies have provided ranges for the normal reference values of cerebral hemodynamic parameters. These reports are not fully convergent in relation to the range of values or to the age and sex dependence of blood flow parameters. The aim of the present study was to provide data regarding normal reference ranges. SUBJECTS AND METHODS: We examined 182 healthy volunteers (79 men and 103 women; age range, 20-86 years old) with color-coded Doppler sonography via a temporal acoustic window with a 2.5-MHz transcranial probe. The subjects were divided into three age groups: 20-40 years old (group 1), 41-60 years old (group 2), and more than 60 years old (group 3). Angle-corrected peak systolic, end-diastolic, and mean velocities as well as impedance indexes were determined in anterior, middle, and posterior cerebral arteries. RESULTS: Mean velocity values for middle, anterior, and posterior cerebral arteries in age group 1 were 81+/-20, 56+/-14, and 52+/-12 cm/sec (mean +/- SD), respectively. In group 2, the values were 73+/-19, 53+/-16, and 51+/-12 cm/sec (mean +/- SD), and in group 3, the values were 59+/-11, 44+/-11, and 40+/-9 cm/sec (mean +/- SD). Decrease in blood flow velocities and a concomitant increase in impedance indexes were found in all vessels with advancing age-findings that were most pronounced in subjects who were more than 40 years old. In the 20- to 40-year-old group, mean velocities for all vessels were higher in women than in men, whereas impedance indexes were not significantly different. CONCLUSION: Flow velocities in basal cerebral arteries range widely and are significantly age dependent. Age and sex matching of Doppler sonographic data is a prerequisite for clinically valuable conclusions.

Adult↗
PubMed1999

[Evaluation of some clinical parameters in patients with retinitis pigmentosa in relationship to the type of inheritance].

PURPOSE: Analysis of selected clinical parameters in patients with various types of retinitis pigmentosa. PATIENTS AND METHODS: We examined 51 patients aged 8-67 suffering from different genetic forms of RP identified on the ground of pedigree analysis. We analyzed onset of nyctalopia, degree of retinal degeneration, degree of visual field loss, dark adapted electroretinographic testing flicker (ERG) and presence of posterior subcapsular cataract. CONCLUSIONS: XLRP is one of the most severe RP forms. In the groups with ADRP and sRP, the patients have varied expression of disease.

Adolescent↗
PubMed1999

[Color Doppler ultrasonography in diagnosis of post-traumatic optic neuropathy].

PURPOSE: To evaluate the parameters of blood flow in orbital arteries of patients with traumatic optic neuropathy. MATERIAL AND METHODS: Colour Doppler imaging of the ophthalmic artery, central retinal artery and posterior ciliary arteries was carried out in 13 patients with traumatic injury of the optic nerve. The peak-systolic, end-diastolic flow velocities and resistance index were measured. RESULTS: In 4 patients, whose vision was intact immediately after the injury and later deteriorated, the parameters of blood flow in the central retinal artery (CRA) were normal. Also in 3 patients with loss of vision to 1/50-3/50 after the injury the parameters of blood flow in the CRA were in the normal limit. In 3 other patients, who had only light perception after injury, there was decreased peak systolic blood flow and only trace or no flow was demonstrated in the CRA during the diastolic phase. In the remaining 3 patients, who displayed no light perception after the injury, no flow was observed in the CRA with Colour Doppler method. CONCLUSION: Colour Doppler ultrasonography is a useful supplementary method in diagnostics of traumatic optic neuropathy. The Colour Doppler findings seem to correlate well with clinical pathologies of the optic nerve after its traumatic injury.

Adolescent↗
PubMed1999

[Late manifestations of the optic nerve damage after closed head trauma].

PURPOSE: A follow-up assessment of the visual system in patients who had undergone close head injury and in whom simple atrophy of the optic nerve occurred several months after the trauma. PATIENTS: Among patients treated in Department of Ophthalmology in Białystok in the years 1984-1995 there were 2 women and 3 men, aged 19-61 years, who suffered from advancing simple atrophy of the optic nerve and who had undergone severe closed head trauma 3-5 months earlier. In one case the time interval between trauma and the visual sequelae amounted to 11 years. METHODS: The patients underwent a follow-up examination at 3 to 11 years after their initial treatment in the Department of Ophthalmology. Besides a conventional ophthalmologic examination, a static perimetry was performed as well as ultrasonography in projection B and Colour-Coded Doppler sonography (TCCD) of the orbital vessels. RESULTS: When compared to the findings at discharge, in 2 patients visual acuity improved to 5/12, in the remaining 3 no improvement was noted. In all patients the optic discs were white, while other structures of the globe appeared within normal limits. Blood flow in the central retinal artery, ophthalmic artery and in the long posterior cilliary arteries remained undisturbed, as assessed with TCCD. CONCLUSIONS: 1. Lack of visual disturbances immediately after head injury does not preclude their development in the protracted period after the trauma. 2. The reason of the late development of visual sequelae after head trauma is not clear. Normal flow, found in the major vessels of the globe, might indirectly suggest disturbances of microcirculation within the optic nerve with a consequent optic atrophy.

Adult↗
PubMed1999

The influence of post-traumatic syndrome in determining capacity to return to work after closed head injury.

Neuropsychological deficits following closed head injury are responsible for a significant part of the post-traumatic syndrome. Nonetheless such deficits frequently elude standard neurological examination and head injured subjects are not recognised as suffering from any impairments, despite these having a significant effect on their ability to return to work. As a result, subjects are refused disability status, resulting in a large number of litigation appeals. The criteria for determining disability status after head injury are often inadequate, as they do not take into account the post-traumatic syndrome, and medical experts, if they are sensitive to these issues are left in a quandary as to how to justify their decisions before the courts. Equally, psychological assessment, where it is included, is frequently limited to the examination of intellectual functions and memory, which are not always grossly disturbed in these cases. It is recommended that neuropsychological assessments should form part of routine practice in the evaluation of outcome in closed head injury and the test instruments be of adequate sensitivity to measure the deficits occurring after head injury. However, it is necessary to bear in mind that these subjective symptoms, which in reality hamper subjects' ability to return to work, may be the result of disruption of fine cognitive functions, which are inaccessible to currently available test methods.

Adult↗
PubMed1999

[Variations of Doppler blood flow parameters in central retinal artery in relation to position of sample volume].

PURPOSE: To determine variability in measurements of Doppler blood flow parameters in central retinal artery in relation to sample volume location from the optic disc. MATERIAL AND METHOD: Eighty central retinal arteries were examined using color Doppler ultrasonography in 40 healthy volunteers (22 female, 18 male), aged 45 +/- 9 with 7.5 MHz linear-array probe. The measurements of blood velocities and resistance indices in the arteries were obtained at points where distance from optic disc surface ranged from 1.5 mm to 6 mm. RESULTS: Blood velocities increased significantly when sampled closer to the globe (r = -0.61, and r = -0.32 for peak-systolic and end-diastolic velocities, respectively). Mean peak-systolic velocities were 13.0 +/- 2.7 cm/s when distance 2.1 +/- 0.46 mm from optic disc, and 9.3 +/- 2.5 cm/s when distance 4.27 +/- 0.9 mm. Mean end-diastolic velocities were 4.3 +/- 1.2 cm/s and 3.6 +/- 1.1 cm/s, respectively. Resistance indices inclined to increase when the distance between the measurement site and the globe shortened. Resistance indices were 0.67 +/- 0.06 when measured closer to the globe and 0.60 +/- 0.06 when measured farther from it. CONCLUSION: Position of sample volume in relation to optic disc has to be taken into account and defined if measurements of blood flow Doppler parameters of the central retinal artery are to be reproducible.

Blood Flow Velocity↗
PubMed1999

[Blood flow parameters in ocular vessels of patients with glaucoma].

PURPOSE: To determine Doppler flow parameters in ocular vessels of glaucomatous patients. MATERIAL AND METHODS: 38 glaucomatous patients, aged 64 +/- 16, and 57 healthy volunteers were examined with 7.5 MHz linear-array probe. Consistently identified arterial structures included ophthalmic artery, central retinal artery and short posterior ciliary arteries. The peak systolic, end-diastolic and mean velocities were measured from Doppler spectra. Resistance and pulsatility indices were also determined. RESULTS: End-diastolic and mean velocities in central retinal artery of glaucomatous eyes were: 1.5 +/- 1.9 cm/s, 4.0 +/- 2.0 cm/s, whereas in healthy eyes they were significantly higher: 3.5 +/- 1.0 cm/s, 5.4 +/- 1.5 cm/s, respectively. These velocities in short posterior ciliary arteries in glaucomatous patients were significantly lower: 2.4 +/- 2.3 cm/s, 5.6 +/- 2.2 cm/s, comparing to healthy subjects: 4.8 +/- 1.7 cm/s, 7.3 +/- 2.2 cm/s. Resistance and pulsatility indices in central retinal artery and short posterior ciliary arteries were significantly higher in the group of patients: RI = 0.85 +/- 0.18, PI = 2.11 +/- 0.92--in central retinal artery and RI = 0.81 +/- 0.18, PI = 1.96 +/- 0.91--in short posterior ciliary arteries, comparing to healthy subjects: RI = 0.61 +/- 0.08, PI = 1.20 +/- 0.17--in central retinal artery, RI = 0.61 +/- 0.09, PI = 1.13 +/- 0.18--in short posterior ciliary arteries. Impedance indices were increasing progressively with intraocular pressure elevation. There were no significant differences of Doppler blood flow parameters in ophthalmic artery between patients and control group. CONCLUSIONS: Blood flow velocities in central retinal and short posterior ciliary arteries are lower, and resistance and pulsatility indices are higher in glaucomatous eyes in comparison to healthy subjects, whereas in ophthalmic artery doppler parameters are similar in both groups.

Adult↗
PubMed1998

Neural network technique for detecting emergency states in neurosurgical patients.

The problem of reliable detection of life-threatening situations in the neurosurgical patient undergoing treatment in the ICU is still far from reaching a satisfactory solution, although several methods of clinical and instrumental evaluation have recently been developed for the early detection of oncoming signs of danger. Continuous monitoring of intracranial pressure (ICP) provides neurosurgeons with valuable information about the current condition of the patient. However, it is increasingly felt that traditional methods of extracting information from the ICP signal have reached their natural limits, mostly because of difficulties in fitting the appropriate mathematical model to this non-linear and non-stationary process. Successful implementations of artificial neural networks in many medical tasks have encouraged the application of this method of ICP processing. Two problems are considered: the prediction of trends in ICP, and recognition of the configuration of unfavourable symptoms likely to signal danger for the neurosurgical patient. The construction of neural network predictors of ICP trends is based on wavelet pre-processing of the original signal. The approach to the second task involves pre-processing of the ICP with spectral and statistical methods and classification of the extracted features of the current signal on an arbitrarily selected scale of danger.

Brain Diseases↗
PubMed1998

No specific brain protection against thermal stress in fever.

Knowledge about human brain temperature is still very limited, despite evidence demonstrating the critical influence of mild increases in temperature on the ischaemic brain. It has been suggested that in passive and exercise hyperthermia the brain may be protected against thermal damage by a mechanism of selective brain cooling (SBC). It is said to bring about suppression of the temperature of the brain, rendering it significantly lower than trunk and arterial blood temperature. Yet very little is known about the possible role of this mechanism in fever, a condition fundamentally different from "physiological" hyperthermia, especially when it occurs in brain-damaged patients. In our investigation we retrospectively analysed the results of direct recordings of cerebral temperature within the subdural space (Tsd) and within the brain parenchyma (Tbr-16 cases) in 63 unanaesthetized patients following neurosurgical procedures, including 23 with fever > 38 degrees C. The difference between trunk temperature, measured in the rectum (Tre) or in the oesophagus (Tes), and the intracranial temperature, were calculated in all subjects. A statistically significant reduction of these differences, in step with increasing fever, would be compatible with demonstrating a process of selective brain cooling. The offsets Tre-Tsd, Tre-Tbr, and Tes-Tsd were plotted against Tre over a wide range of body temperature and near zero correlation was found. This finding suggests that brain temperature in fever was not selectively suppressed by any specific thermolytic mechanism and that dissipation of the main bulk of cerebral metabolic heat both in normothermia and in fever depends on heat uptake by arterial blood. The results suggest that the brain in fever can be seriously jeopardized by heat stress and no specific cooling mechanism exists, to reduce it below body temperature in feverish neurosurgical patients. Tbr and/or Tsd remained the highest body temperature in 14 out of the 23 patients during fever.

Aged↗
PubMed1997

[Activity of cathepsin a in subretinal fluid in primary retinal detachment].

PURPOSE: To evaluate cathepsin A activity in the subretinal fluid in the primary retinal detachment. MATERIALS AND METHODS: The studies were performed on subretinal fluids taken from 38 patients operated for the primary retinal detachment. Duration of the detachment was contained between 1 week and 6 months. Cathepsin A activity was determined by the ninhydrin method with synthetic substrate (N-Cbz-Phe-Ala) at its optimum pH 5.0. RESULTS: Cathepsin A activity was demonstrated in all investigated fluids. The highest activity was found at about the 4th week of the detachment and then it decreased. No differences of enzyme activity according to sex and refraction error were found. CONCLUSION: The increasing proteolytic activity in the subretinal fluid could be an important factor in gradual degrading of the structure and function of the detached retina, because cathepsins are involved in digestion of outer segment proteins of rods and cones and degradation of mucopolysaccharide interphotoreceptor matrix. Retinal degradation during detachment is probably induced by both insufficient nutrition and the effect of increasing lysosomal enzymes.

Adult↗
PubMed1997

[Combined operations of cataract and glaucoma].

PURPOSE: To discuss results and possible complications of combined, simultaneous operations of cataract and glaucoma. MATERIAL: 21 patients suffering from cataract and glaucoma; 16 women, aged from 59 to 88 years, and 5 men from 66 to 84 years. The patients were treated in the Department of Ophthalmology, Medical Academy in Białystok in the years 1991 to 1996. METHODS: Intracapsular extraction of cataract with lens implantation to the anterior chamber and trabeculectomy was performed in 3 patients with simple glaucoma and hypermatured or brown cataract. In 7 patients only extracapsular cataract extraction was carried out along with trabeculectomy, whereas in 11 remaining ones--trabeculectomy with extracapsular removal of cataract followed by implantation of lens to the posterior chamber (10 subjects) or anterior chamber (1 subject). RESULTS: Postoperative visual acuity was 5/50-5/16 in 28% of patients. In the remaining 72% it amounted to 5/12 or more. Intraoperative and early postoperative complications occurred in 15 patients (71%), but they were only transitory. Delayed follow-up demonstrated that visual acquity had not worsened as compared to the preoperative status, though visual field deteriorated in 3 cases. Intraocular pressure was within normal limits in all patients. CONCLUSIONS: Combined, simultaneous operation of glaucoma and cataract does not seem to give rise to more complications than both procedures performed separately.

Aged↗
PubMed1997

[Incidence of cataract and risk factors in Northeastern Poland].

PURPOSE: Retrospective analysis of the incidence and risk factors of senile and pre-senile cataract in patients from North-East Region of Poland, operated on cataract in the years 1986-1995. MATERIAL AND METHODS: In the analysed decade, 6038 patients were operated on cataract in the Ophthalmology Department of the Clinical Hospital and Ophthalmology Department of the District Hospital in Bialystok. There were 2603 males and 3435 females, mean age amounted to 69 +/- 11 years. 44% of the patients came from rural communities (560.000 inhabitants in the region), whereas 56% of the patients were of urban province (796.000 inhabitants). Statistical analysis was performed on such variables like age, gender, place of residence, cataract history and presence of concomitant diseases: arterial hypertension, diabetes, lung and joints disorders, intestinal diseases. RESULTS AND CONCLUSIONS: Residence in rural communities increases the risk of cataract, although the condition in this environment tends to develop in older age. Gender distribution of the patients does not differ from male/female ratio in the population of the region, so both genders are exposed to similar risk of cataract. Females contract cataract in older age, on average about 3 years later than males. Age is the most important risk factor of cataract; 52% of the patients are older than 70, 43% are in the age of 51-70 years. Mean value of duration of cataract history before operation decreased during the analysed 10 years from 3.8 years in 1986 to 2.2 years in 1995. In 14% of patients cataract coexisted with arterial hypertension, in 8% with diabetes, and in 15% with other diseases. During the analysed 10 years period the number of patients with cataract increased in the same degree in all examined communities. The mean age of patients operated on cataract decreased in this period by 2 years in spite of increasing number of patients older than 75 years. This result can be explained by the fact that the disease tends now to develop earlier and by concomitant decreasing of the time between onset of the disease and decision for operation.

Adult↗
PubMed1996

Cathepsin A activity of normal bovine ocular tissues and pathological human intraocular fluids.

Cathepsin A activity assayed with N-Cbz-Phe-Ala, N-Cbz-Glu-Tyr and N-Cbz-Glu-Phe as substrates, was measured in fresh corneas, lenses, aqueous humor, vitreous humor and choroid plus retinal pigment epithelium taken from normal bovine eye balls and in human intraocular fluids from the eye balls in various ocular diseases (cataract, glaucoma, diabetes, intraocular tumors). Cathepsin A exhibited a pH optimum at 5.0 and showed the highest specificity towards N-Cbz-Phe-Ala as a substrate. In bovine ocular tissues high cathepsin A activity was found in the choroid plus retinal pigment epithelium and in cornea. The lens and the vitreous humor showed low enzyme activity and the aqueous humor none at all. In the human aqueous humor of the eye with cataract cathepsin A activity was more than three times higher then in the eye with choroid tumor. In human vitreous humor in absolute glaucoma the activity was twice as high as in melanoma and almost three times higher than in the case of lung metastatic tumor. Diabetes in glaucoma increased seven fold cathepsin A activity in the vitreous humor.

Animals↗
PubMed1996

[Surgery of orbital tumors with the Krönlein-Berke-Reese method in material from the Ophthalmology Clinics in Bałystok].

PURPOSE: To analyse the results of surgical treatment of tumors located in the posterior part of the orbit. MATERIAL AND METHODS: 12 patients (5 women and 7 men, aged 10-70 years) with tumors located in the posterior part of the orbit, operated on in the years 1985-1995 in Ophtalmology Clinic in Bialystok with the use of Krönlein-Berke-Reese lateral orbitotomy method. Tissues of removed tumor were evaluated histopathologically. RESULTS: In 7 cases tumor was removed completely, including 3 cases with simultaneous optic nerve removal. In 3 other cases tumor was removed partially, whereas in 2 cases eventration of the orbit was necessary. Persistent postsurgical defects of the eyeball mobility were not found in any of the patients. In 2 patients with partially removed tumor a constant blepharoptosis was observed, which required further operation. Visual acuity in patients with preserved optic nerve remained unchanged in 6 out of 7 cases. In 1 case-completely removed cavernoma-visual acuity decreased from 5/7 to 5/16. CONCLUSIONS: Lateral orbitotomy enables successful removal of tumors located in the posterior part of the orbit. Moreover, this method is relatively safe, especially in comparison with cranial approach to tumors badly located in the orbit.

Adolescent↗