An entropy spring model for the Young’s modulus change of biodegradable polymers during biodegradation

This paper presents a model for the change in Young’s modulus of biodegradable polymers due to hydrolysis cleavage of the polymer chains. The model is based on the entropy spring theory for amorphous polymers. It is assumed that isolated polymer chain cleavage and very short polymer chains do not affect the entropy change in a linear biodegradable polymer during its deformation. It is then possible to relate the Young’s modulus to the average molecular weight in a computer simulated hydrolysis process of polymer chain sessions. The experimental data obtained by Tsuji [Tsuji, H., 2002. Autocatalytic hydrolysis of amorphous-made polylactides: Effects of L-lactide content, tacticity, and enantiomeric polymer blending. Polymers 43, 1789–1796] for poly(L-lactic acid) and poly(D-lactic acid) are examined using the model. It is shown that the model can provide a common thread through Tsuji’s experimental data. A further numerical case study demonstrates that the Young’s modulus obtained using very thin samples, such as those obtained by Tsuji, cannot be directly used to calculate the load carried by a device made of the same polymer but of various thicknesses. This is because the Young’s modulus varies significantly in a biodegradable device due to the heterogeneous nature of the hydrolysis reaction. The governing equations for biodegradation and the relation between the Young’s modulus and average molecular weight can be combined to calculate the load transfer from a degrading device to a healing bone.     

Aging and exercise affect the level of protein acetylation and SIRT1 activity in cerebellum of male rats

Aging is associated with a gradual decline in cognitive and motor functions, the result of complex biochemical processes including pre- and posttranslational modifications of proteins. Sirtuins are NAD⁺ dependent protein deacetylases. These enzymes modulate the aging process by lysine deacetylation, which alters the activity and stability of proteins. Exercise can increase mean life-span and improve quality of life. Data from our laboratories revealed that 4 weeks of treadmill running improves performance in the Morris Maze test for young (4 months, old) but not old (30 months, old) male rats, and the exercise could not prevent the age-associated loss in muscle strength assessed by a gripping test. The positive correlation between protein acetylation and the gripping test suggests that the age-dependent decrease in relative activity of SIRT1 in the cerebellum impairs motor function. Similarly to the acetylation level of total proteins, the acetylation of ά -tubulin is also increased with aging, while the effect of exercise training was not found to be significant. Moreover, the protein content of nicotinamide phosphoribosyltransferase, one of the key enzymes of NAD biosynthesis, decreased in the young exercise group. These data suggest that aging results in decreased specific activity of SIRT1 in cerebellum, which could lead to increased acetylation of protein residues, including ά-tubulin, that interfere with motor function.     

A possible explanation of the germicide effect of carbon dioxide in supercritical state based on molecular-biological evidence

Supercritical carbon dioxide (CO₂) possesses germicide (bactericide and sporicide) effect. Despite of the fact, that this effect is used in industrial sterilization processes, the sterilization mechanism at molecular level is unclear. Our hypotheses can provide a molecular-biological explanation for the phenomenon.     

Effect of perinatal stress on the biogenic amine neurotransmitter level of the adult rat's brain

The amount of biogenic amines (dopamine and serotonin) and their metabolites (DOPAC, HVA, 5-HIAA, and 5-HTOL) in five regions of the brain (frontal cortex, hypothalamus, hippocampus, striatum, and brainstem) was studied in the male and female offspring of control and perinatally (48 h before birth or 48 h after birth) food and water deprived dams, when they were three months old, by using HPLC-EC determination. The increase of amine or metabolite level was dominant (19 values increased and 10 decreased related to control). Before-birth stress caused increase in 9 case and only 2 decreased, while in the case of after-birth stress 10 increased and 8 decreased. However, though there is no possibility to decide an exact tendency of direction, the after-birth stress (transmitted by milk) has more expressed effect. Striatum and brainstem were the most touched regions. There was a gender dependence with the dominance of males, except striatum. Blood plasma nociceptin level was also studied and there was a significant elevation in males after pre- and postnatal deprivation, while in females only after postnatal deprivation. The importance of the results in correlation with other stress effects is discussed.     

Beta lactoglobulin homologue placental protein 14 (PP14) in serum of patients with trophoblastic disease and non-trophoblastic gynecologic malignancy

Summary Serum levels of beta lactoglobulin homologue placental protein 14 (PP14) were measured by a sensitive radioimmunoassay in various trophoblastic diseases and non-trophoblastic gynecologic malignancies. While trace amounts of protein were detected in sera of non-pregnant subjects (22.3±13.7 g/l), during first half of normal pregnancy a dramatic rise of serum-PP14 levels was demonstrable with a peak-value at 7th–10th week of gestation, followed by a decline thereafter. Serial determinations of PP14 have been performed in 31 patients with trophoblastic tumour (20 hydatidiform moles, 4 invasive moles and 7 choriocarcinomas). In patients with hydatidiform moles and invasive moles (273.5±106.5g/l and 162.2±109.6g/l) respective values before therapy were much exceeding the nonpregnant controls. After therapy there was a rapid decline of the serum-PP14 levels within two weeks. In patients with choriocarcinoma the PP14 values were moderately elevated (66.4±25.7g/l), and declined following the remission of disease. In 32 gynecological tumours (21 carcinomas of the cervix, 4 endometrial carcinomas, 5 ovarian carcinomas, 2 carcinomas of the vulva) the pretreatment levels were not different to normal controls.     

Serum levels of placenta-specific tissue protein 12 (PP12) in pregnancies complicated by pre-eclampsia, diabetes or twins

PP12 is one of the recently discovered soluble tissue antigens of the placenta. During normal pregnancy maternal serum PP12 levels rise during the first 18 weeks reaching a mean peak value of 139.9 +/- 40.26 micrograms/l; after that there is a fall to a mean value of 111.9 +/- 42.39 micrograms/l between 28 and 40 weeks. Significantly higher mean serum PP12 levels were found in the third trimester in two high risk pregnancy groups (281.09 +/- 117.08 micrograms/l in pre-eclamptic toxaemia and 203.71 +/- 73.77 micrograms/l in diabetes) while serum PP12 levels remained normal (114.94 +/- 58.06 micrograms/l) in twin pregnancy. The increase of serum PP12 concentration in toxaemia and in diabetes may be of considerable diagnostic significance.     

Comparison of 150 simultaneous bilateral and 300 unilateral percutaneous nephrolithotomies

PURPOSE: To compare the results, complications, efficiency, and safety of simultaneous bilateral percutaneous nephrolithotomy (SBPN) and unilateral percutaneous nephrolithotomy (PCNL). PATIENTS AND METHODS: We compared the results and complications of 150 SBPNs with those of 300 unilateral PCNLs. All the procedures were performed by one surgeon which provides relatively constant parameters. The success rates, preoperative and postoperative laboratory results, and complications were compared on the basis of stone size and the number of nephrostomy tracks. RESULTS: There were no significant differences between the results and complications of SBPN and PCNL. The SBPN itself did not cause more blood loss than unilateral PCNL. In both groups, the blood loss was in direct proportion to the size of the stones and the number of nephrostomy tracks. After SBPN, kidney function improved >20% in 12.2% of the patients and worsened for more than 3 days in only 4%. Temporary worsening of kidney function occurred in the unilateral procedure group as well (8%), mostly in cases of solitary kidneys or bilateral stones. The SBPN was not more hazardous than unilateral PCNL (complication rate 11.3% v 14.3%, respectively). In both groups, most of the complications were in proportion to the size and difficulties of the stones. CONCLUSION: Simultaneous bilateral percutaneous nephrolithotomy is a safe and advantageous procedure that is not more hazardous than the separate PCNL in cases of bilateral large stone burdens. To our knowledge, these are the largest reported series of these procedures and the only comparative analysis of SBPN and PCNL.     

Positron emission tomography in presurgical localization of epileptic foci

The success of cortical resection for intractable epilepsy of neocortical origin is highly dependent on the accurate presurgical delineation of the regions responsible for generating seizures. In addition to EEG and structural imaging studies, functional neuroimaging such as positron emission tomography (PET) can assist lateralization and localization of epileptogenic cortical areas. In the presented studies, objectively delineated focal PET abnormalities have been analyzed in patients (mostly children) with intractable epilepsy, using two different tracers: 2-deoxy-2-[18F]fluoro-D-glucose (FDG), that measures regional brain glucose metabolism, and [11C]flumazenil (FMZ), that binds to GABAA receptors. The PET abnormalities were correlated with scalp and intracranial EEG findings, structural brain abnormalities, as well as surgical outcome data. In patients with extratemporal foci and no lesion on MRI, FMZ PET was more sensitive than FDG PET for identification of the seizure onset zone defined by intracranial EEG monitoring. In contrast, seizures commonly originated from the border of hypometabolic cortex detected by FDG PET suggesting that such areas are most likely epileptogenic, and should be addressed if subdural EEG is applied to delineate epileptic cortex. In patients with cortical lesions, perilesional cortex with decreased FMZ binding was significantly smaller than corresponding areas of glucose hypometabolism, and correlated well with spiking cortex. Extent of perilesional hypometabolism, on the other hand, showed a correlation with the life-time number of seizures suggesting a seizure-related progression of brain dysfunction. FMZ PET proved to be also very sensitive for detection of dual pathology (coexistence of an epileptogenic cortical lesion and hippocampal sclerosis). This has a major clinical importance since resection of both the cortical lesion and the atrophic hippocampus is required to achieve optimal surgical results. Finally, the author demonstrated that in patients with neocortical epilepsy, FDG PET abnormalities correctly regionalize the epileptogenic area, but their size is not related to the extent of epileptogenic tissue to be removed. In contrast, complete resection of cortex with decreased FMZ binding predicts good surgical outcome suggesting that application of FMZ PET can improve surgical results in selected patients with intractable epilepsy of neocortical origin.     

The role of scintigraphy in the diagnosis of mandibular bone changes

Investigating the scintigraphic images of jaws may have a diagnostic value of bone alterations of dental origin. Anterior view of whole body bone scintigraphy revealed hot spot on jaws of 61% (279) of patients. Twenty-six patients (mean age 58.3 year) from all of those who had increased tracer uptake (ITU) in the maxillo-mandibular region were called back for dental examination. 279 out of 459 (61%) patients had ITU in the maxillo-mandibular region. Dental examination revealed the dental origin of ITU in all cases. In case of periapical pathosis tracer uptake showed 28.79% increase compared to the contralateral side. In marginal periodontitis 23.82% ITU was found. In case of loading due to prosthesis 13.06% ITU was observed. The mean DMF-T value was 26.36 +/- 4.52 (D = 4.12, M = 20.8, F = 1.44). The prosthetic index was 0.42 on the mandible. The above mentioned data mean very low oral health conditions of the patients included in this examination. The results show that bone scintigraphy is a valuable procedure in detecting tooth related jaw lesions. Bone scintigraphy provides very useful data on oral health of these patients. Enrolling of these patients into regular dental care is inevitable.