Investigation of Cognitive Impairment in the Course of Post-COVID Syndrome

(1) Background: The study presents results from an investigation of cognitive impairment in patients hospitalized in the first psychiatric clinic in Bulgaria to treat patients with COVID-19 during the pandemic period between 2020 and 2022. One hundred and twenty patients who had recovered from acute COVID-19 infection (up to 12 weeks ago) and had no previous history of cognitive impairment participated in the study. In 23 of them (19.17%), disturbance of cognitive functioning was observed. (2) Methods: All 23 patients underwent neuropsychological (Luria's test, Platonov's Maze test, MMSE, Boston Naming test) and neuroimaging examinations. Only seven of them had evidence of cortical atrophy on CT/MRI images. The most significantly demonstrative image of one of those patients is presented. (3) Results: The neuropsychological testing results of both groups show a certain decrease in fixation and memory retention as well as in the range, concentration, distribution and switching of attention. Deviations from the norm on the MMSE, as well as on the Boston Naming Test, were found in the group of patients with cortical atrophy (mild to moderate aphasia). Neuroprotective agents such as Citicoline, Piracetam and Memantine were prescribed to the patients with evident cortical atrophy. After 3 months, positive results of the neuropsychological examination were reported in both groups. (4) Conclusions: Although there are limited data on the benefit of prescribing pro-cognitive agents in the post-COVID period, our clinical experience suggests that it might be useful in the recovery process from the infection's consequences on cognition for patients with brain pathology.

Tripeptidyl peptidase I activity in porcine lumbar spinal ganglia - a histochemical study

Distribution of tripeptidyl peptidase I (TPPI) activity in the structures of porcine lumbar spinal ganglia (LSG) was studied by enzyme histochemistry on cryostat sections from all the ganglia using the substrate glycyl-L-prolyl-L-methionyl-5-chloro-1-anthraquinonyl hydrazide (GPM-CAH) and 4-nitrobenzaldehyde (NBA) as visualization factor. Light microscopic observations showed TPPI activity in almost all the LSG structures. The enzyme reaction in different cell types was compared semi-quantitatively. Strong reaction was observed in the small neurons, satellite ganglia cells and some nerve fibers. Weak reactivity was found in the large sensory somatic neurons, whereas moderate reaction for TPPI was determined in the middle sensory somatic neurons and some nerve fibers. Statistical analysis by one-way ANOVA showed no significance of difference (when p⟨0.05) for the number of TPPI positive neurons per mm2. The original data obtained by the enzyme histochemistry method give us a reason to presume that TPPI actively participates in the functions of all the neuronal structures in porcine LSG. According to our results, it could be suggested that TPPI activity is important for the functions of autonomic and somatic sensory neurons.

Zika Virus Nonstructural Protein 1 Disrupts Glycosaminoglycans and Causes Permeability in Developing Human Placentas

BACKGROUND

During pregnancy, the Zika flavivirus (ZIKV) infects human placentas, inducing defects in the developing fetus. The flavivirus nonstructural protein 1 (NS1) alters glycosaminoglycans on the endothelium, causing hyperpermeability in vitro and vascular leakage in vivo in a tissue-dependent manner. The contribution of ZIKV NS1 to placental dysfunction during ZIKV infection remains unknown.

METHODS

We examined the effect of ZIKV NS1 on expression and release of heparan sulfate (HS), hyaluronic acid (HA), and sialic acid on human trophoblast cell lines and anchoring villous explants from first-trimester placentas infected with ZIKV ex vivo. We measured changes in permeability in trophoblasts and stromal cores using a dextran-based fluorescence assay and changes in HA receptor expression using immunofluorescent microscopy.

RESULTS

ZIKV NS1 in the presence and absence of ZIKV increased the permeability of anchoring villous explants. ZIKV NS1 induced shedding of HA and HS and altered expression of CD44 and lymphatic endothelial cell HA receptor-1, HA receptors on stromal fibroblasts and Hofbauer macrophages in villous cores. Hyaluronidase was also stimulated in NS1-treated trophoblasts.

CONCLUSIONS

These findings suggest that ZIKV NS1 contributes to placental dysfunction via modulation of glycosaminoglycans on trophoblasts and chorionic villi, resulting in increased permeability of human placentas.

Abstract P5-11-07: The significance of androgen receptor co-expression in ER+ metastatic breast cancer patients treated with palbociclib

Background: The PALOMA-1 and PALOMA-3 studies demonstrated a significant progression-free survival (PFS) advantage for palbociclib, a CDK4/6 inhibitor, in combination with letrozole or fulvestrant in the first or second line setting compared to these therapies alone in estrogen receptor (ER)+, HER2-negative metastatic breast cancer (MBC). Recent studies have revealed preliminary efficacy signals for androgen receptor (AR) blockade in MBC, predominately in AR+, triple negative patients. We sought to further evaluate AR expression and its significance in ER+ MBC patients treated with palbociclib early in their metastatic treatment course.

Methods: A retrospective review identified 22 patients treated with palbociclib for ER+, HER2- MBC after its FDA approval between January 1st, 2015 and October 1st, 2016 at our center with available pre-treatment tumor samples for analysis. Records were reviewed and clinical characteristics for each patient were analyzed. Archival tumor tissue was tested for AR, phosphorylated retinoblastoma (pRb), CDK6, p16, and CyclinE1 by immunohistochemistry assay for each patient. For AR, nuclear staining >0% was considered positive. For all other IHC studies, intensity of staining >2+ or staining in >10% of cells was considered positive.

Results: The median age was 63.5 years (range 34-84); 23% were ≥ age 70. Our cohort was 35% African American, 60% Caucasian, and 5% Asian American. 64% of patients were post-menopausal and 59% had visceral metastases. 45% of patients were on their first line of treatment, 23% second line, and 32% third line. 68% of patients were on an aromatase inhibitor. Median follow up was 18.7 months (95% CI 13.9, 23.3 months). The AR was expressed in 59% of patients; 55% had expression >10% and 41% had expression >20%. AR+ patients were significantly more likely to experience event-free survival (EFS) (HR 0.26, p=0.01), with a median EFS of 18.8 months (AR- median EFS 5.4 months). AR expression was significantly associated with expression of pRb (100% of AR+ patients, p=0.02). CDK6, p16, and CyclinE1 expression were not associated with AR expression or EFS.

Conclusions: Our data show preliminary evidence of the significance of ER and AR co-expression in ER+, HER2- MBC. ER+, AR+ patients have significantly improved EFS when treated with palbociclib and endocrine therapy as compared with AR-, ER+ patients. There is evidence that AR expression is associated with pRB expression, which may represent a mechanism by which cell cycle inhibition with palbociclib is particularly efficacious in these patients. AR expression rates in ER+, HER2- MBC are significant, and may provide rationale for combining CDK4/6 inhibitors with AR targeting as a subsequent line of targeted therapy in these patients before cytotoxic chemotherapy is initiated. Further studies based on these results are underway.

Citation Format: Landry CA, Ru M, Jaffer S, Dimitrova M, Tiersten A. The significance of androgen receptor co-expression in ER+ metastatic breast cancer patients treated with palbociclib [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-11-07.

CD300c is uniquely expressed on CD56 bright Natural Killer Cells and differs from CD300a upon ligand recognition

Paired receptors on NK cells recognize similar ligands with varied strength of binding ability and perform different functions. The CD300 molecules are emerging as novel immune regulators in health and disease due to their interaction with their lipid-nature ligands. Particularly, the paired receptors CD300c and CD300a have been shown to elicit activating and inhibitory capabilities, respectively. In the current study, we seek to investigate the expression and function of CD300c on human NK cells. We demonstrate that IL-2 and IL-15 treatment significantly induce CD300c expression exclusively on CD56(bright) NK cells. CD300c up-regulation requires STAT5 and its expression is inhibited by IL-4. Consistently, IL-2 secreted from activated CD4(+) T cells specifically induces the expression of CD300c on CD56(bright) NK cells. Crosslinking CD300c with a specific antibody enhances the proficiency of CD56(bright) NK cells to degranulate and induce chemokine and cytokine secretion. We also show the differential binding of CD300a and CD300c to their ligands phosphatidylethanolamine (PE) and phosphatidylserine (PS) and their differential ability to affect CD56(bright) NK cell functions. Our results provide an insight into the novel set of paired receptors CD300a and CD300c that are distinctively expressed on CD56(bright) NK cells with varied effector functions.

Patient doses from hybrid SPECT-CT procedures

The aim of this work is to estimate patient doses from hybrid single-photon emission computed tomography (SPECT) and computed tomography (CT) procedures. The study involved all four SPECT-CT systems in Bulgaria. Effective dose was estimated for about 100 patients per system. Ten types of examinations were considered, representing all diagnostic procedures performed in the SPECT-CT systems. Effective doses from the SPECT component were calculated applying the ICRP 53 and ICRP 80 conversion coefficients. Computed tomography dose index and dose length product were retrospectively obtained from the archives of the systems, and effective doses from the CT component were calculated with CT-Expo software. Parallel estimation of CT component contribution with the National Radiological Protection Board (NRPB) conversion coefficients was performed where applicable. Large variations were found in the current practice of SPECT-CT imaging. Optimisation actions and diagnostic reference levels were proposed.

A Human Anti-M2 Antibody Mediates Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC) and Cytokine Secretion by Resting and Cytokine-Preactivated Natural Killer (NK) Cells

The highly conserved matrix protein 2 (M2) is a good candidate for the development of a broadly protective influenza vaccine that induces long-lasting immunity. In animal models, natural killer (NK) cells have been proposed to play an important role in the protection provided by M2-based vaccines through a mechanism of antibody-dependent cell-mediated cytotoxicity (ADCC). We investigated the ability of the human anti-M2 Ab1-10 monoclonal antibody (mAb) to activate human NK cells. They mediated ADCC against M2-expressing cells in the presence of Ab1-10 mAb. Furthermore, NK cell pro-inflammatory cytokine and chemokine secretion is also enhanced when Ab1-10 mAb is present. We also generated cytokine-preactivated NK cells and showed that they still displayed increased effector functions in the presence of Ab1-10 mAb. Thus, our study has demonstrated that human resting and cytokine-preactivated NK cells may have a very important role in the protection provided by anti-M2 Abs.

Changes in the functional characteristics of tumor and normal cells after treatment with extracts of white dead-nettle

Lamium album L. is a perennial herb widely used in folk medicine. It possesses a wide spectrum of therapeutic activities (anti-inflammatory, astringent, antiseptic, antibiotic, antispasmodic, antioxidant and anti-proliferative). Preservation of medicinal plant could be done by in vitro propagation to avoid depletion from their natural habitat. It is important to know whether extracts from L. album plants grown in vitro possess similar properties as extracts from plants grown in vivo. For these reasons, it is important to examine changes in the composition of secondary metabolites during in vitro cultivation of the plant and how they affect the biological activity.

We used A549 human cancer cell line and normal kidney epithelial cells MDCKII (Madin–Darby canine kidney cells II) as controls in assessing the anti-cancer effect of plant extracts. To elucidate changes in some key functional characteristics, adhesion test, MTT (3-(4,5-dimethylthiazol-2-yl)-2-5-diphenyl tetrazolium bromide), transepithelial resistance (TER), immunofluorescence staining and trypan blue exclusion test were performed.

Methanol and chloroform extracts of in vivo and in vitro propagated plants affected differently cancerous and non-cancerous cells. The most pronounced differences were observed in the morphological analysis and in the cell adhesive properties. We also detected suppressed epithelial transmembrane electrical resistance of MDCK II cells, by treatment with plant extracts, compared to non-treated MDCK II cells. A549 cells did not polarize under the same conditions. Altered organization of actin filaments in both cell types were noticed suggesting that extracts from L. album L. change TER and actin filaments, and somehow may block cell mechanisms, leading to the polarization of MDCK II cells.

Discharge tube with coaxial geometry for efficient production of metal hydrides

The production of metal hydrides in vapour phase is one of the problems which makes their spectroscopic investigation at high resolution difficult. The molecular densities are usually low and the absorption is often increased by the use of multipass cells or intracavity setups. In this contribution a discharge tube with coaxial geometry is investigated, which is able to produce relatively high densities of NiH (≈10(12) cm(-3)). Additional advantage of the present geometry is that the densities are very homogeneous along the discharge length, 250 mm in our case, which can be made in principle arbitrary long. As a result, reliable absorption was detected even in a single pass experiment. We also present the results of a numerical model which explains the general properties of the plasma in the tube. Based on this understanding, we discuss possible improvements and other applications of this discharge geometry.

DNA priming prior to inactivated influenza A(H5N1) vaccination expands the antibody epitope repertoire and increases affinity maturation in a boost-interval-dependent manner in adults

DNA priming improves the response to inactivated influenza A(H5N1) vaccination. We compared the immunogenicity of an H5 DNA prime (using strain A/Indonesia/5/2005) followed by an H5N1 monovalent inactivated vaccine boost at 4, 8, 12, 16, or 24 weeks to that of 2 doses of H5N1 monovalent inactivated vaccine in adults. Antibody epitope repertoires were elucidated by genome-fragment phage-display library analysis, and antibody avidities for HA1 and HA2 domains were measured by surface plasmon resonance. H5 DNA priming expanded the H5-specific antibody epitope repertoire and enhanced antibody avidity to the HA1 (but not the HA2) domain in an interval-dependent manner. Enhanced HA1 binding and avidity after an interval of ≥12 weeks between prime and boost correlated with improved neutralization of homologous and heterologous H5N1 strains. Clinical trials registration NCT01086657.

Scintimammography and single-photon emission computed tomography for postoperative image guidance for radiation treatment planning in breast cancer patients

PURPOSE

To evaluate post-surgical tumor-metabolic regions outside of the computed tomography (CT)-defined volume for radiation therapy (RT) planning using functional imaging of scintimammography (SMG) ± single photon emission computerized tomography (SPECT) in breast cancer (BC) patients.

METHODS

62 operated high-risk BC females, mean age 50.45 years, underwent SMG±SPECT before RT planning. Twenty-one and twelve patients with stage I and IIa respectively had lumpectomy (LT) with axillary lymph node dissection (ALND), and modified radical mastectomy (Patay) + ALND was realized in 29 stage IIb-III patients. All SMG images, positive for viable tumor tissue (VTT) or metastatically involved lymph nodes (LNs) were verified cytologically/ histologically. Three early planar and delayed images were acquired after i.v. administration of 550-740 MBq 99mTc- MIBI or 99mTc-TF. Uptake values (UV) > 1.65 revealed VTT.

RESULTS

Data in 49 (79%) of 62 patients were characterized as true-negative (TN; UV<1.35). In 13 (21%) patients SMG visualized 22 true-positive (TP) malignant lesions: 2 residual VTT in scars, 1 newly defined BC in the contralateral breast and 18 regional LN metastases (6 axillary, 6 parasternal, 1 sub- and 5 supraclavicular). All 22 TP VTT lesions were imaged by scintigraphy using different tumor-seeking radiopharmaceuticals: 99mTc-MIBI - 17 (77%) and 99mTc- TF - 5 (23%) of the TP lesions. One false-positive (FP) (inflammation: UV>1.65) and one false-negative (FN) (UV<1.35) foci were found. Applying SMG±SPECT for BC restaging after surgery, the RT volume was changed in 13 of 62 (21%) patients.

CONCLUSION

SMG is a reliable imaging method for evaluating residual VTT, LN metastases or altered biological activity in the scars after BC surgery and could modify the irradiated volume, optimizing the therapeutic effect and minimizing RT side effects.

Does single-dose cell resistance to the radio-mimetic zeocin correlate with a zeocin-induced adaptive response in Chlamydomonas reinhardtii strains?

This study aimed to test whether a correlation exists between single-dose resistance to zeocin and the ability to develop a zeocin-induced adaptive response (AR) in Chlamydomonas reinhardtii strains. Three genotypes were used: wild type (WT) strain 137C and two strains (H-3 and AK-9-9), which are highly resistant to radiation based on survival studies. Based on a micro-colony assay, the strains could be arranged according to their single-dose resistance to zeocin as follows: AK-9-9 > H-3 > 137C. However, zeocin induced a similar level of DSB in strains AK-9-9, H-3 and 137C. The radio- and zeocin-resistant strains AK-9-9 and H-3 showed higher DSB rejoining capacity than the WT strain 137C, suggesting that DSB rejoining can at least partly account for different cell survival. Both WT and radio-resistant strains develop zeocin-induced AR involving increased DSB rejoining. The radio- and zeocin-resistant strains AK-9-9 and H-3 again showed higher DSB rejoining capacity than the WT strain 137C. The higher resistance of strains H-3 and AK-9-9 did not abrogate their ability to adapt, albeit with a smaller magnitude as compared to the WT strain. The obtained results characterize new radio-resistant C. reinhardtii strains, which enrich the collection of resistant C. reinhardtii strains.

[Model for early childhood caries risks]

Risk factors of early childhood caries were studied on 406 children of 12-47 months age. The results showed that pathological pregnancy, sleeping with bottle of blend or sweet liquid, use of candy and caramel on sticks and sour-sweet fruit juices were significant factors leading to early childhood caries. During simultaneous action of all these risk factors domination belonged to use of sour-sweet fruit juices. The probability of caries occurrence at simultaneous action of all these risk factors was equal to 62%.

Helicobacter pylori and gastric carcinoma

The aim of the study was to evaluate the relation of Helicobacter pylori (HP) infection and gastric cancer and a possible relation with a certain histopathological type of gastric cancer and localization within the stomach. A cross-section study was conducted on 60 consecutive patients (45 men and 15 women) with an established histological diagnosis of gastric cancer. The patients were divided into 2 groups (HP positive and HP negative) and additionally, depending on histopathological type, into intestinal, diffuse and cardia cancer, and localization as cardia carcinoma, proximal and distal carcinoma. HP was detected with a rapid ureasa endoscopic test and a serologic immune essay. Forty-two out of 60 patients 42 (70%) were HP positive. There were 36 intestinal type of gastric cancer, 34 (94.4%) HP positive (statistically significant), 19 patients with diffuse type, and 8 (42.1%) HP positive. The remaining 5 were carcinoma of cardia and all were HP negative. Thirty-seven (61.7%) were distal carcinomas, up to (76.2%) in the HP positive group, there were 18 (30%) proximal carcinomas and 5 (8.3%) localized on the cardia. This study confirmed the high incidence of HP infection in patients with gastric carcinoma, particularly in those with an intestinal type of cancer. Carcinomas were predominantly localized in the distal part of the stomach, especially in the HP positive group of intestinal type. Carcinomas of cardia were negatively associated with HP infection.

Induction of DNA double-strand breaks by zeocin in Chlamydomonas reinhardtii and the role of increased DNA double-strand breaks rejoining in the formation of an adaptive response

This study aimed to test the potential of the radiomimetic chemical zeocin to induce DNA double-strand breaks (DSB) and "adaptive response" (AR) in Chlamydomonas reinhardtii strain CW15 as a model system. The AR was measured as cell survival using a micro-colony assay, and by changes in rejoining of DSB DNA. The level of induced DSB was measured by constant field gel electrophoresis based on incorporation of cells into agarose blocks before cell lysis. This avoids the risk of accidental induction of DSB during the manipulation procedures. Our results showed that zeocin could induce DSB in C. reinhardtii strain CW15 in a linear dose-response fashion up to 100 microg ml(-1) which marked the beginning of a plateau. The level of DSB induced by 100 microg ml(-1) zeocin was similar to that induced by 250 Gy of gamma-ray irradiation. It was also found that, similar to gamma rays, zeocin could induce AR measured as DSB in C. reinhardtii CW15 and this AR involved acceleration of the rate of DSB rejoining, too. To our knowledge, this is the first demonstration that zeocin could induce AR in some low eukaryotes such as C. reinhardtii.

Bone scintigraphy in the monitoring of treatment effect of bisphosphonates in bone metastatic breast cancer

PURPOSE

The aim of this retrospective study was to assess the possibilities of whole-body bone scintigraphy (WB BSc) in the monitoring of the effect of biphosphonate treatment in patients with breast cancer and bone metastases.

PATIENTS AND METHODS

51 breast cancer patients with bone metastases, aged from 33 to 73 years, were included.WB BSc was performed on a Siemens DIACAM gamma camera, 2-4 h after i.v. injection of 740 MBq 99mTc-MDP, before the start of the biphosphonate treatment (baseline scintigraphy) with zoledronic acid(Zometa) and at least 6 months thereafter (control scintigraphy) in order to avoid the "flare" effect.

RESULTS

At the baseline WB BSc 41 (80.4%) patients presented with multiple (over 3) bone metastatic lesions, 9 (17.6%) patients with single (up to 3) lesions and 1 (1.96%) patient with a solitary bone metastasis. All bone metastases had osteoblastic appearance. At the control scintigraphy 4 (8%) patients showed complete therapeutic response (CR; no bone lesions were visualized); 21 (41%) patients partial response (PR; decrease in the number and the intensity of the lesions); 16 (31%) patients stable bone lesions (SD; no change in the number or the intensity of the bone metastases); and 10(20%) patients showed disease progression (PD).

CONCLUSION

WB BSc is a reliable functional imaging modality for assessment of the biphosphonate therapeutic effect and an important method in the multimodal treatment planning of breast cancer patients.

99mTc-MIBI myocardial perfusion scintigraphy for assessment of myocardial damage after radiotherapy in patients with breast cancer

PURPOSE

After radiation therapy (RT) to the thorax, cardiac injuries may be induced involving the myocardial capillaries and causing myocardial fibrosis. The aim of this study was to assess the role of 99mTc-MIBI myocardial perfusion scintigraphy (MPS) for mapping the RT-induced cardiac injuries.

PATIENTS AND METHODS

The study involved 56 patients: 46 with left-sided(study group) and 10 with right-sided (control group) breast cancer who, after breast surgery, received postoperative RT. In the cases of the study group, the anterior wall of the myocardium was included in the target field. All of the patients were asymptomatic and without risk factors concerning heart. 99m Tc-MIBI MPS was performed using Siemens Diacam gamma camera. 555 MBq of tracer was injected in each occasion. MPS was performed 30-60 min after injection and the images were analyzed using a semi quantitative four-point system.

RESULTS

MPS was normal in all patients of the control group and in 33 (76%) patients of the study group. In 11 (24%) of the patients in the study group MPS indicated moderately reduced perfusion: 7 of the patients had hypo-perfusion of the anterior wall segments, 4 had hypoperfused septum and apex. Comparison of the 2 groups showed statistically significant difference (p<0.001).

CONCLUSION

Cardiac injury after irradiation of the thorax is not rare and its early detection may minimize severe cardiac damage. MPS may be a feasible method to that purpose.

Slow and fast fatigable frog muscle fibres: electrophysiological and histochemical characteristics

Continuous activity of isolated frog gastrocnemius muscle fibres provoked by repetitive stimulation of 5 Hz was used as an experimental model for fatigue development in different fibre types. Parameter changes of the elicited intracellular action potentials and mechanical twitches during the period of uninterrupted activity were used as criteria for fatigue evaluation. Slow fatigable muscle fibre (SMF) and fast fatigable muscle fibre (FMF) types were distinguished depending on the duration of their uninterrupted activity, which was significantly longer in SMFs than in FMFs. The normalized changes of action potential amplitude and duration were significantly smaller in FMFs than in SMFs. The average twitch force and velocity of contraction and relaxation were significantly higher in FMFs than in SMFs. Myosin ATPase (mATPase) and succinate dehydrogenase activity were studied by histochemical assessment in order to validate the fibre type classification based on their electrophysiological characteristics. Based on the relative mATPase reactivity, the fibres of the studied muscle were classified as one of five different types (1-2, 2, 2-3, 3 and tonic). Smaller sized fibres (tonic and type 3) expressed higher succinate dehydrogenase activity than larger sized fibres (type 1-2, 2), which is related to the fatigue resistance. The differences between fatigue development in SMFs and FMFs during continuous activity were associated with fibre-type specific mATPase and succinate dehydrogenase activity.

Integrity of endothelium in cryopreserved human cornea

The aim of the present study was to elaborate an optimal method for cryopreservation of human donor cornea for transplantation and to follow the morphological changes in the structure of the endothelial cell layer using scanning electron microscopy (SEM). Sixteen groups, with four donor cornea each, were cryopreserved at cooling rates of 1 degree C per min and 5 degree C per min. Four cryoprotectants (glycerol, dimethyl sulfoxide, 1,2-propanediol, polyethylene glycol-400) in two concentrations (5% and 10% v/v) were prepared on the bases of medium Optisol GS supplied with 20% v/v human serum albumin. Four additional human cornea were used as controls. Endothelial cell recovery of the cornea after thawing and 24 hours culture, was calculated as a percent of the preserved recovered cells. Sufficient recovery of the endothelial cell layer, making the cornea suitable for transplantation was obtained using the cryoprotectants dimethyl sulfoxide and especially polyethylene glycol-400.

Reactivity descriptors for the hydrogen bonding ability of pyridine bases

The hydrogen bonding interaction between pyridine bases and water was theoretically studied by applying density functional theory computations at the B3LYP/631G(d,p) level. The theoretically determined binding energies for the complexation process correlate well with the experimental solvatochromic parameters beta for the respective bases. A very good linear relationship was also found between the evaluated binding energies of hydrogen bond formation and the respective electrostatic potential at nuclei (EPN) values at the pyridine nitrogen atom. It was found that the theoretical EPN values correlated linearly with the beta constants and the quantities could be employed as alternative. It was concluded that the electrostatic potential at nuclei characterized quantitatively the reactivity of the studied molecules toward the hydrogen bond formation. EPN values could be applied as hydrogen bond descriptors in QSAR studies.

New fluorescent method for the histochemical detection of tripeptidyl peptidase I using glycyl-l-prolyl-l-met-2-anthraquinonyl hydrazide as substrate

A new substrate for tripeptidyl peptidase I (TPP I; E.C.3.4.14.9)-Gly-L-Pro-L-Met-2-anthraquinonyl hydrazide (Gly-Pro-Met-2-AH) is synthesized and used for the fluorescent histochemical detection of the enzyme. The enzyme liberates low soluble 2-anthraquinonylhydrazine, which-couples quickly with 3-nitrobenzaldehyde (3-NBA) yielding a highly fluorescent water-insoluble hydrazone--3-nitrobenzylidene-2-anthraquinonylhydrazone. The latter compound is localized precisely at sites of enzymatic activity and marks them with a very bright and stable orange-red fluorescence after excitation with conventional monochromatic andlaser green light (lambda(exc)=520-580 nm). The new technique is used successfully for the visualization of the enzyme in tissue sections of different rat organs - and represent the first fluorescent histochemical method for that peptidase.

New fluorescent method for the histochemical detection of dipeptidyl peptidase IV using glycyl-l-prolyl-2-anthraquinonyl hydrazide as substrate

Glycyl-4-prolyl-2-anthraquinonylhydrazide (Gly-Pro-2-AH) was synthesized and used as a new fluorogenic substrate for the histochemical detection of dipeptidyl peptidase IV activity (DPP IV). The enzymatic hydrolysis liberates 2-anthraquinonyl hydrazine (2-AH). Further on, the primary reaction product reacts with an aromatic aldehyde to give an insoluble hydrazone. The final reaction product fluoresces orange-red when exited by green light (lambda(exc)=520-580 nm) and marks sites of enzymatic activity by an intensive fluorescence. This fluorescent method permits highly sensitive enzyme detection and causes only very low background tissue fluorescence. Thus enzyme locations in the capillary bed endothelium properly and sensitively stained, which has not been achieved by now. The new method is used successfully to demonstrate the enzyme in cryotome tissue sections from several rat organs.

Increased redistribution of 99mTc-MIBI under the action of nitrate administration--a good tool for detection of myocardial vitality in patients with severe CAD

BACKGROUND

The purpose of the study was to investigate and assess patients with severe, coronarographically documented coronary artery disease (CAD), previous myocardial infarction and left ventricular dysfunction, using radionuclide method for myocardial perfusion scintigraphy with 99mTc-MIBI and nitrate administration for detection of viable myocardium.

MATERIAL AND METHODS

We investigated 56 patients (37 male, 19 female, mean age 58 +/- 8 years) with CAD and previous myocardial infarction, mean EF 38% +/- 12; divided into 2 groups: Group I--28 patients, investigated at rest, i.v. injected 370 MBq (99m)Tc-MIBI, scintigraphy performed at 30 min and 4th hour; Group II--28 patients, investigated at rest, i.v. injected 37 MBq (99m)Tc-MIBI, scintigraphy performed at 30 min, immediately after that administration of 20 mg Isosorbitdinitrate per os and delayed scintigraphy at 2nd and 4th hour. Myocardial SPECT imaging using Siemens Diacam with semiquantitative analysis of acquisition data was performed.

RESULTS

The results established significant but low tracer redistribution in Gr. I, mean redistribution 17.5% +/- 5.6. After nitrate administration (Gr. II) we detected increased tracer redistribution, mean 30.4% +/- 7.8. The redistribution is higher at the 4th hour, compared to that obtained at 2nd hour after injection. Comparison of the results before and after PTCA showed sensitivity and specificity 93% and 67% respectively.

CONCLUSION

It is concluded that after nitrate administration (99m)Tc-MIBI redistribution enhances noticeably and may play a feasible role in detection of viable myocardium in patients with severe CAD.

Original method for the histochemical demonstration of tripeptidyl aminopeptidase I

The original histochemical method for the visualization of tripeptidyl aminopeptidase I (TPP I, EC 3.4.14.9) is developed. The method is based on the new synthetic substrates Gly-L-Pro-L-Met(or L-Ala)-5-chloro-1-anthraquinonyl hydrazide (Gly-Pro-Met[Ala]-CAH). The final reaction product is represented as tripeptidyl-5-chloro-1 anthraquinonyl hydrazides (TPP-CAH). Upon the enzyme action the practically in aqueous media insoluble brown-reddish dye 5-chloro-1-anthraquinonyl hydrazine (CAH) is released, which reacts simultaneously with aromatic aldehydes as e.g. 4-anisaldehyde (p-AA) or 4-nitrobenzaldehyde (p-NBA), resulting in microcrystalline or amorphous deeply colored hydrazones. The last compounds mark accurately the locations of enzymatic activity. The biochemically suggested lysosomal localization of this collagen-degrading exopeptidase is thus confirmed on tissue sections. More information about the distribution of TPP I in different rat organs is presented as well.

Histochemical method for dipeptidyl aminopeptidase II with a new anthraquinonyl hydrazide substrate

A new method for the histochemical visualization of lysosomal aminopeptidase dipeptidyl peptidase II activity (DPP II) is developed. The substrate L-Lys-L-Ala-5-chloro-1-anthraquinonylhydrazide-2HBr (Lys-Ala-CAH) is readily hydrolyzed by the enzyme to release 5-Cl-1-anthraquinonylhydrazine (CAH). The last compound is simultaneously coupled to an aromatic aldehyde, e.g. 4-nitrobenzaldehyde (p-NBA) or piperonal (3,4-methylenedioxybenzaldehyde; PPL), to form a highly insoluble deeply colored hydrazone, marking the enzyme locations. Using the new method, DPP II is successfully localyzed in tissue sections from different rat organs.

New method for the histochemical demonstration of dipeptidyl aminopeptidase I activity using a novel anthraquinoyl hydrazide substrate

A new method for the histochemical localization of dipeptidyl aminopeptidase I (DPP I, cathepsin C), based on a newly synthesized substrate-Gly-L-Phe-5-chloro-1-anthraquinoyl hydrazide.HCl (Gly-Phe-CAH), is proposed. The enzyme activity liberates 5-chloro-1-anthraquinoyl hydrazine (CAH)--a water-insoluble brown-reddish compound, which precipitates on the enzyme locations. The primary reaction product reacts simultaneously or, otherwise, by post-coupling with p-anisaldehyde (p-AA), thus converting to the reddish-violet amorphous hydrazone--the final reaction product. The validity of enzyme localization is thus assured by the insolubility of the primary reaction product and does not depend on the rate of the second reaction step. The enzyme studied is successfully localized in different rat organs using the newly proposed technique.