Effects of glucagon as a neurohormone on the central nervous system and glucose homeostasis

OBJECTIVE

This study aimed to elucidate the possible effects of the acute/long-term infusion of glucagon in the brain as the regulatory role on the endocrine secretions of the pancreas.

MATERIALS AND METHODS

Ninety male Wistar albino rats were divided as Control, artificial Cerebrospinal Fluid (aCSF) (120 min), Glucagon (120 min), pancreatic denervation (PD)+aCSF (120 min), PD+Glucagon (120 min), aCSF (7 days), Glucagon (7 days), PD+aCSF (7 days) and PD+Glucagon (7 days). Glucagon and solvent (aCSF) were administered after pancreatic denervation (PD) by Hamilton syringe and osmotic mini pump (1 µg/10 µl/min) in the third ventricle of the brain.

RESULTS

Acute intracerebroventricular (icv) administration of glucagon resulted in an elevation of glucagon levels and a concurrent reduction in blood glucose levels. Furthermore, in both the PD+aCSF (7 days) and PD+Glucagon (7 days) groups, there was a notable decrease in propiomelanocortin (POMC) and agouti-related protein (AgRP). Significant changes were observed in feed consumption and body weight, as well as pancreatic glucagon levels, with a simultaneous decrease in insulin levels in the PD (7 days), Glucagon (7 days), and PD+Glucagon (7 days) groups. These alterations were statistically significant when compared to the control group (p<0.05).

CONCLUSIONS

The research outcomes established that pancreas-secreted glucagon functions as a neurohormone within the brain, activating central pathways linked to blood glucose regulation. The presence of glucagon led to a decrease in POMC levels. Surprisingly, this reduction in POMC resulted in the suppression of AgRP. Contrary to expectations, the suppression of AgRP led to an increase in food intake rather than a decrease. As already highlighted in the results section, it was emphasized that POMC may play a more significant role than AgRP in influencing feeding behavior.

Effect of Discontinuation of Renin Angiotensin-System Inhibitors in Patients With Advanced Chronic Kidney Disease: A Meta-Analysis

Renin-angiotensin system inhibitors (RAS) inhibitors include angiotensin receptor blockers (ARBs) and angiotensin-converting enzyme (ACE) inhibitors decrease proteinuria, progression of chronic kidney disease (CKD), and protect against heart failure hospitalizations and cardiovascular events. There is uncertainty about the appropriate time for discontinuing ARB and ACE inhibitor treatment in patients with low estimated glomerular filtration rate (eGFR). In the present meta-analysis, we examined the effect of RAS inhibitor discontinuation on clinical outcomes in patients with advanced CKD compared to the continuation of RAS inhibitors. Two authors conducted electronic database searches in PubMed, the Cochrane Library, and Excerpta Medica Database (EMBASE) for relevant studies published from the inception of the databases to March 15th, 2023, using the following combination of keywords or key terms: "Renin-angiotensin-system," "angiotensin-converting-enzyme inhibitors", "Angiotensin receptor blockers," and "advanced chronic kidney disease." Primary outcomes assessed in this meta-analysis included cardiovascular events. Secondary outcomes assessed included all-cause mortality and end-stage kidney disease (ESKD). A total of four studies were included in this meta-analysis. The pooled analysis showed that cardiovascular events were significantly higher in patients in the discontinuation group compared to the continuation group (HR: 1.38, 95% CI: 1.21-1.58), ESKD was also significantly higher in the discontinuation group (HR: 1.29, 95% CI: 1.18-1.41). No significant differences were reported between the two groups in all-cause mortality. In conclusion, our meta-analysis provides evidence that continuation of RAS inhibitors could be beneficial in patients with advanced CKD, as it is associated with less risk of cardiovascular events and ESKD.

Remote patient monitoring at home using ambient sensors: a systematic review

Background

The world population is ageing, and their health needs imply substantial demands on health systems. Remote Patient Monitoring (RPM) may help elderly patients live independently in their homes for longer. The essence of RPM is the continuity of use, which is challenging for wearable devices and patient-led technologies. Unobtrusive (ambient) sensors could be an innovative solution, such as motion detectors and similar technologies. This study aims to review the evidence on the effect of ambient sensors on healthcare use by the elderly.

Methods

This is a systematic review for narrative synthesis, searching five databases, Medline, Embase, CINHAL, Scopus and Web of Science, on 21 Feb 2022 without setting a lower time limit. No restrictions on the design of studies were applied. A meta-analysis was not feasible due to the heterogenicity of the studies.

Results

Out of 5,653 search results, 180 studies were subjected to full-text review, of which 6 studies were included in the final synthesis. All the included studies were conducted in the USA. Four studies assessed the technology's cost-efficiency, while only one reported significant cost savings. One study reported a significant reduction in hospital days and visits to a physician among the users. Using ambient sensors was associated with an increased length of stay in facilities where the elderly can live independently, including at home. The impact on the number of hospitalisations or emergency room visits was unclear.

Conclusions

Our review identified limited evidence on the effect of ambient sensors on healthcare use by the elderly. The potential has been demonstrated for ambient sensor technologies to result in cost savings; however, further research is needed to assess the impact on health outcomes.

Key messages

Range of factors in the reduction of hyperhydricity associated with in vitro shoots of Salvia santolinifolia Bioss

Hyperhydricity is a serious physiological disorder and affects In vitro propagation of many plants and as well of Salvia santolinifolia. The donor material to initiate the in vitro culture was the callus taken from the in vitro shoots produced on Murashig and Skoogs (MS) medium at 4.0 mg/l BA. This callus formed numerous hyperhydric shoots on culturing upon the medium of the same composition. The aim was to systematically evaluate the effect of cytokinins (Benzyladnine (BA) and N6-(-2-isopentenyl) adenine (2iP), culture vessels magnitude, medium solidification, source of nitrogen and calcium chloride for the alleviation of hyperhydricity. In the tissue cultures of S. santolinifolia BA and 2iP induced severe hyperhydricity, when other factors i.e. culture vessels magnitude and a suitable concentration of agar, ammonium nitrate (NH4NO3), potassium nitrate (KNO3) & calcium chloride (CaCl2.2H2O) were not optimized. After 30 days' culture, we observed 83.82% hyperhydric shoots at increased level (1.5 mg/l 2iP) and 81.59% at decreased levels (1.0 mg/l 2iP). On the other hand, hyperhydricity percentage at decreased (0.4%) and at increased (0.8%) levels of agar were 72.37% and 39.08%, respectively. MS medium modification with NH4NO3 (412 mg/l), KNO3 (475 mg/l) and CaCl2.2H2O (880 mg/l) was found the best medium to reduced hyperhydricity (23.6%).

Study of human knowledge and attitude toward urban birds in Faisalabad city, Pakistan

Birds are very valuable indicators of species richness and endemic patterns in a specified ecosystem, which eventually help the scientist to measure the environmental degradation. The aim of present study was to know human knowledge and attitude toward urban birds in Faisalabad city, Pakistan. The study conducted in four consecutive months: November 2019 to February 2020. Population of birds was noted from eight residential towns of Faisalabad city, data were collected through questionnaire. Faisalabad has a reasonably large population of birds and present data show that, there is a significant difference between favorite bird of residential areas and institutions. The pigeon received the most likeness in bird population among residential area residents, while the myna received the least. The most popular bird in Faisalabad institutions was the sparrow, while the least popular bird was the common myna. Bird adaptation percentage of residential areas and institutional areas of Faisalabad was the highest for parrot and sparrow respectively. People in residential areas and institutions, on the other hand, adapted least to common myna. It is concluded that people of the study area like birds and offered food and high population of birds are present in study area.

Sex-based differences in clinical outcomes and resource utilization of type 2 myocardial infarction

Background

Sex-based differences in clinical outcomes have been previously well described in type 1 myocardial infarction (MI). However, type 2 MI is common in contemporary practice with scarce data regarding sex-based differences of clinical outcomes and resource utilization.

Purpose

To examine the association of sex category with clinical outcomes and resource utilization in hospitalizations with type 2 MI.

Methods

The Nationwide Readmission Database 2018 was queried for hospitalizations within the United States with type 2 MI using The International Classification of Diseases, Tenth Revision (ICD-10) diagnosis code I21.A1. Comorbidities and outcomes were identified using the corresponding ICD-10 codes. Complex samples multivariable logistic and linear regression models were used to determine the association between type 2 MI and outcomes (in-hospital mortality, index length of stay [LOS], hospital costs, discharge to nursing facility, and 30-day all-cause readmissions) in females compared to males with type 2 MI.

Results

A total of 252,641 hospitalizations [119,783 (47.4%) females and 132,858 (52.6%) males] were included in this analysis. Females with type 2 MI were more likely to be older (72.8 years vs. 69.7 years; P&lt;0.001), admitted on the weekend (26.5% vs. 25.9%; P=0.02), and have a higher prevalence of chronic pulmonary disease (35.6% vs. 32.0%; P&lt;0.001), obesity (17.9% vs. 15.7%; P&lt;0.001), neurological disorders (22.9% vs. 22.3%; P=0.02), deficiency anemias (7.5% vs. 6.6%; P&lt;0.001), and hypothyroidism (22.1% vs. 10.1%; P&lt;0.001) compared to males with type 2 MI. Female with type 2 MI was associated with lower in-hospital mortality, shorter LOS, less hospital costs, and increased nursing home discharge compared to males with type 2 MI. Females and males with type 2 MI had similar rates of 30-day all-cause readmission [Table 1].

Conclusion

Among type 2 MI hospitalizations, females have lower in-hospital mortality, less hospitalization cost, shorter LOS, but increased rates of nursing home discharge compared to males. Thirty-day all-cause readmission was similar between males and females with type 2 MI.

Funding Acknowledgement

Type of funding sources: None.

Molecular Epidemiology of Plasmodium species in Conflicted Federally Administered Tribal Area (FATA) Pakistan

Military conflicts have been significant obstacles in detecting and treating infectious disease diseases due to the diminished public health infrastructure, resulting in malaria endemicity. A variety of violent and destructive incidents were experienced by FATA (Federally Administered Tribal Areas). It was a struggle to pursue an epidemiological analysis due to continuing conflict and Talibanization. Clinical isolates were collected from Bajaur, Mohmand, Khyber, Orakzai agencies from May 2017 to May 2018. For Giemsa staining, full blood EDTA blood samples have been collected from symptomatic participants. Malaria-positive microscopy isolates were spotted on filter papers for future Plasmodial molecular detection by nested polymerase chain reaction (nPCR) of small subunit ribosomal ribonucleic acid (ssrRNA) genes specific primers. Since reconfirming the nPCR, a malariometric study of 762 patients found 679 positive malaria cases. Plasmodium vivax was 523 (77%), Plasmodium falciparum 121 (18%), 35 (5%) were with mixed-species infection (P. vivax plus P. falciparum), and 83 were declared negative by PCR. Among the five agencies of FATA, Khyber agency has the highest malaria incidence (19%) with followed by P. vivax (19%) and P. falciparum (4.1%). In contrast, Kurram has about (14%), including (10.8%) P. vivax and (2.7%) P. falciparum cases, the lowest malaria epidemiology. Surprisingly, no significant differences in the distribution of mixed-species infection among all five agencies. P. falciparum and P. vivax were two prevalent FATA malaria species in Pakistan's war-torn area. To overcome this rising incidence of malaria, this study recommends that initiating malaria awareness campaigns in school should be supported by public health agencies and malaria-related education locally, targeting children and parents alike.

Diversity, distribution and relative abundance of the mosquito fauna (Diptera: Culicidae) of Malakand and Dir Lower, Pakistan

The present study was conducted to evaluate the diversity, distribution (C) and relative abundance (RA) of the mosquito fauna (Diptera: Culicidae) of Malakand and Dir Lower, Pakistan. Collection of specimens (n = 1087) was made during September 2018 to July 2019 at six different habitats including freshwater bodies, rice fields, animal sheds, indoors, drains and sewage waters. Specimens were collected through light traps, pyrethrum spray, aspirators and nets and subsequently killed, preserved and then arranged in entomological boxes for identification. Three genera were identified namely Culex, Anopheles and Aedes. A total of fourteen species were identified namely: Cx. quinquefasciatus (Say, 1823), An. stephensi (Liston, 1901), Cx. tritaeniorhynchus (Giles, 1901), Ae. vittatus (Bigot, 1861), An. maculatus (Theobald, 1901), An. fluviatilis (James, 1902), Cx. vishnui (Theobald, 1901), Ae. aegypti (Linnaeus, 1762) An. subpictus (Grassi, 1899), An. dthali (Patton, 1905), An. culicifascies (Giles, 1901), An. pallidus (Theobald, 1901), Ae. albopictus (Skuse, 1894) and An. annularis (van der Wulp, 1884). Cx. quinquefasciatus was found constantly distributed in the study area with RA = 16.5% and C = 100%. An. annularis was found as a satellite species, sporadically distributed in the study area having RA = 0.9% and C = 17%. Diversity indices of mosquitoes in the studied habitats were found as, Shannon-Wiener Index (2.415), Simpson Index (9.919), Fisher's Index (2.269) and Margalef's Index (1.859). A statistically significant difference was recorded in mosquito diversity in the six habitats (Kruskal-Wallis, chi-squared, H = 17.5, df = 5, P = 0.003 at α = 0.05). The present study encompasses mosquito fauna of Malakand, Pakistan with respect to diversity, relative abundance and distribution in diverse habitats and all seasons of the year. This will assist scientists working in various fields related with epidemiology, medical and veterinary entomology, ecology and allied areas of biological sciences.

Case Report

BACKGROUND

Thyroid hormone resistance (RTH) is defined as a decrease in response to thyroid hormones in the target tissue. Most patients present with nonspecific findings. In this article, we aimed to represent a 22-year-old female patient who presented with palpitation, fatigue, and heat intolerance. She was thought to have thyroid hormone resistance and her genetic examination revealed NM_001128177.1 (THRβ): c.1034G > A (p.Gly345Asp) pathogenic variation in the THRβ gene.

CASE REPORT

A 22-year-old female patient presented with complaints of fatigue, heat intolerance and palpitations. She was taking Propranolol twice daily at admission. Her family history revealed hypothyroidism in her grandmother. Her physical examination results were as follows: height 160 cm, weight 65 kg, body mass index 25.4kg/m², body temperature 36.5°C, respiratory rate 18/min, heart rate 86 beats/min, blood pressure 120/80 mmHg. Her palms were sweaty. The heart sounds were normal, and no heart murmur was auscultated. The laboratory results were TSH: 5.31uU/mL, fT3: 6.83 pg/mL, and fT4: 2.43 ng/dL. THRβ gene mutation analysis was requested for our patient whose clinical history and laboratory results were compatible with thyroid hormone resistance. The pathogenic variation NM_001128177.1(THRβ):c.1034G>A (p.Gly345Asp) was detected after analysis.

CONCLUSION

A diagnosis of RTH requires high clinical suspicion and a genetic mutation analysis should be requested in the case of clinical suspicion. In this way, unnecessary anti-thyroid treatment can be prevented.

Evaluation of sulfadimidine, amprolium and triquen to treat coccidiosis in wild pigeons

Coccidiosis remains one of the major problems in poultry all over the world. Very limited data on anticoccidial drugs in wild pigeons is available. The current study was aimed to understand the comparative efficacy of sulfadimidine, amprolium and triquen in wild pigeons of Dir district, Pakistan suffering from coccidiosis. The faecal matter of wild pigeons were purchased from the local market for coccidian infection. Results revealed that 88.8% (16/18) were found infected with Eimeria spp. Three positive groups were treated with sulfadimidine (0.2mg/L), amprolium (25mg/L) and triquen. Sulfadimidine was most effective (45%) followed by amprolium (44.6%) while triquen (24.0%) showed less effectiveness against coccidiosis in pigeons. Number of oocysts were 79, 81 and 80 before treatment and 60, 44 and 44 after treatment with sulfadimidine, amprolium and triquen respectively. This study showed that sulphadimidine, amprolium and triquen could not significantly reduce the coccidiosis in pigeons. Further studies are required to clear the mechanism of anti-coccidial drugs in wild pigeons.

Urinary incontinence in women aged 40 and older: Its prevalence, risk factors, and effect on quality of life

Background

Urinary incontinence (UI) paves the way for many health problems ranging from discomforts of continuous wetness and irritation to social isolation and depression in women.

Aim

The aim of this study was to determine the prevalence of UI in women aged 40 and older as well as its risk factors and also its effect on quality of life.

Materials and Methods

This cross-sectional study was conducted with 286 women included in the sample. Subjects were selected randomly. The data were collected using a questionnaire, which was prepared by the researchers, and the Incontinence Quality of Life Questionnaire. The data were analyzed using number, percentage, mean, Chi-square test, and binary logistic regression analysis in the SPSS program.

Results

It was found that 86 (30.1%) of the women experienced the symptom of UI. The women had mostly the mixed UI. The correlations between UI and age, educational level, status of employment, the presence of chronic diseases, chronic constipation, difficult birth history, and state of menopause were significant. Total mean score of the women with UI for the Incontinence Quality of Life Questionnaire was 73.62 ± 24.36 and the most affected domain of the quality of life field was social embarrassment.

Conclusions

In the present study, it was found that UI was prevalent in Turkish women and impaired their quality of life. The results can help to provide education and counseling services to women in a society-sensitive manner.

Potential of essential oil combinations for surface and air disinfection

In this study, it was aimed to develop a novel disinfectant from various essential oils containing active components with antimicrobial activity. The mixture of oregano, cinnamon and clove oils (1 : 1 : 1) with 10% oil concentration (SOM) was used as potential disinfectant on various areas and showed the highest antimicrobial activity among oil combinations tested. SOM reduced the numbers of total mesophilic aerobic bacteria (TMAB; 2·27 log CFU per 25 cm² ) and Escherichia coli (4·60 log CFU per 25 cm² ) under the detection limits. Application of SOM (1, 2, 3, 4 and 6%) into incubators reduced TMAB and mould-yeast counts of incubator air by 82·9 and 100% respectively. SOM application (3%) into ambient air also reduced its TMAB and mould-yeast counts by 92 and 84·6% respectively. While ethanol is commonly used for the disinfection of environments, equipment and surfaces, SOM is an important alternative that may also be used for the disinfection of various surfaces as well as air.

Using in silico modelling and FRET-based assays in the discovery of novel FDA-approved drugs as inhibitors of MERS-CoV helicase

A Förster resonance energy transfer (FRET)-based assay was used to screen the FDA-approved compound library against the MERS-CoV helicase, an essential enzyme for virus replication within the host cell. Five compounds inhibited the helicase activity with submicromolar potencies (IC₅₀, 0.73-1.65 µM) and ten compounds inhibited the enzyme with micromolar potencies (IC₅₀, 19.6-502 µM). The molecular operating environment (MOE) was used to dock the identified inhibitors on the MERS-CoV helicase nucleotide binding. Strong inhibitors docked well in the nucleotide-binding site and established interactions with some of the essential residues. There was a reasonable correlation between the observed IC₅₀ values and the MOE docking scores of the strong inhibitors (r ² = 0.74), indicating the ability of the in silico docking model to predict the binding of strong inhibitors. In silico docking could be a useful complementary tool used with the FRET-based assay to predict new MERS-CoV helicase inhibitors. The identified inhibitors could potentially be used in the clinical development of new antiviral treatment for MERS-CoV and other coronavirus related diseases, including coronavirus disease 2019 (COVID-19).

A Rare Case of Lithium-induced Partial Nephrogenic Diabetes Insipidus

Chronic lithium therapy in patients with bipolar disorder and other psychiatric illnesses can lead to a very common side effect of complete or partial nephrogenic diabetes insipidus. After confirmation of hypotonic polyuria, water deprivation test with desmopressin injection is used to make the diagnosis. Incomplete response to desmopressin suggests partial nephrogenic diabetes insipidus. We report a rare case of a 58-year-old patient who presented with hypernatremia and hypotonic polyuria secondary to chronic lithium therapy. She was diagnosed with partial nephrogenic diabetes insipidus secondary to chronic lithium therapy and was treated with amiloride resulting in improvement.

Towards characterization of photo-excited electron transfer and catalysis in natural and artificial systems using XFELs

The ultra-bright femtosecond X-ray pulses provided by X-ray Free Electron Lasers (XFELs) open capabilities for studying the structure and dynamics of a wide variety of biological and inorganic systems beyond what is possible at synchrotron sources. Although the structure and chemistry at the catalytic sites have been studied intensively in both biological and inorganic systems, a full understanding of the atomic-scale chemistry requires new approaches beyond the steady state X-ray crystallography and X-ray spectroscopy at cryogenic temperatures. Following the dynamic changes in the geometric and electronic structure at ambient conditions, while overcoming X-ray damage to the redox active catalytic center, is key for deriving reaction mechanisms. Such studies become possible by using the intense and ultra-short femtosecond X-ray pulses from an XFEL, where sample is probed before it is damaged. We have developed methodology for simultaneously collecting X-ray diffraction data and X-ray emission spectra, using an energy dispersive spectrometer, at ambient conditions, and used this approach to study the room temperature structure and intermediate states of the photosynthetic water oxidizing metallo-protein, photosystem II. Moreover, we have also used this setup to simultaneously collect the X-ray emission spectra from multiple metals to follow the ultrafast dynamics of light-induced charge transfer between multiple metal sites. A Mn-Ti containing system was studied at an XFEL to demonstrate the efficacy and potential of this method.

Thymoquinone is protective against 2,3,7,8-tetrachlorodibenzo-p-dioxin induced hepatotoxicity

We investigated changes in rat liver tissues following administration of thymoquinone (TQ) against 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced hepatotoxicity. Fifty rats were assigned randomly to five groups of 10 as follows: control, corn oil, TCDD, TQ and TCDD + TQ. Biochemical and histopathological analyses were conducted on liver tissue. We found that 30 day TCDD administration caused histopathological changes in liver including thickening of Glisson's capsule, intracytoplasmic vacuolization in hepatocytes, sinusoidal dilation, vascular and sinusoidal congestion and inflammatory cell infiltration. TCDD administration increased malondialdehyde (MDA), total oxidant status (TOS), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) levels in rat liver tissue and reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT) and total antioxidant status (TAS) levels compared to all other groups. In the TQ treated group, GSH, SOD, CAT and TAS levels increased compared to all other groups. MDA, TOS, ALT, AST, ALP levels decreased compared to all other groups. Our histological findings were consistent with the biochemical findings. The oxidative and histologic effects of TCDD were eliminated by TQ treatment. TCDD administration caused oxidative stress in rat liver and TQ administered with TCDD prevented TCDD induced hepatotoxicity. TQ could be considered an alternative anti-TCDD toxicity agent.

Evaluation of nutritional parameters of hemodialysis patients

BACKGROUND

This study was performed to investigate nutritional parameters of hemodialysis patients by using anthropometric and biochemical measurements.

METHODS

Data from the last 6 months of 22 adult hemodialysis patients with a mean age of 61 ± 14 years were analyzed retrospectively. Dialysis vintage, normalized protein catabolic rate (nPCR), serum biochemical parameters, mid arm muscle circumference (MAMC) were determined as mean and standard deviation. Correlations between the variables were computed by coefficient p of Pearson.

RESULTS

We found significant positive correlations: age of patients versus C-reactive protein, MAMC versus LDL-Cholesterol, MAMC versus body mass index, albumin versus hemoglobin. There were also significant negative correlations: age versus serum creatinine, age versus albumin, age versus intact parathyroid hormone (iPTH), dialysis vintage versus MAMC.

CONCLUSION

In conclusion, age seem to be negatively associated with iPTH and albumin. As dialysis vintage increases, muscle mass seems to decrease.

Effects of dexmedetomidine or methylprednisolone on inflammatory responses in spinal cord injury

BACKGROUND

The aim of this study was to compare the anti-inflammatory response of methylprednisolone and the alpha2-agonist dexmedetomidine in spinal cord injury (SCI).

METHODS

Twenty-four male adult Wistar albino rats, weight 200-250 g, were included in the study. The rats were divided into four groups as follows: the control group (n: 6) received only laminectomy; the SCI group (n: 6) with trauma alone; the SCI+methylprednisolone group (n: 6) with trauma and 30 mg/kg methylprednisolone, followed by a maintenance dose of 5.4 mg/kg/h; and the SCI+dexmedetomidine group (n: 6) with trauma and 10 microg/kg dexmedetomidine treatment intraperitoneally. Twenty-four hours after the trauma, spinal cord samples were taken for histopathological examination and serum samples were collected for interleukin-6 (IL-6) and tumor necrosis factor (TNF)-alpha measurement.

RESULTS

TNF-alpha (P=0.009) and IL-6 (P=0.009) levels were significantly increased in the SCI group. TNF-alpha and IL-6 levels were significantly decreased with methylprednisolone (P=0.002, 0.002) and dexmedetomidine (P=0.002, 0.009) treatment, respectively. Methylprednisolone and dexmedetomidine treatment reduced neutrophils' infiltration in SCI.

CONCLUSIONS

The current study does not clarify the definitive mechanism by which dexmedetomidine decreases inflammatory cytokines but it is the first study to report the anti-inflammatory effect of dexmedetomidine in SCI. Further studies are required to elucidate the effects of dexmedetomidine on the inflammatory response.

Phenotype-dependent susceptibility of cholinergic neuroblastoma cells to neurotoxic inputs

A preferential loss of brain cholinergic neurons in the course of Alzheimer's disease and other encephalopathies is accompanied by a proportional impairment of acetyl-CoA synthesizing capacity in affected brains. Particular susceptibility of cholinergic neurons to neurodegeneration might results from insufficient supply of acetyl-CoA for energy production and acetylcholine synthesis in these conditions. Exposure of SN56 cholinergic neuroblastoma cells to dibutyryl cAMP and retinoic acid for 3 days caused their morphologic differentiation along with the increase in choline acetyltransferase activity, acetylcholine content and release, calcium content, and the expression of p75 neurotrophin receptors. Acetyl-CoA content correlated inversely with choline acetyltransferase activity in different lines of SN56 cells. In differentiated cells, aluminum (1 mM), amyloid beta(25-35) (0.001 mM), and sodium nitroprusside (1 mM), caused much greater decrease of pyruvate dehydrogenase and choline acetyltransferase activities and cell viability than in nondifferentiated ones. Aluminum (1 mM) aggravated suppressory effects of amyloid beta on choline acetyltransferase and pyruvate dehydrogenase activities and viability of differentiated cells. Similar additive inhibitory effects were observed upon combined exposure of differentiated cells to sodium nitroprusside and amyloid beta(25-35). None or much smaller suppressory effects of these neurotoxins were observed in nondifferentiated cells. Increase in the fraction of nonviable differentiated cells positively correlated with losses of choline acetyltransferase, pyruvate dehydrogenase activities, and cytoplasmic cytochrome c content in different neurotoxic conditions. These data indicate that highly differentiated cholinergic neurons may be more susceptible to aluminum and other neurotoxins than the nondifferentiated ones due to relative shortage of acetyl-CoA, increased content of Ca(2+), and expression of p75 receptors, yielding increase in cytoplasmic cytochrome c and subsequently grater rate of death of the former ones.

The effects of VEGF and VEGFR-2 on survival in patients with gastric cancer

Prognostic criteria of the patients with gastric cancer are of critical importance in their management and follow-up. Angiogenesis is essential for the growth and metastasis of solid tumors. Tumor angiogenesis is a multi-step interactive process, and vascular endothelial growth factor (VEGF) and its receptors have a major role in tumor angiogenesis. Thus, we investigated the effects of VEGF and VEGF receptor-2 (VEGFR-2, KDR) on survival in patients with gastric cancer. We analyzed 51 patients who had undergone total or subtotal gastric resection. The patients were divided into two subgroups according to their VEGF and VEGFR-2 (KDR) expression in resected specimens. There was no significant difference between sex, surgical method, lymph node metastasis, serosal invasion, hematogenous metastasis, chemotherapy status of the two subgroups. Mean follow-up time was 24.22 +/- 15.38 months. We found the survival rates of the patients with VEGF positive tumors to be significantly shorter than those of the patients with VEGF negative tumors. There was no significant difference between the survival rates of VEGFR-2 (KDR) positive and negative patients. It was established that the presence of VEGF expression was significantly associated with the short survival rates in patients with gastric cancer. Analysis of VEGF expression in resected specimens may provide additional guidance in determining the prognosis of such patients. If more extensive studies confirm the significance of VEGF and its receptors in gastric cancer, new therapeutic approaches targeting VEGF and its receptors may be considered in gastric cancer management.

Ionization characteristics and chemical influences of aspartic acid residue 158 of papain and caricain determined by structure-related kinetic and computational techniques: multiple electrostatic modulators of active-centre chemistry

The pK(a) of (Asp(158))-CO(2)H of papain (EC 3.4.22.2) was determined as 2.8 by using 4-chloro-7-nitrobenzofurazan (Nbf-Cl) as a reactivity probe targeted on the thiolate anion component of the Cys(25)/His(159) nucleophilic-acid/base motif of the catalytic site. The possibility of using Nbf-Cl for this purpose was established by modelling the papain-Nbf-Cl Meisenheimer intermediate by using QUANTA/CHARMM and performing molecular orbital calculations with MOPAC interfaced with Cerius 2. A pH-dependent stopped-flow kinetic study of the reaction of papain with Nbf-Cl established that the striking rate maximum at pH 3 results from reaction in a minor ionization state comprising (Cys(25))-S(-)/(His(159))-Im(+)H (in which Im represents imidazole) produced by protonic dissociation of (Cys(25))-SH/(His(159))-Im(+)H with pK(a) 3.3 and (Asp(158))-CO(2)H. Although the analogous intermediate in the reaction of caricain (EC 3.4.22.30) with Nbf-Cl has similar geometry, the pH-k profile (k being the second-order rate constant) lacks a rate maximum under acidic conditions. This precludes the experimental determination of the pK(a) value of (Asp(158))-CO(2)H of caricain, which was calculated to be 2.0 by solving the linearized Poisson-Boltzmann equation with the program UHBD ('University of Houston Brownian dynamics'). A value lower than 2.8 had been predicted by consideration of the hydrogen-bonded networks involving Asp(158) and its microenvironments in both enzymes. The difference between these pK(a) values (values not previously detected in reactions of either enzyme) accounts for the lack of the rate maximum in the caricain reaction and for the differences in the electronic absorption spectra of the two S-Nbf-enzymes under acidic conditions. The concept of control of cysteine proteinase activity by multiple electrostatic modulators, including (Asp(158))-CO(2)(-), which modifies traditional mechanistic views, is discussed.

The kinetic basis of a general method for the investigation of active site content of enzymes and catalytic antibodies: first-order behaviour under single-turnover and cycling conditions

The theoretical foundation has been laid for the investigation of catalytic systems using first-order kinetics and for a general kinetic method of investigation of the active site content, E(a), of enzymes, catalytic antibodies, and other enzyme-like catalysts. The method involves a combination of steady-state and single-turnover kinetics to provide Vmax and Km and k(lim)(obs) and K(app)(m), respectively. The validity of the method is shown to remain valid for two extensions of the simple two-step enzyme catalysis model (a) when the catalyst preparation contains molecules (Eb) that bind substrate but fail to catalyse product formation and (b) when the catalyst itself binds substrate non-productively as well as productively. The former is a particularly serious complication for polyclonal catalytic antibodies and the latter a potential complication for all catalysts. For the simple model and for (b) Vmax/k(lim)(obs) provides the value of [Ea]T and for (a) its upper limit. This can be refined by consideration of the relative values of Km and the equilibrium dissociation constant of EbS. For the polyclonal catalytic antibody preparation investigated, the fact that K(app/m) > Km demonstrates for the first time the presence of a substrate-binding but non-catalytic component in a polyclonal preparation. First-order behaviour in catalytic systems occurs not only with a large excess of catalyst over substrate but also with lower catalyst/substrate ratios, including the equimolar condition, when K(app)(m) >> [S]0, a phenomenon that is not widely appreciated.

Therapeutic potential of platelet-activating factor antagonism in the management of myocardial infarction

BACKGROUND

Antagonists of platelet-activating factor (PAF) reduce myocardial postischemia reperfusion injury when given before the onset of ischemia. However, the effects of PAF antagonists when administered at a clinically modelled time (during ischemia but before reperfusion) are controversial. Moreover, the extended survival (eight day) and the characteristics of scar formation after treatment with PAF antagonists have not been investigated.

OBJECTIVES

To determine the therapeutic potential of PAF antagonist TCV-309 for the treatment of regional myocardial ischemia-reperfusion injury; and to determine the effects of TCV-309 on cardiovascular recovery, evolution of scar formation and survival eight days after a myocardial infarction treated with reperfusion.

ANIMALS AND METHODS

Swine underwent regional myocardial ischemia for 60 mins by ligation of the left anterior descending coronary artery, followed by reperfusion for eight days. The treated group (n=7) received PAF antagonist TCV-309 (0.1 mg/kg) 45 mins after ligation; the untreated group (n=7) received vehicle only.

RESULTS

Untreated animals experienced significantly (P<0.001) lower systemic arterial blood pressure during the reperfusion period than animals treated with TCV-309. Furthermore, untreated animals required significantly more (P<0.01) antiarrhythmic and inotropic support. Only two of seven animals in the untreated group survived, which was significantly different (P<0.05) from the six of seven treated animals that survived for eight days. Morphometric analyses did not show differences between groups in the characteristics of scar formation following reperfusion for eight days.

CONCLUSIONS

PAF antagonist TCV-309 improves survival and reduces cardiovascular dysfunctions associated with regional myocardial ischemia reperfusion injury when administered at a clinically modelled time.

A general kinetic approach to investigation of active-site availability in macromolecular catalysts

A potentially general kinetic method for the investigation of active-site availability in preparations of macromolecular catalysts was developed. Three kinetic models were considered: (a) the conventional two-step model of enzyme catalysis, where the preparation contains only active catalyst (E(a)) and inert (i.e. non-binding, non-catalytic) material (E(i)); (b) an extension of the conventional model (a) involving only E(a) and E(i), but with non-productive binding to E(a) (in addition to productive binding); (c) a model in which the preparation contains also binding but non-catalytic material (E(b)), predicted to be present in polyclonal catalytic antibody preparations. The method involves comparing the parameters V(max) and K(m) obtained under catalytic conditions where substrate concentrations greatly exceed catalyst concentration with those (klim/obs, the limiting value of the first-order rate constant, k(obs), at saturating concentrations of catalyst; and Kapp/m) for single-turnover kinetics, in which the reverse situation obtains. The active-site contents of systems that adhere to model (a) or extensions that also lack E(b), such as the non-productive binding model (b), may be calculated using [E(a)](T)=V(max)/klim/obs. This was validated by showing that, for alpha-chymotrypsin, identical values of [E(a)](T) were obtained by the kinetic method using Suc-Ala-Ala-Pro-Phe-4-nitroanilide as substrate and the well-known 'all-or-none' spectroscopic assay using N-trans-cinnamoylimidazole as titrant. For systems that contain E(b), such as polyclonal catalytic antibody preparations, V(max)/klim/obs is more complex, but provides an upper limit to [E(a)](T). Use of the kinetic method to investigate PCA 271-22, a polyclonal catalytic antibody preparation obtained from the antiserum of sheep 271 in week 22 of the immunization protocol, established that [E(a)](T) is less than approx. 8% of [IgG], and probably less than approx. 1% of [IgG].

A classical enzyme active center motif lacks catalytic competence until modulated electrostatically

The cysteine proteinase superfamily is a source of natural structural variants of value in the investigation of mechanism. It has long been considered axiomatic that catalytic competence of these enzymes mirrors the generation of the ubiquitous catalytic site imidazolium-thiolate ion pair. We here report definitive evidence from kinetic studies supported by electrostatic potential calculations, however, that at least for some of these enzymes the ion pair state which provides the nucleophilic and acid-base chemistry is essentially fully developed at low pH where the enzymes are inactive. Catalytic competence requires an additional protonic dissociation with a common pKa value close to 4 possibly from the Glu50 cluster to control ion pair geometry. The pH dependence of the second-order rate constant (k) for the reactions of the catalytic site thiol groups with 4,4'-dipyrimidyl disulfide is shown to provide the pKa values for the formation and deprotonation of the (Cys)-S-/(His)-Im+H ion pair state. Analogous study of the reactions with 2,2'-dipyridyl disulfide reveals other kinetically influential ionizations, and all of these pKa values are compared with those observed in the pH dependence of kcat/Km for the catalyzed hydrolysis of N-acetylphenylalanylglycine 4-nitroanilide. The discrepancy between the pKa value for ion pair formation and the common pKa value close to 4 related to generation of catalytic activity is particularly marked for ficin (pKa 2.49 +/- 0.02) and caricain (pKa 2.88 +/- 0.02) but exists also for papain (pKa 3.32 +/- 0.01).

Evidence for conformational changes in Escherichia coli porphobilinogen deaminase during stepwise pyrrole chain elongation monitored by increased reactivity of cysteine-134 to alkylation by N-ethylmaleimide

Porphobilinogen deaminase from Escherichia coli becomes progressively more susceptible to inactivation by the thiophilic reagent N-ethylmaleimide (NEM) as the catalytic cycle proceeds through the enzyme-intermediate complexes ES, ES2, ES3, and ES4. Site-directed mutagenesis of potentially reactive cysteines has been used to identify cysteine-134 as the key residue that becomes modified by the reagent and leads to inactivation. Since cysteine-134 is buried at the interface between domains 2 and 3 of the E. coli deaminase molecule, the observations suggest that a stepwise conformational change occurs between these domains during each stage of tetrapyrrole assembly. Interestingly, mutation of the invariant active-site cysteine-242 to serine leads to an enzyme with up to a third of the catalytic activity found in the wild-type enzyme. Electrospray mass spectrometry indicates that serine can substitute for cysteine as the dipyrromethane cofactor attachment site.