Concentration gradient effects of sodium and lithium ions and deuterium isotope effects on the activities of H+-ATP synthase from chloroplasts.

We explored the concentration gradient effects of the sodium and lithium ions and the deuterium isotope's effects on the activities of H(+)-ATP synthase from chloroplasts (CF(0)F(1)). We found that the sodium concentration gradient can drive the ATP synthesis reaction of CF(0)F(1). In contrast, the lithium ion can be an efficient enzyme-inhibitor by blocking the entrance channel of the ion translocation pathway in CF(0). In the presence of sodium or lithium ions and with the application of a membrane potential, unexpected enzyme behaviors of CF(0)F(1) were evident. To account for these observations, we propose that both of the sodium and lithium ions could undergo localized hydrolysis reactions in the chemical environment of the ion channel of CF(0). The protons generated locally could proceed to complete the ion translocation process in the ATP synthesis reaction of CF(0)F(1). Experimental and theoretical deuterium isotope effects of the localized hydrolysis on the activities of CF(0)F(1), and the energetics of these related reactions, support this proposed mechanism. Our experimental observations could be understood in the framework of the well-established ion translocation models for the H(+)-ATP synthase from Escherichia coli, and the Na(+)-ATP synthase from Propionigenium modestum and Ilyobacter tartaricus.

Intrathecally injected granulocyte colony-stimulating factor produced neuroprotective effects in spinal cord ischemia via the mitogen-activated protein kinase and Akt pathways.

Granulocyte colony-stimulating factor (G-CSF) is a potent hematopoietic factor. Recently, this factor has been shown to exhibit neuroprotective effects on many CNS injuries. Spinal cord ischemic injury that frequently results in paraplegia is a major cause of morbidity after thoracic aorta operations. In the present study, we examined the neuroprotective role of G-CSF on spinal cord ischemia-induced neurological dysfunctions and changes in the mitogen-activated protein kinase (MAPK) and Akt signaling pathways in the spinal cord. Spinal cord ischemia was induced in male Wistar rats by occluding the descending aorta with a 2F Fogarty catheter for 12 min 30 s. Immediately after ischemia surgery, the rats were administered G-CSF (10 mug) or saline by intrathecal (i.t.) injection. The rats were divided into four groups: control, ischemia plus saline, ischemia plus G-CSF and G-CSF alone. The neurological dysfunctions were assessed by calculating the motor deficit index after ischemia surgery. The expressions of MAPK and Akt were studied using Western blotting and double immunohistochemistry. First, we observed that ischemia plus i.t. G-CSF can significantly reduce the motor function defects and downregulate phospho-p38 and phospho-c-Jun N-terminal kinase protein expressions-this can be compared with the ischemia plus saline group. In addition, G-CSF inhibited the ischemia-induced activation of p38 in the astrocytes. Furthermore, we concluded that i.t. G-CSF produced a significant increase in phospho-Akt and phospho-ERK in the motor neurons and exhibited beneficial effects on the spinal cord ischemia-induced neurological defects.

Bacterial brain abscess: microbiological features, epidemiological trends and therapeutic outcomes.

BACKGROUND: Despite the advent of modern neurosurgical techniques, new antibiotics, and powerful imaging technologies, brain abscess remains a potentially fatal central nervous system infection. AIM: To determine the epidemiological trends, prognostic factors, and outcomes of bacterial brain abscess, to improve the therapeutic strategy for this disease. DESIGN: Retrospective hospital-based epidemiology study. METHODS: Over a period of 15 years (1986-2000), 123 patients were retrospectively identified as having brain abscesses at Kaohsiung Chang Gung Memorial Hospital. To compare changes over time, the appearance of disease among our patients was divided into two time periods: 1986-1993 and 1994-2000. RESULTS: The prevalence rate of brain abscesses caused by Gram-negative organisms significantly increased in the second study period. Viridans streptococci and Klebsiella pneumoniae were the two prevalent pathogens associated with haematogenous spread. Metastatic septic abscess, a devastating complication of K. pneumoniae septicaemia, frequently occurs in diabetic patients, with a high mortality rate. Viridans streptococci were the most prevalent pathogens from infection in paranasal sinusitis, but no fatality occurred. In recent years, head trauma and/or post-neurosurgical states have become important predisposing factors, and nosocomial infections also play an important role. DISCUSSION: Despite the availability of new antibiotics and the development of better neurosurgical techniques, therapeutic outcomes of brain abscess showed no significant change when comparing the two study periods, and only the presence of septic shock influenced outcome.

Changes of bilateral palmar skin temperature in transthoracic endoscopic T-2 sympathectomy.

OBJECT: Transthoracic endoscopic T-2 sympathectomy is currently the treatment of choice for palmar hyperhidrosis (PH). Intraoperative monitoring of palmar skin temperature (PST) is often used to assess the adequacy of sympathetic ablation. The aim of this study was to investigate the time course of PST changes during the operation and to determine factors involved in the sympathetic modulation of the palmar skin blood flow. METHODS: Eighty-one patients with PH underwent bilateral transthoracic endoscopic sympathectomy of T-2 in which continuous intraoperative PST monitoring was used. Palmar skin temperature data, recorded every 30 seconds throughout the operation, were plotted against time, and a graph of two PST curves was obtained in each case. A multiphasic curve pattern of great similarity was observed in nearly 70% of cases. Specific PST readings at different operative stages were collected and averaged for all cases. The trend of PST changes in response to different procedures during the operation was analyzed. It was found that unilateral procedures caused simultaneous bilateral PST alterations. In almost all cases, bilateral PST was dramatically lowered when unilateral skin incision and intercostal muscle dissection were performed. The temperature remained low until the T-2 sympathectomy was finished on one side. In addition, unilateral T-2 sympathectomy induced synchronous elevation of bilateral PST. However, the ipsilateral response was significantly stronger than that on the contralateral side. CONCLUSIONS: Although intraoperative monitoring of PST is a reliable guide for surgeons performing endoscopic transthoracic sympathectomy, it is important to realize that PST fluctuates at different stages during the operation and that surgical procedures themselves can significantly influence PST readings. The PST data recorded at specific time points, therefore, can be misleading in terms of accuracy and the completeness of ablation of the target sympathetic ganglia, especially when the sympathetic trunk or ganglia are anatomically aberrant.

Non-traumatic cerebrospinal fluid rhinorrhea indirectly caused by remote brain tumor: a case report and review of the literature.

Non-traumatic cerebrospinal fluid rhinorrhea indirectly caused by a remote brain tumor has rarely been reported. Here we describe a case of non-traumatic cerebrospinal fluid rhinorrhea that occurred as the initial symptom of a posterior falx meningioma. In addition, based on the period of occurrence of cerebrospinal fluid rhinorrhea before or after the tumor operation, we introduced a novel classification for these cases into pre-treatment and post-treatment types. The findings of the present case and the results of our literature research suggest that different treatments should be used for patients with these two types of non-traumatic cerebrospinal fluid rhinorrhea resulting from remote brain tumor. After tumor excision, patients of the pre-treatment type may receive conservative management or cerebrospinal fluid shunting, while patients of the post-treatment type need direct repair of the fistula.

Streptococcal brain abscess: analysis of clinical features in 20 patients.

BACKGROUND: To assess the clinical features and therapeutic outcomes of brain abscess caused by streptococci. METHODS: Twenty patients, 18 males and 2 females, aged 3 to 76 years, collected over a 14-year period, have been identified at Kaohsiung Chang Gung Memorial Hospital. RESULTS: Among these 20 patients, 13 had viridans streptococci infection alone, one had non-A, non-B, and non-D streptococci infection alone, and the other 6 had mixed infections each including streptococci. The locations of all of the abscesses were supratentorial. Among these patients, 18 had a single abscess and 2 had multiple abscesses. Underlying conditions were common in our patients, including head trauma, heart disease, otopharyngeal infection, and medical procedures. Nineteen patients were treated surgically and 1 was treated with antibiotics alone. Nineteen survived and 1 died, with an overall mortality rate of 5%. CONCLUSION: The clinical presentations and underlying conditions varied according to the different streptococcal species. Streptococcal brain abscesses accounted for 17% of our cases with brain abscesses, and 30% of our streptococcal infections had polymicrobial infections. Although streptococcal brain abscesses were commonly associated with otopharyngeal infections or infectious endocarditis, they also appeared to be often related to neurosurgical events or medical procedures in recent years. Based on our study, prognosis is favorable with early diagnosis and prompt treatment.

Suppressive effects of intrathecal granulocyte colony-stimulating factor on excessive release of excitatory amino acids in the spinal cerebrospinal fluid of rats with cord ischemia: role of glutamate transporters.

Recently, the hematopoietic factor, granulocyte colony-stimulating factor (G-CSF), has been shown to exhibit neuroprotective effects in CNS injuries. Our previous study demonstrated that intrathecal (i.t.) G-CSF significantly improved neurological defects in spinal cord ischemic rats. Considerable evidence indicates that the release of excessive amounts of excitatory amino acids (EAAs) plays a critical role in neuron injury induced by ischemic insult. In the present study, we used a spinal cord ischemia-microdialysis model to examine whether i.t. G-CSF exerted antiexcitotoxicity effects in a rat model of spinal cord ischemia. I.t. catheters and a microdialysis probe were implanted in male Wistar rats. The results revealed that spinal cord ischemia-induced neurological defects were accompanied by a significant increase in the concentration of EAAs (aspartate and glutamate) in the spinal dialysates from 30 min to 2 days after reperfusion. I.t administration of G-CSF immediately after the performance of surgery designed to induce ischemia led to a significant reduction in ischemia-induced increases in the levels of spinal EAAs. Moreover, i.t. G-CSF also brought about a significant reduction in the elevation of spinal EAA concentrations induced by exogenous i.t. administration of glutamate (10 microl of 500 mM). I.t. G-CSF attenuated spinal cord ischemia-induced downregulation of expression of three glutamate transporters (GTs), glial transporter Glu-Asp transporter (GLAST), Glu transporter-1 (GLT-1), and excitatory amino acid carrier 1 (EAAC1) protein 48 h after spinal cord ischemic surgery. Immunohistofluorescent staining showed that i.t. G-CSF significantly upregulated expression of the three GTs in the gray matter of the lumbar spinal cord from 3 to 24 h after injection. We propose that i.t. G-CSF possesses an ability to reduce the extent of spinal cord ischemia-induced excitotoxicity by inducing the expression of glutamate transporters.

Identification, purification, and characterization of a thermophilic imidase from pig liver.

This study investigates thermophilic imidase activity of the liver. We demonstrate that imidase catalyzes the hydrolysis of imides at a temperature substantially higher than that of its native environment. Then, a thermophilic imidase is purified to homogeneity from pig liver, and its thermoproperties are studied. About 2500-fold of purification and 15% yield of imidase activity are obtained after ammonium sulfate precipitation, octyl, DEAE, chelation, and gel filtration chromatography. While avoiding heat treatment for the protein purification, this study also indicates that only one enzyme is responsible for the imidase activity. This homogenous enzyme prefers to catalyze hydrolysis of imides at above 60 degrees C rather than at the body temperature of a pig. Although stable at below 50 degrees C, imidase quickly loses its activity at above 65 degrees C. Thus, the temperature effect on imidase activity is limited mainly by its thermostability. Substrate specificity of imidase is also temperature dependent. Our results demonstrate that the hydrolysis of physiological substrates is the most temperature dependent and that of hydantoins is the least temperature dependent. When increasing the reaction temperature from 25 to 60 degrees C, specific activities increase 50- and 60-fold for dihydrouracil and dihydrothymine, respectively. The temperature effect on the K(m) and V(max) of imidase is substrate dependent.

Effects of Stirring and Hydrogen on Fermentation Products of Clostridium thermocellum.

Clostridium thermocellum produces ethanol, acetate, H(2), and CO(2) as major fermentation products from cellulose and cellobiose. The performance of three strains of this microorganism was studied to assess the potential use in producing ethanol directly from cellulosic fiber. Depending on the bacterial strain, an ethanol/acetate product ratio from 1 to as high as 3 was observed in unstirred cultures. Vigorous stirring during growth resulted in a threefold decrease in the ethanol/acetate ratio. The H(2) content in the unstirred culture broth was three times greater than that in the stirred one. Addition of exogenous H(2) to the gas phase during growth increased the ethanol/acetate ratio much more in the stirred than in the unstirred fermentations. The addition of sufficient H(2) to the gas phase almost relieved the effect of stirring, and the ethanol/acetate ratio approached that in the unstirred condition. Addition of tritium to the gas phase of the culture resulted in the formation of tritiated water (H(2)O), which indicates that C. thermocellum possesses hydrogenase(s) that catalyzes the reverse reaction. The rate of H(2)O formation was about three times higher in the stirred culture than in the unstirred culture. These results demonstrate that the H(2) concentration in the broth plays an important role in the product formation. The H(2) supersaturation present in the unstirred cultures is responsible for the observed effect of stirring. A hydrogen feedback control mechanism regulating the relative concentrations of reduced and oxidized electron carriers is proposed to account for the effect of hydrogen on the metabolite distribution.

Biodegradation of bisphenol A and other bisphenols by a gram-negative aerobic bacterium.

A novel bacterium designated strain MV1 was isolated from a sludge enrichment taken from the wastewater treatment plant at a plastics manufacturing facility and shown to degrade 2,2-bis(4-hydroxyphenyl)propane (4,4'-isopropylidenediphenol or bisphenol A). Strain MV1 is a gram-negative, aerobic bacillus that grows on bisphenol A as a sole source of carbon and energy. Total carbon analysis for bisphenol A degradation demonstrated that 60% of the carbon was mineralized to CO2, 20% was associated with the bacterial cells, and 20% was converted to soluble organic compounds. Metabolic intermediates detected in the culture medium during growth on bisphenol A were identified as 4-hydroxybenzoic acid, 4-hydroxyacetophenone, 2,2-bis(4-hydroxyphenyl)-1-propanol, and 2,3-bis(4-hydroxyphenyl)-1,2-propanediol. Most of the bisphenol A degraded by strain MV1 is cleaved in some way to form 4-hydroxybenzoic acid and 4-hydroxyacetophenone, which are subsequently mineralized or assimilated into cell carbon. In addition, about 20% of the bisphenol A is hydroxylated to form 2,2-bis(4-hydroxyphenyl)-1-propanol, which is slowly biotransformed to 2,3-bis(4-hydroxyphenyl)-1,2-propanediol. Cells that were grown on bisphenol A degraded a variety of bisphenol alkanes, hydroxylated benzoic acids, and hydroxylated acetophenones during resting-cell assays. Transmission electron microscopy of cells grown on bisphenol A revealed lipid storage granules and intracytoplasmic membranes.

Klebsiella brain abscess in adults.

BACKGROUND: We analyzed the clinical manifestations and therapeutic outcomes of Klebsiella brain abscesses. PATIENTS AND METHODS: The clinical data of 15 patients with Klebsiella brain abscesses, retrospectively collected over a 14-year period, were studied. RESULTS: The 15 patients included 13 cases of Klebsiella pneumoniae infection and two cases of Klebsiella oxytoca. All but one case were community-acquired infections. Locations of all of these abscesses were supratentorial. 12 cases involved a single abscess, and three involved multiple abscesses. Gas formation was also found in two cases (13%). Common predisposing factors included metastatic spread, chronic otitis media and neurosurgical procedures. Among these 15 patients, 11 were treated surgically and four received antibiotics alone. In total, 11 patients survived and four died, with an overall mortality rate of 26.7%. CONCLUSION: The clinical presentations and therapeutic outcomes varied according to the different Klebsiella species. While debilitating diseases were common in K. pneumoniae infections, they were not common in K. oxytoca infection. And while metastatic septic abscess is a well-known, devastating complication of K. pneumoniae septicemia, usually seen as a brain abscess with a gas-forming appearance, all of these K. oxytoca infections had both otogenic infections and more favorable outcomes.