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PubMedDate not supplied

An evaluation of lidocaine hydrocarbonate compared with lidocaine hydrochloride for inferior alveolar nerve block.

The purpose of this study was to measure the degree of anesthesia obtained with 2.2% lidocaine hydrocarbonate, 2.2% lidocaine hydrocarbonate with 1:100,000 epinephrine, and 2% lidocaine hydrochloride with 1:100,000 epinephrine for inferior alveolar nerve block. Using a repeated-measures design, 30 subjects randomly received an inferior alveolar injection of each solution over the course of three successive appointments. The first molar, first premolar, lateral incisor, and contralateral canine (control) were blindly tested with an Analytic Technology pulp tester at 3-min cycles for 60 min. Anesthetic success was defined as no subject response to the maximum output (80 reading) of the pulp tester within 16 min and maintenance of this reading for the remainder of the testing period. Although subjects felt numb subjectively, anesthetic success as defined here ranged from 3% to 10% for the plain lidocaine hydrocarbonate; for the lidocaine hydrocarbonate and lidocaine hydrochloride solutions with epinephrine, success ranged from 37% to 63%. We conclude that 2.2% lidocaine hydrocarbonate without vasoconstrictor is not as effective as the other two preparations for inferior alveolar nerve block. The 2.2% lidocaine hydrocarbonate with epinephrine and 2%.

Adult↗
PubMed2006

[Effects of Le-Fort-I-Osteotomy on nasalance scores].

BACKGROUND: Nasalance represents a measure of the relative amount of oral and nasal acoustic energy produced by a speaker. Literature shows changes in nasalance after surgery of the oropharynx. The aim of this prospective study was to evaluate the outcome of speech and nasalance scores after Le-Fort-I-Osteotomy. PATIENTS AND METHODS: A total of 20 individuals with normal speech development were examined preoperatively and 6 weeks postoperatively with the Nasometer 6200 (Kay-Elemetrics, USA) after bimaxillary surgery. The tone materials used comprised the standardized text passage: "Ein Kindergeburtstag", the vowels: /a/, /e/, /i/, /o/, /u/ and a syllable repetition subtest. RESULTS: All patients showed changes in nasalance scores 6 weeks postoperatively. There were no significant changes reading the standard text. The syllable repetition test showed significant changes for repetition of "ma ma ma" and "na na na" (p=0,003, respectively p=0,033). Intonation of the vowel /a/1 also revealed significant changes regarding the pre- and postoperative values (p=0,006). However, the obtained values had no significant impact on the nasality characteristics of speech. CONCLUSION: This study confirms that maxillary osteotomies can result in significant changes of nasalance scores. However these changes do not have any impact on normal speech and voice.

Adolescent↗
PubMed2005

Anesthetic efficacy of bupivacaine solutions in inferior alveolar nerve block.

The purpose of this study was to compare the anesthetic efficacy of 2 bupivacaine solutions. Twenty-two volunteers randomly received in a crossover, double-blinded manner 2 inferior alveolar nerve blocks with 1.8 mL of racemic bupivacaine and a mixture of 75% levobupivacaine and 25% dextrobupivacaine, both 0.5% and with 1 : 200,000 epinephrine. Before and after the injection, the first mandibular premolar was evaluated every 2 minutes until no response to the maximal output (80 reading) of the pulp tester and then again every 20 minutes. Data were analyzed using the Wilcoxon paired test and the paired t test. No differences were found between the solutions for onset and duration of pulpal anesthesia and duration of soft tissue anesthesia (P > .05). It was concluded that the solutions have similar anesthetic efficacy.

Adult↗
PubMed1992

Multiple endocrine neoplasia syndrome--type 2b. Case report and review.

The multiple endocrine neoplasia syndromes are an association of tumours of 2 or more endocrine glands. Multiple endocrine neoplasia type 2b (MEN 2b) patients develop medullary thyroid carcinoma and pheochromocytomas as well as unique physical characteristics. Most commonly, MEN2b is inherited with an autosomal dominant pattern although sporadic cases are not uncommon. If untreated the disease may be lethal. The facial, oral and ocular characteristics are reliable markers of the disease. These patients give a history most commonly of slipped capital femoral epiphysis, hypertension and life-long diarrhoea and/or constipation. MEN2b is most commonly characterised by nodules on the anterior aspect of the tongue, thickened lips with nodules, thickened upper eyelids, broadened nasal bridge, thickened corneal nerves and dilated, symmetrical, pedunculated nodules on the cheek mucosa. The patient described has most of these characteristics. Radiographic features of the jaws which have not been previously described are reported. These include a markedly enlarged and bifurcated inferior alveolar canal and shortened roots of the lower incisor teeth. Due to the lethality of the disease, patients who present with the above physical characteristics must be further investigated to exclude MEN2b.

Adrenal Gland Neoplasms↗
PubMed1997

Human papillomavirus (HPV) in head and neck cancer. An association of HPV 16 with squamous cell carcinoma of Waldeyer's tonsillar ring.

BACKGROUND: Certain strains of human papillomavirus (HPV) have been shown to be etiologically related to the development of uterine cervical and other genital cancers, but their role in the development of malignancies at other sites is less well established. Previous studies have shown HPV DNA in tumors of the head and neck, but its prevalence has varied depending on the detection methods and the types of tumor and/or tissue examined. This study was undertaken to estimate the frequency of HPV DNA in squamous cell carcinoma (SCC) at different sites of the esophagus, head and neck and to compare the clinical behavior of HPV positive and negative tumors. METHODS: DNA was extracted from frozen tissue of 167 SCCs of the esophagus, head and neck. The DNA was screened for HPV sequences by polymerase chain reaction with two sets of consensus primers, one to a conserved region in the L1 gene (MY09/ MY11) and the other to a conserved region in the E1 open reading frame (IU/IWDO). The products were run on agarose gels, detected by ethidium bromide staining, and then the gels were subjected to Southern blot analysis and hybridized with probes specific to HPV 6, 16, and 18. All tumors found to be HPV positive with the consensus primers were amplified with type specific primers, and in selected cases the presence of HPV DNA was confirmed by restriction enzyme digestion of the tumor DNA with conventional Southern blot analysis. RESULTS: Overall, HPV sequences were found in 25 of 167 tumors (15%), but HPV was detected most frequently in tumors in Waldeyer's tonsillar ring. In that area, 9 of 15 (60%) were HPV positive. No HPV DNA was detected in 11 esophageal SCCs, 7 tumors of the pharynx/hypopharynx, or 6 pyriform sinus carcinomas. HPV DNA was detected in the following tumor sites: 1 of 28 (3.6%) in the larynx, 1 of 10 (10%) in the oral cavity, 5 of 39 (12.8%) in the tongue, 2 of 15 (13.5%) in the floor of the mouth, 3 of 21 (14.3%) supraglottic, and 1 of 7 (14.3%) in the lip. A high incidence of HPV DNA was also found in metastatic tumors located in cervical lymph nodes for which no primary site was clinically identified (3 of 8, 37.5%). With respect to age, gender, and tobacco and alcohol consumption, analysis of clinical data obtained by retrospective review showed no difference between patients with HPV DNA in their tumors and those in which no HPV was detected. However, HPV positive patients had larger tumors (P = 0.09) and a higher incidence of lymph node metastasis (P = 0.003). In spite of the higher stage of disease at presentation in HPV positive patients, there was no significant difference in 3-year survival rates between HPV positive patients and HPV negative patients (43.1% vs. 48.8%, respectively). Median follow-up was 27 months. CONCLUSIONS: In the head and neck, HPV-associated SCC had site specificity with the viral DNA frequently found in tumors in Waldeyer's tonsillar ring. Patients with HPV positive tumors presented with a higher stage of disease than patients with HPV negative tumors, but there was no significant difference in the 3-year survival rates between these two groups of patients.

Carcinoma, Squamous Cell↗
PubMed1986

Effects of white noise masking and low pass filtering on speech kinematics.

The effects of reduced auditory information on spatial and temporal parameters of speech production were investigated using cinefluorographic techniques. While subjects read a series of test words embedded in carrier sentences, they received normal auditory information, auditory information regarding only the first formant of their production, or high level noise to mask all formant information. Kinematic analyses indicated that while there were some changes across conditions, these changes were not consistent either within or across the subjects. Parameters that were affected included mean displacement, vocal tract shape, interarticulator timing, and steady state duration. The results suggest that auditory information plays a role in maintaining dynamic aspects of speech kinematics. That is, while speech can be produced without auditory information, the precise action and coordination that characteristic normal production may be altered.

Adult↗
PubMed1995

Von Hippel-Lindau syndrome.

After a decade of intensive clinical and molecular genetic efforts the von Hippel-Lindau (VHL) gene was cloned in 1993. The open reading frame encodes the putative protein of 284 amino acids. A large number of different mutations have been identified so far, including single base mutations, deletions, rearrangements and more complex mutations. So far, in about 75% of the VHL families germline mutations were detected. Geno-phenotypic comparison has revealed specific mutations with distinct manifestation patterns. Not all of the 6 classical lesions (hemangioblastoma of the CNS, retinal angiomatosis, pancreatic cysts, renal cysts and carcinoma, pheochromocytoma and epididymal cystadenoma) are present in VHL families. Pedigrees with pheochromocytoma but without renal cancer in general have point mutations. These recent results provide insight in the pathogenesis of a multiorgan cancer susceptibility tumor suppressor gene and allow determination of carrier status.

Brain↗
PubMed2001

Abnormal haemorheology, endothelial function and thrombogenesis in relation to hypertension in acute (ictus < 12 h) stroke patients: the West Birmingham Stroke Project.

While the blood vessels are exposed to high pressures in hypertension, the main complications of hypertension (stroke and myocardial infarction) are paradoxically thrombotic rather than haemorrhagic. To investigate abnormalities of haemorheology (plasma viscosity, fibrinogen), endothelial dysfunction (von Willebrand factor), platelet activation (soluble P-selectin) and thrombogenesis (plasminogen activator inhibitor and fibrin D-dimer) in stroke and the effects of concurrent hypertension, we studied 86 consecutive patients (58 male, 28 female) aged < 75 years (mean age +/- SD, 64.2 +/- 9.2 years) with acute stroke (ictus < 12 h). Baseline blood tests on admission were compared with 46 'hospital controls' (patients with uncomplicated essential hypertension; mean age +/- SD, 65.9 +/- 3.8 years) and 24 healthy normotensive controls (mean age +/- SD, 65 +/- 14.0 years). Further comparisons were made between stroke patients with hypertension (systolic blood pressure > 160 mmHg and/or diastolic > 90 mmHg) on admission and those without hypertension. Mean plasma viscosity (one-way analysis of variance, P = 0.026) and fibrinogen levels (P = 0.016) were significantly higher in stroke patients and hospital controls, when compared with healthy controls. The von Willebrand factor, plasminogen activator inhibitor soluble P-selectin and fibrin D-dimer levels were highest in the acute stroke patients, intermediate in hospital controls and lowest in healthy controls (all P < or = 0.001). There were no significant differences in measured indices of haemorheology, endothelial dysfunction and thrombogenesis between the three stroke pathological subtypes (ischaemic/thrombotic, haemorrhagic or transient ischaemic attack). There were also no significant differences in the measured parameters for stroke patients with or without systolic blood pressure > 160 mmHg or diastolic blood pressures > 90 mmHg using clinical (manual) readings or mean daytime or night-time ambulatory blood pressure monitoring recordings. There were no statistically significant differences between the measured parameters on admission and at 3 months follow-up in 26 patients (all P = not significant). Plasma viscosity was significantly correlated with mean daytime systolic blood pressure (r = 0.314, P = 0.021) and mean night-time systolic blood pressure (r = 0.309, P = 0.025). This study of hypertension and haemostasis in acute stroke has demonstrated clear abnormalities of haemorheology, endothelial dysfunction, platelet activation and thrombogenesis, which do not appear to be affected by the height of the blood pressure or the presence of hypertension. This is despite the known hypercoagulable state found in hypertension and the relationship of haemostatic abnormalities to vascular complications.

Aged↗
PubMed2004

Different aspects of visual impairment as risk factors for falls and fractures in older men and women.

UNLABELLED: Visual impairment has been implicated as a risk factor for falling and fractures, but results of previous studies have been inconsistent. The relationship between several aspects of vision and falling/fractures were examined in a prospective cohort study in 1,509 older men and women. The analyses showed that impaired vision is an independent risk factor for both recurrent falling and fractures. INTRODUCTION: Falls and fractures are a major health problem among the elderly. Visual impairment has been implicated as a risk factor for both falls and fractures. However, results from studies are inconsistent. The inconsistency between findings can primarily be attributed to differences in the designs of these studies. Most studies have been cross-sectional or case-control studies, and many have not correctly adjusted for potential confounders. Furthermore, until now, the potential mediating effects of functional limitation, physical performance, and physical activity have not been examined. MATERIALS AND METHODS: A total of 1,509 people was examined in 1995-1996. Contrast sensitivity was assessed with the VCTS_6000-1 chart for near vision. In addition, self-reported visual impairment was assessed by questions on recognizing faces from a distance of 4 m, reading the small print in the newspaper, and problems with glare. Furthermore, many potential confounders and mediators were assessed. Falls and fractures were assessed prospectively during a 3-year follow-up period. The associations between the vision variables and falls and fractures were examined using Cox proportional hazards analyses. RESULTS: After adjustment for potential confounders, contrast sensitivity was shown to be associated with recurrent falling (hazard ratio [HR] = 1.5), and the question on recognizing faces was shown to be associated with fractures (HR = 3.1). Furthermore, functional limitations and physical performance were shown to be mediators in the relationship between vision variables and recurrent falling/fractures. CONCLUSIONS: The results indicate that impaired vision is an independent risk factor for falling and fractures, but different aspects of visual functioning may have different relationships to falling and fractures.

Accidental Falls↗
PubMed1979

Pilot electromyographic studies of resting oral activity in obese and normal subjects.

Subjects were placed alone in a room where purposeful oral activity such as eating, talking and smoking was not permitted, while activity such as pursing the lips sucking on cheeks, grimaces etc was measured by a specially designed electromyometer. This was done via electrodes attached to the peri-oral area and was recorded in a standardized fashion. In contrast to expectations, total resting activity in the obese did not differ significantly from that of normals. However, the two groups differ in that the time lapse prior to major peaking is significantly shorter in normals than in the obese. Analysis of patterns of both obese and normals suggests cyclic activity of approximately 120 min duration, and this was confirmed with a small group of ten obese subjects. The implications of these findings, in terms of previous work on oral cycles in the obese as well as implications for future research, are discussed.

Adult↗
PubMed1998

Child sexual abuse: victim age, victim gender, and observer gender as factors contributing to attributions of responsibility.

OBJECTIVE: The purpose of this study was to investigate the effects of victim gender, and observer gender on the tendency to attribute responsibility for extrafamilial child sexual abuse to the victim and the nonoffending parents. METHOD: A 2 (Victim Age) x 2 (Victim Gender) x 2 (Observer Gender) between-subjects design was employed. Undergraduate students (N = 145) read a vignette describing a sexually abusive interaction between an adult male neighbor and a child. In this vignette, the child's gender and age (6 years old, 13 years old) varied. After reading the vignette, participants used a 5-point scale to indicate the degree to which they believed the victim and the parents (a) were responsible for, (b) were to blame for, (c) caused, and (d) could have prevented the abuse. RESULTS: Greater responsibility was assigned to older than younger victims. Both parents were ascribed similar levels of responsibility, and were ascribed greater responsibility when the child victim was younger than older. Male observers attributed greater responsibility and causality to the victim and the parents than did female observers. CONCLUSIONS: The results indicate that responsibility attributions directed toward the victim and the nonoffending parents may be a function of the victim's age. In addition, the findings support previous research suggesting that male observers may tend to hold victims more responsible for their abuse than female observers. Implications for treatment and research are discussed.

Adolescent↗
PubMed2004

Morphologic comparison of two neutral zone impression techniques: a pilot study.

STATEMENT OF PROBLEM: Several studies have compared dentures fabricated using neutral zone and conventional techniques. However, studies comparing swallowing and phonetic techniques for assessing the location and shape of the neutral zone could not be identified in the literature. PURPOSE: The purpose of this pilot study was to compare the outline form of the phonetic and swallowing neutral zone impression techniques for the same subjects. MATERIAL AND METHODS: Nine denture wearers with advanced mandibular ridge resorption were included in this study. For each subject 2 trays were prepared in autopolymerizing acrylic resin. One method used phonetics and tissue conditioner to shape the neutral zone; the second method used swallowing and modeling plastic impression compound. The resulting neutral zone impressions were leveled to the same occlusal height by gently grinding the occlusal surface on sandpaper until it corresponded with landmarks (corners of the mouth, two thirds of the height of the retromolar pads, bilaterally) noted on the cast. The impression was inverted onto graph paper, and the contour was outlined with a lead pencil. One impression was made for each subject, for each technique. The buccal contours of both neutral zones coincided at the median line. The maximum distance between the zones was measured in a buccolingual direction in the anterior, premolar, and molar regions bilaterally. When the location of the phonetic neutral zone in relation compared to the swallowing neutral zone was buccally oriented, a plus score was given. When the phonetic neutral zone was lingually located, a minus score was given. When the 2 lines coincided, a score of 0 was given. Measurements were made from direct readings on the graph paper. Statistical analysis was performed using the Sign test (alpha=.05). RESULTS: Significant differences were noted buccally in the left molar (P =.031) and right molar (P =.003) regions and also in the left and right premolar regions (P =.007), where the swallowing neutral zone was found to be located buccal to the phonetic neutral zone. Significant differences were also noted lingually, in the right premolar region (P =.015), where the swallowing neutral zone was found to be located lingual to the phonetic neutral zone. There was no significant difference between the techniques for the anterior region. CONCLUSION: Within the limits of this study, the phonetic neutral zone appears to be narrower posteriorly compared to the swallowing neutral zone, thus limiting premolar and molar positioning.

Aged↗
PubMedDate not supplied

Effectiveness of sequencing connexin 26 (GJB2) in cases of familial or sporadic childhood deafness referred for molecular diagnostic testing.

PURPOSE: Hearing loss is a common congenital disorder that is frequently associated with mutations in the GJB2 gene encoding the connexin 26 protein (Cx26). We sought to evaluate the effectiveness of direct DNA sequencing for detection of Cx26 mutations as a clinical diagnostic test. METHODS: We designed a clinical assay using a three-step polymerase chain reaction (PCR)-based DNA sequencing strategy to detect all possible mutations in the open reading frame and flanking sequences of Cx26. The results of the first 324 cases of childhood deafness referred for diagnostic testing were analyzed. RESULTS: A total of 127 of the 324 (39.2%) cases had at least one mutant Cx26 allele (36.1% of sporadic cases, 70% of familial cases). Of these 127 case, 57 (44.8%) were homozygotes or compound heterozygotes. Thirty-four different mutations were identified, including 10 novel mutations, 6 of which (T8M, K15T, R32L, M93I, N206S, and 511-512insAACG) may be pathogenic. We also provide new evidence on the pathogenicity or nonpathogenicity of 12 previously reported mutations, and clarify the confusing nomenclature of the 313-326del14 mutation. CONCLUSION: A simple and rigorous method for efficient PCR-based sequence analysis of Cx26 is a sensitive clinical assay for evaluating deaf children. Its widespread use is likely to identify additional pathogenic mutations and lead to a better understanding of the clinical significance of previously identified mutations.

Alleles↗
PubMed2001

An event-related fMRI study of overt and covert word stem completion.

In fMRI studies of language processing, it would be extremely useful to obtain high-quality images during tasks requiring spoken output. Recent studies have suggested that this may be possible, particularly if event-related fMRI methods are used. This study assesses the feasibility of acquiring interpretable images during speech by applying event-related methods to visual word stem completion, a task that has been studied extensively. On each trial, a different three-letter word stem (e.g., COU) was presented visually and subjects were required to generate a word beginning with that stem (e.g., COUSIN). In covert runs, subjects were instructed to say the word once to themselves, without moving their lips. In overt runs, subjects were instructed to say the word once aloud. Ten subjects were scanned during six overt runs and six covert runs at three presentation rates. Data were analyzed using an implementation of the general linear model making no assumptions about response shape. Images were relatively free of artifacts, and regions demonstrating task-related activation were similar to those reported in previous imaging studies. Regions active during overt task performance were similar to those active during covert task performance, with the addition of several regions commonly associated with motor aspects of speech production. Consistent with other studies, magnitude of activation was greater in the overt condition than in the covert condition, and there was a modest decrease in magnitude at the fastest presentation rate. Together, these results help to validate the use of event-related fMRI during tasks that require spoken output. Press

Adolescent↗
PubMed2005

Comparison of nasalance scores obtained with the Nasometer, the NasalView, and the OroNasal System.

OBJECTIVE: To compare nasalance scores obtained with the Nasometer, the NasalView, and the OroNasal System; evaluate test-retest reliability of the three systems; and explore whether three common text passages used for nasalance analysis could be shortened to a sentence each. SUBJECTS: Seventy-six adults with normal speech and hearing (mean age 26.5 years). PROCEDURES: Subjects read the complete Zoo Passage, Rainbow Passage, and Nasal Sentences. MAIN OUTCOME MEASURES: Mean nasalance magnitudes and mean nasalance distances were obtained with the three devices. RESULTS: The Nasometer had the lowest nasalance scores for the nonnasal Zoo Passage. The NasalView had the highest nasalance scores for the phonetically balanced Rainbow Passage. The OroNasal System had the lowest nasalance scores for the Nasal Sentences. The nasalance distance was largest for the Nasometer and smallest for the OroNasal System. Over 90% of the recordings were within 4% to 6% nasalance for most materials recorded with the Nasometer and the NasalView and within 7% to 9% for materials recorded with the OroNasal System. There were significant differences between the complete Zoo Passage and the Nasal Sentences and the individual sentences from these passages for the Nasometer and the OroNasal System. CONCLUSIONS: The three systems measure nasalance in different ways and provide nasalance scores that are not interchangeable. Test-retest variability for the Nasometer and the NasalView may be higher than previously reported. Individual sentences from the Zoo Passage and the Nasal Sentences do not provide nasalance scores that are equivalent to the complete passages.

Adult↗
PubMed1997

Ambulatory blood pressure monitoring in acute stroke. The West Birmingham Stroke Project.

BACKGROUND AND PURPOSE: Ambulatory blood pressure monitoring (ABPM) devices are increasingly used in the assessment of hypertension, but their value in patients after a stroke is unknown, despite the fact that hypertension is an important cause of stroke and many patients have relatively high blood pressure (BP) levels at presentation. We therefore investigated the clinical use of a 24-hour oscillometric ABPM device in patients after acute stroke. We also investigated ABPM in different types of stroke (thrombosis, hemorrhage, and transient ischemic attack) and ethnic and sex differences. METHODS: BP was measured manually with a standard mercury sphygmomanometer, and ABPM measurements were made with an oscillometric device. The first reading obtained with the ABPM device was compared with simultaneous manual BP measurements. Mean daytime and nighttime pressures were also analyzed to determine the frequency of nocturnal BP falls ("dipping"). RESULTS: We studied 86 patients (48 men; mean +/- SD age, 64.2 +/- 9.2 years) admitted with acute-onset stroke (ictus within 12 hours) in a district general hospital. Thirty-one patients (36.0%) had a previous history of hypertension. The median percentage of successful BP readings by ABPM was 92% (interquartile range, 72 to 98). There was no significant difference in manual BP levels compared with the first simultaneous systolic or diastolic ABPM measurements. Systolic BPs recorded by ABPM were significantly higher in black patients with acute stroke and in patients with intracerebral hemorrhage, who also showed a trend toward higher nocturnal BPs. There was no difference in BPs between men and women and those who were alive or dead 6 months later (P = NS). There was also no difference between mean day and night systolic BP (mean difference, 1.9 mm Hg; P = .08), although mean daytime diastolic BP was higher than mean nighttime diastolic BP (mean difference, 2.4 mm Hg; P = .01). Patients with stroke therefore demonstrated a loss of diurnal BP rhythm and may be considered "nondippers"; there was also a trend toward "reverse dipping" in patients with intracranial hemorrhage. CONCLUSIONS: This study demonstrates higher systolic BPs as recorded by ABPM (but not manually) in patients with intracerebral hemorrhage than in those with cerebral infarcts; higher levels were also found in blacks. ABPM recordings are useful in the assessment of BP in patients with stroke, who may be considered nondippers.

Black or African American↗
PubMed2001

Ligninolytic enzyme production in selected sub-tropical white rot fungi under different culture conditions.

Lignin peroxidase (LiP), manganese peroxidase (MnP) and laccase activities in selected sub-tropical white rot fungal species from Zimbabwe were determined. The enzyme activities were assayed at varying concentrations of C, N and Mn2+. Manganese peroxidase and laccase activities were the only expressed activities in the fungi under the culture conditions tested. Trametes species, T. cingulata, T. elegans and T. pocas produced the highest manganese peroxidase activities in a medium containing high carbon and low nitrogen conditions. High nitrogen conditions favoured high manganese peroxidase activity in DSPM95, L. velutinus and Irpex spp. High manganese peroxidase activity was notable for T. versicolor when both carbon and nitrogen in the medium were present at high levels. Laccase production by the isolates was highest under conditions of high nitrogen and those conditions with both nitrogen and carbon at high concentration. Mn2+ concentrations between 11-25 ppm gave the highest manganese peroxidase activity compared to a concentration of 40 ppm or when there was no Mn2+ added. Laccase activity was less influenced by Mn2+ levels. While some laccase activity was produced in the absence of Mn2+, the enzyme levels were higher when Mn2+ was added to the culture medium.

Basidiomycota↗
PubMed1999

Relative stability of recombinant versus native peroxidases from Phanerochaete chrysosporium.

Two types of glycosylated peroxidases are secreted by the white-rot fungus Phanerochaete chrysosporium, lignin peroxidase (LiP) and manganese peroxidase (MnP). The thermal stabilities of recombinant LiPH2, LiPH8, and MnPH4, which were expressed without glycosylation in Escherichia coli, were lower than those of corresponding native peroxidases isolated from P. chrysosporium. Recovery of thermally inactivated recombinant enzyme activities was higher than with that of the thermally inactivated native peroxidases. Removal of N-linked glycans from native LiPH8 and MnPH4 did not affect enzyme activities or thermal stabilities of the enzymes. Although LiPH2, LiPH8, and MnPH4 contained O-linked glycans, only the O-linked glycans from MnPH4 could be removed by O-glycosidase, and the glycan-depleted MnPH4 exhibited essentially the same activity as nondeglycosylated MnPH4, but thermal stability decreased. Periodate-treated MnPH4 exhibited even lower thermal stability than O-glycosidase treated MnPH4. The role of O-linked glycans in protein stability was also evidenced with LiPH2 and LiPH8. Based on these data, we propose that neither N- nor O-linked glycans are likely to have a direct role in enzyme activity of native LiPH2, LiPH8, and MnPH4 and that only O-linked glycans may play a crucial role in protein stability of native peroxidases.

Cloning, Molecular↗