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Biomedical subjects

M Beck

Publications and source records attributed to M Beck.

At least 145 records · Page 8Linked to original sources
PubMed1999

Anesthetic efficacy of the mylohyoid nerve block and combination inferior alveolar nerve block/mylohyoid nerve block.

OBJECTIVE: The purpose of this study was to measure the degree of anesthesia obtained with the mylohyoid nerve block and the combination mylohyoid nerve block/conventional inferior alveolar nerve (IAN) block in mandibular teeth. STUDY DESIGN: With the use of a repeated-measures design, 30 subjects randomly received each of 3 combinations of injections at 3 separate appointments. The combinations were as follows: mylohyoid nerve block (1.8 mL of 2% lidocaine with 1:100,000 epinephrine) + IAN block (3.6 mL of 2% lidocaine with 1:100,000 epinephrine); mock mylohyoid nerve block + IAN block (3.6 mL of 2% lidocaine with 1:100,000 epinephrine); mylohyoid nerve block (1.8 mL of 2% lidocaine with 1:100,000 epinephrine) + mock IAN block. The mylohyoid injections were aided by the use of a peripheral nerve stimulator. Mandibular anterior and posterior teeth were blindly tested with a pulp tester at 4-minute cycles for 60 minutes postinjection. Anesthesia was considered successful when 2 consecutive 80 readings were obtained. RESULTS: One hundred percent of the subjects had lip numbness with the mylohyoid nerve block + IAN block and mock mylohyoid nerve block + IAN block techniques. For these 2 techniques, anesthetic success rates were higher in posterior teeth (73% to 93%) than in anterior teeth (33% to 60%). There were no significant differences (P > .05) between the 2 techniques. The mylohyoid nerve block + mock IAN block technique resulted in a very low success rate (0% to 17%) and was significantly different (P < .05) from the mylohyoid nerve block + IAN block technique. CONCLUSIONS: The results of this study suggest that the mylohyoid nerve block does not by itself predictably provide pulpal anesthesia in mandibular teeth and does not significantly enhance pulpal anesthesia when administered in combination with the IAN block.

Adult↗
PubMed1999

The use of ultrasound for guiding needle placement for inferior alveolar nerve blocks.

OBJECTIVE: The degree of pulpal anesthesia obtained with an ultrasound-assisted inferior alveolar nerve block was compared to that obtained with a conventional inferior alveolar nerve block for mandibular teeth to determine whether needle placement assisted by ultrasound results in more successful anesthesia. STUDY DESIGN: Through use of a repeated-measures design, each of 40 subjects randomly received an ultrasound-assisted inferior alveolar nerve block and a conventional inferior alveolar nerve block at 2 separate appointments. Mandibular anterior and posterior teeth were blindly tested by means of a pulp tester at 4-minute cycles for 60 minutes postinjection. Anesthesia was considered successful when 2 consecutive readings of 80 were obtained. RESULTS: One hundred percent of the subjects had profound lip numbness with both the ultrasound-assisted inferior alveolar nerve block and the conventional inferior alveolar nerve block. For these 2 techniques, anesthetic success rates for individual teeth ranged from 38% to 92%. There were no significant differences (P > .05) between the 2 techniques. CONCLUSIONS: It was concluded that accurate needle placement with ultrasound for the inferior alveolar nerve block did not result in more successful pulpal anesthesia in the mandible. Therefore, accuracy of needle placement is not the primary reason for pulpal anesthetic failure with this block.

Adult↗
PubMed1999

Anesthetic efficacy and heart rate effects of the supplemental intraosseous injection of 2% mepivacaine with 1:20,000 levonordefrin.

OBJECTIVE: The purpose of this study was to determine the anesthetic efficacy and heart rate effects of a supplemental intraosseous injection of 2% mepivacaine with 1:20,000 levonordefrin. STUDY DESIGN: Through use of a repeated-measures design, 40 subjects randomly received 3 combinations of injections at 3 separate appointments. The combinations were as follows: inferior alveolar nerve (IAN) block (with 3% mepivacaine) + intraosseous injection of 1.8 mL of 2% mepivacaine with 1:20,000 levonordefrin; IAN block + intraosseous injection of 1.8 mL of 2% lidocaine with 1:100,000 epinephrine (positive control); IAN block + mock intraosseous injection (negative control). Each first molar, second molar, and second premolar was blindly tested with a pulp tester at 2-minute cycles for 60 minutes after injection. Anesthesia was considered successful when 2 consecutive readings of 80 were obtained. Heart rate (pulse rate) was measured with a pulse oximeter. RESULTS: One hundred percent of the subjects had lip numbness with the IAN block + intraosseous mock technique and IAN block + intraosseous techniques. The anesthetic success rates for IAN block + mock intraosseous injection, IAN block + intraosseous lidocaine, and IAN block + intraosseous mepivacaine, respectively, were as follows: 80%, 100%, and 100% for the first molar; 90%, 100%, and 100% for the second molar; 77%, 97%, and 97% for the second premolar. For the first molar and second premolar, the differences were significant (P< .05) when the intraosseous mepivacaine and lidocaine techniques were compared with the IAN block + mock intraosseous injection. There were no significant differences between the intraosseous mepivacaine and lidocaine techniques. Eighty percent of the subjects had a mean increase in heart rate of 23-24 beats per minute with the intraosseous injection of the mepivacaine and lidocaine solutions; there were no significant differences between results with the 2 solutions. CONCLUSIONS: We concluded that intraosseous injection of 1.8 mL of 2% lidocaine with 1:100,000 epinephrine or 2% mepivacaine with 1:20,000 levonordefrin, used to supplement an IAN block, significantly increased anesthetic success in first molars and second premolars. The 2 solutions were equivalent with regard to intraosseous anesthetic success rate, failure rate, and heart rate increase after IAN block.

Adult↗
PubMed1999

The effect of dietary wheat middlings and enzyme supplementation. 1. Late egg production efficiency, egg yields, and egg composition in two strains of Leghorn hens.

A study was conducted to test the effects of wheat middlings (WM) with and without enzyme (xylanase and protease) supplementation on late egg production (EP), egg yields, and egg composition in two strains of Leghorn hens (DeKalb Delta and Hisex White). Six diets were randomly assigned to 300 birds (150 birds per strain) from 42 to 60 wk of age. Diet 1 was a corn-soybean meal control, Diets 2 and 3 had 8 and 16% WM, respectively, Diet 4 had 8% WM with 0.1% enzyme, and Diets 5 and 6 had 16% WM with 0.1 and 0.2% enzyme, respectively. Each dietary treatment was replicated five times per strain. Egg production, feed consumption (FC), feed efficiency (FE), percentage dirty eggs, specific gravity (SP), egg weight (EW), and egg mass (EM) were measured on a weekly basis. Egg components (EC) were measured biweekly and birds were weighed every 4 wk. Egg production was not significantly affected by diet, with averages of 83.7, 85.7, 84.1, 84.2, 82.3, and 84.0% for Diets, 1, 2, 3, 4, 5, and 6, respectively. Strain had a marked effect on FC, with Hisex having higher FC than DeKalb hens. Feed consumption also showed a significant diet by strain effect, being lower for Hisex hens fed diets with enzyme compared to diets without enzyme. DeKalb hens had better FE than Hisex hens, and addition of enzyme to 16% WM improved it further. Strain and diet had a significant effect on EC with higher percentages of albumen and yolk for diets with enzyme and for DeKalb hens. Percentage shell was lower for DeKalb hens than for Hisex hens but was not affected by diet. There was also a significant increase in EW for Diets 4 (63.1 g), 5 (63.8 g), and 6 (63.2 g) compared to Diets 1 (62.1 g), 2 (62.4 g), and 3 (63.0 g), with DeKalb hens showing an increase with Diet 5 compared to Hisex hens. Egg mass improved with the higher rate of enzyme in 16% WM diet compared to the lower enzyme level. Specific gravity declined with enzyme supplementation in WM diets. Eggs from DeKalb hens had lower SP than those from Hisex hens for all diets. Percentage dirty eggs did not differ significantly among treatments but was higher for the Hisex strain than for the DeKalb strain. There were no differences in BW between the two strains of hens or among diets. Adding protease and xylanase to diets rich in fiber can improve the egg output without affecting production parameters.

Animal Husbandry↗
PubMed1999

Selective use of temporary intravascular shunts in coincident vascular and orthopedic upper and lower limb trauma.

BACKGROUND: Combined vascular and skeletal injuries are associated with a high limb loss rate. One of the major factors resulting in amputation is frequently because the allowable warm ischemia time for skeletal muscle is exceeded before adequate revascularization. METHODS: Temporary vascular shunting has been used in selected patients with complete ischemia to minimize the ischemic time of the injured limb, allowing identification of vital structures, thorough debridement, and rigid internal fixation before definitive vascular repair. RESULTS: Five male and two female patients with a median age of 46 years (range, 27-76 years) admitted with combined orthopedic and vascular injuries of the upper limbs in four and the lower limbs in three patients underwent primary vascular shunting. The median ischemic time for all patients was 180 minutes (range, 120-210 minutes). Shunt insertion was accomplished in all cases within 30 minutes. Median dwell time for the shunt was 185 minutes (range, 90-390 minutes). No shunt-related complications or limb loss occurred. During follow-up ranging from 2 to 24 months, all vascular repairs remained patent. All fractures healed primarily, except for one patient in whom a necrosis of the humeral head occurred. Five patients had an excellent and two patients a good result. CONCLUSION: Initial temporary vascular shunting in selected patients with combined skeletal and vascular injury of the upper or lower limb may reduce the complications resulting from prolonged ischemia and permits an unhurried and reasonable sequence of treatment.

Adult↗
PubMed1999

Cardiovascular effects of intraosseous injections of 2 percent lidocaine with 1:100,000 epinephrine and 3 percent mepivacaine.

BACKGROUND: Because a number of patients have reported an increase in heart rate with the intraosseous, or i.o., injection, it is important to evaluate changes in the cardiovascular system with this injection technique. The purpose of this study was to determine the cardiovascular effects of an i.o. injection of 2 percent lidocaine with 1:100,000 epinephrine and 3 percent mepivacaine. METHODS: With the use of a repeated-measures design, the authors randomly assigned 42 subjects to receive i.o. injections of 1.8 milliliters of 2 percent lidocaine with 1:100,000 epinephrine or 1.8 mL of 3 percent mepivacaine in a double-blinded manner at two appointments. At each appointment the authors monitored electrocardiographic findings, cardiac rate, systolic and diastolic blood pressure, and mean arterial pressure before, during and after administration of anesthetic solutions. RESULTS: With the 2 percent lidocaine with 1:100,000 epinephrine solution, 28 (67 percent) of 42 subjects experienced an increase in heart rate that might be attributed to the effect of the epinephrine. In 22 (79 percent) of these subjects, the heart rate returned to within 5 beats of baseline values within four minutes after solution deposition. The authors found no significant increase in heart rate in subjects receiving the 3 percent mepivacaine. No significant differences (P > .05) were found in mean diastolic, mean systolic or mean arterial blood pressure values between the subjects receiving 2 percent lidocaine with 1:100,000 epinephrine and those receiving 3 percent mepivacaine. CONCLUSIONS: The majority of subjects receiving the i.o. injection of the 2 percent lidocaine-epinephrine solution experienced a transient increase in heart rate. No significant increase in heart rate was seen with the i.o. injection of 3 percent mepivacaine. CLINICAL IMPLICATIONS: While patients would likely notice the heart rate increase with the lidocaine-epinephrine solution, it would not be clinically significant in most healthy patients. In patients whose medical condition, drug therapies or epinephrine sensitivity suggests caution, 3 percent mepivacaine is a good alternative for i.o. injections.

Adolescent↗
PubMed1999

[Remedies and quackeries].

Several unorthodox drugs for healing cancer recommended widely in the USA and Hungary are discussed. Credulity plays a decisive role in the application of the drugs of doubtful effect and/or "remedies" that are undoubtedly without any effect. Typical examples are Krebiozen, Laetrile, Celladam and water with decreased deuterium concentration. In connection with Avemar, the most recent Hungarian remedy with so far clinically unproven physiological effect it is surprising why an expensive seminatural material is sold when the agen, in fact, is a well-known and synthetically easily available compound.

Complementary Therapies↗
PubMed1999

Mucopolysaccharidosis type IIIB (Sanfilippo B): identification of 18 novel alpha-N-acetylglucosaminidase gene mutations.

Mucopolysaccharidosis type IIIB (MPS IIIB or Sanfilippo B disease) is an autosomal recessive storage disorder caused by deficiency of the lysosomal enzyme a-N-acetylglucosaminidase. Mutation screening was performed on a group of 22 patients using a combination of SSCP/heteroduplex analysis of amplified genomic fragments and direct sequencing of cDNA fragments. Twenty-one different mutations were identified, 18 of them novel. Together they account for 82% of the disease alleles. The mutation spectrum consists of two small insertions, two small deletions, three nonsense mutations, and 14 different missense mutations, one of them (M1L) affecting the initiation codon. The vast genetic heterogeneity seen in this disorder is reflected by the fact that only three of the mutations were identified in more than one patient.

Acetylglucosaminidase↗
PubMed1998

Evidence for the specific interaction of a lipid molecule with rhodopsin which is altered in the transition to the active state metarhodopsin II.

Comparing the FTIR difference spectra of the rhodopsin --> metarhodopsin II transition in membranes and in dodecylmaltoside detergent, characteristic variations are observed between 1715 and 1750 cm(-1). By repeating the measurements with the rhodopsin mutant D83N/E122Q, the spectral variation between the samples in membranes versus detergent could be assigned to a difference band at 1743(+)/1724(-) cm(-1), which does not exhibit a deuteration-induced downshift. We provide evidence that this band is probably caused by the C=O stretch of only one ester group of one lipid molecule. This group interacts with the dark state of rhodopsin, whereas in metarhodopsin II, the lipid molecule behaves as if it were in the bulk lipid phase.

Amino Acid Substitution↗
PubMed1998

Spectroscopic evidence for interaction between transmembrane helices 3 and 5 in rhodopsin.

Recent molecular models of rhodopsin (Rho) propose a specific interaction between transmembrane (TM) helices 3 and 5, which appears to be mediated by amino acid residues Glu122 and His211 on TM helices 3 and 5, respectively. To test this proposed interaction, four single-site histidine replacement mutants (H100N, H152N, H211N, and H211F), two single-site glutamic acid replacement mutants (E122Q and E122A), and three double-site replacement mutants (E122Q/H211F, E122Q/H211N, and E122A/H211F) of Rho were prepared. The expressed mutant pigments reconstituted into membranes were studied by FTIR difference spectroscopy addressing especially the transition to metarhodopsin I (MI). It is shown that the lipid environment influences bands typical of the MI state. Spectra of mutants with substituted Glu122 allowed assignments of the C=O stretch of protonated Glu122 in the dark state and in MI of Rho. Mutation of His211, but not of other histidine residues, affects these vibrational modes assigned to Glu122. In addition, replacements of His211 affect protein modes that are proposed to arise from a third, hydroxyl-bearing group, which also interacts with Glu122. These modes are influenced as well when Glu122 is replaced by Ala in mutant E122A but not when it is replaced by Gln in mutant E122Q. These results provide direct experimental evidence for an interaction between TM helices 3 and 5 in Rho, which is mediated by Glu122 and His211.

Alanine↗
PubMed1998

Interactions between ouabain, atrial natriuretic peptide, angiotensin-II and potassium: effects on rat zona glomerulosa aldosterone production.

The effects of ouabain, atrial natriuretic peptide, angiotensin-II and potassium on aldosterone production by collagenase dispersed rat zona glomerulosa cells were studied. A-II and 10(-4) M ouabain-induced increases in aldosterone production was inhibited by 10(-9) M ANP at all potassium concentrations examined. 10(-4) M ouabain inhibited the A-II induced increase in aldosterone production at all potassium concentrations. The degree of this inhibition was smaller at higher potassium levels. Ouabain enhanced the inhibitory effect of ANP on A-II-induced aldosterone synthesis at all potassium concentrations. Interactions between A-II, ANP, ouabain and potassium may be of physiological significance in the regulation of aldosterone secretion.

Aldosterone↗
PubMed1998

Anesthetic efficacy of the supplemental intraosseous injection of 2% lidocaine with 1:100,000 epinephrine in irreversible pulpitis.

The purpose of this study was to determine the anesthetic efficacy of a supplemental intraosseous injection of 2% lidocaine with 1:100,000 epinephrine in teeth diagnosed with irreversible pulpitis. Fifty-one patients with symptomatic, vital maxillary, and mandibular posterior teeth diagnosed with irreversible pulpitis received conventional infiltrations or inferior alveolar nerve blocks. Pulp testing was used to determine pulpal anesthesia after "clinically successful" injections. Patients who were positive to the pulp tests, or were negative to the pulp tests but felt pain during endodontic access, received an intraosseous injection using 1.8 ml of 2% lidocaine with 1:100,000 epinephrine. The results demonstrated that 42% of the patients who tested negative to the pulp tests reported pain during treatment and required supplemental anesthesia. Eighty-one percent of the mandibular teeth and 12% of maxillary teeth required an intraosseous injection due to failure to gain pulpal anesthesia. Overall, the Stabident intraosseous injection was found to be 88% successful in gaining total pulpal anesthesia for endodontic therapy. We concluded that, for posterior teeth diagnosed with irreversible pulpitis, the supplemental intraosseous injection of 2% lidocaine (1:100,000 epinephrine) was successful when conventional techniques failed.

Adult↗
PubMed1998

Anesthetic efficacy of the intraosseous injection of 0.9 mL of 2% lidocaine (1:100,000 epinephrine) to augment an inferior alveolar nerve block.

OBJECTIVE: The purpose of this study was to determine the anesthetic efficacy of an intraosseous injection of 0.9 mL of 2% lidocaine with 1:100,000 epinephrine to augment an inferior alveolar nerve block in mandibular posterior teeth. STUDY DESIGN: With the use of a repeated-measures design, each of 38 subjects randomly received one or the other of 2 combinations of injections at 2 separate appointments. The combinations were inferior alveolar nerve block + intraosseous injection (on the distal of the second premolar) through use of 0.9 mL of 2% lidocaine with 1:100,000 epinephrine and inferior alveolar nerve block + mock intraosseous injection. The first molar, second premolar, and second molar were blindly tested with an Analytic Technology pulp tester at 2-minute cycles for 120 minutes postinjection. Anesthesia was considered successful when 2 consecutive 80 readings were obtained. RESULTS: One hundred percent of the subjects had lip numbness with the inferior alveolar nerve block + intraosseous injection combination technique. The respective anesthetic success rates for the inferior alveolar nerve block + mock intraosseous injection combination and the inferior alveolar nerve block + intraosseous injection combination were 60% and 100% for the second premolar, 71% and 95% for the first molar, and 74% and 87% for the second molar. The differences were significant (P < .05) for the second premolar through 50 minutes and for the first molar through 20 minutes. There were no significant (P > .05) differences for the second molar. Sixty-eight percent of the subjects had a subjective increase in heart rate with the intraosseous injection. CONCLUSIONS: The results of this study indicate that the supplemental intraosseous injection of 0.9 mL of 2% lidocaine with 1:100,000 epinephrine, given distal to the second premolar, significantly increased the success of pulpal anesthesia in the second premolar (for 50 minutes) and first molar (for 20 minutes) in comparison with the inferior alveolar nerve block alone. The intraosseous injection did not statistically increase success in the second molar.

Adolescent↗
PubMed1998

Cholinergic regulation of the rat adrenal zona glomerulosa.

Using histochemical and immunocytochemical methods, cholinergic nerve fibres were demonstrated in the rat adrenal cortex, primarily in the capsule and zona glomerulosa, and in the medulla. Some terminated among the glomerulosa cells or around blood vessels. Occasional fibres were also seen in the fasciculata, ending in islets of chromaffin tissue without ramifications on cortical cells. To clarify the role of cholinergic innervation, a microvolume perifusion system was used to study steroid production by the rat adrenal capsule-glomerulosa. Acetylcholine (ACh) itself had no reproducible effects; however, since variable amounts of endogenous ACh were present, the actions of antagonists were also studied. The M1 muscarinic receptor antagonist pirenzepine (10 and 100 microM) stimulated aldosterone secretion. This stimulation was abolished by co-incubation with carbachol, the M1 agonist McN A-343 and by atropine. We found that the action of pirenzepine was blocked by nifedipine (Ca2+ channel blocker), suggesting that pirenzepine (through release of endogenous ACh) provides an acute stimulus by enhancing Ca2+ inflow. Hemicholine, a choline uptake blocker, reduced the stimulatory effect of pirenzepine on steroid secretion, confirming that stimulation was of neural origin. Neither the non-selective muscarinic receptor antagonist atropine, the selective M1-M3 muscarinic receptor antagonist 4-DAMP, nor the selective M2 muscarinic receptor antagonist methoctramine influenced aldosterone output. Receptor-binding studies revealed the existence of M3 receptors in capsule-glomerulosa homogenates. We conclude that pirenzepine acts on presynaptic M1 autoreceptors to increase spontaneous ACh release from varicose axon terminals that lie in close proximity to the glomerulosa cells. In turn ACh may thus stimulate steroidogenesis acutely through M3 receptors. These results support the concept of a direct cholinergic influence on zona glomerulosa function in the rat.

(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethy↗