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Heralded as the model multicultural global city of the future in the 1980s, Los Angeles was suddenly seen as the hotbed of civil unrest in 1992. This shift in image, whether accurate or not, has prompted many to wonder what has taken place in Los Angeles over the past twenty years in regards to the problem of racial conflict. Hate crime reports provide one source of data that is regularly collected over time and is also location specific. Though these data are problematic, hate incidents are an extremely useful measure as part of a fuller study of race relations. This paper provides a profile of the problem of hate crime in Los Angeles County using hate crime data collected between 1994 and 1997. Geographic information systems (GIS) technology is used to identify clusters. We then analyze clusters to develop a profile of race-bias hate crimes for the county. We conclude with a discussion of the use of hate crime data in the study of racial conflict and outline directions for future research.

This article presents a descriptive profile of race-bias hate crimes in Los Angeles County using primarily law enforcement data collected during 1994-1997. Geographic information systems technology is used to map 1,837 reported bias incidents. Maps are created to locate clusters where hate crimes occur in relatively high density. Interviews and archival research were conducted in two "cluster" areas. Findings include the location of clusters and the racial characteristics of victims and suspects involved in the incidents located within clusters. While previous research has shown that hate crimes are usually perpetrated by individuals who are not members of organized hate groups, this preliminary study suggests we may find more frequent membership of perpetrators in gangs where hate crimes cluster. Related to this, there is strong evidence of race-bias hate crime among racial minority group-based gangs in which the major motive is not the defense of territorial boundaries against other gangs, but hatred towards a group defined by racial identification regardless of any gang-related territorial threat. The article concludes with a discussion of the uses of hate crime data in the study of race relations and outlines directions for future research. [ABSTRACT FROM AUTHOR]

Background: The exact pathophysiology of premenstrual syndrome (PMS) and premenstrual dysphoric disorder (PMDD) is still unknown. This study aimed to investigate the concentration of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in plasma in relation to the menstrual cycle and the severity of premenstrual symptoms in young Japanese women. Methods: The study included 21 healthy Japanese women 19-24 years of age. Fourteen women had no or mild PMS [PMS (-)], while five women had moderate to severe PMS and two women exhibited PMDD [PMS (+)]. The concentration of 8-OHdG in plasma was measured by means of high-performance liquid chromatography-electrochemical detector. The Center for Epidemiologic Studies Depression (CES-D) scale was used to evaluate the depressive tendency. Results: The concentration of 8-OHdG before menstruation was significantly higher than that after menstruation in total subjects ( p  = 0.04). In the PMS (+) group, the 8-OHdG concentration before menstruation was higher than that after menstruation ( p  = 0.02). Moreover, the PMS (+) group showed a higher 8-OHdG concentration compared with the PMS (-) group before menstruation ( p  < 0.01), as well as higher CES-D scores compared with the PMS (-) group both before and after menstruation ( p  < 0.01). Conclusions: These results suggested that the oxidation of DNA occurred before menstruation in PMS. The depression was associated with PMS symptoms both before and after menstruation in patients with PMS. Oxidation of DNA due to oxidative stress and depression in PMS patients may be involved in the pathogenesis of PMS. Clinical Trial Registration number 15-02-011., Competing Interests: No competing financial interests exist., (© Kaori Yama et al., 2021; Published by Mary Ann Liebert, Inc.)

A nanoporous gold (NPG) electrode prepared through a facile anodization technique was employed in the electrochemical reductive amination of biomass-derivable α-keto acids in the presence of a nitrogen source to produce the corresponding amino acids. NPG showed a clear reductive current in the presence of α-keto acid and NH 2 OH, and the electrolysis experiments confirmed the production of L-amino acid. A reductive voltammetric signal at the NPG electrode appeared at a more positive potential by 0.18-0.79 V, compared with those at the planar-gold electrode without anodization and other previously reported electrode systems, indicating the high activity of the prepared nanostructure for the electrochemical reaction. Maximum Faradaic efficiencies (FEs) of 74-93% in the reductive molecular conversion to amino acids of Ala, Asp, Glu, Gly, and Leu were obtained under the optimized conditions. The FE values were strongly dependent on the applied potential in the electrolysis, suggesting that the hydrogen evolution reaction at the electrode surface was more significant as the applied potential became more negative. The effect of potential at the NPG was lower than that at the planar-gold electrode. These results indicate that nanostructurization decreases the overpotential for the electrochemical reductive amination, resulting in high FE.

Background: Patient awareness surveys on polypharmacy have been reported previously, but no previous study has examined the effects of sending feedback to health professionals on reducing medication use. Our study aimed to conduct a patient survey to examine factors contributing to polypharmacy, feedback the results to health professionals, and analyze the resulting changes in the number of polypharmacy patients and prescribed medications., Methods: After conducting a questionnaire survey of patients in Study 1, we provided its results to the healthcare professionals, and then surveyed the number of polypharmacy patients and oral medications using a before-after comparative study design in Study 2. In Study 1, we examined polypharmacy and its contributing factors by performing logistic regression analysis. In Study 2, we performed a t-test and a chi-square test., Results: In the questionnaire survey, significant differences were found in the following 3 items: age (odds ratio (OR) = 3.14; 95% confidence interval (CI) = 2.01-4.91), number of medical institutions (OR = 2.34; 95%CI = 1.50-3.64), and patients' difficulty with asking their doctors to deprescribe their medications (OR = 2.21; 95%CI = 1.25-3.90). After the feedback, the number of polypharmacy patients decreased from 175 to 159 individuals and the mean number of prescribed medications per patient decreased from 8.2 to 7.7 (p < 0.001, respectively)., Conclusions: Providing feedback to health professionals on polypharmacy survey results may lead to a decrease in the number of polypharmacy patients. Factors contributing to polypharmacy included age (75 years or older), the number of medical institutions (2 or more institutions), and patients' difficulty with asking their physicians to deprescribe their medications. Feedback to health professionals reduced the percentage of polypharmacy patients and the number of prescribed medications., Trial Registration: UMIN. Registered 21 June 2020 - Retrospectively registered, https://www.umin.ac.jp/ctr/index-j.htm.

Background/aims: Laparoscopic surgery reduces the risk of postoperative adhesion compared with open surgery. The aim of this study was to assess the advantage of laparoscopic surgery in terms of postoperative adhesion., Methodology: Eleven patients participated in this study (laparoscopic surgery: 6 patients, open surgery: 5 patients). Body temperature, heart rate, the duration until the first postoperative flatus and the beginning of diet were investigated on postoperative day 0, 1, 3, and 5, respectively. Serum level of WBC and CRP, PAI-1 and IFN-gamma level in the drainage tube were also measured at the same time., Results: There is no significant difference between the two groups in body temperature. The laparoscopic group revealed significantly lower WBC on POD 0 and CRP on POD 1 compared with the open group. PAI-1 was significantly lower on POD 3 and 5 in the laparoscopic group. IFN-gamma in the laparoscopic group tended to be suppressed compared with the open group., Conclusions: Laparoscopic surgery may decrease the risk of postoperative abdominal adhesion compared with open surgery by suppressing early postoperative inflammation.

Introduction: The feasibility of laparoscopic surgery for clinically staged T3 and T4 rectal cancer has not been clearly defined specifically in cases following preoperative chemoradiation therapy (CRT). Our aim was to investigate the feasibility of laparoscopic surgery after preoperative CRT for clinically staged T3 and T4 rectal cancer., Methods: Between May 2003 and June 2009, 57 patients (T3: n = 50, T4: n = 7) who underwent preoperative CRT for rectal cancer were identified. Forty-three patients with laparoscopic surgery (Lap group) were compared with 14 patients who underwent open surgery (Open group). Perioperative data including postoperative morbidity were assessed between the two groups., Results: All patients underwent complete laparoscopic operations, and none was converted to laparotomy. Operating time was longer in the Open group (331 vs 375 min, P < 0.01). Blood loss was lower in the Lap group (160 vs 316 mL, P < 0.01). Lymph node harvest and morbidity rate were similar in both groups. The distal tumor margin was negative in all patients. No patients had perioperative mortality associated with surgery after CRT., Conclusion: Laparoscopic surgery after preoperative CRT is a feasible and a safe option for T3 and T4 rectal cancer compared to conventional open surgery., (© 2012 Japan Society for Endoscopic Surgery, Asia Endosurgery Task Force and Blackwell Publishing Asia Pty Ltd.)

Purposes: The inflammatory response after surgery is associated with various postoperative complications. The aim of the present prospective study was to evaluate the effects of Daikenchuto (DKT) (a Japanese herbal medicine) on the inflammatory response in patients following laparoscopic colorectal resection., Methods: Thirty patients who underwent laparoscopic colectomy for colorectal carcinoma were divided into two groups: a DKT intake group (D group, n = 15) and a control group (C group, n = 15). The D group took 7.5 g/day of DKT from the day after surgery until the 7th postoperative day. The body temperature, heart rate, WBC count, lymphocyte count, C-reactive protein (CRP) level, β-D: -glucan level and Candida index were compared between the two groups., Results: The patients' mean age in the D group was significantly younger than that in the C group. D3 lymph node dissection was performed more often in the D group. The time until first flatus was significantly shorter in the D group (1.8 ± 0.5 days) than in the C group (2.7 ± 0.5 days). The CRP level was significantly lower in the D group (4.6 ± 0.6 mg/dl) than in the C group (8.3 ± 1.1 mg/dl) on the 3rd postoperative day., Conclusions: Postoperative DKT administration significantly suppressed the CRP level and shortened the time until first flatus. DKT administration also significantly suppressed postoperative inflammation following surgery for colorectal cancer.

Introduction: After adopting preoperative assessment of the perigastric vessels using 3D-CT and standardization of the procedures, obesity still influences smooth laparoscopy assisted gastrectomy (LAG). We evaluated the impact of body mass index (BMI) and area of visceral fat tissue on the risks of LAG., Methods: Sixty-six patients who underwent LAG for gastric cancer were included. The patients were divided into two groups by BMI (<25 BMI-L group: n = 53; ≥25 BMI-H group: n = 13) and area of intraperitoneal fat tissue (<100 cm(2) AF-L group: n = 35; ≥100 cm(2) AF-H group: n = 31), respectively. Fat scan(®), which was computer software operating on abdominal CT, was used to measure the visceral fat areas (VFA). The incidence of postoperative complications, operation time, intraoperative blood loss, and number of dissected lymph nodes were compared between each two groups., Results: The incidence of postoperative complications of BMI-L and BMI-H groups was 11.3% and 30%, respectively (p = 0.18). The mean blood loss was 85 and 134 g, respectively (p = 0.21). There were no significant differences in operation time and the number of retrieved LNs. The incidence postoperative complications (29%) and mean blood loss (148 g) of then VFA-H group were significantly higher than those of the VFA-L group (5.7%, 48 g). The number of retrieved LNs of the VFA-H group (n = 25) was significantly lower than that of the VFA-L group (n = 34). There was no significant difference in operation time., Conclusions: In the VFA-H group, the incidence of postoperative complications and intraoperative blood loss increased, and the dissected number of LNs decreased. The area of visceral fat tissue was useful to predict risks of LAG and postoperative complications with higher precision compared with BMI.

Background/aims: Barrett's esophagus is a major risk factor for esophageal adenocarcinoma. It is important to decide when and how to treat the patients with Barrett's esophagus (BE). It was reported that HDAC-1 (Histone Deacetylase-1) and MTA-1 (Metastasis-Associated Protein-1) were associated with initiation and progression of cancer. The aim of this study is to assess malignant potential of BE using the expression of HDAC-1 and MTA-1., Methodology: Seven BE cases with pathological specialized columnar epithelium and CK7/20 in an immunohistochemically positive state were selected from resected specimens of 23 patients with gastro-esophageal junction cancer. The expression of HDAC-1 and MTA-1 protein was evaluated using an immunohistochemical method., Results: All seven cases with Barrett's esophagus were diagnosed as low grade dysplasia. Positive expression of HDAC-1 and MTA-1 was found in 0 out of 7 cases (0%) with normal esophageal epithelium, and 0 out of 7 cases (0%) with normal gastric epithelium. On the other hand, positive expression of both HDAC-1 and MTA-1 was found in 6 out of 7 (85.7%) cases with Barrett's epithelium and 7 out of 7 (100%) cases with gastro-esophageal-junction-cancer, respectively., Conclusion: Positive expression of HDAC-1 and MTA-1 was found even in low grade dysplasia. Therefore, BE with HDAC-1 and MTA-1 expression is considered to be a precancerous lesion re quiring curative treatment.

Case 1: An 86-year-old woman had an invasive breast cancer with dermal infiltration. Bone metastases were found in the femur and lumbar vertebrae. She was treated with 2 courses of 70 mg docetaxel (DOC) chemotherapy every 3 weeks, after which the tumor dramatically decreased in size. Following this treatment, she underwent a radical mastectomy. Case 2: An 80-year-old woman had a 10 cm tumor in the right breast. Lung and bone metastases were also found. Two 80 mg courses of DOC reduced the lung and bone metastases, and the size of the breast tumor. She underwent a local excision. Hormonal therapy is a standard treatment for hormone-sensitive breast cancer in elderly patients. It is suitable for patients who have a declining quality of life (QOL), although chemotherapy shows a higher response rate and takes less time than hormonal therapy. However, it is difficult to continue chemotherapy until pCR is achieved, even for chemotherapy-effective patients because the side effects of chemotherapy are severe. Therefore, local excision after chemotherapy is necessary for breast cancer patients to improve their QOL, even if there are distant metastatic lesions.

A survey of nutrient and food oral intake was undertaken to clarify problems in nourishment support of chemotherapy outpatients with cancer diseases. The ingestion frequency survey (Food Frequency Questionnaire Based on Food Groups: FFQg) of nutrient and food intake was carried out in 54 patients, after chemotherapy at an outpatient clinic in Hyogo Prefectural Nishinomiya Hospital during three weeks from June 25,2007 to July 13,2007. Among them, 50 patients (92.6%) reported a valid response (14 breast, 13 colon, 6 stomach, 9 pancreas, and 8 other cancers). Body mass index (BMI; kg/m2, mean +/-SD) grouped by the type of the cancer was 22.3+/-3.1 in breast, 21.3+/-2.6 in colon, 17.9+/-2.0 stomach, 18.0+/-1.2 in pancreas and 22.6+/-1.8 in other cancers. BMIs in stomach or pancreas cancer patients were significantly low compared to those in patients with breast, colon, or other cancers. Each group's caloric intake per standard weight (kcal: mean+/-SD) was 31.4+/-5.3 in breast, 27.7+/-5.6 in colon, 34.2+/-10.3 in stomach, 29.1+/-5.0 in pancreas, and 26.8+/-6.4 in other cancers. No significant differences were recognized among them. In conclusion, oral intake in chemotherapy outpatients was secured from the result for each type of cancer; however, BMI was low in outpatients with stomach or pancreas cancer in spite of ingestion of food enough to maintain standard weight.

A new set of plasmids for plant transgenic studies was developed. Its strong point is that independent gene cassettes are connected within one binary vector by the restriction endonuclease-based technique only. Using the set, two overexpressing cassettes and three RNA interference (RNAi) cassettes were successfully introduced into rice. Our plasmid set is useful for producing commercial transgenic plants, especially in the case of rice.

Proanthocyanidins (PAs) or condensed tannins are a major group of phenolic compounds in the leaves of birch trees and many other woody and herbaceous plants. These compounds constitute a significant allocation of carbon in leaves and are involved in plant responses to environmental stress factors, such as pathogens or herbivores. In some plants, PA concentrations are affected by atmospheric carbon dioxide (CO(2)) and ozone (O(3)) levels that may influence, for example, species fitness, community structure, or ecosystem nutrient cycling. Therefore, a study on the quantitative response of PAs to elevated concentrations of carbon dioxide (CO(2)) and ozone (O(3)) was undertaken in seedlings of Betula platyphylla, Betula ermanii, and Fagus crenata. Seedlings were exposed to ambient or elevated O(3) and CO(2) levels during two growing seasons in the Kanto district in Japan. Ten open-top chambers were used for five different treatments with two replicates: filtered air (FA), ambient air (ambient O(3), 43 ppb; ambient CO(2), 377 ppm), elevated O(3) (1.5 x ambient O(3), 66 ppb), elevated CO(2) (1.5 x ambient CO(2), 544 ppm), and elevated O(3) and CO(2) combined. In addition, seedlings growing in natural conditions outside of chambers were studied. Leaf samples were analyzed for total PA concentrations by butanol-HCl assay and for polymeric PA concentrations by normal-phase high-performance liquid chromatography. Total PA concentrations in leaves of all species were similarly affected by different treatments. They were significantly higher in seedlings treated with elevated CO(2) and O(3) combined, and in seedlings growing outside chambers compared with the FA controls. F. crenata contained only traces of polymeric PAs, but significant species x treatment interaction was observed in the polymeric PA concentrations in B. ermanii and B. platyphylla. In B. platyphylla, leaves treated with elevated CO(2) + O(3) differed significantly from all other treatments. It was suggested that the strongest effect of elevated CO(2) and O(3) combined on leaf PA contents resulted from the additive effect of these environmental factors on phenolic biosynthesis.

Background: Magnetic resonance imaging (MRI) of a patient with atherosclerotic internal carotid artery (ICA) occlusion demonstrated medullary streaks in the deep white matter, which were previously observed only in moyamoya disease and may indicate decreased cerebral blood flow. Cerebral perfusion and metabolism were evaluated using positron emission tomography (PET)., Case Description: A 46-year-old man presented with right hemiparesis and motor aphasia. Cerebral angiography showed left cervical ICA occlusion. MRI showed medullary streaks in the deep white matter of the left middle cerebral artery (MCA) territory. PET imaging of this region revealed decreased cerebral blood flow and increased oxygen extraction fraction and cerebral blood volume. MRI after superficial temporal artery-MCA anastomosis revealed decreased intensity of the medullary streaks., Conclusions: Medullary streaks in patients with atherosclerotic ICA occlusion may indicate reduced perfusion pressure and increased risk of recurrent stroke.

Objective and Importance: Cerebral hyperperfusion syndrome is a rare but potentially devastating complication that typically occurs within several days after carotid endarterectomy., Clinical Presentation: A 66-year-old man experienced asymptomatic cerebral hyperperfusion as demonstrated by single-photon emission computed tomography (SPECT) during a 2-week period after undergoing right carotid endarterectomy. This phenomenon occurred despite intensive pharmacological control of blood pressure. On the 28th postoperative day, repeat SPECT demonstrated resolution of hyperperfusion, and intensive blood pressure control was discontinued., Intervention: Twelve hours later, the patient experienced left motor seizures with secondary generation. SPECT performed 36 hours after the onset of seizures demonstrated the reappearance of hyperperfusion. Intensive blood pressure control was reinstituted and maintained until the 36th postoperative day. On the next day, SPECT demonstrated resolution of hyperperfusion., Conclusion: The present case suggests that cerebral hyperperfusion syndrome may occur at later time points (e.g., 1 mo) after carotid endarterectomy. This delayed hyperperfusion syndrome may be related to prolonged impairment of cerebrovascular autoregulation.

Object: The purpose of this study was to determine whether the preoperative measurement of acetazolamide-induced changes in cerebral blood flow (CBF), which is performed using single-photon emission computerized tomography (SPECT) scanning, can be used to identify patients at risk for hyperperfusion following carotid endarterectomy (CEA). In addition, the authors investigated whether monitoring of CBF with SPECT scanning after CEA can be used to identify patients at risk for hyperperfusion syndrome., Methods: Cerebral blood flow and cerebrovascular reactivity (CVR) to acetazolamide were measured before CEA in 51 patients with ipsilateral internal carotid artery stenosis (> or = 70% stenosis). Cerebral blood flow was also measured immediately after CEA and on the 3rd postoperative day. Hyperperfusion (an increase in CBF of > or = 100% compared with preoperative values) was observed immediately after CEA in eight of 12 patients with reduced preoperative CVR. Reduced preoperative CVR was the only significant independent predictor of post-CEA hyperperfusion. Forty-three patients in whom hyperperfusion was not detected immediately after CEA did not exhibit hyperperfusion on the 3rd postoperative day and did not experience hyperperfusion syndrome. In two of eight patients in whom hyperperfusion occurred immediately after CEA, CBF progressively increased and hyperperfusion syndrome developed, but intracerebral hemorrhage did not occur. In the remaining six of eight patients in whom hyperperfusion was detected immediately after CEA, the CBF progressively decreased and the hyperperfusion resolved by the 3rd postoperative day., Conclusions: Preoperative measurement of acetazolamide-induced changes in CBF, which is performed using SPECT scanning, can be used to identify patients at risk for hyperperfusion after CEA. In addition, post-CEA monitoring of CBF performed using SPECT scanning results in the timely and reliable identification of patients at risk for hyperperfusion syndrome.

To elucidate one way of the shock mechanisms, the hemodynamic alterations were examined in 7 dogs with heartworm (HW) extract-induced shock. The first alteration observed after injection of HW extract was a decrease in right ventricular end-diastolic pressure (RVEDP). After that, left ventricular (LV) end-diastolic pressure, LV systolic pressure, and LV dp/dt fell significantly, followed by a decrease in the cardiac output of all dogs to below the detectable level (1.00 l/min). Since RVEDP depends on blood flow into the right ventricle, the decrease in RVEDP means a reduction in venous return. Therefore, this study showed that the first trigger of a decrease in blood pressure in HW extract-induced shock is the reduction in venous return.

The protective effect of pre- and postischemia treatment of the brain by surface perfusion with nicardipine (Nic) and/or magnesium (Mg) was evaluated in a rat focal cerebral ischemia model. Artificial cerebrospinal fluid was perfused into the subarachnoid space of rats, containing Nic or Nic/Mg prior to vessel occlusion and Nic/Mg after occlusion. Reductions in the total amount of glutamate in the microdialysis perfusate and the volume of infarction tissue stained with 2,3,5-triphenyltetrazolium chloride were significant in all treated groups, even in rats treated after ischemia. An additive effect of Mg was also observed. These results suggest that this method may have clinical applications in patients suffering from ischemic insult., (Copyright 2001 S. Karger AG, Basel.)

In order to determine the inflammatory mechanisms of skin lesions in patients with drug hypersentivity, we examined eosinophil activation and interleukin-5 (IL-5) production in infiltrating lymphocytes. First, we showed that the number of peripheral eosinophils and the level of serum IL-5 at the eruption-active stage were both significantly higher than those in healed skin eruptions. Histological and immunohistological examination revealed that CD4+ T cells and eosinophils significantly more densely infiltrated drug eruptions than control skin lesions. The infiltrating eosinophils were also shown to be activated by immunostaining using anti-secreted formed eosinophilic cationic protein monoclonal antibody. The expression of mRNA for IL-5 in the infiltrating mononuclear cells at drug eruptions was shown by in situ hybridization. These results suggest that infiltrating CD4+ T cells might regulate both peripheral and tissue eosinophils and facilitate allergic inflammation at drug eruptions by means of IL-5 production.

It has been shown that CD4+ lymphocytes and eosinophils pathologically infiltrate the dermis in skin eruptions due to hypersensitivity to the administration of certain drugs associated with peripheral eosinophilia. However, the mechanisms involved in drug related skin eruptions with eosinophilia are largely unknown. There are several methods of diagnosing drug hypersensitivity, but no single in vitro method is available for the detection of the sensitizing drug. In order to elicit the mechanism of drug related skin eruption with eosinophilia and to establish effective methods for diagnosing drug hypersensitivity, we studied in vitro IL-5 production by peripheral mononuclear cells (PBMC) from patients with drug related skin eruptions (n = 8). Significant increase in IL-5 from exposure to drug alone (n = 3) and drug with PHA (n = 3) were noted, whereas PBMC from normal subjects (n = 7) exhibited no such stimulation. Six of the eight cases showed a significant decrease in the number of peripheral blood eosinophils when the skin eruptions healed compared with those at the onset. Histopathological features revealed mild to moderate infiltration of eosinophils. Immunohistopathologically, infiltration of CD4+ and CD8+ lymphocytes and CD4+ cells were predominant within the dermis of drug related skin eruption sites in all cases. This study suggested that the IL-5 production of sensitized mononuclear cells might be a critical mediator in drug hypersensitivity with eosinophilia and an important diagnostic marker.

A 48-year-old male presented with a rare subclavian artery aneurysm associated with absence of the ipsilateral internal carotid artery. The aneurysm was resected and replaced with a Gore Tex artificial graft. Computed tomography, angiography and cerebral blood flow findings suggest that defect of the right internal carotid artery occurred in the developmental stage. There was no past history of trauma, nor histological evidence of inflammatory or sclerotic changes in the aneurysmal wall. The two vascular lesions may have been influenced by a synchronous causative factor in his developmental stage.

A masking level difference (MLD) paradigm was used to investigate the presence of an electrophysiologic correlate of the psychoacoustic MLD in the middle and late auditory evoked potentials. In experiment 1, middle latency potentials were recorded in six normal-hearing young adults using vertex and temporal electrode montages. Tone bursts of 500 Hz presented in SoNo and Spi No conditions produced no threshold differences that were consistent with an MLD. In experiment 2, late latency potential (P2) thresholds to 500-Hz tone bursts under various phase conditions in noise were measured and compared to behavioral thresholds from the same stimuli. Ten subjects provided behavioral and P2 thresholds to SoNo, S pi No, So N pi S pi N pi, SmNo, and SmNm conditions. The rank order of behavioral and P2 thresholds and MLDs was consistent with previous literature on the behavioral MLD. Cortical contributions were confirmed as necessary for the production of the electrophysiologic MLD and, by analogy, the psychoacoustic MLD.

This study investigated the possibility of a correlate of the masking level difference (MLD) in the auditory brainstem response (ABR), given that behavioral data indicate the brainstem origination of the MLD. Previous studies have reported MLD characteristics in the late auditory evoked potentials. In the present study, stimuli were presented in S(o)N(o) and S pi N(o) to female adults with normal hearing. In experiment 1, a binaural phasic difference potential (BPD) was derived by subtracting the suprathreshold ABRs to S(o)N(o) from S pi N(o) for tone pips of 500 to 4000 Hz. The magnitude of the BPD was inversely related to frequency. In experiment 2, thresholds to 500-Hz tone pips in S(o)N(o) and S pi N(o) were equal. In a case study of a subject with no behavioral MLD, the 500-Hz BPD was abnormal on one side, suggesting unilateral interruption of phase synchrony in the brain stem. Thus, the results of this study, in conjunction with previous studies on late potential correlates of the MLD, suggest that the ability to maintain phase information through the brain stem is necessary but not sufficient to generate the MLD.

High-frequency hearing losses can substantially confound the interpretation of click-evoked auditory brainstem responses (ABRs). One method proposed to circumvent the problem is to use frequency-specific tone pips to stimulate equivalent areas on the basilar membrane in normal and pathologic groups, or in both ears of asymmetrically impaired patients. This retrospective study investigated the ABRs to clicks and 1000-Hz tone pips from 90 asymmetrically impaired subjects with cochlear pathology. The 4000 Hz threshold significantly affected the wave V latencies from both clicks and tone pips for the most severely impaired subjects. The wave V latencies were highly correlated between ears for both stimuli, but the correlation was higher with the 1000-Hz tone pips. It was concluded that the use of 1000-Hz tone pips can supplement the interpretation of click-evoked ABRs, particularly in patients whose 2000- and/or 4000-Hz thresholds are worse than 75 dB HL.

The masking level difference (MLD) is a psychoacoustic phenomenon derived from the subtraction of S pi No thresholds (signals pi radians out of phase and noise in phase at the two ears) from SoNo thresholds (signals and noise in phase at the two ears). The purpose of this study was to determine if the MLD derived from the late components (P1, N1, P2, N2) of the auditory evoked potentials was a physiological correlate of the behavioral MLD. Subjects were 15 young adults with normal hearing. Comparisons were made between behavioral and late potential thresholds to 500 Hz stimuli in So and S pi conditions in quiet, and to 500 Hz stimuli in SoNo and S pi No conditions in narrow band (50 Hz) and wide band (600 Hz) noise. No significant differences were seen for behavioral or late-potential thresholds to So and S pi conditions. The S pi No thresholds was significantly lower than the SoNo threshold, yielding an MLD for both the behavioral and physiological responses. The magnitudes of both the behavioral and late-potential MLD were larger with the narrow band noise than with the wide band noise. Evidence, therefore, is provided that the late-potential MLD reflects similar processes as are responsible for the behavioral MLD.

The purpose of this study was to determine whether the masking-level difference (MLD) obtained with the late (P2) auditory evoked potentials has characteristics similar to those reported for the behavioral MLD with respect to the effects of noise level. Psychoacoustic studies have shown that the magnitude of the MLD increases as a function of the noise level. In the present study, P2 thresholds were measured in SoNo (signals and noise in phase at the ears) and S pi No (signals out of phase and noise in phase at the ears) conditions for noise levels of 0-60 dB pressure spectrum level (Lps). Subjects were 5 normal-hearing young adults. The difference in SoNo and S pi No thresholds, or the MLD, increased linearly as the noise levels increased through 60 dB Lps, whereas the behavioral MLD magnitude is reported to saturate at high noise levels. These results suggest that the late-potential MLD reflects characteristics similar to, but not identical with, those of the behavioral MLD.